Search

Mid-sized mammals (i.e., mesomammals) fulfill important ecological roles, serving as essential scavengers, predators, pollinators, and seed dispersers in the ecosystems they inhabit. Consequently, declines in mesomammal populations have the potential to alter ecological processes and fundamentally change ecosystems. However, ecosystems characterized by high functional redundancy, where multiple species can fulfil similar ecological roles, may be less impacted by the loss of mesomammals and other vertebrates. The Greater Everglades Ecosystem in southern Florida is a historically biodiverse region that has recently been impacted by multiple anthropogenic threats, most notably the introduction of the Burmese python (Python molurus bivittatus). Since pythons became established, mesomammal populations have become greatly reduced. To assess whether these declines in mesomammals have affected two critical ecosystem functions—scavenging and frugivory—we conducted experiments in areas where mesomammals were present and absent. We did not observe significant differences in scavenging or frugivory efficiency in areas with and without mesomammals, but we did observe significant differences in the communities responsible for scavenging and frugivory. Despite the observed evidence of redundancy, the changes in community composition could potentially lead to indirect consequences on processes like seed dispersal and disease dynamics within this ecosystem, emphasizing the need for further study. [ABSTRACT FROM AUTHOR]

Invasive Burmese pythons (Python bivittatus) in the Everglades of Florida, United States, have drastically reduced populations of mammals, yet populations of some rodents appear unaffected by the invasion. To understand this pattern, we radio-tagged cotton rats (Sigmodon hispidus) in areas of high and low python occurrence densities (hereafter occurrence) and quantified the effects of python occurrence, seasonality, and sex on their survival and cause-specific mortality. Cotton rat survival was not influenced by difference in python occurrence (hazard ratio = 1.32, 95% CI = 0.77–2.26, P = 0.30). However, cotton rats were at greater risk from mortalities caused by mammals in areas of low python occurrence. In areas with elevated python occurrence, we attributed most cotton rat mortalities to birds of prey (48.6%) and reptiles (non-python = 24.3%, python = 16.2%). Where python occurrence was relatively low, we attributed cotton rat mortalities to native reptilian (28.6%), avian (35.7%), and mammalian predators (35.7%) with no python-related deaths. In total, pythons were responsible for 11.8% of all cotton rat mortalities. Finding no difference in the survival of cotton rats, despite differences in the causative agents of mortality, suggests that predation pressure from an invasive predator was compensatory for cotton rat population dynamics. This type of compensatory mortality is common for small mammals and helps explain why mammal communities in python-invaded portions of the Greater Everglades Ecosystem are increasingly dominated by cotton rats and other rodents. [ABSTRACT FROM AUTHOR]

Aim: Over the gradually warming Holocene, many species' range limits shifted poleward. However, some populations persisted in climate refugia, such as mountain tops. These climate relict populations are critical components of regional biodiversity, but their isolation renders them vulnerable to other threats, including changes in environmental conditions indirectly related to a warming global climate. We aimed to quantify the role of these indirect climate effects on Florida saltmarsh vole (Microtus pennsylvannicus dukecampbelli; hereafter: "vole"), a poorly understood, endangered climate relict. Location: The Gulf of Mexico between Sopchoppy and Pine Island, Florida, USA. Methods: We surveyed for voles broadly across their potential range using camera traps and modelled the relationships between vole occurrence and two climate‐driven threats: hurricane storm surge and shifting vegetation communities. We quantified these threats using both field‐collected and remotely sensed data at fine (3‐m) and coarse (150‐m) spatial scales. Results: Though seemingly suitable habitat exists outside their previously known range, voles appeared restricted to the outer marshes between the Suwannee and Withlacoochee Rivers. Within this range, the sites we surveyed had shorter grass heights, greater Distichils spp. cover, greater potential habitat within 150 m, and were less vulnerable to inundation when compared to sites outside of their range. Main conclusions: The complex and varied ways in which climate change alters the physical environment can expose small‐ranging species to multiple threats. Even climate relicts, which have endured historical changes in the global climate, may fail to cope with the rapid pace of anthropogenic climate change. [ABSTRACT FROM AUTHOR]

The composition of wildlife communities can have strong effects on transmission of zoonotic vector-borne pathogens, with more diverse communities often supporting lower infection prevalence in vectors (dilution effect). The introduced Burmese python, Python bivittatus, is eliminating large and medium-sized mammals throughout southern Florida, USA, impacting local communities and the ecology of zoonotic pathogens. We investigated invasive predator-mediated impacts on ecology of Everglades virus (EVEV), a zoonotic pathogen endemic to Florida that circulates in mosquito-rodent cycle. Using binomial generalized linear mixed effects models of field data at areas of high and low python densities, we show that increasing diversity of dilution host (non-rodent mammals) is associated with decreasing blood meals on amplifying hosts (cotton rats), and that increasing cotton rat host use is associated with increasing EVEV infection in vector mosquitoes. The Burmese python has caused a dramatic decrease in mammal diversity in southern Florida, which has shifted vector host use towards EVEV amplifying hosts (rodents), resulting in an indirect increase in EVEV infection prevalence in vector mosquitoes, putatively elevating human transmission risk. Our results indicate that an invasive predator can impact wildlife communities in ways that indirectly affect human health, highlighting the need for conserving biological diversity and natural communities. Burkett-Cadena et al. use a combination of field survey methods, citizen science data, and molecular analysis to determine how the invasive Burmese python distribution affects mammal host use and virus infection by vector mosquitoes. This study shows how python predation has shifted vector host use towards virus-amplifying rodents, increasing virus infection rates, and illustrates the indirect effects an invasive species has on the disease ecology of wildlife and public health. [ABSTRACT FROM AUTHOR]

Climate change will alter natural areas on a global scale within the next century. In areas vulnerable to climate change, scientists are regularly challenged to justify the resources needed for research and conservation. We face what may seem like a losing battle, especially in low-lying coastal areas where sea-level rise is predicted to severely degrade or destroy many ecosystems. Using sea-level rise in the low-elevation state of Florida, USA, as a case study, we argue that it is critical to remain engaged in the research, restoration, and conservation of natural areas threatened by climate change for as long as possible. These areas will continue to provide invaluable ecological and societal benefits. Additionally, uncertainty surrounding climate change forecasts and their ecological impact leaves room for optimism, research, and actions that are necessary for developing adaptation plans and mitigating further sea-level rise and other consequences of climate change. We urge scientists and particularly students beginning their careers not to forego research and conservation efforts of these imperiled lands but to face this unprecedented challenge with determination, creativity, and solution-based strategies. [ABSTRACT FROM AUTHOR]

Live‐trapping is important for studying wildlife. In 2016 at Ordway‐Swisher Biological Station in Melrose, Florida, USA, we tested the efficacy of a modified pitfall trap designed to safely and effectively capture southeastern pocket gophers (Geomys pinetis). When compared with the commonly used Hart trap, the new design captured 92% of all live captures of southeastern pocket gophers. The novel trap has a simple, passive design that eliminates dependence on trigger mechanisms, allows for safe overnight trapping, and reduces on‐site hours by researchers. The new trap adds to the few live traps available to study ecologically important and understudied fossorial species. © 2019 The Wildlife Society. We developed and tested the efficacy of a modified pitfall trap designed to safely and effectively capture southeastern pocket gophers. We found the new trap design provides an efficient, safe, and flexible option for live‐trapping southeastern pocket gophers, while reducing labor demands associated with maintaining and checking traps. [ABSTRACT FROM AUTHOR]

For polytypic mammal species, biogeographic barriers including rivers have often been used to delineate taxonomic units under the assumption that barriers have structured their distribution. We tested the importance of major riverine systems as biogeographic barriers in fox squirrels (Sciurus niger) across the state of Florida, where 4 currently recognized subspecies are delineated at major rivers. We also explored whether phylogeographic structure may be limited to ecologically divergent subspecies, specifically between S. n. avicennia and S. n. shermani. Using a multilocus approach to examine diversity, we found that restricted gene flow was only present between S. n. avicennia, located south of the Caloosahatchee River in south Florida, and the rest of S. niger, which is widespread across the state. Mitochondrial DNA revealed that 2 divergent groups of haplotypes are present and widespread across Florida, thus supporting the hypothesis that fox squirrels persisted in multiple refugia during the Pleistocene, and that S. n. avicennia diverged ecologically from other populations of fox squirrels relatively recently. This was supported by isolation with migration models that indicated matrilineal isolation since the onset of divergence between S. n. avicennia and S. n. shermani, which corresponds to the onset of ecological divergence in south Florida during the early Holocene. Isolation by distance at 8 microsatellite loci from the western panhandle to the southern end of the peninsula was significant only when S. n. avicennia was included; however, this was due to the hierarchical genetic patterns identified between S. n. avicennia and the other subspecies as determined by Bayesian clustering, and not due to spatially restricted dispersal. We postulate that the demographic isolation of S. n. avicennia is the result of adaptation to the unique ecological conditions of south Florida. [ABSTRACT FROM AUTHOR]

Understanding the distributions and environmental associations of rare species is a critical 1st step in their conservation and management. Federally endangered Florida bonneted bats (Eumops floridanus) are endemic to southern Florida and are believed to have one of the most limited geographic distributions of any bat in the United States. We conducted a large-scale acoustic survey of 330 points spread across approximately 38,000 km2 over a 2-year period and used a hierarchical Bayesian approach accounting for imperfect detection to model the distribution and environmental associations of the Florida bonneted bat. Bat occupancy was negatively correlated with the amount of developed land within 5 km of the sampling point and positively correlated with the amount of crop-based agriculture within 5 km of the sampling point. Bat occupancy probabilities increased with the 30- year mean for minimum spring temperature and levels of annual precipitation, and decreased with the 30-year mean for levels of spring precipitation. Bat detection was positively influenced by Julian date and minimum temperature of the survey night. This study offers new insight into the habitat use of this endangered species. Results confirm that predicted changes in land cover and climate will be threats to the Florida bonneted bat. [ABSTRACT FROM AUTHOR]

Urbanization and other land cover changes have been particularly detrimental to wetlands throughout the planet. One wetland specialist that may be sensitive to land cover changes surrounding wetlands is the round-tailed muskrat ( Neofiber alleni; hereafter RTM). The RTM is a wetland obligate rodent that appears to have declined over the last half century and is a species of concern in Florida, where it is a near endemic. To determine if urbanization or other land cover influenced the distribution of RTMs we took a multi-scaled approach to examine the occurrence of RTMs and their associated vegetation in North-Central Florida. We detected RTMs on 19 of 72 sample plots and used a Classification And Regression Tree (CART) to determine that dogfennel ( Eupatorium capillifolium) was negatively associated with RTMs and maidencane ( Panicum hemitomon) was positively associated with their occurrence on sampling plots. Examining the influence of landscape composition for 2 km surrounding our plots we found that RTM occurrence was negatively related to urban land cover. Further, we found that dogfennel increased and maidencane decreased as urbanization increased in the surrounding landscape. Our research suggests that conservation of RTMs and their associated vegetation should focus on limiting urban sprawl at least within 2 km of wetlands. [ABSTRACT FROM AUTHOR]

Estimates of the demographic information necessary to project future population changes are lacking for the endangered Florida bonneted bat (Eumops floridanus). We conducted a mark-recapture study on a population of bonneted bats using bat houses on Babcock-Webb Wildlife Management Area, Charlotte County, Florida, United States. We captured 175 individuals during 6 capture events that recurred every 4 months between April 2014 and December 2015. We implanted passive integrated transponder tags in all captured individuals and used open population capture-recapture models to estimate apparent survival, recruitment, and population growth rates of this population. Key model assumptions were evaluated via simulation. Apparent survival estimates were lower than estimates for most other bat species. Juveniles had lower annual apparent survival (φ = 0.09 [95% confidence interval [CI]: 0.04-0.19]) than adults (φ = 0.46 [0.36-0.57]). Recruitment was constant between sexes and over time (f = 0.48 [0.23-0.75]). Apparent survival had a greater influence on population growth rates than did recruitment, indicating that low survival rates could lead to population declines. Models of population growth rates showed a stable to potentially declining population trend, although the trend was highly variable, with estimates ranging from large declines to increases (λ = 0.89 [0.65-1.22]). Any potential declines in the population may be more pronounced in adult females (λ = 0.81 [0.58-1.13] compared to λ = 1.11 [0.74-1.69] for males); however, the 95% CI of the population growth rate included 1, indicating a need for additional research to derive more precise estimates. This work represents the 1st estimates of demographic parameters of this endangered species. [ABSTRACT FROM AUTHOR]

ABSTRACT Fox squirrels ( Sciurus niger) in the southeastern United States have been difficult to survey because of their sparse distribution, large home ranges, and low capture success. Remote cameras have proven to be an effective tool for surveying larger mammals, including identifying individual animals using their unique markings. To test whether cameras can be used to identify individual fox squirrels in the southeastern United States, we 1) inspected digital photographs of fox squirrels; 2) identified variable pelage features for individual identification; 3) tested the ability of wildlife students and professionals to identify individuals; and 4) evaluated whether training improved participants' ability to identify individuals. We found that fox squirrels could be individually identified using a combination of sex and 10 variable pelage features, including the color morph, presence of an eye ring, distribution of white on the rostrum, and facial markings. In total, we developed ≥25,920 possible combinations of features to identify southeastern fox squirrels. We found survey participants were capable of identifying fox squirrels without training, but their average ability to do so increased significantly from 73.6% to 80.3% after training ( t[df = 106] = 5.068, P < 0.001). The results from this study demonstrate that camera-trapping, particularly when combined with training that focuses on which features vary between individuals, provides an alternative method to live-trapping for population-level studies of southeastern fox squirrels. © 2015 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT Camera traps have increased our knowledge of animal distribution, activity, and behavior, but they are rarely used for small mammal research. This is likely because there are few techniques to that allow for species identification, reduce disturbance of bait from non-target animals (e.g., raccoon [ Procyon lotor]), and that can be used in all environments. In this paper we present a small mammal camera-trapping methodology, the Hunt trap, which was designed to 1) work in tidal environments, 2) eliminate capture myopathy, 3) allow for successful identification of small mammal species, and 4) allow for continued trapping after disturbance by non-target species. We tested the Hunt trap in the Lower Suwannee National Wildlife Refuge, Florida, USA, during February 2012 to February 2013. Live traps are still the best option when individuals must be physically captured for marking, radiotagging, demographic studies, or physiological assessments. However, if such data are not required, the Hunt trap design is an excellent technique to monitor species diversity, community composition, habitat selection, and distribution with efficiency and minimal effort. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

The endangered Florida Key deer (Odocoileus virginianus clavium) is endemic to the Lower Florida Keys. In recent years, habitat fragmentation and restricted dispersal have resulted in small, isolated herds on some islands. Recovery biologists proposed translocations to increase the island herds that had declined or remained low; however, efficacy of Key deer translocations had yet to be evaluated. Our objective was to evaluate survival, ranges, reproduction, and dispersal of translocated deer. During 2003-2005, we translocated 39 adult or yearling deer to Sugarloaf (approx. 19 km from trap site; 10 M, 14 F) and Cudjoe (approx. 15 km from trap site; 6 M, 9 F) keys. We kept deer in large, high-fenced holding pens (Sugarloaf = 7.7 ha, Cudjoe = 10.7 ha) on the destination islands for 3-6 months (i.e., soft release). We observed low mortality (n=6 mortalities) of translocated deer with average annual survival (S) of 0.796 for both sexes. We found translocated deer had larger seasonal ranges than did resident deer (i.e., those located on Big Pine and No Name keys). In evaluating effects of acclimation period on ranges and dispersal, we found no difference in 95% ranges or 50% core areas ≤4 month postrelease versus 4-8 months postrelease. We found, however, postrelease dispersal distances were dependent on time kept in pen. Only 2 of 39 (5%) translocated deer left the destination islands by the end of the study. With high survival and low dispersal indicating success, we credit soft release translocation in establishing deer herds on Sugarloaf and Cudjoe keys. Our data support translocations as an effective strategy for creating sustainable outer-island Key deer herds. [ABSTRACT FROM AUTHOR]