animal invaders – Center for Invasive Species Prevention

A New Year …Will there be a new priority on countering invasive species?

Alaska yellow cedar (*Chamaecyparis nootkatensis*); one of the species vulnerable to *Phytophthora austrocedri*; APHIS has determined it is too late to try to slow its spread. Photo by Nucatum amygdalarum via Wikimedia

On 30 December 2025, US Department of Agriculture Secretary Brooke L. Rollins issued a Secretary’s Memorandum setting five new priorities for research and development. One is to protect agriculture from invasive species. Another is to resolve longstanding trade barriers due to sanitary and phytosanitary concerns.

The Secretary’s intention is to strengthen US agriculture to benefit both farmers and consumers. He justifies the action by claiming that President Lincoln’s original purpose in establishing USDA was to acquire and diffuse useful information on subjects connected with agriculture. According to this interpretation, Lincoln recognized that working to improve agriculture and secure the nation’s food supply would benefit everyone. The emphasis on research and development was reiterated by the almost simultaneous adoption of the Morrill Act of 1862, which created the system of land-grant universities and development of the Cooperative Extension System via the Smith-Lever Act of 1914.

The memorandum specifies five priority areas of research to be pursued by all USDA agencies and offices – to the maximum extent permitted by law and in accordance with any applicable regulations and procedural requirements.

Increasing Profitability of Farmers & Ranchers — especially reducing volatility in profitability. Goals include reducing inputs or increasing mechanization and automation.
Expanding Markets for US agricultural products. Two approaches are mentioned: generating science and data to resolve longstanding sanitary and phytosanitary trade barriers; and expanding use of agricultural commodities in novel biobased products and bioenergy.
Protecting the Integrity of American agriculture from Invasive Species. The memorandum lists four examples of current invasive pest and pathogen threats: new world screwworm in Mexico; continued westward expansion of spotted lanternfly; persistence of highly pathogenic avian influenza in poultry flocks; and citrus greening. It notes that invasive species threaten both agriculture and natural resources. The research is to focus on new and effective methods for preventing, detecting, controlling,and eradicating these threats.
Promoting Soil Health to Regenerate Long-Term Productivity of Land. The research is to promote soil health practices, increase water-use efficiency, & reduce the need for inputs.
Improving Human Health through Precision Nutrition and Food Quality. Research on “precision nutrition” is said to improve understanding of how healthy dietary patterns impact individuals. Research will also focus on increasing foods’ nutritional content and quality.

*Vaccinium myrtillus* (photo by Anneli Salo via WikiMedia); one of several species in genera shared with North America that are infected by *Phytophthora* spp in the Italian alps

The memorandum also instructs USDA’s Office of the Chief Scientist (that is, the Under Secretary for Research, Education, & Economics) to coordinate these priorities within USDA and among key partners in other federal agencies.

Does This Policy Mean Substantially Stronger USDA Efforts to Counter Bioinvasions?

Can we expect new energy in USDA’s programs aimed at managing non-native forest pests and invasive plants that damage forests, wetlands, grasslands, and other natural systems? The first paragraph of the memorandum states that it is USDA policy to reaffirm a focus on the Department’s original objectives of maximizing and promoting American agriculture; ensuring a safe, nutritious, and secure food supply; enhancing rural prosperity; and protecting our National Forests & Grasslands. That is promising.

The explicit recognition that invasive species pose severe threats to both agriculture and natural resources is also promising. I welcome the inclusion of two plant pests among the examples. Livestock diseases usually receive far more attention in USDA pronouncements.

I note three caveats:

The prominence of enhancing markets for US agricultural exports (# 2). In the past, this longstanding emphasis has led to undercutting phytosanitary agencies’ ability to counter suspected — but incompletely understood — pest risks. I discussed the impracticality of determining a newly detected species’ probable impacts in Chapter 3 of my report, Fading Forests II.
The memorandum makes no reference to implementing stronger sanitary or phytosanitary policies. In my view, the Animal and Plant Health Inspection Service has sufficient knowledge to support adoption of a more assertive regulatory stance with regard to both new introductions and spread within the country? Does the memorandum signal support for such a stance by high-ranking USDA officials?

These officials have often reminded APHIS that it is not a research agency. However, its staff do “methods development” and it funds considerable research through the Plant Pest and Disease Management and Disaster Prevention Programs – Section 7721 of the Plant Protection Act and a matching program for animal diseases.

The US Forest Service does have a research division – although the Trump Administration proposed its virtual elimination in early 2025. The Congressional appropriators have provided funding for USFS R&D – but those bills have not yet been enacted into law. I have complained for years that USFS R&D allocates too few resources (about 1% of the total budget) to research on introduced pests and disease pathogens. Might this new directive help fix this problem?

I hope the emphasis on protecting National Forests & Grasslands does not result in narrowing the types of invasive pests addressed.

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

https://fadingforests.org

Welcome high-level attention to bioinvasions – although key issues remain unresolved

Japanese knotweed (*Reynoutria japonica*) – one of the worst invaders around globe. Photo by Will Parson, Chesapeake Bay Program via Flickr

On 23 October, Science published a five-page, data-packed analysis of bioinvasion impacts on terrestrial ecosystems!!!

Thakur, Gu, van Kleunen, and Zhou (full citation at end of this blog) analyzed 775 studies with the goal of improving understanding of factors contributing to invasions’ impacts – as distinct from “invasibility” (ability to establish). This knowledge is essential to assessing the risk posed by introduced species and setting priorities for management. They analyzed five ecological contexts—diversity of native species and introduced species in the recipient systems, latitude, invader residence time, and invader traits.

They concluded that ecological factors commonly used to explain invasion success do not consistently translate into strong predictors of invasion impacts. Impacts vary in response to the context of the invasion.

[In January 2026, the authors announced changes in details of the article due to some errors in the database and their understanding of it. (Science 8 Jan 2026 Vol. 391 Issue 6781) They conclude that the corrected analysis did not alter the trends described or the overall conclusions.]

limber pine (*Pinus flexilis*) – one of the species killed by *Cronartium ribicoli*; photo by F.T. Campbell

Among the studies available for analysis, reports on plants dominated: 605 focused on plant invasions, 114 on animal invasions, and only 56 on microbial invasions. Among the animals were one study of Adelges tsugae (hemlock woolly adelgid), two studies of Agrilus planipennis (emerald ash borer) and one study each of Lymantria dispar (spongy moth), and Ips pini (North American pine engraver). Studies also addressed earthworms, ants, rats, and feral hogs. Microorganisms included Cronartium ribicoli (white pine blister rust) and several Phytophthora species, including P. agathidicida (kauri dieback), P. alni (affects alders), and P. ramorum (sudden oak death).

Thakur et al. note the skewed taxonomic coverage and say that the low number and narrow taxonomic/ecological variety in the animals and microorganisms probably limit their ability to reach robust conclusions about the impacts of such invasions.

The most consistent negative impact they found is reductions in native plant diversity. While this is not surprising given the studies analyzed, I think it is still important since it counters the widespread sense that plant invasions are somehow less deserving of a robust response.

The authors also detected some broader ecosystem impacts of plant invasions. Plant invasions increased soil organic carbon; soil nitrogen (ammonium and nitrate), and available phosphorus; soil moisture, litter biomass; and emissions of carbon dioxide (CO₂), nitrous oxide (N₂O), and methane (CH₄). The changes in biogeochemical properties might reinforce impacts on native plant communities. The reported increase in greenhouse gas emissions might reflect a bias in the studies so Thakur et al. call for more research to solidify this finding.

High native plant species richness had only a weak overall effect on ecosystem-level impacts. While plant invasions often resulted in higher overall plant species richness, when considering only native community responses, the gain in species numbers did not necessarily indicate conservation benefits. Native plants’ biomass increased after invasion. This might reflect short-term increases in productivity in response to altered resource conditions or structural facilitation, rather than a long-term reversal of competitive exclusion. Finally, the longer the invasive [plant] species had been present, the greater the negative effects on native diversity. However, soil abiotic property impacts weakened over time. In fact, the initial increase in soil organic carbon and total nitrogen disappeared after 6 to 10 years. This development might reflect fertilization of ecosystems by long-established nitrogen-fixing invaders such as non-native legumes.

Traits of non-native plant species related to growth and resource acquisition were overall weak predictors of ecosystem impacts. Thakur et al. consider that this finding reflects the relatively narrow range of specific leaf area exhibited by the plant species studied most commonly.

Consequently, Thakur et al. urge managers to focus on containment and impact mitigation, and to prioritize persistent losses of native plant diversity. When considering abiotic responses that might lessen over time, managers should apply “adaptive monitoring” (which is not defined).

Thakur et al. had greater difficulty determining the impacts of animal and microorganism invasions because of the smaller number of studies. They could not determine the effect of native species richness. The observed decline in soil organic carbon they thought was attributable to the large proportion of studies (9 out of 114) that focused on introduced earthworms. Earthworms reduce organic matter by consuming litter. Mammals were also found to reduce soil organic carbon. Introduced insects had no significant ecosystem effects on soil organic carbon. Non-native animals also increased soil emissions of carbon dioxide and nitrous oxide. The microorganisms included in reviewed studies decreased soil ammonium and increased nitrate, consistent with elevated nitrification. While data on body size of invasive animals were sparse, the authors could determine that larger-bodied species tended to increase soil nitrate while reducing effects on total soil N.

Applying the Results

Thakur et al. report that residence time outperformed other factors as a predictor of invasion impacts. The authors regret the scarcity of long-term studies, especially in the Global South, that could increase our understanding of whether these impacts persist or shift under sustained invasion pressure.

How can scientists apply this information in risk assessments evaluating not-yet introduced species or in deciding what is the appropriate intensity of immediate response to newly detected incursions. Should they give greater weight to others’ studies that focus on long-established invasions by the species in question? Otherwise, this finding seems to largely duplicate the long-established “invasion curve”.

I hope scientists will note that observational studies generally showed stronger impacts than experimental ones, particularly in the case of plant invasions. Perhaps this is true because observational studies better incorporate environmental heterogeneity and longer time spans.

Agrostis stolonifera – one of the plants invading on Prince Edward Island, an Antarctic region island under South African jurisdiction. Photo by Stefan Iefnaer via Wikimedia

Thakur et al. note that one factor they analyzed, “latitude”, incorporates several ecological and anthropogenic components relevant to invasion impacts. One element is the greater native bioidiversity in warmer, lower-latitude, regions. According to the “biotic resistance” hypothesis, greater diversity might make these systems more resistant to bioinvasion. However, the situation is complicated by the fact that temperate regions have also often experienced longstanding and intensive land-use modifications — which are believed to facilitate invasive species establishment and spread. I regret that the authors make no attempt to separate the effects of factors that are anthropogenic from those arising from immutable conditions, e.g., latitude, topography, weather patterns, etc.

Thakur et al. call for more studies that cover a wider geographic range. In addition, the studies should include more experimental designs and explore the relationship between invaders’ traits and impacts — especially regarding animals and microbes.

SOURCE

Thakur, M.P., Z. Gu, M. van Kleunen, X. Zhou. 2025. Invasion impacts in terrestrial ecosystems: Global patterns and predictors. Science 23 October 2025

Posted by Faith Campbell

https://fadingforests.org

Status of Hawaiian species threatened by bioinvasion

stand of *Miconia* under albizia overstory on Big Island, Hawai`i; photo by F.T. Campbell

As I will describe in another blog, participants in the annual meeting of the National Plant Board link in Honolulu learned the basics about the uniqueness of agriculture and native species on remote Pacific islands. I want to complement this information by reminding you about other Hawaiian and Guamaian species at risk – although did not learn anything new.

As Martin and Andreozzi pointed out, the Pacific islands import nearly all their food and other consumables. Considerable interest in some quarters in Hawai`i to increase agricultural production. However, large swaths of land in the low-elevation area surrounding Pahoa on the Big Island is completely dominated by the albizia (Falcataria Molucca) [see photo above]. J.B. Friday says it is cost-prohibitive to remove these trees in order to restore agriculture in the area. Local people are concerned because in storms the trees fall onto houses and roads, causing considerable damage.

I saw numerous clumps of the notorious invasive plant Miconia calvescens. Dr. Friday told me that conservationists now focus on keeping this plant out of key areas, not trying to eradicate it completely.

area being restored by volunteers; photo by F.T. Campbell

Local people trying to restore disease-damaged forests by planting other native plants and hand-clearing invasive plants. Some of the ohia seedlings infected by Austropuccinia psidii.

ohia seedling with symptoms of ohia rust (*Austropuccinia psdii*); detected by J.B. Friday; photo by F.T. Campbell

Dr. Friday showed me many areas where ʻōhiʻa trees have been killed by rapid ʻōhiʻa death. Since this mortality occurred a decade or more ago, other plants have grown up. Pic In many if not most cases, this jungle includes dense growths of guava Latin the most widespread invasive tree on the islands (Potter). ‘Ōhi‘a trees continue to thrive in Hawai`i Volcanoes National Park – also on the Big Island – because the NPS makes considerable efforts to protect them from wounding by feral pigs. Demonstrates importance of fencing and mammal eradication in efforts to protect this tree species.

healthy ʻōhiʻa tree on cinder cone created by eruption of Kilauea Iki in 1959; photo by F.T. Campbell

I also saw healthy koa (Acacia koa) in the park, especially at sites along the road to the trail climbing Mauna Loa.

Regarding the wiliwili tree, I was told that it remains extremely scarce on Oahu.

wiliwili tree in flower; photo by Forrest Starr

I heard nothing about the status of naio – another shrub native to the Big Island – but on the dry western side of the island.

I rejoice that scientists are making progress in protecting and restoring Hawaii’s endemic bird species. Specifically, they are at the early stages of controlling mosquitoes that transmit fatal diseases. All 17 species of endemic honeycreepers that have persisted through the 250 years since Europeans first landed on the Islands are now listed as endangered or threatened under the federal Endangered Spp Act. The “Birds, not Mosquitoes” project has developed lab-reared male mosquitoes that, when they mate with wild female, the resulting eggs are sterile. (Male mosquitoes don’t bite, so increasing their number does not affect either animals or people.) Over time, the invasive mosquito population will be reduced, giving vulnerable native bird populations the chance to recover. Scientists began releasing these modified mosquitoes in remote forests on Maui and Kaua‘i in November 2023. In spring 2025, they began testing releases using drones. Use of drones instead of helicopters reduces the danger associated with flying close to complicated mountain rides in regions with variable weather. This project should be able to continue; the Senate Appropriations Committee report for FY26 allocates $5,250,000 for this project.

American Bird Conservancy is sponsoring a webinar about this program. It will be Wednesday, August 27, 2025 4:00 PM – 5:00 PM ET. Sign up for the webinar here

thicket of guava on the Big Island, Hawai`i; photo by F.T. Campbell

Finally, scientists are releasing a biocontrol agent targetting strawberry guava, Psidium cattleyanum, the most widespread invasive tree on the Islands (Potter et al. 2023). Distribution involves an interesting process. A stand of guava is cut down to stimulate rapid growth. The leaf-galling insect Tectococcus ovatus reproduces prolifically on the new foliage. Twigs bearing the eggs of these insects are collected and tied into small bundles. The bundles are then dropped from helicopters into the canopies of dense guava stands, where they establish and feed – damaging the unwanted host.

Guam

Guam’s endemic birds have famously been extinguished by the non-native brown tree snake. Dr. Aaron Collins, State Director, Guam and Western Pacific, USDA APHIS Wildlife Services, informed participants at the National Plant Board meeting about the extensive efforts to suppress snake populations in military housing on the island, reduce damage to the electric grid, and prevent snakes from hitchhiking to other environments, especially Hawai`i and the U.S. mainland.

The program began more than 30 years ago, in 1993. The program now employs 80 FTEs and has a budget of $4 million per year. It was initiated because live and dead snakes had been found in shipments and planes that landed in Hawai`i and the U.S. mainland. Avoiding the snake’s establishment on Hawai`i is estimated to save $500 million per year. The program is a coordinated effort by USDA, U.S. Fish and Wildlife Service, and the Department of Defense. Probably this estimate helped advocates reverse a decision by the “Department of Government Efficiency” to defund the program.

The program enjoys some advantages over vertebrate eradication programs on the mainland. For example, since Guam has no native snakes, it can use poison, e.g., in mouse-baited traps that can be dropped from planes. A recent innovation is auto-resetting traps baited with mammals; they can electrocute numerous snakes per night.

SOURCE

Potter, K.M., C. Giardina, R.F. Hughes, S. Cordell, O. Kuegler, A. Koch, E. Yuen. 2023. How invaded are Hawaiian forests? Non‑native understory tree dominance signals potential canopy replacement. Lands. Ecol. https://doi.org/10.1007/s10980-023-01662-6

Posted by Faith Campbell

https://fadingforests.org

Invasive species cost more than extreme weather attributable to climate change; 17 times more than previously estimated!

ash tree killed by emerald ash borer; photo courtesy of (then) Mayor of Ann Arbor John Hieftje

Since the 1990s, scientists have been trying to the determine costs imposed by invasive species. They hope that measuring monetary costs will motivate political decision-makers to take more assertive actions to counter this ecological treat. As Daigne et al. (2021) point out, too few countries are implementing effective control and mitigation strategies. They say this inaction stems, largely, from undervaluing bioinvasions’ impacts by the general public, stakeholders and decision-makers.

A major step in this effort was creation of the InvaCost database. The goal was to provide a reliable, comprehensive, standardized and easily updatable synthesis of bioinvasions’ monetary costs worldwide.

Several publications based on this database appeared. I have blogged about studies published in 2021 or 2022: a) the costs of bioinvasions generally (Cuthbert et al. 2022); b) the costs imposed by invasive species in protected areas (Moodley et al. 2022; c) a focus on the “worst” 100 invasives (as determined by the IUCN) (Ahmed et al. 2022); and d) assessing costs associated with various pathways of introduction (Turbelin et al. 2022).

The InvaCost database, as applied in these studies, demonstrated that bioinvasions impose tremendous costs –a minimum of US $1.288 trillion for the period 1970 – 2017. These costs increased on average three times per decade (Daigne et al. 2022).

Still, everyone has recognized that InvaCost data have significant limitations. First, three-quarters of the records in the original database came from North America, Oceania and Europe; and referred to animal taxa, even though plants are a major group of invaders. Also, a large proportion of total invasion costs – for all taxa – probably is undetected. Finally, the many non-market values of species and ecosystems are extremely difficult to calculate (Daigne et al. 2022).

As a result of these deficiencies, the earlier studies discussed in the blogs referenced above substantially underestimated the true costs associated with bioinvasion (Cuthbert et al. 2022).

Now a new study, led by Ismael Soto, finds that the underestimate is huge. Global costs associated with a subset of 162 species (17% of all the species in the InvaCost database) is nearly 17 times higher than reported in the InvaCost database.

Soto et al. (2025) applied species distribution models and macroeconomic data to interpolate these 162 species’ probable impacts in 172 countries

Japanese knotweed – one of the invasive plants proving very costly in Europe, according to I. Soto

The newly identified costs were greatest in Europe; second place fell to North America. This is because both higher damage costs and management expenditures are linked to higher gross domestic product and extent of agricultural area, in addition to environmental suitability. Analysis of monetary costs per unit area revealed that ‘cost hot spots’ are predominantly located in densely populated urban areas and locations hosting key industries. These tend to be in coastal zones, i.e., Europe, the east coast of China, and the east and west coasts of the US.

cypress aphid *Cinara cupressi* – a threat to both native & plantation trees in Africa; photo by Blackman & Eastop via Wikimedia

The authors found that the greatest increase in estimated costs for countries in Africa and Asia. These countries had not previously recorded any economic costs arising from invasions by these 162 species. I have blogged about forest pest threats in Africa.

The authors also significantly increased estimated costs linked to invasive plants. Daigne et al. found that invasive insects caused ~90% of reported costs in the InvaCost database as of 2022. Vertebrates ranked second, plants third. In contrast, Soto et al. determined that invasive plants had the highest average estimated damage costs (US $42.10 billion) and management expenditures ($0.81 billion).

Substantial total costs were also reported for arthropods, mammals and birds. Reported damage and management costs were much lower for molluscs, fish, reptiles and amphibians. Daigne et al. suggest this might be due to their lower (observable) damage to human infrastructure, research biases leading to fewer studies, or disparities resulting from the filtering process used in their own study.

Williams et al. (2023) focus on insects, which cause damage primarily to agriculture, human health, and forestry. Insects constitute the highest number of species introduced as ‘Contaminants’ (n = 74) and ‘Stowaways’ (n = 43). They also impose the highest costs among species using these two pathways.

Forest insects and pathogens account for less than 1% of the records in the InvaCost database. I believe that this figure reflects significant under-reporting of these invasion events. Even at this paltry level of reported invasions, forest insects and pathogens were responsible for causing 25% of total annual costs ($43.4 billion) (Williams et al. 2023). This discrepancy illustrates the huge economic cost associated with widespread mortality of trees. Yet authorities in most countries continue to provide completely inadequate resources to counter this threat.

The authors of these publications examining economic losses associated with bioinvasion all note that ecological damage is additional. Soto et al. note that bioinvasions contribute to 60% of already recorded global extinctions. Interestingly, the species ranked third using the criterion of monetary damage is the cactus moth Cactoblastis cactorum. This insect threatens flat-padded Opuntia cacti across the United States and in the center of endemism, Mexico.

a flat-padded *Opuntia* — vulnerable to the cactus moth; photo by F.T. Campbell

Soto et al. found a lag of ~46 years between first (reported) detection of an introduced species and the peak of damage costs. They suggest that the rising monetary cost reflects the species becoming more abundant or occupying a larger area. The authors also say this finding demonstrates the value of implementing mitigation measures as soon as possible. Their finding thus validates others’ advocacy for investing in prevention and rapid response measures (see Cuthbert et al. and Daigne et al.). Soto et al. were cheered by the fact that spending on management measures – when it was reported – often followed soon after a species’ detection – or even before (e.g., prevention).

But Decision-Makers Usually Delay – Why?

Prevention is a hard sell. Decision-makers find it difficult to justify management expenditures before impacts become obvious. By that time, of course, management of the invasion is extremely difficult and expensive – if it is possible at all. Ahmed et al. found particularly effective wording to describe this problem: bioinvasion costs can be deceitfully slow to accrue, so policy makers don’t appreciate the urgency of taking action. Another contributing factor is that when efficient proactive management succeeds in preventing any impact, it paradoxically undermines evidence of the value of this action!

Programs to minimize the economic and ecological consequences of bioinvasion are severely obstructed – if not doomed! – by the following difficulties:

Resources are in short supply. Experts find that demands to address other threats to agriculture or natural systems outcompete appeals to ramp up invasive species efforts.
Prediction is uncertain. Cuthbert et al. found that none of the species with the highest pre-invasion investment was among the top 10 costliest invaders in terms of damages. Cuthbert et al. do not discuss whether this is evidence that the prevention efforts were effective? Or, alternatively, that prevention efforts target the wrong species.
Harm is in the eye of the beholder. Stakeholders’ perceptions of whether an introduced species causes a detrimental impact vary. For example, Moodley et al. point out that species imposing the highest economic costs might not be the ones causing the greatest ecological harm.
Externalities. Those harmed by a bioinvasion often are different from those that decide whether to act. Ahmed et al. argue that this creates a moral dilemma.

These decisions are political — influenced by citizens’ expressed wishes. Changing decision-makers’ perceptions of what is important is up to us!!! Start a parade!!!

SOURCES

Ahmed, D.A., E.J. Hudgins, R.N. Cuthbert, .M. Kourantidou, C. Diagne, P.J. Haubrock, B. Leung, C. Liu, B. Leroy, S. Petrovskii, A. Beidas, F. Courchamp. 2022. Managing biological invasions: the cost of inaction. Biol Invasions (2022) 24:1927–1946 https://doi.org/10.1007/s10530-022-02755-0

Cuthbert, R.N., C. Diagne, E.J. Hudgins, A. Turbelin, D.A. Ahmed, C. Albert, T.W. Bodey, E. Briski, F. Essl, P. J. Haubrock, R.E. Gozlan, N. Kirichenko, M. Kourantidou, A.M. Kramer, F. Courchamp. 2022. Bioinvasion costs reveal insufficient proactive management worldwide. Science of The Total Environment Volume 819, 1 May 2022, 153404

Diagne, C., B Leroy, A-C. Vaissière, R.E. Gozlan, D. Roiz, I. Jaric, J-M. Salles, C.A. Bradshaw, and F. Courchamp. 2021. High and rising econ costs of bioinvasions worldwide Published online: 31 March 2021

Moodley, D., E. Angulo, R.N. Cuthbert, B. Leung, A. Turbelin, A. Novoa, M. Kourantidou, G. Heringer, P.J. Haubrock, D. Renault, M. Robuchon, J. Fantle-Lepczyk, F. Courchamp, C. Diagne. 2022. Surprisingly high economic costs of bioinvasions in protected areas. Biol Invasions. https://doi.org/10.1007/s10530-022-02732-7

Soto, I., P. Courtois, A. Pili, E. Tordoni, E. Manfrini, E. Angulo, C. Bellard, E. Briski, M. Buric, R.N. Cuthbert, A. Kouba, M. Kourantidou, R.L. Macêdo, B. Leroy, P.J. Haubrock, F. Courchamp and B. Leung. 2025. Using species ranges and macroeconomic data to fill gap in costs of biological invasions. Nat Ecol Evol doi: 10.1038/s41559-025-02697-5

Turbelin, A.J., C. Diagne, E.J. Hudgins, D. Moodley, M. Kourantidou, A. Novoa, P.J. Haubrock, C. Bernery, R.E. Gozlan, R.A. Francis, F. Courchamp. 2022. Introduction pathways of economically costly invasive alien spp. Biol Invasions (2022) 24:2061–2079 https://doi.org/10.1007/s10530-022-02796-5

Williams, G.M., M.D. Ginzel, Z. Ma, D.C. Adams, F.T. Campbell, G.M. Lovett, M. Belén Pildain, K.F. Raffa, K.J.K. Gandhi, A. Santini, R.A. Sniezko, M.J. Wingfield, and P. Bonello. 2023. The Global Forest Health Crisis: A Public Good Social Dilemma in Need of International Collective Action. Annual Review of Phytopathology Vol. 61, 2023

Posted by Faith Campbell

www.fadingforests.org

From Dire Wolves & a new “God Squad” to Rocket Launches on a remote atoll: rare wildlife in the crosshairs

whooping crane; photo by Jason Mracina via Flickr

We have already seen threats to the Clean Air Act of 1970, the Clean Water Act of 1972 from the Trump Administration. Now the Endangered Species Act of 1973 (16 U.S.C. 1531-1544) faces severe risks.

The Washington Post has reported that the Trump Administration is saying that scientists’ ability to revive extinct species through biotechnology justifies relaxing legal protections. The Post quoted Interior Secretary Doug Burgum as saying that innovation – not government regulation — will save species. He has already met with Dallas-based Colossal Biosciences about using its animals in federal conservation efforts, as well as for potential species restoration. I note that having a few “engineered” specimens living in a zoo is not the goal of the Act or sensible biodiversity conservation programs.

This is just the Administration’s latest maneuver aimed at reducing the Act’s protections, which have been in place since adoption of the Endangered Species Act in 1973. The Fish and Wildlife Service — an agency in the Interior Department — has sought White House comments on a proposed redefinition of “harm” under the act. The term is not defined in the text of the Act, so a rule change could allow for significant reductions in protections, especially regarding listed species’ habitats.

Already, President Trump and his administration have overridden endangered species protections. First, he demanded that the Bureau of Reclamation open water transfer systems to drain water from a Northern California river system to southern California. Ostensibly the action was to protect the area from the devastating wildfires, although scientists declared that a lack of water for firefighters was not the reason the fires caused so much damage. The water had been stored, in part, to protect the habitat of the delta smelt.

President Trump also has revived the long-dormant “God Squad.” a federal committee that can override protections for endangered species. Members include Secretary Burgum and five other high-level officials. It was created by Congressional amendment in the late 1970s, during the fight over whether to build the Tellico Dam on the Tennessee River. It is empowered to approve projects even if they result in the extinction of a species.

In February, Interior Secretary Burgum also rescinded guidance adopted by the Biden Administration aimed at minimizing ship strikes on the Rice’s whale, one of the most endangered marine mammals. He has also ordered staff to consider economic factors when deciding habitat protections.

Other threats came earlier. Elon Musk’s SpaceX launch site is only about 10 miles from Aransas National Wildlife Refuge, which provides winter habitat for one of the “iconic” endangered species, whooping cranes. The Midwestern population of piping plovers is also listed as endangered; it winters along the Gulf coast, including at Aransas. The Refuge is home to 400 bird species, primarily ducks, herons, egrets, ibises, and roseate spoonbills. The few studies of noise impacts on birds focus on nesting – which neither whoopers nor plovers engage in while at Aransas … Still ….

Another refuge — in the middle of the Pacific Ocean – is also under threat from rocket activities. The Post reports that the U.S. Space Force – a branch of the U.S. Air Force – will soon publish an Environmental Assessment regarding plans to build two landing pads on Johnston Atoll. The facilities are intended to expedite movement of military cargo around the globe – by transporting it on large commercial rockets. Johnson Atoll is an unincorporated U.S. territory consisting of four tiny islands about 800 miles southwest of Honolulu. Although tens of thousands of red-tailed tropicbirds, red-footed boobies and sooty terns nest on the atoll, the Space Force said in its notice of intent that it expects the construction and operation of the demonstration project will have no significant environmental impact. This finding has been criticized by several organizations, including the Conservation Council for Hawaii, National Wildlife Refuge Association, and Union of Concerned Scientists. See also this statement by the American Bird Conservancy.

red-footed booby adult & nestling on Johnson Atoll; photo by Jordan Akiyama, USFWS via Flickr

One concern is that construction and operation could re-introduce various invasive species. The Post mentions yellow crazy ants; their acids can cause deformities in birds and, in some cases, deadly infections. The U.S. Fish and Wildlife Service spent a decade eradicating the ants. I note that rats very often are introduced to remote islands by cargo ships and are a significant threat to ground-nesting birds.

red-tailed tropic bird swarmed by yellow crazy ants – on Johnson Atoll; photo by Sheldon Plentovich USFWS via Flickr

Congressional Republicans – who now control both houses of the legislature — are preparing amendments to the Endangered Species Act that would slash protections for at-risk species that are – or might later be – qualified for listing under the Act. One approach is to legislatively remove, or “delist,” those species that have gotten in the way of various activities. The Post names gray wolves and grizzly bears, which ranchers say prey on livestock; plus a lizard in Texas oil country; and the northern long-eared bat, which lives in forests that the timber industry wants to log.

range of northern long-eared map in US & Canada

Citing the fact that only 3% of listed species have recovered, Representative Bruce Westerman of Arkansas, Chairman of the House Committee on Natural Resources, wants to amend the Act to give more power to states. He also plans to limit courts’ power to review agencies’ decisions to remove protections for plants and animals.

Posted by Faith Campbell

www.fadingforests.org

Non-Native Moths in England: Ever Upward

*Platyperigea kadenii* — one of the moth species that feeds on native plant species introduced recently to Great Britain. Photo by Tony Morris via Flickr

Will phytosanitary agencies and the international system respond to continuing introductions of non-native species?

A new study confirms that introductions of insects continue apace, links this pattern to the horticultural trade, and examines the role of climate change in facilitating introductions. This study focuses on moths introduced to the United Kingdom (Hordley et al.; full citation at the end of the blog). The study sought to detect any trends in numbers of species establishing and the relative importance of natural dispersal vs. those assisted – intentionally or inadvertently – by human activities.

The authors determined that moths continue to be introduced by both processes; there is no sign of “saturation”. This finding agrees with that of Seebens and 44 others (2017; citation below), which analyzed establishments of all types of non-native species globally. The British scientists found that rapidly increasing global trade is the probable driver of the recent acceleration of human-assisted introductions. They emphasize the horticultural trade’s role specifically. Climate change might play a role in facilitating establishment of species entering the UK via human activities.

Hordley et al. found that long-term changes in climate, not recent rapid anthropogenic warming, was important in facilitating introductions of even those moth species that arrived without human assistance. As they note, temperatures in Great Britain have been rising since the 17^th Century. These changes in temperature have probably made the British climate more suitable for a large number of Lepidoptera. The data show that the rate of natural establishments began rising in the 1930s, 60 years before anthropogenic changes in temperatures became evident. Hordley et al. point out that an earlier study that posited a more significant role for climate change did not distinguish between insect species which have colonized naturally and those benefitting from human assistance.

The authors expect introductions to continue, spurred by ongoing environmental and economic changes. Fortunately, very few of the introduced moths had any direct or indirect negative impacts. (The box-tree moth (Cydalima perspectalis) is the exception. [Box-tree moth is also killing plants in North America.]

boxtree moth; photo by Tony Morris via Flickr

Still, they consider that introductions pose an ongoing potential risk to native biodiversity and related human interests. Therefore, they advocate enhanced biosecurity. Specifically, they urge improved monitoring of natural colonizations and regulation of the horticultural trade.

Hordley et al. estimated the rate of establishment during the period 1900 – 2019 for (i) all moth species; (ii) immigrants (i.e., those introduced without any human assistance); (iii) immigrants which feed on native hosts; (iv) immigrants which feed on non-native hosts; (v) adventives (i.e., species introduced with human assistance); (vi) adventives which feed on native hosts; and (vii) adventives which feed on NIS hosts.

Their analysis used data on 116 moth species that have become established in Great Britain since 1900. Nearly two-thirds of these species – 63% – feed on plant species native to Great Britain; 34% on plant species that have been imported – intentionally or not. Data were lacking on the hosts of 3 species.

Considering the mode of introduction, the authors found that 67% arrived through natural colonization; 33% via human assistance. Sixty-nine percent of the 78 species that were introduced through natural processes (54 species) feed on plant species native to Great Britain; 31% (24 species) feed on non-native plants. Among the 38 species whose introduction was assisted by human activities, one-half (19 species) feed on native plant species; 42% (16 species) feed on introduced hosts.

Regarding trends, they found that when considering all moth species over the full period, 21.5% more species established in each decade than in the previous decade. This average somewhat obscured the startling acceleration of introductions over time: one species was reported as established in the first decade (1900–1909) compared to 18 species in the final decade (2010–2019).

The rate of introduction for all immigrant (naturally introduced) species was 22% increase per decade. Considering immigrant species that feed on native plants, the rate of establishment was nearly the same – 23% increase per decade – when averaged over the 120-year period. However, a more detailed analysis demonstrated that these introductions proceeded at a steady rate until 1935, then accelerated by 11% per decade thereafter. In contrast, immigrants that feed on non-native plants have maintained a steady rate of increasing establishments – 13% per decade since 1900.

Adventive species (those introduced via human assistance) increased by 26% per decade. The data showed no signs of saturation. The rates of introduction were similar for adventives that feed on both native plants (22%) and non-native hosts (26%). Again, additional analysis demonstrated a break in rates for adventives that feed on native hosts. The rate was steady until the 1970s, then significantly increased during the years up to 2010. (The scientists dropped data from the final decade since lags in detection might artificially suppress that number.)

In summary, Hordley et al. found no significant differences in trends between

the number of species that established naturally (20%) vs. adventives (26%).
immigrant or adventive species that feed on native vs. non-native hosts.

The authors discuss the role of climate change facilitating bioinvasion by spurring natural dispersal, changing propagule pressure in source habitats, changing the suitability of receiving habitat, and changing in pathways for natural spread, e.g., altered wind and ocean currents. They recognize that the two modes of colonization – adventives and immigrants – can interact. They stress, however, that the two colonization modes require different interventions.

Although their findings don’t support the premise that a surge of natural colonizers has been prompted by anthropogenic warming, Hordley et al. assert that climate clearly links to increased moth immigration to Britain and increased probability of establishment. They note that even so assisted, colonists still must overcome both the natural barrier of the English Channel and find habitats that are so configured as to facilitate breeding success. They report that source pools do not appear to be depleted — moth species richness of neighboring European countries greatly exceeds that in Great Britain.

I would have liked to learn what factors they think might explain the acceleration in both natural and human-assisted introductions of species that feed on plant species native to Great Britain. In 2023 I noted that scientists have found that numbers of established non-native insect species are driven primarily by diversity of plants – both native and non-indigenous.

Hordley et al. assert that Great Britain has advantages as a study location because as a large island separated from continental Europe by the sea – a natural barrier – colonization events are relatively easy to detect. However the English Channel is only 32 km across at its narrowest point. I wonder, whether this relatively narrow natural barrier might lead to a misleadingly large proportion of introduced species being natural immigrants. I do agree with the authors that moths are an appropriate focal taxon because they are sensitive to climate and can be introduced by international trade. Furthermore, Britain has a long tradition of citizen scientists recording moth sightings, so trends can be assessed over a long period.

Hordley et al. stress that they measured only the temporal rate of new species’ establishments, not colonization pressure or establishment success rate. They had no access to systematic data regarding species that arrived but failed to establish. Therefore, they could not deduce whether the observed increase in establishment rates are due to:

(1) more species arriving—due either to climate-driven changes in dispersal or to accessibility of source pools; or

(2) higher establishment success due to improved habitat and resource availability; or

(3) both.

Hordley et al. noted two limitations to their study. First, they concede that there is unavoidably some subjectivity in classifying each species as colonizing naturally or with human assistance. They tried to minimize this factor by consulting two experts independently and including in the analysis only those species on which there was consensus.

Second, increases in detection effort and effectiveness might explain the recent increases in establishment rates. They agree that more people have become “citizen scientists” since 1970. Also, sampling techniques and resources for species identification have improved considerably. They note, however, that Seebens et al. (2018) tested these factors in their global assessment and found little effect on trends.

Hordley et al. believe that they have addressed a third possible limitation – the lag between introduction and detection – by running their analyses both with and without data from final decade (2010-2019). The results were very similar qualitatively.

SOURCE

Hordley, L.A., E.B. Dennis, R. Fox, M.S. Parsons, T.M. Davis, N.A.D. Bourn. 2024. Increasing rate of moth species establishment over 120 years shows no deceleration. Insect Conserv. Divers. 2024;1–10. DOI: 10.1111/icad.12783

Seebens, H. et al. 2017. No saturation in the accumulation of alien species worldwide. Nature Communications. January 2017. DOI: 10.1038/ncomms14435

Seebens, H. et al. 2018. Global rise in emerging IAS results from increased accessibility of new source pools. Proceedings of the National Academy of Sciences. www.pnas.org/cgi/doi/10.1073/pnas.1719429115

Posted by Faith Campbell

www.fadingforests.org

Feral pigs – 20 years of APHIS engagement

feral hogs in state wildlife area, Florida; photo by Craig Oneal via Flickr

Most invasive species detection and control programs suffer from inadequate funding. Feral hogs (Sus scrofa) are the exception. True, feral hogs are widely considered among the most damaging of invasive species. They are conspicuous. And they cause damage to agricultural crops – thus energizing a politically powerful constituency. (The extent of that damage is open to question; see my discussion below.) Can we learn from the political success of this program to build support for countering other invasive species?

[Several forest pests are also listed as among the “100 worst” invasive species: Asian longhorned beetle, chestnut blight, gypsy or spongy moths, Dutch elm disease, Phytopthora cinnamomi. Many invasive plant species present in the United States are also listed. These bioinvaders have not elicited the same level of response.]

According to a US Department of Agriculture report (USDA 2018), feral hogs only recently spread throughout the United States. In 1982, they were thought to inhabit only a small percentage of counties in 17 states. As of 2018, they were recognized as present in ~ 43% of all counties in the country; those counties were in 38 states and three US territories. USDA APHIS lists the following impacts from feral hog activities: damage to crops (including tree seedlings), livestock pastures and feed supplies, other kinds of property, and natural resources. In addition, feral pigs might transmit disease to the human food supply and possibly to livestock, and occasionally threaten public safety. In response, APHIS proposed to develop a national response. The goal was to reduce the risks and damages and encourage better coordination among the states and with Canada and Mexico. Since environmental conditions and laws vary among states, APHIS provides resources and expertise while allowing operational flexibility. The early focus was on primarily northern states where eradication was considered viable. By 2019, Idaho, Iowa, Maine, New Jersey, and New York had been declared “pig free”.

The Feral Swine Eradication and Control Pilot Program was officially established as by the 2018 Farm Bill. It was funded at $75 million over the five-year life of the 2018 Farm Bill – or ~$15 million per year. The program is implemented jointly by USDA Natural Resources Conservation Service (NRCS) and APHIS. According to the website, USDA focused these efforts where feral swine pose the highest threat.

APHIS has published a report covering the initial 2014 – 2018 program. I expect they will shortly publish a report covering 2018- 2023. My quick review of the available but outdated report shows that nearly all the pig removal projects funded by the program aimed to protect property, particularly agriculture. Protection of natural resources benefited from far fewer projects. The states funding natural resource projects most generously were Washington (92% of projects!); Illinois (62%); Nevada (48%); Florida (47%); Idaho and Missouri (both at 44%); Wisconsin and New Hampshire (both at 41%); Ohio (35%); Utah (34%); and Arizona (32%). Some of the Western states have considerable land managed by federal agencies; this might explain their relative focus on natural resources. Pennsylvania allocated only 1% of its projects to protecting natural resources. West Virginia and the U.S. Virgin Islands allocated none. I hope this tilt lessens in more recent years – although the program will clearly always be focused on agriculture.

There were no programs in five states: Massachusetts, Montana, Nebraska, South Dakota, and Wyoming.

Note that the summary of the draft Senate Farm Bill says this program would be funded at $75 million per year in future. This would increase funding 15 fold. I think this is probably a mistake in writing the summary; that the total funding would continue to be $75 million over five years.

I also reviewed the annual report issued by the APHIS Wildlife Services program’s National Wildlife Research Center (NWRC). The Center lists 17 publications by NWRC staff and cooperators dealing with various aspects of feral pig management [other than swine fever transmission]. Topics included feral pigs’ social structure; factors that influence reproductive rates; factors that influence efficacy of bait/trap programs; in-field methods to determine animal’s weight; and the extent to which hunters, farmers and the public accept various control techniques.

feral hog damage in a corn field; photo by Craig Hicks, USDA APHIS

Two of the studies – Didero et al. and VerCauteren et al. – aim to answer a fundamental economic question of feral hog management: how to determine the level of damage feral hogs cause to agricultural crops. Interestingly, authors of both studies conclude that existing data do not allow that determination. According to VerCauteren et al., understanding of wild pig damage is limited largely to one kind of damage — rooting – as it affects some natural resources (e.g., wetlands), some crops (e.g., grains, nuts, and beans), and some property (e.g., golf courses and cemeteries). They found few reports documenting damage from other behaviors or effects on pasture, livestock, sensitive species, public recreation spaces, and historical sites. Furthermore, they could not generalize the findings of even those studies that attempt to link the level of damage to pig population density. This is because these studies use many different metrics. They say that designing studies to capture the full scope of damage even in a local area will be complex because of the variety of resources at risk and of mechanisms by which damage might occur (e.g., rooting, consuming plants or animals, wallowing …). VerCauteren et al. suggest specific approaches that should be applied in future studies so that economic estimates will be consistent, shareable, and repeatable. I encourage you to read the articles to learn details of what is known about feral hog damage.

I rejoice that one set of NWRS studies focuses on Missouri. As I have blogged previously, Missouri has operated an aggressive program since the 1990s. I appreciate that APHIS is trying to learn how Missouri officials determined which approaches work best, and built support for the program among farmers, landowners, hunters, etc.

NWRC staff and cooperators also studied some other issues relating to invasive species impacts. One study sought to predict the level of suppression of brown treesnakes that must be achieved to protect birds that might be reintroduced on Guam. A second study sought to find out whether invasive coqui frogs can survive in the colder climates of high elevations in Hawai`i. There is concern that the frogs might compete with native birds for food.

SOURCES

Didero, N.M., K.H. Ernst, S.C. McKee, and S.A. Shwiff. 2023. A call and suggested criteria for standardizing economic estimates of wild pig damage. Crop Protection 165:106149. doi: 10.1016/j.cropro.2022.106149

United States Department of Agriculture National Feral Swine Damage Management Program Five Year Report FY14 – FY18

United States Department of Agriculture Animal and Plant Health Inspection Service Wildlife Services. 2024. Innovative Solutions to Human Wildlife Conflicts. National Wildlife Research Center Accomplishments, 2023.

VerCauteren, K.C., K.M. Pepin, S.M. Cook, S. McKee, A. Pagels, K.J. Kohen, I.A. Messer, M.P. Glow, N.P. Snow. 2024. What is known, unknown, and needed to be known about damage caused by wild pigs. Biol Invasions (2024) 26:1313–1325 https://doi.org/10.1007/s10530-024-03263-z

Posted by Faith Campbell

www.fadingforests.org

California bill – model for other states?

invasion of wild/black mustard *Brassica nigra*; photo by carlbegge via Flickr

A California state legislator has proposed a bill to expand state efforts to counter invasive species. Should we support it – and others like it in other states?

The bill is Assembly Bill 2827 introduced by Assembly Member (and former Majority Leader) Eloise Reyes of the 50th Assembly District. She represents urban parts of southwestern San Bernardino County, including the cities of Rialto, Colton, and Fontana.

According to media reports, Reyes was prompted to act by the current outbreak of exotic fruit flies, which as of some months ago resulted in detections in 15 California counties.

The bill is much broader than agricultural pests, however. It would find and declare that it is a primary goal of the state to prevent the introduction, and suppress the spread, of invasive species within its borders. I applaud the language of the “findings” section:

(a) Invasive species have the potential to cause extensive damage to California’s natural and working landscapes, native species, agriculture, the public, and economy.

(b) Invasive species can threaten native flora and fauna, disrupt ecosystems, damage critical infrastructure, and result in further loss of biodiversity.

Paragraph (c) cites rising threats associated with increased movement of goods, international travel, and climate change — all said to create conditions that may enhance the survival, reproduction, and spread of these invasive species, posing additional threats to the state.

(d) It is in the best interest of the state to adopt a proactive and coordinated approach to prevent the introduction and spread of invasive species.

California sycamore attacked by invasive shot hole borer; photo by Beatriz Nobua-Behrmann

The bill calls for

The state agencies, in collaboration with relevant stakeholders, to develop and implement pertinent strategies to protect the state’s agriculture, environment, and natural resources.
The state to invest in research, outreach, and education programs to raise awareness and promote responsible practices among residents, industries, and visitors.
State agencies to coordinate efforts with federal, local, and tribal authorities.

However, the bill falls short when it comes to action. Having declared that countering bioinvasion is “a primary goal of the state”, and mandated the above efforts, the bill says only that the California Department of Food and Agriculture (which has responsibility for plant pests) is to allocate funds, if available, to implement and enforce this article. Under this provision, significant action is likely to depend on holding agencies accountable and providing increased funding.

removing coast live oak killed by goldspotted oak borer; photo by F.T. Campbell

Would this proposed legislation make a practical difference? I have often complained that CDFA has not taken action to protect the state’s wonderful flora. For example, CDFA does not regulate firewood to prevent movement of pests within the State. It has not regulated numerous invasive plants or several wood-boring insects. These include the goldspotted oak borer; the polyphagous and Kuroshio shothole borers; and the Mediterranean oak borer.

On the other hand, CDFA is quick to act against pests that might enter the state from elsewhere in the country, e.g., spongy moth (European or Asian), emerald ash borer and spotted lanternfly.

I hope Californians and the several non-governmental organizations focused on invasive species will lobby the legislature to adopt Assembly Bill 2827. I hope further that they will try to identify and secure a source of funds to support the mandated action by CDFA and other agencies responsible for managing the fauna, flora, and other taxa to which invasive species belong.

I applaud Ms. Reyes’ initiative. I hope legislators in other states will consider proposing similar bills.

Posted by Faith Campbell

www.fadingforests.org

Europe outlaws “ecocide”

American bullfrog (*Lithobates catesbeianus*); photo by Will Brown via Wikimedia; one of invasive animals deliberately introduced to Europe in the past

In February 2024 the European Parliament approved legislation outlawing “ecocide” and providing sanctions for environmental crimes. Member states now have two years to enshrine its provisions in national law.

The new rules update the list of environmental crimes adopted in 2008 and enhance the sanctions. The goal is to ensure more effective enforcement. Listed among the offenses are:

the import and use of mercury and fluorinated greenhouse gases,
the import of invasive species,
the illegal depletion of water resources, and
pollution caused by ships.

This action followed an in-depth analysis of the failures of the previous EU environmental directive, first adopted in 2008 (Directive 2008/99/EC). The review found that:

The Directive had little effect on the ground.
Over the 10 years since its adoption few environmental crime cases were successfully investigated and sentenced.
Sanction levels were too low to dissuade violations.
There had been little systematic cross-border cooperation.

EU Member states were not enforcing the Directive’s provisions. They had provided insufficient resources to the task. They had not developed the needed specialized knowledge and public awareness. They were not sharing information or coordinating either among individual governments’ several agencies or with neighboring countries.

The review found that poor data hampered attempts by both the EU body and national policy-makers to evaluate the Directive’s efficacy.

The new Directive attempts to address these weaknesses. To me, the most important change is that complying with a permit no longer frees a company or its leadership from criminal liability. These individuals now have a “duty of care”. According to Antonius Manders, Dutch MEP from the Group of the European People’s Party (Christian Democrats), if new information shows that actions conducted under the permit are “causing irreversible damage to health and nature – you will have to stop.” This action reverses the previous EU environmental crime directive – and most member state laws. Until now, environmental crime could be punished only if it is unlawful; as long as an enterprise was complying with a permit, its actions would not be considered unlawful. Michael Faure, a professor of comparative and international environmental law at Maastricht University, calls this change revolutionary.

Another step was to make corporate leadership personally liable to penalties, including imprisonment. If a company’s actions cause substantial environmental harm, the CEOs and board members can face prison sentences of up to eight years. If the environmental harm results in the death of any person, the penalty can be increased to ten years.

Financial penalties were also raised. Each Member state sets the fines within certain parameters. Fines may be based on either a proportion of annual worldwide turnover (3 to 5%) or set at a fixed fine (up to 40 million euros). Companies might also be obliged to reinstate the damaged environment or compensate for the damage caused. Companies might also lose their licenses or access to public funding, or even be forced to close.

Proponents of making ecocide the fifth international crime at the International Criminal Court argue that the updated directive effectively criminalizes “ecocide” — defined as “unlawful or wanton acts committed with knowledge that there is a substantial likelihood of severe and either widespread or long-term damage to the environment being caused by those acts.”

Individual member states also decide whether the directive will apply to offences committed outside EU borders by EU companies.

Some members of the European Parliament advocate for an even stronger stance: creation of a public prosecutor at the European Union level. They hope that the Council of Europe will incorporate this idea during its ongoing revision of the Convention on the Protection of the Environment through Criminal Law. To me, this seems unlikely since the current text of the Convention, adopted by the Council in 1998, has never been ratified so it has not come into force.

The Council of Europe covers a wider geographic area than the European Union – 46 member states compared to 27. Members of the Council of Europe which are not in the EU include the United Kingdom, Norway, Switzerland, Bosnia-Hercegovina, Serbia, Kosovo, Albania; several mini-states, e.g., Monaco and San Remo; and countries in arguably neighboring regions, e.g., Armenia, Azerbaijan, Georgia, and Turkey.

While I rejoice that invasive species are included in the new Directive, I confess that I am uncertain about the extent to which this inclusion will advance efforts to prevent spread. The species under consideration would apparently have to be identified by some European body as “invasive” and its importation restricted. As we know, many of the most damaging species are not recognized as invasive before their introduction to a naïve environment. On the other side, the requirement that companies recognize new information and halt damaging actions – even when complying with a permit! – provides for needed flexibility.

Posted by Faith Campbell

www.fadingforests.org

Read both: a short call to action (41 pp) based on a long report (952 pp!) Then Act!!!

U.S. Department of Agriculture headquarters; lets lobby these people! photo by Wikimedia

Twenty-three scientists based around the world published a Letter to the Editor titled “Overwhelming evidence galvanizes a global consensus on the need for action against Invasive Alien Species” It appears in the most recent edition of Biological Invasions (2024) 26:621–626.

The authors’ purpose is to draw attention to the release of a new assessment by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services’ (IPBES).

The report was issued in September 2023. It is described as the most comprehensive global synthesis of the current knowledge on the bioinvasion process and the impacts of invasive alien species (952 pages!). Its preparation took nearly a decade. Most important, it represents the first consensus among governments and scientists worldwide on the magnitude and extent of the threats that bioinvasions pose to nature, people, and the economy.

The proposed solutions are astoundingly broad and ambitious: transformation of how governments and societies perform. I don’t disagree! However, we need interim steps – “bites of the elephant.” In my view, the report falls short on providing these.

Our challenge: join others in bringing this analysis to decision-makers’ attention. Can we pull out information that will help persuade U.S. decision-makers – governmental and non-governmental – that the threat is both urgent and solvable? How do we more effectively advocate for the aggressive, science-based action that we all know is needed?

(I hope that the fact that the report was prepared under the auspices of the Convention on Biodiversity, to which the U.S. is not a party, does not intensify the challenge for us.)

Why we need to restructure the behavior of governments and societies

Bioinvasions are facilitated by policies, decision-making structures, institutions, and technologies that are almost always focused on achieving other goals. Species transport and introduction are driven by policies aimed at promoting economic growth – especially trade. Later stages of invasions, i.e., establishment and some spread, are accelerated by certain uses of land and sea plus climate change. For example, activities that fragment habitats or cause widespread habitat disturbance provide ready places for bioinvasions. Rarely are those who gain by such policies held accountable for the harms they produce via bioinvasions.

To address these unintended consequences, the IPBES report calls for “integrated governance.” Its authors want coordination of all policies and agencies that touch on the indirect drivers, e.g., conservation; trade; economic development; transport; and human, animal, and plant health. Policy instruments need to reinforce – rather than conflict with — strategic invasive species management across sectors and scales. This involves international agreements, national regulations, all governmental sectors, as well as industry, the scientific community, and ordinary people – including local communities and Indigenous Peoples.

The report also calls for establishment of open and inter-operable information systems. This improved access to information is critical for setting priorities; evaluating and improving regulations’ effectiveness; and reducing costs by avoiding duplication of efforts.

Critically important information that is often unspoken:

Indirect causes underlying the usual list of human activities that directly promote bioinvasions are the rapid rise of human population and even more rapid rise in consumption and global trade.
Biosecurity measures at international borders have not kept pace with the growing volume, diversity, and geographic origins of goods in trade.

Continuation of current patterns is expected to result in one-third more invasive species globally by 2050. However, this is an underestimate because today’s harms reflect the consequences of past actions – often from decades ago. Drivers of invasions are expected to grow in both volume and impact.
We can prevent and control invasive alien species – but that success depends on the availability of adequate, sustained resources, plus capacity building; scientific cooperation and transfer of technology; appropriate biosecurity legislation and enforcement; and engaging the full range of stakeholders. These require political will.
A major impact of bioinvasion is increased biotic homogenization (loss of biological communities’ uniqueness). This concerns us because we are losing the biotic heterogeneity that provides insurance for the maintenance of ecosystem functioning in the face of ongoing global change.
The IPBES study asserts that successfully addressing bioinvasions can also strengthen the effectiveness of policies designed to respond to other drivers, especially programs addressing conservation of biological diversity, ensuring food security, sustaining economic growth, and slowing climate change. All these challenges interact. The authors affirm that evidence-based policy planning can reflect the interconnectedness of the drivers so that efforts to solve one problem do not exacerbate the magnitude of others and might even have multiple benefits.

More Key Findings

Overall, 9% (3,500) of an estimated 37,000 alien species established in novel environments are invasive (those for which scientists have evidence of negative impacts). Proportions of invasives is high among many taxonomic groups: 22% of all 1,852 alien invertebrates; 14% of all 461 alien vertebrates; 11% of all 141 alien microbes; and 6% of all 1,061 alien plants. (The discussion of probable undercounts relates to aquatic systems and certain geographic regions. However, I believe these data are all undermined by gaps in studies.)
Invasive alien species – solely or in combination with other drivers – have contributed to 60% of recorded global extinctions. Invasive species are the only driver in 16% of global animal and plant extinctions. Some invasive species have broader impacts, affecting not just individual species but also communities or whole ecosystems. Sometimes these create complexoutcomes that push the system across a threshold beyond which ecosystem restoration is not possible. (No tree pests are listed among the examples.)

dead whitebark pine in Glacier National Park; photo by National Park Service

The benefits that some non-native – even invasive – species provide to some groups of people do not mitigate or undo their negative impacts broadly, including to the global commons. The report authors note that beneficiaries usually differ from those people or sectors that bear the costs. The authors cite many resulting inequities.
There are insufficient studies of, or data from, aquatic systems, and from Africa; Latin America and the Caribbean; and parts of Asia.
The number of alien species is rising globally at unprecedented and increasing rates. There are insufficient data specifically on invasive species, but they, too, are thought to be rising at similar rates.
Horticulure is a major pathway for introducing 46% of invasive alien plant species worldwide.
Regarding invasive species’ greater impact on islands,the IPBES report mentions brown tree snakes on Guam and black rats on the Galapagos Islands. It also notes that on more than a quarter of the world’s islands, the number of alien plants exceeds the total number of native ones. See my blogs on non-native plants on Hawai`i and Puerto Rico. In addition, I have posted several blogs regarding disease threats to rare bird species in Hawai`. The IPBES report does not mention these.

Where the Report Is Weak: Interim Steps

The report endorses adoption of regulated species (“black”) lists.
The report emphasizes risk analysis of species. Unfortunately IPBES’ analysis was completed before publication of the critique of risk analysis methods by Raffa et al. ( (2023) (see references). However, we must take the latter into consideration when deciding what to advocate as U.S. policy.
The report authors call for more countries to adopt national legislation or regulations specifically on preventing and controlling invasive species. (They note that 83% of countries lack such policies). They also list the many international agreements that touch on invasive species-relevant issues. However, Raffa et al. found that the number of such agreements to which a country is a party bears no relationship to the numbers of alien species detected at its border or established on its territory.
The challenge to risk assessment posed by multiple sources of uncertainty can be managed by recognizing, quantifying, and documenting the extent of that uncertainty.

Beech leaf disease – one of many non-native pests that were unknown before introduction to a naive ecosystem. Photo by Jennifer Koch, USDA Forest Service

I appreciate the report’s emphasis on the importance of public awareness and engagement, but I thought the discussion of effective campaigns lacked original ideas.

The report did not fulfill its own goal of fully exploring unappreciated impacts of policies in its discussion of habitat fragmentation. For example, the report notes that grazing by feral alien ungulates facilitates the spread of invasive alien plant species. However, it does not mention the similar impact by livestock grazing (Molvar, et al. 2024).

SOURCES

Molvar, E.M., R. Rosentreter, D. Mansfield, and G.M. Anderson. 2024. Cheat invasions: History, causes, consequences, and solutions. Hailey, Idaho: Western Watersheds Project, 128 pp.

Raffa, K.F., E.G. Brockerhoff, J-C. GRÉGOIRE, R.C. Hamelin, A.M. Liebhold, A. Santini, R.C. Venette, and M.J. Wingfield. 2023. Approaches to forecasting damage by invasive forest insects and pathogens: a cross-assessment. BioScience 85 Vol. 73 No. 2 (February 2023) https://academic.oup.com/bioscience

Posted by Faith Campbell