Christopher E. Comer

Vegetation and Avian Response to Prescribed Fire on Glade Habitats in the Missouri Ozarks

Abstract Due to fire suppression and land use changes, Missouri glade habitats have undergone long-term declines in area and function leading to consequent declines in many bird species that rely on these habitats. We examined breeding bird species composition and vegetation community composition on three glade sites undergoing restoration with prescribed fire and compared them to three unburned glade sites and three unburned forest sites. Although we documented subtle changes in vegetation characteristics in response to prescribed fire, important structural characteristics, such as canopy cover (>55% at all study sites) and grass cover (<10% at all study sites) remain outside ranges used to characterize glades. Despite this, bird community structure shifted towards grass-shrubland (glade) birds (e.g., prairie warbler (Dendroica discolor), blue-winged warbler (Vermivora pinus), yellow-breasted chat (Icteria virens)) in glades that had been managed with prescribed fire. Using canonical correspondence analyses and stepwise forward logistic regression, we found that grass-shrubland (glade) birds were associated with habitat characteristics such as high stem density of small (0–6.3 cm diameter at breast height) trees, greater herbaceous cover, greater rock cover and a more open canopy. However, we did not detect any bird species historically associated with glades, such as Bachmans sparrow (Aimophila aestivalis) or field sparrow (Spizella pusilla) on any study sites but did frequently detect red-eyed vireos (Vireo olivaceous) on all sites. Short term application of prescribed fire has not yet produced functionally restored glades. Long term applications of prescribed fire, used in conjunction with mechanical and/or chemical removal of woody overstory, are necessary to achieve restoration at these sites.

Artificial Nests Identify Possible Nest Predators of Eastern Wild Turkeys

Abstract Poor nest survival is a critical limiting factor in the recruitment of wild birds. Nest predation is often cited as one of the main causes of nest failure, especially for ground-nesting species. We monitored artificial Meleagris gallopavo silvestris (Eastern Wild Turkey) nests, using time-lapse and motion-sensitive trail cameras to determine which predators were likely to be responsible for preying on Wild Turkey nests in the Pineywoods of East Texas. Sixty-one percent of all artificial nests were preyed upon. Corvus brachyrhynchos (American Crow) preyed on 48% of artificial nests and Procyon lotor (Raccoon) preyed on 35%. There was a seasonal increase in the number of artificial nests preyed upon from spring to summer. Mammalian mesopredators, Raccoon and Didelphis virginiana (Opossum), were primarily responsible for this increase, suggesting an increase in search effort by mesopredators that coincided with increased dietary diversity in a period of reduced prey resources. Predators other than mesopredators—American Crows, Picoides sp. (woodpeckers), Dasypus novemcinctus (Nine-banded Armadillo), and snakes—were responsible for 53% of all predation on the artificial Wild Turkey nests, with American Crows being the most important of these. After nest deployment, American Crows located and preyed on artificial nests more quickly than other nest predators. We suggest video monitoring of natural Eastern Wild Turkey nests to confirm the identity of nest predators.

Coyote, fox, and bobcat response to anthropogenic and natural landscape features in a small urban area

Increasing urbanization across the southeastern United States presents unique challenges for wildlife; however certain species have learned to adapt and thrive in these environments. Coyotes (Canis latrans), bobcats (Lynx rufus), red foxes (Vulpes vulpes) and gray foxes (Urocyon cinereoargenteus) are four common medium-sized carnivores that have become closely associated with urban areas. The goal for this study was to determine how urban landscape features influence density and occurrence of these species in a small urban area and to evaluate if any effects were similar to those observed in larger urban areas. We conducted two eight-week camera surveys in the city of Nacogdoches, Texas (pop. 32,699) and immediate surrounding areas in summer and fall 2013. We evaluated single-season spatially explicit capture-recapture and occupancy models to estimate density, and occurrence, respectively, based on anthropogenic and natural features around each camera site. Coyotes (fall: 1.38 coyotes/km2) and bobcats (fall: 0.64 coyotes/km2) were associated with areas of green space, but their response to large and small green spaces changed seasonally. Conversely, red foxes (fall: 2.53 red foxes/km2) were more likely to occur near developed areas and were less detectable in areas with greater probability of coyote presence in fall only. In summer, gray foxes (fall: 0.05 gray foxes/km2) were more likely to occur in areas with lower building density and closer to buildings. This study indicates coyotes, foxes and bobcats respond to small-scale urbanization in a similar manner as large-scale urbanization.

Prey Selection by Three Mesopredators that are Thought to Prey on Eastern Wild Turkeys (Meleagris gallopavo sylvestris) in the Pineywoods of East Texas

Abstract Predation, especially during the nesting and poult-rearing seasons, may inhibit Meleagris gallopavo (Wild Turkey) recruitment in east Texas. Numerous authors cite Lynx rufus (Bobcat), Canis latrans (Coyote), and Procyon lotor (Raccoon) as predators of Wild Turkey. Consequently, we investigated prey selection of these 3 common mesopredators using scat analysis. We also investigated prey-population dynamics using capture—mark—recapture techniques for small mammals (Rodentia), and spotlight surveys and track plate counts for Sylvilagus floridanus (Eastern Cottontail). We found no evidence that mesopredators preyed upon Wild Turkeys. Small mammals and lagomorphs were the primary components of mesopredator diets. Small-mammal numbers varied seasonally; however, Cottontail relative abundance did not. Mesopredator diets were most diverse in summer. In summer, Bobcats increased their use of small mammals, whereas Coyotes and Raccoons diversified their diets to include seasonal fruits. Decline in small-mammal populations and increase in mesopredator dietary diversity coincided with Wild Turkey nesting and poultrearing seasons, which potentially could result in an increased threat to Wild Turkeys during the nesting and poult-rearing season.

Using Infrared-Triggered Cameras to Monitor Activity of Forest Carnivores

Abstract The activity patterns of 4 forest predator species were monitored, using infrared-triggered cameras, within a 1318-ha study area in East Texas. We recorded 161 photographic capture events in 1925 trap-nights over 17 weeks. Photographic capture events included 18 Lynx rufus (Bobcat), 109 Procyon lotor (Raccoon), 21 Didelphis virginiana (Virginia Opossum), and 13 Canis latrans (Coyote). We developed an easily replicated method of measuring time on a percent scale to compare activity data over several months, accounting for changes in sunrise and sunset times. Bobcat activity was 38.9% crepuscular and 22.1% diurnal. The activity of the other 3 species was mostly nocturnal: Raccoon 94.5%, Virginia Opossum 100%, and Coyote 77%. Moon phase based on percentage of visible light did not affect either Raccoon or Virginia Opossum nocturnal activity level.

Seedbank Potential of Chinese Tallow Tree (Triadica sebifera) in a Texas Bottomland Hardwood Forest

ABSTRACT: Chinese tallow tree (Triadica sebifera) is arguably one of the most deleterious exotic invasive plants in the southern United States, where it alters ecosystem structure and function, especially near the Gulf Coast. Chinese tallow continues to expand into riparian floodplain forests, which likely facilitate regional invasion by dispersing seeds during seasonal flooding and providing corridors of favorable habitat. We attempted to estimate existing Chinese tallow soil seedbank presence and density in a bottomland hardwood forest located at Old Sabine Bottom Wildlife Management Area (OSBWMA) in northeastern Texas, where heavy infestation has not occurred to date, though mature seed-bearing trees are present regionally. No Chinese tallow seeds were detected across the study area, despite the occurrence of mature, seed-bearing plants on adjacent properties. Based on this lack of detected seeds, combined with the lack of observed Chinese tallow plants at OSBWMA, it appears the species continues to occur at low densities within apparently suitable habitats in northeastern Texas, perhaps reflecting a lack of en masse water-mediated dispersal into the region due to its upstream location in relation to heavily infested areas further south.

Evidence for exposure to selenium by breeding interior snowy plovers ( Charadrius nivosus ) in saline systems of the Southern Great Plains

Interior snowy plover (Charadrius nivosus) population declines and deteriorating conditions throughout the Southern Great Plains (SGP) of Texas, New Mexico, and Oklahoma may be linked to environmental contaminants. Concentrations of V, As, Cd, Pb, and Se were quantified in breeding snowy plover blood, feathers (5th primary; P5), and potential prey (tiger beetles [Cicindela circumpicta and C. togata]). Se was (a) most commonly detected relative to other quantified elements and (b) frequently quantified at levels exceeding background or toxicity thresholds. Of samples greater than instrumentation detection limits, 98% of snowy plover blood and 22% of feather samples were greater than Se toxicity thresholds of 1 ppm ww for blood and 5 ppm dw for feathers (blood quantifiable range: 0.83–15.12 ppm; feathers quantifiable range: 1.90–27.47 ppm). Almost all tiger beetle Se concentrations were below reported invertebrate thresholds of 30 ppm dw (quantifiable range: 0.54–45.84 ppm). Snowy plover blood Se concentrations were related to sex, individual body condition, and local tiger beetle Se concentrations, while plover P5 Se concentrations were related to state, sex, and presence of body molt. Tiger beetle Se concentrations were related to individual study sites in Texas. These results provide some of the first evidence of Se exposure risk for interior snowy plovers nesting in saline lake and alkali flat environments of the SGP. Future efforts should focus upon specific Se uptake pathways during breeding and nonbreeding seasons, as snowy plovers breeding in the SGP appear to be exposed to Se throughout their annual cycle.

Dietary Composition of Four Common Chiropteran Species in a Bottomland Hardwood Forest

Understanding foraging habits can be important for elucidating the ecology of any species and for designing appropriate conservation strategies. Common methods for determining bat diets, such as morphological examination of fecal material or recovery of prey fragments under feeding roosts, can be biased towards larger prey with harder exoskeletons by underestimating frequency/occurrence of smaller, softer bodied prey items. Our objectives were to determine prey selection for several common chiropteran species of bottomland hardwood forests in east Texas and to evaluate the use of DNA barcoding for dietary studies by comparing dietary composition to prey availability in four species of bats. We amplified the cytochrome coxidase subunit 1 gene from fecal samples collected from 19 bats of four species and identified arthropods by comparison to the Barcode of Life Data System database. We compared frequency of occurrence in fecal samples to frequency in concurrent night-flying insect sampling. We identified nine insect species from three orders consumed by Perimyotis subflavus, nine species from four orders consumed by Lasiurus seminolus, seven species from three orders consumed by Nycticeius humeralis, and 11 species from two orders consumed by Lasiurus borealis. Coleoptera was the most abundant order available by biomass, but beetles were never found in fecal samples from L. seminolus (n = 5) or L. borealis (n = 7) bats. However, Coleoptera comprised a substantial portion of prey identified from P. subflavus (n = 2) and N. humeralis samples (n = 5). Lepidopteran prey items were found in 13 of 19 bat fecal samples across all species but represented < 7% of arthropod biomass. Although dipteran species were a negligible portion (< 1%) of the available biomass, large numbers of dipterans were identified in fecal samples from all species of bats (13 of 19 samples across all species). Lasiurus seminolus and L. borealis may be selecting prey based on digestibility rather than availability; whereas, both N. humeralis and P. subflavus exhibited a more opportunistic approach to foraging. Based on comparison to other studies of bat diets, traditional techniques for analyzing diet from fecal samples are likely underrepresenting soft-bodied arthropods like dipterans.

Nesting ecology of early-successional birds in restored longleaf and loblolly pine stands

ABSTRACT After historic declines in acreage and function, longleaf pine (Pinus palustris) savannah is considered one of the most important ecological communities in need of protection and restoration along the Atlantic and Gulf Coastal Plains. Numerous state and federal programs are available to encourage restoration on private lands; however, the success of these programs in producing quality habitat for longleaf pine savannah specialist species is largely unknown. To assess quality of restored longleaf pine forests in east Texas, we compared nest success, nest survival, and nest site selection of Prairie Warblers (Setophaga discolor), Yellow-breasted Chats (Icteria virens), Indigo Buntings (Passerina cyanea), and Northern Cardinals (Cardinalis cardinalis), in young (0–5 years) and mid-aged (5–10 years) stands of longleaf pines to these same parameters in young, managed stands of loblolly pines (P. taeda). We monitored 65 nests for all four species combined, where 28 (43%) occurred in longleaf stands, and 37 (58%) occurred in loblolly stands. Of these, cardinals accounted for 35% of all nests, and this was the only species in which we monitored more nests in habitats of longleaf than loblolly. For all focal species, Mayfield nest success estimates were low (4–17%) in stands of both longleaf and loblolly pines, except the values for Prairie Warblers (54%). The primary reason for nest failures was predation (43% of all active nests), where each stand was comprised of mostly (~80%) edge habitat. Restored young longleaf stands did not appear to provide differential nesting habitat or greater nesting success for our focal species compared to loblolly stands of comparable age.

Roosts of Rafinesque's Big-Eared Bats and Southeastern Myotis in East Texas

Abstract Because diurnal roosts can be important in determining bat occupancy and abundance in forested habitats, we identified characteristics of cavity trees that influence roost selection by Corynorhinus rafinesquii (Rafinesques Big-eared Bats) and Myotis austroriparius (Southeastern Myotis) in east Texas. We identified used and non-used cavity trees with a combination of transect searches, radiotelemetry, and historical records at 7 study areas. Both bat species selected similar cavity trees for summer diurnal roosts, showing an affinity for tupelo trees (Nyssa spp.), with 55% of diurnal roosts in Nyssa aquatica (Water Tupelo) and 33% in N. sylvatica (Blackgum). Of 17 tree and habitat variables we measured at used and unused cavity trees, those related to cavity size and availability (cavity height and diameter, tree diameter, density of large trees in the area) were the most important predictors of use. Characteristics of the surrounding stand at both local and landscape scales were less important. Rafinesques Big-eared Bats and Southeastern Myotis appeared to use the largest cavity trees present and we speculate that the availability of suitable trees with large cavities may limit abundance in this region.