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Myotis leibii (Eastern Small-footed Bat) is a rare species in eastern North America that is threatened by habitat loss and white-nose syndrome. Although rare, this species cannot be adequately evaluated for listing on the Endangered Species Act because of data deficiencies, including about its distribution and roost habitat. Our objectives were to document the distribution of Eastern Small-footed Bats and determine landscape and local characteristics that influence their probability of presence in the mountains of west-central Arkansas. Using acoustic monitoring, visual searches of rock formations, and mist-netting, we found that presence of Eastern Small-footed Bats was more likely in regions with talus slopes and nearby forest cover. These features may benefit the species by providing abundant options for roost switching, unique thermal properties, and short distances to foraging habitat.
Pituophis ruthveni (Louisiana Pine Snake) occurs in parts of western Louisiana and eastern Texas and was recently listed as a threatened species under the Endangered Species Act. It is considered a diet specialist because it mostly feeds upon Geomys breviceps (Baird's Pocket Gopher), which make up ∼75% of its estimated total prey biomass. Diet specialization is rare among vertebrates. One factor that can influence dietary diversity is the availability and abundance of prey items. To gain more insight on the Louisiana Pine Snake's diet, we sampled terrestrial and subterranean small mammals across 3 study sites within the range of this snake species in Louisiana to determine their relative abundance and availability. We compared these results to diet studies of the Louisiana Pine Snake to determine if any small mammal species were consumed more often than expected. The total of 59 small mammals captured consisted of Baird's Pocket Gopher, Sigmodon hispidus (Hispid Cotton Rat), Peromyscus spp. (deer mice), and Reithrodontomys spp. (harvest mice). Baird's Pocket Gopher had significantly higher relative abundances and biomass than terrestrial small mammals. When compared to proportions of actual consumed prey species, the Louisiana Pine Snake preyed upon Baird's Pocket Gopher significantly more than expected based on their availability in the environment. Finally, Chesson's prey selection index determined that the Louisiana Pine Snake positively selected Baird's Pocket Gopher, while the other species were either randomly or negatively selected. The results of this research provide some insight into the factors affecting the diet choices of the Louisiana Pine Snake.
Populations of some cave-hibernating bats have undergone declines in recent years due to an introduced fungus (Pseudogymnoascus destructans) that causes the disease white-nose syndrome (WNS), which is often fatal to bats during hibernation. Unprecedented declines in cave-hibernating species have the potential to change community composition via numerous mechanisms, including competitive release. We trapped bats for 6 years in the Ouachita Mountains of Arkansas prior to the arrival of WNS in the region and compared capture rates of 7 species to capture rates collected in 2020–2021 after WNS establishment. We found a 98% decline in Myotis septentrionalis (Northern Long-eared Bat) and a 77% decline in Perimyotis subflavus (Tricolored Bat) after WNS became prevalent. Nycticeius humeralis (Evening Bat) captures increased by 220% after WNS. Capture rates of Eptesicus fuscus (Big Brown Bat) increased by 100%, but this increase was not significant. We also found no significant differences in captures rates for Lasiurus borealis (Eastern Red Bat), Lasiurus seminolus (Seminole Bat), and Lasiurus cinereus (Hoary Bat) after the arrival of WNS. Our results indicate that the forest bat community of the Ouachita Mountains has been altered since the arrival of WNS in 2012, but it is unknown if these changes are permanent or if species will decline further or recover via adaptive or genetic changes in their populations in the future.
Winter Bird Population Studies (WBPS) were initiated in 1948. The recommended minimum number of surveys for WBPS plots has been 8, but examination of the influence of the number of surveys on counts of individual species on WBPS plots has been restricted to only a few types of forested habitats in eastern North America. This study documents that 10 surveys, not 8, were required to produce stable mean counts of most common and some uncommon species on a WBPS plot in an open to semi-open, urban habitat (central business district of Rockingham, NC). However, more studies are needed to produce stronger inferences about the minimum number of surveys required for counts of individual species on WBPS plots in other urban and non-urban habitat types. Until our knowledge is refined, observers should strongly consider conducting a minimum of 10 surveys on WBPS plots in urban habitat types.
We performed systematic surveys for members of the Eurycea quadridigitata (Dwarf Salamander) complex in Georgia to determine the distribution of member species. Over 409 person-hours of search effort, we sampled 211 locations in 38 counties, detecting 108 individuals, including many that bridge substantial distribution gaps. Molecular data document Georgia specimens belong to 2 species, E. hillisi and E. quadridigitata. No specimens attributable to E. chamberlaini were found in Georgia, indicating this species has a distribution restricted to South and North Carolina. We used color patterns and measures of body size and shape of specimens identified by molecular methods to separate 4 species of 4-toed Eurycea from the Coastal Plain of Alabama, Florida, Georgia, South Carolina, and North Carolina. Large body size and the presence of melanophores across the chin and surrounding the cloaca separated E. quadridigitata from all others. Additionally, E. sphagnicola and E. quadridigitata possessed dark sides to the body and tail, with these features being disrupted by irregular white stripes or spots. In contrast, E. chamberlaini and E. hillisi possessed light sides to the body and tail that lacked irregular white stripes. Small body size distinguished E. sphagnicola from E. quadridigitata, but no feature distinguished E. chamberlaini from E. hillisi.
Etheostoma pallididorsum (Paleback Darter) is endemic to the headwater reaches of 2 river systems in the Ouachita Highlands of Arkansas. Records of low abundance and habitat alterations have resulted in the species' imperiled conservation status and being petitioned for federal listing under the Endangered Species Act. The objective of this study was to conduct seasonal surveys across the Paleback Darter's distribution to better characterize growth, spawning patterns, and mortality using the seasonal von Bertalanffy statistic with an optimized electronic length frequency analysis (ELEFAN), as well as assess sex ratios throughout a calendar year to better inform future conservation management decisions for the species. We established seasonal survey collection sites at 4 localities and sampled with a backpack electrofishing unit and dip nets from January 2016 to October 2017. The study indicated relatively high abundance, based on catch per unit effort (CPUE), across all sampled localities throughout the duration of the study, with representation of the entire population from 3 age classes: 0, 1, and 2. Growth and coarse spawning patterns, based on the seasonal von Bertalanffy statistic, were comparable between the populations, suggesting similar and stable environmental factors throughout the distribution. Lastly, there was evidence of multiple spawn events occurring during winter and late spring or early summer that has not been documented for this species, warranting additional research. Collectively, this study, though narrow in scope and with limited data, suggest that the Paleback Darter populations assessed are not impaired. The endemic status and narrowly fragmented distribution of the Paleback Darter, however, still renders this species vulnerable to extirpation or extinction by stochastic events.
Chad M. Harrison, Joseph Colbert, Collin J. Richter, Preston J. McDonald, Lauren M. Trumbull, Schyler A. Ellsworth, Michael P. Hogan, Darin R. Rokyta, Mark J. Margres
On 17 June 2019, we collected a unique juvenile rattlesnake from a wildlife response call on Jekyll Island State Park, GA. The snake exhibited intermediate color patterns and gross anatomical features suggesting potential hybridization between Crotalus horridus (Canebrake/Timber Rattlesnake) and Crotalus adamanteus (Eastern Diamondback Rattlesnake). Using mitochondrial and nuclear genetic sequencing, venom analyses, and morphological characteristics to test that hypothesis, we were able to verify that this specimen represents only the second documented observation of natural hybridization between C. adamanteus and C. horridus and the first reported with multiple lines of evidence sufficient for confirmation. Surprisingly, genetic analyses found evidence of previous introgression between these species, suggesting hybridization may not be a rare occurrence in the area (and perhaps specifically on Jekyll Island). We will continue to monitor the hybrid individual via radio-telemetry to assess its survival and any subsequent F2 hybridization reproduction events.
Natural field observations of salamander predation are uncommon, in some cases limiting the ability of scientists to study the evolution of toxicity, aposematism, and mimicry in these amphibians. Here, we document field observations of recently depredated salamanders: 1 Pseudotriton ruber (Red Salamander) and 2 Gyrinophilus porphyriticus (Spring Salamander), members of a putative Müllerian mimetic complex involving Notophthalmus viridescens (Eastern Newt). We used molecular methods to identify the likely avian predator of the Spring Salamanders and underscore the opportunities for future research enabled by the pairing of traditional natural history with modern molecular techniques.
Florida is renowned for its non-native reptile communities, with 2 such pervasive nonnative species including the apex predator Python bivittatus (Burmese Python) and the herbivorous Iguana iguana (Green Iguana) that showcase the spectrum of their ecological impacts. Both species have recently expanded into the Florida Keys. We used a camera trap to survey a radio-tagged Burmese Python and documented both non-native reptiles cohabitating in the active, natural stick-nest of an endangered rodent, Neotoma floridana smalli (Key Largo Woodrat), in Dagny Johnson Botanical State Park, Key Largo, FL. An additional nest visitor included Peromyscus gossypinus allapaticola (Key Largo Cotton Mouse), another endangered rodent and potential prey for the python. Camera placement allowed us to detect both rodents on the exterior of the stick-nest. The presence of the Key Largo Woodrat and Key Largo Cotton Mouse at the nest warrant continued monitoring of the 2 reptile species and their interactions with the endangered small mammals as their presence becomes more common in the Florida Keys.
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