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We conducted the first assessment of small mammal diversity for three unusually low-elevation stands of Rocky Mountain juniper, known locally as swamp cedars, in White Pine County, Nevada, between 24 May and 1 June 2016. These small patches of woodland add considerable habitat diversity to the expansive low-elevation shrublands in Spring Valley and White River Valley. Spring Valley stands supported unique small mammal communities, most notably through the occurrence of pinyon mice (Peromyscus truei). In contrast, no pinyon mice were detected in the much sparser and smaller White River Valley stand. Instead, it harbored typical Great Basin shrubland mammals. Our results suggest the novel communities in Spring Valley swamp cedar habitats may be threatened by planned groundwater removal.
We investigate the taxonomic status of the Texas garter snake, Thamnophis sirtalis annectens, a species of greatest conservation need in Texas. We broadly test the hypothesis that an integrative approach to species conservation has greater utility than using only a single data type (e.g., molecular, morphological, behavioral, or ecological) by demonstrating how ecological niche modeling and molecular genetics can be used synergistically to resolve taxonomic classifications. Using a phylogenetic analysis based on molecular data, we found that some putative T. s. annectens specimens actually represent a co-occurring subspecies (the red-sided garter snake, Thamnophis sirtalis parietalis), which is not of conservation concern. However, both T. s. annectens and T. s. parietalis are genetically distinctive from another co-occurring subspecies, Thamnophis sirtalis sirtalis, and the ecological distinctness of T. s. annectens from T. s. parietalis suggests that T. s. annectens is, in fact, a distinct evolutionary subunit. Only when both genetic and ecological information were included was the distinctiveness of T. s. annectens apparent, thus highlighting the need for integrative approaches in conservation management regardless of the taxa in question.
The objective of this study was to obtain information on the food of the free-tailed bats under the Congress Avenue Bridge in Austin, Texas, because these bats are so well known. We collected guano there on three occasions. The dominant foods in October 1991 were moths, beetles (particularly leaf and ground beetles), and true bugs (particularly leafhoppers and chinch bugs). In September 2013, the major foods were moths, flies (particularly crane flies), true bugs (particularly leafhoppers), and beetles (particularly leaf beetles). In 1991 few bats remained under this bridge in winter, but by 2012–2013, many of the bats remained all winter. In winter, flies and moths were the dominant foods.
A 1993–1997 study of the southern rubber boa (Charina bottae umbratica) in the San Bernardino Mountains identified the local population as dwarf forms. We identified four additional populations of northern rubber boa (C. b. bottae) that are also of this dwarf phenotype. All dwarf-morph populations cluster together in southern California. We suggest other dwarf populations occur in the same region but lack adequate samples for verification.
Pelagic-broadcast spawning riverine fishes (pelagophils), species that produce eggs and larvae that drift laterally and downstream with the current, are declining throughout their native ranges in North America. Persistence and recolonization of pelagophils require upstream dispersal of later life stages; however, observations of dispersal are limited. We performed a mark–recapture study of stocked Rio Grande silvery minnow (Hybognathus amarus) in the Middle Rio Grande, New Mexico, during 2002 to assess dispersal of this imperiled pelagophil. Approximately 11,500 hatchery-reared Rio Grande silvery minnows marked with a fluorescent-colored visible implant elastomer were released by the Southwestern Native Aquatic and Technology Center (Dexter, New Mexico) at two locations in the 94.1-km San Acacia Reach of the Middle Rio Grande in January 2002. We recaptured 66 marked individuals (0.57%) through May 2002, upstream and downstream of both release locations. Distances traveled ranged from 0.0 to 25.2 km (0.3 – 5.3 km [mean – SD]), and movement rates ranged from 0.0 to 220 m/day (19 – 63 m/day). We recaptured two individuals >20 km upstream of their release location. Overall, stocked fish tended to disperse downstream. We often recaptured marked fish with wild conspecifics, implying repatriation of a portion of stocked fish. Gravid and spent marked female Rio Grande silvery minnows recaptured during April and May indicated that stocked fish were reproductively active concurrent with the wild population. Our study documented long-distance upstream dispersal of stocked Rio Grande silvery minnows and thus has conservation implications for restoring connectivity in the Middle Rio Grande to support the recovery of this federally listed endangered species.
Scat of meso-mammals provides nutrients to cave-obligate species. If there are too few nutrient inputs, cave-obligate species have no resources, but too much and caves are invaded by terrestrial species. Our goal for this project was to determine what combination of variables most influence meso-mammal cave use by building a multinomial regression model using data collected from cave entrances in central Texas. Variables of importance in our model relate to cave accessibility, including the raccoons' (Procyon lotor) and Virginia opossums' (Didelphis virginiana) greater dexterity, and the added bulk from the North American porcupine's (Erethizon dorsatum) quills. Our model can be used to predict and manage meso-mammal cave use in central Texas. This will be especially useful in this region because North American porcupine have only recently expanded their range into central Texas and their prolific nutrient inputs, previously absent from the ecosystem, could endanger cave-obligate species.
The golden-cheeked warbler (Setophaga chrysoparia) is an endangered songbird whose eastern breeding range is undergoing rapid urbanization and concomitant changes to the predator community. We document the first observation of a golden-cheeked warbler nest depredated by the range-expanding blue jay (Cyanocitta cristata) to highlight the potential impacts of warbler nest predation by corvids in urban landscapes.
Urbanization creates new ecological landscapes that may alter the behavior of animals occupying them. Northern cardinals (Cardinalis cardinalis) inhabit both urban and rural habitats in northeastern Oklahoma, where food availability, predator type, and plant phenology can differ. Relative to birds in rural habitats, cardinals in urban environments formed smaller nonbreeding groups during winter, began singing earlier in the spring and responded more strongly to temperature, and occupied territories at higher densities. These results are in accord with the hypothesized greater food availability (provided by bird feeders), larger numbers of mammalian predators (domestic cats), and earlier availability of nesting sites (through earlier plant leaf-out because of the heat island effect) in urban areas. Urbanization has led to relatively dramatic changes in northern cardinal social behavior and singing phenology.
Harris County, Texas, is home to both species of North American night herons, black-crowned (Nycticorax nycticorax) and yellow-crowned (Nycticorax violacea). Both species are carnivorous, consuming a wide variety of vertebrates and invertebrates, although records of either species consuming bats have not been reported. During studies at a local colony of free-tailed bats living under the Waugh Bridge (Houston, Texas), significant feeding behavior observations of both herons were made. Both species were recorded foraging on this urban bat population, utilizing different methods for acquiring the bats as prey. Some of the behaviors are novel as well and are also discussed.
The stable carbon and oxygen isotopic ratios present in dentine and tooth enamel from one Mixotoxodon larensis specimen from Hihuitlán, Michoacán, México, were analyzed. Similar to other specimens in Honduras and Panama, δ13C and δ18O values showed that this individual had a mixed diet and lived in a forested zone.
The occurrence of five juvenile nine-banded armadillos (Dasypus novemcinctus) is reported from a trail-camera picture. This photo was taken as part of a larger study investigating the dynamics of a medium-sized mammal community in an urban area. While quadruplets through polyembryony are the normal number of offspring born in a litter, the occurrence of more than four juveniles with an adult is documented along with a snapshot of the interaction between two of the juveniles.
Invasive species are a major threat to the persistence of native species, particularly in systems where ephemeral aquatic habitats have been replaced by permanent water and predators, such as fish, have been introduced. Within the Altar Valley, Arizona, the invasive American bullfrog, Lithobates catesbeianus (formerly Rana catesbeianus), has been successfully eradicated to help recover Chiricahua leopard frogs (Lithobates chiricahuensis). However, other nonnative predators including sunfish (Lepomis) are present in some permanent water bodies. During four consecutive years (2014–2017), we detected both the federally threatened Chiricahua leopard frog and sunfish at one permanent water body in the Altar Valley. This suggests that despite the potential negative effect of predatory fish on amphibians, there may be conditions where the Chiricahua leopard frog can co-occur with this nonnative predator. A better understanding of rare situations of co-occurrence with nonnative predators may contribute to our understanding of why co-occurrence happens in some, but not all, systems and whether conservation strategies can be developed in situations where eradication of nonnative predators is infeasible.