Lora L. Smith

Bird assemblage response to restoration of fire‐suppressed longleaf pine sandhills

The ecological restoration of fire-suppressed habitats may require a multifaceted approach. Removal of hardwood trees together with reintroduction of fire has been suggested as a method of restoring fire-suppressed longleaf pine (Pinus palustris) forests; however, this strategy, although widespread, has not been evaluated on large spatial and temporal scales. We used a landscape-scale experimental design to examine how bird assemblages in fire-suppressed longleaf pine sandhills responded to fire alone or fire following mechanical removal or herbicide application to reduce hardwood levels. Individual treatments were compared to fire-suppressed controls and reference sites. After initial treatment, all sites were managed with prescribed fire, on an approximately two- to three-year interval, for over a decade. Nonmetric multidimensional scaling ordinations suggested that avian assemblages on sites that experienced any form of hardwood removal differed from assemblages on both fire-suppressed sites and reference sites 3-4 years after treatment (i.e., early posttreatment). After >10 years of prescribed burning on all sites (i.e., late posttreatment), only assemblages at sites treated with herbicide were indistinguishable from assemblages at reference sites. By the end of the study, individual species that were once indicators of reference sites no longer contributed to making reference sites unique. Occupancy modeling of these indicator species also demonstrated increasing similarity across treatments over time. Overall, although we documented long-term and variable assemblage-level change, our results indicate occupancy for birds considered longleaf pine specialists was similar at treatment and reference sites after over a decade of prescribed burning, regardless of initial method of hardwood removal. In other words, based on the response of species highly associated with the habitat, we found no justification for the added cost and effort of fire surrogates; fire alone was sufficient to restore these species.

Landscape-level influences of terrestrial snake occupancy within the southeastern United States.

Habitat loss and degradation are thought to be the primary drivers of species extirpations, but for many species we have little information regarding specific habitats that influence occupancy. Snakes are of conservation concern throughout North America, but effective management and conservation are hindered by a lack of basic natural history information and the small number of large-scale studies designed to assess general population trends. To address this information gap, we compiled detection/nondetection data for 13 large terrestrial species from 449 traps located across the southeastern United States, and we characterized the land cover surrounding each trap at multiple spatial scales (250-, 500-, and 1000-m buffers). We used occupancy modeling, while accounting for heterogeneity in detection probability, to identify habitat variables that were influential in determining the presence of a particular species. We evaluated 12 competing models for each species, representing various hypotheses pertaining to important habitat features for terrestrial snakes. Overall, considerable interspecific variation existed in important habitat variables and relevant spatial scales. For example, kingsnakes (Lampropeltis getula) were negatively associated with evergreen forests, whereas Louisiana pinesnake (Pituophis ruthveni) occupancy increased with increasing coverage of this forest type. Some species were positively associated with grassland and scrub/shrub (e.g., Slowinskis cornsnake, Elaphe slowinskii) whereas others, (e.g., copperhead, Agkistrodon contortrix, and eastern diamond-backed rattlesnake, Crotalus adamanteus) were positively associated with forested habitats. Although the species that we studied may persist in varied landscapes other than those we identified as important, our data were collected in relatively undeveloped areas. Thus, our findings may be relevant when generating conservation plans or restoration goals. Maintaining or restoring landscapes that are most consistent with the ancestral habitat preferences of terrestrial snake assemblages will require a diverse habitat matrix over large spatial scales.

Snake co‐occurrence patterns are best explained by habitat and hypothesized effects of interspecific interactions

Snakes often occur in species-rich assemblages, and sympatry is thought to be facilitated primarily by low diet overlap, not interspecific interactions. We selected, a priori, three species pairs consisting of species that are morphologically and taxonomically similar and may therefore be likely to engage in interspecific, consumptive competition. We then examined a large-scale database of snake detection/nondetection data and used occupancy modelling to determine whether these species occur together more or less frequently than expected by chance while accounting for variation in detection probability among species and incorporating important habitat categories in the models. For some snakes, we obtained evidence that the probabilities that habitat patches are used are influenced by the presence of potentially competing congeneric species. Specifically, timber rattlesnakes (Crotalus horridus) were less likely than expected by chance to use areas that also contained eastern diamond-backed rattlesnakes (Crotalus adamanteus) when the proportion of evergreen forest was relatively high. Otherwise, they occurred together more often than expected by chance. Complex relationships were revealed between habitat use, detection probabilities and occupancy probabilities of North American racers (Coluber constrictor) and coachwhips (Coluber flagellum) that indicated the probability of competitive exclusion increased with increasing area of grassland habitat, although there was some model uncertainty. Cornsnakes (Pantherophis guttatus or Pantherophis slowinskii) and ratsnakes (Pantherophis alleghaniensis, Pantherophis spiloides, or Pantherophis obsoletus) exhibited differences in habitat selection, but we obtained no evidence that patterns of use for this species pair were influenced by current interspecific interactions. Overall, our results are consistent with the hypothesis that competitive interactions influence snake assemblage composition; the strength of these effects was affected by landscape-scale habitat features. Furthermore, we suggest that current interspecific interactions may influence snake occupancy, challenging the paradigm that contemporary patterns of snake co-occurrence are largely a function of diet partitioning that arose over evolutionary time.

The Vertebrate Fauna of Ichauway, Baker County, GA

Abstract Less than 4% of the once extensive Pinus palustris (longleaf pine) ecosystem remains today. Although longleaf pine habitats are recognized for their high species diversity, few published accounts document the vertebrate faunas of remaining tracts. Here we report on the vertebrate species richness of Ichauway, an 11,300-ha property in Baker County, GA. The property includes ca. 7300 ha of longleaf pine with native ground cover, along with more than 30 seasonal wetlands and ca. 45 km of riparian habitat associated with Ichawaynochaway Creek, Big Cypress Creek, and the Flint River. The fauna includes 61 species of fish, 31 amphibians, 53 reptiles, 191 birds, and 41 mammals. Despite the relative isolation of the property from other natural ecosystems, the vertebrate fauna of Ichauway is remarkably diverse and may offer an example of reference conditions to guide restoration of longleaf pine forests, associated seasonal wetlands, and riparian areas elsewhere in the southeastern US.

A method for preventing flying squirrel mortality in PVC pipe treefrog refugia

Wildlife Society Bulletin 2004, 32(4):1313–1315 Peer edited Amphibian population declines (Blaustein and Wake 1990) have prompted research focusing not only on issues of decline but also on developing and improving sampling techniques (Heyer et al. 1994, Dodd 2003). One such technique, the use of polyvinylchloride (PVC) pipes, is widely accepted for detecting hylid treefrogs (Hyla spp.) (Dodd and Scott 1994, Moulton et al. 1996, Boughton et al. 2000,Zacharow et al.2003). The PVC pipes offer an artificial refuge site for many arboreal hylid species that would otherwise seek shelter under bark or in natural cavities. Previous studies evaluating the effectiveness of PVC pipes for detecting treefrogs have focused on the influence of pipe size, architecture, and placement. However, to date, no studies have addressed the effects of nontarget captures on hylid treefrog occupancy rates. In the course of using PVC pipes to monitor treefrog activity patterns in Georgia, we observed significant southern flying squirrel (Glaucomys volans) mortality in pipes placed on trees. The southern flying squirrel is a common nocturnal mammal found in the eastern United States (Nowak 1999). Flying squirrels occupy cavities in trees and presumably enter tree pipes because they mimic natural cavities (Moore 1947). However, the smooth walls of PVC pipes prevent squirrels from exiting, resulting in mortality. We address the influence of flying squirrel mortality in PVC pipes on treefrog occupancy and introduce a simple method to reduce flying squirrel mortality without affecting treefrog occupancy. This method will have utility for amphibian monitoring studies that incorporate use of PVC pipes (Dodd and Scott 1994, Dodd 2003), particularly within the range of flying squirrels (Glaucomys spp.), and in areas with high treefrog diversity such as the southeastern United States.

Effects of an invasive ant and native predators on cotton rat recruitment and survival

We used the imported red-fire ant (Solenopsis invicta; hereafter fire ant) and hispid cotton rat (Sigmodon hispidus) as model species to address the population-level effects of an invasive ant on a semiprecocial small mammal. We stocked cotton rats into 8 enclosures, implementing a 2-way factorial design with predator (ambient or excluded) and fire ant (ambient or reduced) treatments as factors. We trapped monthly from June 2012 to June 2013 and calculated monthly recruitment and survival. Rats in enclosures with ambient predators had a risk of mortality approximately 2 times greater than rats in enclosures with predators excluded. The risk of mortality was 3 and 4.5 times greater for female and male cotton rats, respectively, in enclosures with ambient fire ants and predators compared to enclosures with reduced fire ants and excluded predators. We found no effects on recruitment. Our results indicate that native predators had the greatest influence on cotton rat populations. Nevertheless, in the absence of other predators, the effects of fire ants on cotton rat survival are compensatory.

Southern toads alter their behavior in response to red-imported fire ants

We used the southern toad (Anaxyrusterrestris) as a model species to explore how an invasive species, the red-imported fire ant (Solenopsis invicta; hereafter RIFA), influences amphibian predator avoidance and movement behaviors. Our objective was to determine if toads spent less time near and moved more frequently in the presence of RIFAs compared to pyramid ants by comparing behavioral reactions of toads to RIFAs versus a control and pyramid ants versus a control. Laboratory experiments involved three treatments including no ants, RIFAs, and native pyramid ants (Dorymyrmex bureni) within an experimental arena. We randomly placed ants into one of two containers located at each end of the arena. For each trial we placed a toad into the experimental arena, allowed the toad to acclimate and then recorded its behavior. We calculated the proportion of time the toad spent near ants and the number of movements completed by each toad. Comparing the RIFA treatment to the pyramid ant treatment, toads spent 35xa0% less time on the half of the experimental arena near RIFAs (Pxa0=xa00.0304). Toad movements were 1.5 times more frequent in trials with RIFAs than pyramid ants (Pxa0=xa00.0488). We propose that southern toads associate RIFAs either with increased predation risk or risk of injury compared to pyramid ants. Although the behaviors we observed might lessen the direct effects of RIFAs on southern toads via predation and injury, the indirect effects of increased movement and avoidance of RIFAs could also influence toad fitness by decreasing reproductive and foraging success.

Post-breeding Terrestrial Movements of Ambystoma tigrinum (Eastern Tiger Salamanders)

Abstract To assess use of terrestrial habitat by ambystomatid salamanders, Ambystoma tigrinum (Tiger Salamanders) were monitored with radiotelemetry. Four individuals were tracked as they exited a wetland and made wide use of the surrounding landscape. Salamanders moved up to 255 m from the wetland of origin and found refugia both within forested land and wildlife food plots. Based on the extent of terrestrial movements by Tiger Salamanders, our findings support previous work demonstrating that upland habitat surrounding wetlands are critical areas in amphibian life cycles. Salamander movements did not appear to be influenced by agricultural development, as two individuals traveled through this habitat type.