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Flooding-induced failure of an invasive Burmese Python nest in southern Florida
It is important to understand the factors affecting the reproductive success of an invasive species to estimate population size and develop management plans. There remains much we do not understand about the reproductive biology of invasive Burmese Pythons in both their native and invasive range. Oviposition site selection is an important factor in determining reproductive success as nesting is a vulnerable period in the life of reptiles. Flooding can be particularly influential for nesting outcomes and success of developing embryos in habitats that experience periods of heavy rainfall or seasonal flooding. It is not clear how seasonal flooding may impact oviposition site selection by females or hatchling survival of Burmese Pythons in Florida. On 10 May 2023, a radio-transmitted female python oviposited in a hollow log and during incubation all eggs were completely submerged for variable amounts of time. All eggs were collected (n = 78) and dissected to confirm fertilization and assess the stage of embryo development. Two eggs were found to be infertile, while the remaining fertile eggs contained embryos that died at various stages of development. The observed failure of this python nest was a direct result of oviposition site selection by the female. The frequency at which females lay eggs in suboptimal locations in southern Florida is currently unknown. This maladaptive behavior would suggest Burmese Pythons have fitness levels below theoretical optima.
Multiple records of the introduced parthenogenetic Smooth-scaled Tegulet, Gymnophthalmus underwoodi Grant 1958, in Puerto Rico
The introduction of invasive species to islands can be devastating to local biota. While many invasive species’ successful colonization of new habitats can be attributed to features like high fecundity or low mate selectivity, parthenogenetic species pose a unique threat in their ability to reproduce asexually at high rates. The Smooth-scaled Tegulet ( Gymnophthalmus underwoodi ), first described from Barbados in the 1950s, has since been documented as an introduced species across additional Lesser and Greater Antillean islands as well as northwestern Brazil and Venezuela. Herein we report multiple individuals from Puerto Rico, including the first genetic records, which indicate that the individuals on this island are most closely related to populations recorded from Brazil and Montserrat. Additional genetic information is necessary to determine the timing and migration of this species across the Caribbean. Regardless, the continued geographic expansion of this parthenogen across the Caribbean could present a threat to local fauna.
Species data: National inventory of range maps and distribution models
The Gap Analysis Project (GAP) produces data and tools that help meet critical national challenges such as biodiversity conservation, renewable energy development, climate change adaptation, and infrastructure investment. The GAP species data includes vertebrate range maps and distribution models for the continental United States, as well as Alaska, Hawaii, Puerto Rico, and U.S. Virgin Islands. The vertebrate species include amphibians, birds, mammals, and reptiles. Furthermore, data used to create the distribution models (for example, percent canopy cover, elevation, and so forth) also are available.
Selection of microhabitats, plants, and plant parts eaten by a threatened tortoise: Observations during a superbloom
Populations of the threatened desert tortoise ( Gopherus agassizii ) continue to decline throughout the geographic range, in part because of degraded and fragmented habitats in the Mojave and western Sonoran deserts. The species is herbivorous and highly selective in choice of plant species. To increase options for recovery, we analyzed behaviors, patterns of movements while foraging, and parts of plants consumed during a superbloom. We characterized foraging routes and the habitat strata and microhabitats where tortoises traveled to eat preferred wildflower species. Tortoises walked one foraging route per day in early spring, often switched to two routes per day in middle and late spring with rise of midday temperatures. They chose habitat strata (primarily hills and ephemeral stream channels) and three of seven microhabitats for foraging on preferred food plants. Preferred microhabitats were intershrub open space and small (1–2 m wide) ephemeral stream channels. They rarely took bites of forbs growing under and in the dripline of shrubs or nonnative forbs and grasses. Tortoises typically did not select specific plant parts to eat but important exceptions occurred. For example, they usually ignored the inflorescences of the annual Eremothera boothii and, when eating the non-native annual Erodium cicutarium , tended to focus on fruits. All such information aids recovery efforts to restore declining tortoise populations.
Preparing for a Bsal invasion into North America has improved multi-sector readiness
Western palearctic salamander susceptibility to the skin disease caused by the amphibian chytrid fungus Batrachochytrium salamandrivorans (Bsal) was recognized in 2014, eliciting concerns for a potential novel wave of amphibian declines following the B. dendrobatidis (Bd) chytridiomycosis global pandemic. Although Bsal had not been detected in North America, initial experimental trials supported the heightened susceptibility of caudate amphibians to Bsal chytridiomycosis, recognizing the critical threat this pathogen poses to the North American salamander biodiversity hotspot. Here, we take stock of 10 years of research, collaboration, engagement, and outreach by the North American Bsal Task Force. We summarize main knowledge and conservation actions to both forestall and respond to Bsal invasion into North America. We address the questions: what have we learned; what are current challenges; and are we ready for a more effective reaction to Bsal’s eventual detection? We expect that the many contributions to preemptive planning accrued over the past decade will pay dividends in amphibian conservation effectiveness and can inform future responses to other novel wildlife diseases and extreme threats.
Invasive African clawed frogs ( Xenopus laevis ) in Washington State: Status, response efforts, and lessons learned
The African clawed frog (ACF, Xenopus laevis ), which is indigenous to sub-Saharan Africa, is an aquatic invasive species known to have severe ecological impacts on native fauna when introduced into non-endemic regions. In 2015, ACFs were detected in Washington State, U.S. for the first time, and the species is now documented at three cities across western Washington: Lacey, Bothell, and Issaquah. We cataloged the known ACF occurrences, early management efforts, biological data about the frogs, and status of these invasive populations at the three sites from 2015–2023. The ACFs appear to be established in at least three watersheds in the Puget Sound region despite substantial effort at eradicating them at one site. Presence of ACFs in watersheds that lack surface connectivity implies independent introduction events, and the capture of frogs in multiple subbasins in the same watershed may reflect the potential for further spread. Because the ACF is nocturnal and otherwise behaviorally and visually highly cryptic, other established populations may go undetected. Where the ACFs are largely confined to stormwater ponds — as many of our current observations suggest — eradication may still be possible, though a substantial, focused effort would be required. In addition, significant refinement of eradication approaches will be needed to ensure effectiveness in topographically and vegetatively complex Pacific Northwest aquatic environments.
Tracing invasion routes of Cuban treefrogs into Louisiana using mitochondrial DNA
Understanding the origin and spread of invasive species is critical for predicting when and where new introductions will establish, and impact native species. However, due to the complexity of contributing factors such as multiple introductions, dispersal method, genetic admixture in founding populations, and variable propagule pressure, genetic patterns observed in invasive species may not always conform to a single theoretical expectation. Cuban treefrogs ( Osteopilus septentrionalis ) are invasive in peninsular Florida and sporadically in the Florida panhandle. Though O. septentrionalis has been occasionally reported in Louisiana since the 1990s, established populations were not present until the discovery of a breeding population in New Orleans in 2017. In this study we investigated the source of this novel population using existing and newly generated cytochrome B (cyt-b) mitochondrial gene sequences from the native and invasive range of O. septentrionalis . We recovered a total of 14 cyt-b haplotypes, nine novel and five previously published. Within the 95 Louisiana invasion samples, we recovered seven haplotypes including five novel haplotypes. The haplotypes most common in Louisiana were shared exclusively with west and east Florida localities in central Florida, indicating a possible source population. The presence of haplotypes private to the Louisiana locality suggests other unsampled localities may also be contributing to the Louisiana settlement. Metrics of genetic diversity across native and invasive localities did not significantly differ. Furthermore, the Louisiana samples had higher genetic diversity than any single location sampled within Florida. Thus, genetic diversity and our haplotype connectivity suggest the Louisiana population is derived from multiple introductions from Florida. Our study highlights how demographic and genetic analyses can be utilized to understand the source and future expansion potential of invasive populations.
Efficacy of increased visual and olfactory cues for luring and trapping invasive tegu lizards
Controlling invasive wildlife species relies on the ability to efficiently remove individuals from the invaded environment. Thus, maximizing capture potential is of high interest, particularly for species that are difficult to capture. For invasive species such as the Argentine black and white tegu lizard ( Salvator merianae ), increasing attraction to traps could increase the probability of removal. While it has been established that S. merianae can be lured with a single chicken egg, the efficacy of increasing olfactory or visual cues to increase tegu captures has not been rigorously tested. To test this, we leveraged an ongoing National Park Service trapping effort near Everglades National Park. In 2023 and 2024, we randomly assigned traps to a control treatment (single real egg), increased olfactory and visual treatment (three real eggs), an increased visual plus standard olfactory treatment (one real egg and one decoy egg, or one real egg and two decoy eggs), or visual treatment only (three decoy eggs). We fitted Bayesian binomial models for tegu lizards and non-target species to the trapping data to assess how bait treatment, trap style, and trap location affected the daily probability of capture at a trap. Additionally, we fitted Bayesian linear models to test the effect of bait treatment on the size of tegus captured. We found that increasing the olfactory cue to three real eggs increased the probability of tegu capture, but not the probability of non-target species capture. Conversely, traps with one real egg and two decoy eggs increased the probability of non-target captures while reducing the probability of tegu captures. Trap style and trap location also had statistically significant effects. Bait treatment did not significantly influence the size of tegus captured; however, there was a weak effect suggesting juvenile and male tegus captured in traps with three real eggs were larger compared to traps with a single egg and two decoy eggs. Our results highlight potential improvements in tegu control methods that balance effective capture with minimizing non-target bycatch.
Applying biodiversity metrics as surrogates to a habitat conservation plan
Unabated urbanization has led to environmental degradation and subsequent biodiversity loss across the globe. As an outcome of unmitigated land use, multi-jurisdictional agencies have developed land use plans that attempt to protect threatened or endangered species across selected areas by which some trade-offs between harm to species and additional conservation approaches are allowed among the partnering organizations. Typical conservation plans can be created to focus on single or multiple species, and although they may protect a species or groups of species, they may not account for biodiversity or its protection across the given area. We applied an approach that clustered deductive habitat models for terrestrial vertebrates into metrics that serve as surrogates for biodiversity and relate to ecosystem services. In order to evaluate this process, we collaborated with the partnering agencies who are creating a Multi-Species Habitat Conservation Plan in southern California and compared it to the entire Mojave Desert Ecoregion. We focused on total terrestrial vertebrate species richness and taxon groupings representing amphibians, birds, mammals, and reptiles, and two special status species using the Normalized Index of Biodiversity (NIB). The conservation planning area had a lower NIB and was less species rich than the Mojave Desert Ecoregion, but the Mojave River riparian corridor had a higher NIB and was more species-rich, and while taxon analysis varied across the geographies, this pattern generally held. Additionally, we analyzed desert tortoise ( Gopherus agassizii ) and desert kit fox ( Vulpes macrotis arsipus ) as umbrella species and determined that both species are associated with increased NIB and large numbers of species for the conservation area. Our process provided the ability to incorporate value-added surrogate information into a formal land use planning process and used a metric, NIB, which allowed comparison of the various planning areas and geographic units. Although this process has been applied to Apple Valley, CA, and other geographies within the U.S., the approach has practical application for other global biodiversity initiatives.
Trimorphodon
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Trimorphodon biscutatus
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Trimorphodon tau
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Tantilla bocourti
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Phyllorhynchus decurtatus
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Phyllorhynchus Stejneger, leaf-nosed snakes
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