Eric T. Hileman

Invasive plants are a growing concern for land managers, impacting ecosystem resilience and outcompeting native vegetation. To combat this, invasive plant control treatments can assist in reducing the impacts and spread of damaging, non-native plant species. However, intensive treatments completed at large scales have the potential to negatively impact ecosystem services as well. To monitor these impacts, we utilized a well-known indicator in the Central Appalachian region, Plethodontid salamanders, to assess impacts of invasive plant control treatments in the Central Hardwood forests. We completed 12 visual samples across 60 sites in West Virginia, USA during Spring and Fall of 2025 (720 sampling occasions) on state lands that received invasive plant control treatment during the previous summer. We also collected habitat metrics to observe impacts of invasive plant presence on Plethodontid salamander occupancy. Using a single-species, single-season occupancy model, we identified important predictors of salamander occupancy across landscapes managed for invasive plants. Salamander occupancy on sites that received invasive plant control treatments decreased by 42.1%, whereas occupancy increased by 6.0% for every 1.0% increase in canopy cover. The inclusion of invasive plant ground cover in the occupancy model was uninformative, which is consistent the inconclusive relationship between adult, terrestrial salamanders and invasive plants in previous studies. Overall, our results support findings of recent studies, including that invasive plant control treatments have unintended, negative impacts on Plethodontid salamanders and their associated ecosystem services.

Long‐term studies of plant and animal populations are rare, particularly for long‐lived species with slow life histories. However, such studies are necessary to understand how population dynamics are affected by variation in vital rates. We used a large capture–recapture dataset spanning four decades (1983–2019) to estimate several population parameters for adult females in a metapopulation of a long‐lived North American pitviper (timber rattlesnake, Crotalus horridus ) near the northern extent of the species' geographic range. Apparent survival (ϕ, hereafter; survival) estimates were variable (0.595–0.938) among years, but generally high, whereas the annual recruitment rate ( f ) was low (0.102, 95% CI: 0.088–0.117). Survival increased by a quadratic function of mean body mass of the adult female population, resulting in survival increasing with this temporally varying population‐level covariate until the population average reached approximately 768 g; thereafter, survival decreased with increasing mean mass. The proximate causes of decreased survival for the largest, and thus presumably oldest, snakes remain unknown but are likely related to senescence and increased predation risk with advancing age. The best predictors for encounter probabilities were the additive effects of color morph (higher for yellow‐morph snakes than black‐morph snakes), sampling site, and year. The model‐averaged estimate of realized population growth () was 0.992 (95% CI: 0.980–1.005), but removal of sampling variance from the component of contributed by survival resulted in a 95% upper limit of 0.9997, indicating a declining population. Reflecting attributes of the species' protracted life history (late maturation, low fecundity, and infrequent reproduction), the contribution of survival was on average 8.9 (95% CI: 7.6–10.4) times greater than the contribution of recruitment to , representing the slowest life history documented for any snake population to date. Our findings suggest that management efforts to increase adult survival, such as reducing mortality from anthropogenic factors, should aid in the conservation of timber rattlesnakes and other imperiled species with similar slow life histories.

Small and fragmented populations are at high risk of local extinction, in part because of elevated inbreeding and subsequent inbreeding depression. A major conservation priority is to identify the mechanisms and extent of inbreeding depression in small populations. The eastern massasauga ( Sistrurus catenatus ) rattlesnake is listed as Federally Threatened in the United States, having experienced significant habitat fragmentation and concomitant population declines over the past 200 years. Here, we use long-term monitoring of two wild populations of eastern massasaugas in Michigan to estimate the extent of inbreeding in each population, identify mechanisms that generate inbreeding, and test for the impact of inbreeding on fitness. Using targeted genomic data and spatial coordinates of capture locations from over 1000 individuals, we find evidence of inbreeding and link inbreeding to spatial kinship structure within populations, possibly driven by limited dispersal. We reconstruct multigenerational pedigrees for each population to measure reproductive output and use long-term capture–recapture data to estimate individual survival (i.e., the two major components of fitness). We find evidence of inbreeding depression in both fitness metrics. The 5% most inbred individuals are 13.5% less likely to have any surviving offspring and have 11.6% lower annual survival compared to all less inbred individuals. By combining genomics and long-term monitoring data, we are able to link the life history of eastern massasaugas to inbreeding and detect relationships between fitness and inbreeding. These insights provide important conservation context for future management and for understanding how spatial structure can generate inbreeding depression even at fine spatial scales.

Reliable population estimates are important for making informed management decisions about wildlife species. Standardized survey protocols have been developed for monitoring population trends of the wood turtle (Glyptemys insculpta), a semi-aquatic freshwater turtle species of conservation concern throughout its distribution in east-central North America. The protocols use repeated active search surveys of defined areas, allowing for estimation of survey-specific detection probability (p) and site-specific abundance. These protocols assume population closure within the survey area during the survey period, which is unlikely to be met as wood turtles are a highly mobile species. Additionally, current protocols use a single-pass design that does not allow for separation of availability (p_a) and detectability (p_d). If there are systematic influences on p_a or p_d that are not accounted for in the survey design or data analysis, then resulting abundance estimates could be biased. The objectives of this study were to determine if p_a is a random process and if p_a and p_d are influenced by demographic characteristics. We modified the wood turtle survey protocol used in the upper Midwest to include a double-pass design, allowing us to estimate p_a and p_d using a robust design capture-recapture model. The modified protocol was implemented at 14 wood turtle monitoring sites in Minnesota and Wisconsin between 2017 and 2022. Our results indicated that p_a was non-random and that p_d increased with turtle carapace length. Our study suggests that model assumptions for current wood turtle population models may be violated, likely resulting in an overestimation of abundance. We discuss possible protocol and modeling modifications that could result in more accurate wood turtle abundance estimates.

Capture histories of wild pigs (Sus scrofa) identified using nuclear DNA markers from hair snare samples activated on the Sam D. Hamilton Noxubee National Wildlife Refuge in Mississippi between 2021 and 2022. Hair snares were active for 8 weeks (occassions) with non-grain attractants placed at the center of each snare. Dat includes unique pig identifiers (Pig_ID), capture histories (Capture_Occassion), and associated capture year (Group).

Invasive species are a major threat and primary driver of vertebrate extinctions on islands, including native and endemic lizards such as West Indian Groundlizards (Genus Pholidoscelis). The genus comprises 19 extant species that range collectively from the Bahamas through the Greater Antilles south to Dominica in the Lesser Antilles. Few studies have addressed aspects of Groundlizard population ecology despite invasive mammals being implicated in Groundlizard declines and three extinctions. From 2007 to 2011, we conducted a capture–recapture study of Puerto Rican Giant Groundlizards (Pholidoscelis exsul) on Guana Island. Guana Island is privately owned and hosts a small number of feral cats, but is mongoose-free and has otherwise experienced only minor human modification since the mid-18th Century. Thus, the island provides a unique opportunity to study lizard demography under conditions minimally impacted by human activities. Our objective was to establish benchmark demographic parameter estimates of P. exsul that may be used in future studies to detect ecological changes. We hypothesized that lizards would be encountered more frequently in disturbed habitat than in less-disturbed habitat because of available anthropogenic food subsidies. We also predicted that large lizards would have higher annual survival rates than would small lizards, and lizards with higher indices of body condition would have correspondingly higher annual survival rates than lizards of the same size class with lower indices of body condition. Our results showed that male growth rates were comparable to similar studies, and individuals reached the presumed size of sexual maturity within 1 yr, with growth rates declining thereafter. Annual survival increased with size class (small = 0.155, 95% confidence interval [CI] = 0.069–0.312; large = 0.518, 95% CI = 0.374–0.660), but we found no evidence of a body condition effect on annual survival. The probability of mortality increased to 99.4% by age 6, but evidence of senescence via declining body condition was apparent sooner. Daily capture probabilities were higher in heavily modified habitat (0.081, 95% CI = 0.049–0.132) than in relatively natural habitat (0.025, 95% CI = 0.012–0.054). Mean maximum distance moved between recaptures was 24.4 m (2–350 m). Estimates of annual abundance ranged from 139 to 250 individuals. Density estimates among years based on the upper confidence limit ranged from 41.9–81.5 individuals/ha within the core sampling area (6.01 ha) and 20.1–39.2 individuals/ha when a 12.5-m buffer strip was incorporated into the effective sampling area.

Quantitative evaluation of control tools for managing invasive species is necessary to assess overall effectiveness and individual variation in treatment susceptibility. Invasive brown treesnakes (Boiga irregularis) on Guam have caused severe ecological and economic effects, pose a risk of accidental introduction to other islands, and are the greatest impediment to the reestablishment of extirpated native fauna. An aerial delivery system for rodent‐based toxic baits can reduce brown treesnake abundance and heterogeneity among individuals may influence bait attraction or toxicant susceptibility. Previous baiting trials have either been simulated aerial treatments or relied on slightly different bait capsule compositions and the results of aerial delivery of toxic baits under operational conditions may not be directly comparable. We monitored 30 radio‐tagged adult snakes (990–1,265 mm snout‐vent length) during an aerial baiting operation in a 55‐ha area using transmitters equipped with accelerometers and receivers programed to display a status code indicating mortality if a snake failed to move for >24 hours. We used known‐fate models to estimate mortality and evaluate a priori hypotheses explaining differences in mortality based on size, sex, and treatment effects. Eleven radio‐tagged snakes died in the aerial baiting treatment period (0.37, 95% CI = 0.21–0.55) and no individuals (0.00, 95% CI = 0.00–0.04) died during the non‐treatment period. Our data provide strong evidence for an additive size‐based treatment effect on mortality, with smaller adults (0.59, 95% CI = 0.35–0.80) exhibiting higher mortality than larger snakes (0.14, 95% CI = 0.02–0.37) but did not support a sex effect on mortality. The high mortality of snakes during the treatment period indicates that aerial baiting can reduce brown treesnake abundance, but further refinement or use in combination with other removal tools may be necessary to overcome size‐based differences in susceptibility and achieve eradication. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.

Remarkably little is known about the demography of snakes in the family Boidae. This lack of information may be attributed, in part, to low population densities on the Neotropical mainland, rendering capture‐recapture methods impractical for many species. Conversely, islands support fewer species but snake densities can be much higher. Corallus grenadensis is an arboreal boid endemic to the Grenada Bank and, relative to mainland boids, can be amazingly abundant. As young, its diet is comprised largely of native Anolis lizards, a ubiquitous and abundant food source; it then undergoes an ontogenetic shift in diet to a less abundant resource, rodents. From 2015 to 2019, we marked 254 C. grenadensis and used capture–recapture models to estimate abundance, capture probabilities, survival, and the proportion of transients. We hypothesized that the transient effect would increase with body size (snout–vent length [SVL]), prompted by their ontogenetic shift in diet. Capture probabilities increased with sampling effort and decreased with increasing SVL. Abundance ranged from 96 to 141 individuals and annual resident survival was 0.71, 95% confidence interval (CI) = 0.54–0.83. The proportion of transients increased with increasing SVL, with the estimate being distinguishable from zero starting at ~810 mm SVL, coinciding with the size at which their dietary shift from ectothermic to endothermic prey begins. Ontogenetic dietary shifts are widespread in snakes and occur in at least 11 of 17 species of West Indian boids. Thus, the prominence of transients in our study may be indicative of its demographic and ecological importance among other snake species.