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At least 91 records · Page 5Linked to original sources
USGS2025

Breeder turnover, harvest, and food affect recruitment of young nonbreeders in groups of gray wolves

Groups of cooperative breeders typically have social hierarchies, with breeders at the top guiding group decisions and influencing the behavior of subordinates in the group. Because of breeders' strong influence on group dynamics and behaviors, breeder turnover can affect the survival of remaining group members. We lack a solid understanding of the nuanced but important effects of breeder turnover on group composition. I first asked how harvest (i.e., hunting and trapping) affected rates of breeder turnover in groups of gray wolves ( Canis lupus ) in Idaho, USA, from 2008 to 2020. Then, I asked how breeder turnover, group size, and food availability affected the recruitment of 1- and 2-year-old nonbreeders into groups. Harvest was associated with an increase in breeding female, but not breeding male, turnover. Breeding female turnover was negatively associated with the probability of 1-year-old, but not 2-year-old, nonbreeders being in a group the following year. The only significant variable associated with the recruitment of 2-year-old nonbreeders into groups was sex, as males were less likely than females to be present in groups at time (t+1) . Finally, an index of prey biomass was positively associated with the probability of 1-year-olds being present in groups at time (t+1) (i.e., apparent pup survival to age 1). I show that harvest, social factors such as breeder turnover, and food availability influence the presence of young nonbreeders in groups, ultimately affecting group composition in a cooperative breeder.

Idaho↗
USGS2026

The rising threat of lead: Trends in fatalities of California condors

Endangered species face threats that change over time, and understanding variation in the importance of threats is valuable for guiding species recovery. The reintroduced population of critically endangered California condors has faced a number of threats over the three decades since the species was first released back to the wild. We modeled interannual and interseasonal trends in the leading causes of death for wild condors. Our analysis showed strong evidence ( P = 0.971) that the estimated annual probability of death from lead toxicosis has increased since reintroduction started. This increase was most pronounced in the central California subpopulation. Adults were disproportionately affected by lead toxicosis, a trend that may be explained by increased exposure associated with age-related changes in foraging behavior that lead to decreased reliance on clean proffered food sources. Population-level mortality from trauma showed a temporary increase in 2012, and fire-related mortality was higher during the summer months. Pattens also varied across subpopulations, with the southern California subpopulation of condors showing distinct temporal peaks in deaths from trauma (in 2012) and predation (in 2010). Our analysis suggests that threats to condors have not been static over space and time. Managers can therefore use this information to adaptively manage and target mitigation efforts when and where they are the most effective.

California↗
USGS2006

Population dynamics of the endangered Cape Sable seaside-sparrow

The Cape Sable seaside-sparrow ( Ammodramus maritimus mirabilis ) has disappeared from its only known breeding areas episodically since its discovery early this century. Systematic surveys across its range in the southern Everglades find the sparrow's range to be fragmented into six subpopulations. The sparrow population decreased by 58% between 1992 and 1995, with the near extinction of the western half of the population and the temporary local extinction of some eastern populations. Other similar grassland sparrows have populations that vary considerably from year to year. Yet the decline in the western subpopulation and the local extinction of some of the peripheral populations cannot be explained by natural variability alone. Hurricane Andrew passed over several subpopulations prior to the particularly poor year of 1993. However, the geographical and temporal patterns of subpopulation decline are not consistent with what would be expected following a hurricane. Frequent fires prevent successful breeding as does flooding during the breeding season. Better management can prevent frequent fires and episodic flooding. However, the long-term survival of the sparrow depends on managing the unanticipated risks that attend its small, fragmented population.

Animal Conservation↗
USGS2006

Water levels, rapid vegetational changes, and the endangered Cape Sable seaside-sparrow

The legally endangered Cape Sable seaside-sparrow ( Ammodramus maritimus mirabilis ) is restricted to short-hydroperiod, marl prairies within Florida's Everglades National Park and Big Cypress National Preserve. Marl prairies are typified by dense, mixed stands of graminoid species usually below 1 m in height, naturally inundated by freshwater for 3–7 months annually. Water levels affect the birds directly, by flooding their nests, and indirectly by altering the habitat on which they depend. Managed redistribution of water flows flooded nearly half of the sparrow's geographical range during several consecutive breeding seasons starting in 1993. Furthermore, these high water levels rapidly changed plant communities, so jeopardizing the sparrow's survival by reducing the availability of nesting habitat.

Florida↗
USGS2006

Effects of southern flying squirrels Glaucomys volans on red-cockaded woodpecker Picoides borealis reproductive success

Anecdotal data gathered from many populations suggest that southern flying squirrel (SFS, Glaucomys volans ) use of the endangered red-cockaded woodpecker's (RCW, Picoides borealis ) nest and roost cavities may negatively affect RCW populations. We conducted a controlled experiment to determine the effects of SFSs on RCW reproductive success. During the 1994 and 1995 breeding seasons, SFSs were removed from 30 RCW clusters and 32 clusters served as controls. SFSs were the most frequently encountered occupants of RCW cavities and used 20–33% of RCW cavities in control and treatment clusters over both years. Treatment groups produced significantly more successful nests (≥ 1 fledgling) than control groups in 1994. In 1995 however, there was no difference in the number of successful nests. In both years, RCW groups nesting in treatment clusters produced significantly more fledglings than groups in control clusters in each of four experimental areas, averaging approximately 0.7 additional fledglings per nesting group. Loss of entire clutches or broods, possibly as a result of predation or abandonment, was a major factor limiting reproduction in control groups in 1994. In contrast, differences in partial brood loss appeared to be the cause of differential fledging success in 1995. Usurpation of RCW roost cavities by SFSs may have placed greater energetic demands on RCWs for cavity defence or thermoregulation, thus reducing energy available for reproduction. Our results show that SFS use of RCW cavities during the breeding season has a significant impact on RCWs and that management of RCW populations should include activities that either minimize SFS populations in RCW clusters or limit access of SFSs to RCW cavities.

Animal Conservation↗
USGS2006

Relative vulnerability of female turtles to road mortality

Recent studies suggest that freshwater turtle populations are becoming increasingly male-biased. A hypothesized cause is a greater vulnerability of female turtles to road mortality. We evaluated this hypothesis by comparing sex ratios from published and unpublished population surveys of turtles conducted on- versus off-roads. Among 38 166 turtles from 157 studies reporting sex ratios, we found a consistently larger female fraction in samples from on-roads (61%) than off-roads (41%). We conclude that female turtles are indeed more likely to cross roadways than are males, which may explain recently reported skewed sex ratios near roadways and signify eventual population declines as females are differentially eliminated. ?? 2006 The Zoological Society of London.

Animal Conservation↗
USGS2006

Does avian species richness in natural patch mosaics follow the forest fragmentation paradigm?

As one approaches the north-eastern limit of pinyon (Pinus spp.) juniper (Juniperus spp.) vegetation on the Colorado Plateau, USA, woodland patches become increasingly disjunct, grading into sagebrush (Artemisia spp.)-dominated landscapes. Patterns of avian species richness in naturally heterogeneous forests may or may not respond to patch discontinuity in the same manner as bird assemblages in fragmented agricultural systems. We used observational data from naturally patchy woodlands and predictions derived from studies of human-modified agricultural forests to estimate the effects of patch area, shape, isolation and distance to contiguous woodland on avian species richness. We predicted that patterns of species richness in naturally patchy juniper woodlands would differ from those observed in fragmented agricultural systems. Our objectives were to (1) estimate the effect of naturally occurring patch structure on avian species richness with respect to habitat affinity and migratory strategy and (2) assess the concordance of the effects to predictions from agricultural forest systems. We used the analogy between populations and communities to estimate species richness, where species are treated as individuals in the application of traditional capture-recapture theory. Information-theoretic model selection showed that overall species richness was explained primarily by the species area relationship. There was some support for a model with greater complexity than the equilibrium theory of island biogeography where the isolation of large patches resulted in greater species richness. Species richness of woodland-dwelling birds was best explained by the equilibrium hypothesis with partial landscape complementation by open-country species in isolated patches. Species richness within specific migratory strategies showed concomitant increases and no shifts in species composition along the patch area gradient. Our results indicate that many patterns of species richness considered to be fragmentation effects may be general consequences of patch discontinuity and are ubiquitous in naturally heterogeneous systems. There was no evidence for the effects of patch shape and distance to contiguous woodland in juniper woodland, suggesting edge effects and dependence upon regional species pools are characteristics of fragmented agricultural systems. Natural patch mosaics may provide benchmarks for evaluating fragmentation effects and managing forests by mimicking natural landscape patterns. ?? 2007 The Zoological Society of London.

Animal Conservation↗
USGS2008

Estimation of the bottleneck size in Florida panthers

We have estimated the extent of genetic variation in museum (1890s) and contemporary (1980s) samples of Florida panthers Puma concolor coryi for both nuclear loci and mtDNA. The microsatellite heterozygosity in the contemporary sample was only 0.325 that in the museum samples although our sample size and number of loci are limited. Support for this estimate is provided by a sample of 84 microsatellite loci in contemporary Florida panthers and Idaho pumas Puma concolor hippolestes in which the contemporary Florida panther sample had only 0.442 the heterozygosity of Idaho pumas. The estimated diversities in mtDNA in the museum and contemporary samples were 0.600 and 0.000, respectively. Using a population genetics approach, we have estimated that to reduce either the microsatellite heterozygosity or the mtDNA diversity this much (in a period of c. 80years during the 20th century when the numbers were thought to be low) that a very small bottleneck size of c. 2 for several generations and a small effective population size in other generations is necessary. Using demographic data from Yellowstone pumas, we estimated the ratio of effective to census population size to be 0.315. Using this ratio, the census population size in the Florida panthers necessary to explain the loss of microsatellite variation was c .41 for the non-bottleneck generations and 6.2 for the two bottleneck generations. These low bottleneck population sizes and the concomitant reduced effectiveness of selection are probably responsible for the high frequency of several detrimental traits in Florida panthers, namely undescended testicles and poor sperm quality. The recent intensive monitoring both before and after the introduction of Texas pumas in 1995 will make the recovery and genetic restoration of Florida panthers a classic study of an endangered species. Our estimates of the bottleneck size responsible for the loss of genetic variation in the Florida panther completes an unknown aspect of this account. ?? 2008 The Authors. Journal compilation ?? 2008 The Zoological Society of London.

Animal Conservation↗
USGS2008

Translocation and early post-release demography of endangered Laysan teal

In an attempt to reduce the high extinction risk inherent to small island populations, we translocated wild Laysan teal Anas laysanensis to a portion of its presumed prehistoric range. Most avian translocations lack the strategic post-release monitoring needed to assess early population establishment or failure. Therefore, we monitored the survival and reproduction of all founders, and their first-generation offspring using radio telemetry for 2 years after the first release. Forty-two Laysan teal were sourced directly from the only extant population on Laysan Island and transported 2 days by ship to Midway Atoll. All birds survived the translocation with nutritional and veterinary support, and spent between 4 and 14 days in captivity. Post-release survival of 42 founders was 0.857 (95% CI 0.86-0.99) during 2004-2006 or annualized 0.92 (95% CI 0.83-0.98). Seventeen of 18 founding hens attempted nesting in the first two breeding seasons. Fledgling success was 0.57 (95% CI 0.55-0.60) in 2005 and 0.63 (95% CI 0.62-0.64) in 2006. The effective founding female population (Ne) was 13. We applied these initial demographic rates to model population growth. The nascent population size increased to >100 after only 2 years post-release (?? = 1.73). If this growth rate continues, the size of the Midway population could surpass the source population before 2010. ?? 2008 The Authors. Journal compilation ?? 2008 The Zoological Society of London.

Animal Conservation↗
USGS2010

Invasive reptiles and amphibians: global perspectives and local solutions

In the annals of invasive species biology, higher taxa such asmammals, plants and insects have received the lion’s shareof research attention, largely because many of these invadershave demonstrated a remarkable ability to degrade ecosys-tems and cause economic harm. Interest in invasive reptilesand amphibians (collectively ‘herpetofauna’, colloquially‘herps’) has historically lagged but is now garnering in-creased scrutiny as a result of their escalating pace ofinvasion. A few herpetofaunal invaders have received con-siderable attention in scientific and popular accounts, in-cluding the brown treesnakeBoiga irregularison Guam,Burmese pythonPython molurusin Florida, Coqu´ıEleutherodactylus coquiin Hawaii and cane toadBufomarinusin Australia. However, relatively few are aware ofmany emerging and potentially injurious herpetofaunalinvaders, such as Nile monitorsVaranus niloticusin Flor-ida, common kingsnakesLampropeltis getulain the CanaryIslands, boa constrictorsBoa constrictoron Aruba andCozumel, or a variety of giant constrictor snakes in PuertoRico. For the vast majority of the most commonlyintroduced species, real or potential impacts to nativeecosystems or human economic interests are poorly under-stood and incompletely explored; major pathways of intro-duction have only recently been elucidated, and effectivemanagement interventions have been limited (Kraus, 2009).

Animal Conservation↗
USGS2011

Linking landscape characteristics to local grizzly bear abundance using multiple detection methods in a hierarchical model

Few studies link habitat to grizzly bear Ursus arctos abundance and these have not accounted for the variation in detection or spatial autocorrelation. We collected and genotyped bear hair in and around Glacier National Park in northwestern Montana during the summer of 2000. We developed a hierarchical Markov chain Monte Carlo model that extends the existing occupancy and count models by accounting for (1) spatially explicit variables that we hypothesized might influence abundance; (2) separate sub-models of detection probability for two distinct sampling methods (hair traps and rub trees) targeting different segments of the population; (3) covariates to explain variation in each sub-model of detection; (4) a conditional autoregressive term to account for spatial autocorrelation; (5) weights to identify most important variables. Road density and per cent mesic habitat best explained variation in female grizzly bear abundance; spatial autocorrelation was not supported. More female bears were predicted in places with lower road density and with more mesic habitat. Detection rates of females increased with rub tree sampling effort. Road density best explained variation in male grizzly bear abundance and spatial autocorrelation was supported. More male bears were predicted in areas of low road density. Detection rates of males increased with rub tree and hair trap sampling effort and decreased over the sampling period. We provide a new method to (1) incorporate multiple detection methods into hierarchical models of abundance; (2) determine whether spatial autocorrelation should be included in final models. Our results suggest that the influence of landscape variables is consistent between habitat selection and abundance in this system.

Animal Conservation↗
USGS2012

Bayesian shared frailty models for regional inference about wildlife survival

One can joke that 'exciting statistics' is an oxymoron, but it is neither a joke nor an exaggeration to say that these are exciting times to be involved in statistical ecology. As Halstead et al. 's (2012) paper nicely exemplifies, recently developed Bayesian analyses can now be used to extract insights from data using techniques that would have been unavailable to the ecological researcher just a decade ago. Some object to this, implying that the subjective priors of the Bayesian approach is the pathway to perdition (e.g. Lele & Dennis, 2009). It is reasonable to ask whether these new approaches are really giving us anything that we could not obtain with traditional tried-and-true frequentist approaches. I believe the answer is a clear yes.

Animal Conservation↗
USGS2012

Does translocation influence physiological stress in the desert tortoise?

Wildlife translocation is increasingly used to mitigate disturbances to animals or habitat due to human activities, yet little is known about the extent to which translocating animals causes stress. To understand the relationship between physiological stress and translocation, we conducted a multiyear study (2007–2009) using a population of desert tortoises (Gopherus agassizii) near Fort Irwin, California. Blood samples were collected from adult tortoises in three treatment groups (resident, translocated and control) for 1 year prior to and 2 years after translocation. Samples were analyzed by radioimmunoassay for plasma total corticosterone (CORT), a glucocorticoid hormone commonly associated with stress responses in reptiles. CORT values were analyzed in relation to potential covariates (animal sex, date, behavior, treatment, handling time, air temperature, home-range size, precipitation and annual plant production) among seasons and years. CORT values in males were higher than in females, and values for both varied monthly throughout the activity season and among years. Year and sex were strong predictors of CORT, and translocation explained little in terms of CORT. Based on these results, we conclude that translocation does not elicit a physiological stress response in desert tortoises.

California↗
USGS2026

The WOAH global wildlife health collaborating centre network (WOAH-WildNet): A coordinated and transformative approach to global wildlife health challenges

Wildlife health is integral to functioning, complex ecosystems [ 1 ], directly and indirectly influencing the health of people, animals, plants, and the environment [ 2 – 4 ]. Healthy wildlife populations are essential for ecosystem services and are at the heart of the One Health approach [ 3 , 4 ], which aims to sustainably balance and optimize the health of people, animals, and ecosystems through multisectoral and transdisciplinary collaboration [ 5 ]. Despite its importance, wildlife health initiatives often operate in silos, limiting capacity to address transboundary threats such as emerging diseases, pollution, and environmental changes. Anthropogenic changes, including habitat loss, degradation, fragmentation, and unsustainable harvesting, exacerbate wildlife health challenges [6–9]. These pressures disrupt species biology and alter host-pathogen dynamics [10–12], underscoring the importance of coordinated collective action in addressing harmful effects on the health of wild animals. While local conservation efforts are vital, long-term success in safeguarding biodiversity requires a unified, global network. For instance, without harmonized surveillance and response systems, individual institutions cannot effectively track pathogens across borders or share diagnostic capabilities. The World Organisation for Animal Health (WOAH) Collaborating Centre Network for Wildlife Health—WOAH-WildNet—was established to bridge these gaps. By fostering global collaboration, sharing resources, and enabling data exchange, WOAH-WildNet provides a transformative, systems-based approach to wildlife health, managing risks, and enhancing ecosystem resilience. Central to this mission is breaking down silos to promote intersectoral coordinated responses to complex wildlife health challenges.

PLOS Sustainability and Transformation↗
USGS2022

Priorities for translating goodwill between movement ecologists and conservation practitioners into effective collaboration

Addressing ongoing biodiversity loss requires collaboration between conservation scientists and practitioners. However, such collaboration has proved challenging. Despite the potential importance of tracking animal movements for conservation, reviews of the tracking literature have identified a gap between the academic discipline of movement ecology and its application to biodiversity conservation. Through structured conversations with movement ecologists and conservation practitioners, we aimed to understand whether the identified gap is also perceived in practice, and if so, what factors hamper collaboration and how these factors can be remediated. We found that both groups are motivated and willing to collaborate. However, because their motivations differ, there is potential for misunderstandings and miscommunications. In addition, external factors such as funder requirements, academic metrics, and journal scopes may limit the applicability of scientific results in a conservation setting. Potential solutions we identified included improved communication and better presentation of results, acknowledging each other's motivations and desired outputs, and adjustment of funder priorities. Addressing gaps between science and implementation can enhance collaboration and support conservation action to address the global biodiversity crisis more effectively.

Conservation Science and Practice↗
USGS2010

Vector control improves survival of three species of prairie dogs ( Cynomys ) in areas considered enzootic for plague

Plague causes periodic epizootics that decimate populations of prairie dogs (PDs) ( Cynomys ), but the means by which the causative bacterium ( Yersinia pestis ) persists between epizootics are poorly understood. Plague epizootics in PDs might arise as the result of introductions of Y. pestis from sources outside PD colonies. However, it remains possible that plague persists in PDs during interepizootic periods and is transmitted at low rates among highly susceptible individuals within and between their colonies. If this is true, application of vector control to reduce flea numbers might reduce mortality among PDs. To test whether vector control enhances PD survival in the absence of obvious plague epizootics, we reduced the numbers of fleas (vectors for Y. pestis ) 96–98% (1 month posttreatment) on 15 areas involving three species of PDs ( Cynomys leucurus , Cynomys parvidens in Utah, and Cynomys ludovicianus in Montana) during 2000–2004 using deltamethrin dust delivered into burrows as a pulicide. Even during years without epizootic plague, PD survival rates at dusted sites were 31–45% higher for adults and 2–34% higher for juveniles compared to survival rates at nondusted sites. Y. pestis was cultured from 49 of the 851 flea pools tested (6882 total fleas) and antibodies against Y. pestis were identified in serum samples from 40 of 2631 PDs. Although other explanations are possible, including transmission of other potentially fatal pathogens by fleas, ticks, or other ectoparasites, our results suggest that plague might be maintained indefinitely in PD populations in the absence of free epizootics and widespread mortality among these animals. If PDs and their fleas support enzootic cycles of plague transmission, there would be important implications for the conservation of these animals and other species.

Vector-Borne and Zoonotic Diseases↗