Fred C. Bryant

Wind Energy Development and Wildlife Conservation: Challenges and Opportunities

Abstract Wind energy development represents significant challenges and opportunities in contemporary wildlife management. Such challenges include the large size and extensive placement of turbines that may represent potential hazards to birds and bats. However, the associated infrastructure required to support an array of turbines—such as roads and transmission lines—represents an even larger potential threat to wildlife than the turbines themselves because such infrastructure can result in extensive habitat fragmentation and can provide avenues for invasion by exotic species. There are numerous conceptual research opportunities that pertain to issues such as identifying the best and worst placement of sites for turbines that will minimize impacts on birds and bats. Unfortunately, to date very little research of this type has appeared in the peer-reviewed scientific literature; much of it exists in the form of unpublished reports and other forms of gray literature. In this paper, we summarize what is known about the potential impacts of wind farms on wildlife and identify a 3-part hierarchical approach to use the scientific method to assess these impacts. The Lower Gulf Coast (LGC) of Texas, USA, is a region currently identified as having a potentially negative impact on migratory birds and bats, with respect to wind farm development. This area is also a region of vast importance to wildlife from the standpoint of native diversity, nature tourism, and opportunities for recreational hunting. We thus use some of the emergent issues related to wind farm development in the LGC—such as siting turbines on cropland sites as opposed to on native rangelands—to illustrate the kinds of challenges and opportunities that wildlife managers must face as we balance our demand for sustainable energy with the need to conserve and sustain bird migration routes and corridors, native vertebrates, and the habitats that support them.

Effects of coyote removal on the faunal community in western Texas

Coyotes (Canis latrans) play a keystone role in the population regulation of microherbivores and mesopredators in certain ecosystems. Despite this fact, coyote control measures still are implemented. We evaluated the effects of removing coyotes on sympatric populations of rodents, lagomorphs, raptors, and mammalian mesopredators in a shortgrass prairie ecosystem of western Texas. Faunal communities were examined on 2 treatment and 2 comparison 5,000-ha sites of mixed grassland and shrubland habitats for 1 year before coyote removal and for 2 years during coyote removal. We removed 354 coyotes by aerial gunning on treatment sites. Removal efforts were initiated every third month from April 1990 to January 1992. Coyote density was reduced from 0.12 ± 0.01 (x ± SE) to 0.06 ± 0.01 coyotes/km 2 on treatment sites, Density on comparison sites remained stable at 0.14 ± 0.01 coyotes/km 2 , We found no differences in faunal population estimates between comparison and treatment sites for the year before coyote removal. Within 9 months following the initiation of coyote removal, rodent species richness and rodent diversity declined on treatment sites, Without coyote predation, the Ords kangaroo rat (Dipodomys ordii) became the most abundant rodent in shrublands and was the only rodent species caught in grasslands after 12 months of coyote removal. Rodent density and biomass, black-tailed jackrabbit (Lepus californicus) density, and relative abundance of badgers (Taxidea taxus), bobcats (Felis rufus), and gray foxes (Urocyon cineroargenteus) increased on treatment sites, Variation in the density of desert cottontail rabbits (Sylvilagus audubonii) and raptor richness, diversity, and density was not related to coyote density, Our findings were consistent with the predator-mediated coexistence hypothesis, which suggests that a keystone predator (coyote) can influence faunal community structure.

Assessing the Helicopter and Net Gun as a Capture Technique for White‐Tailed Deer

Abstract The helicopter and net gun is a technique used to capture white-tailed deer (Odocoileus virginianus) and is useful in a variety of habitat types and at various population densities with the ability to be highly selective. During capture, deer may sustain injuries or even die as a result of capture and handling, and may also be prone to capture myopathy. Therefore, our objectives were to determine 1) type and frequency of injuries sustained during the helicopter and net-gun capture, and 2) the effects of capture on survival of radiocollared deer. We captured 3,350 white-tailed deer from 1998 to 2005 using a net gun fired from a helicopter on 5 southern Texas, USA, ranches. Additionally, we captured 51 yearling males and 49 mature (≥4 yr of age) males and fitted them with radiocollars to monitor their survival. We recorded injuries and mortalities during capture and ranked the seriousness of injuries on a scale from 0 to 4. We recorded 281 injuries (8.4%) and as a result of capture, at least 206 deer had broken antlers (6.1%), 55 were injured (1.6%), and 20 were direct mortalities (0.6%). The most common antler injury was broken antler tines and the most common body injury was broken legs. Postcapture mortality rates were low (1%) for this capture method. Based on capture-related injuries, mortalities, and postcapture survival, we found the helicopter and net gun to be a safe capture technique compared to other capture techniques, particularly when conditions are favorable.

Influence of precipitation on demographics of northern bobwhites in southern Texas

Abstract Northern bobwhite (Colinus virginianus) populations in southwestern rangelands are influenced by precipitation; populations increase during relatively wet periods and decrease during drought. Understanding the demographic responses of bobwhites to fluctuations in precipitation might provide a basis for identifying mechanisms responsible for the phenomenon. We compared 10 population variables (bobwhite survival, nesting-season length, nest success, hen success, percent hens nesting and renesting, nesting rate, percent juveniles in fall harvest sample (Nov–Feb), clutch size, and egg hatchability) between a dry (Sep 2000–Aug 2001; 51 cm precipitation) and wet period (Sep 2002–Aug 2003; 93 cm precipitation) in Brooks County, Texas. We monitored radiomarked bobwhites on 3 sites during the dry (n=263 bobwhites) and wet period (n=191 bobwhites) to obtain estimates of survival and reproductive effort. Bobwhite survival curves differed between the dry period (0.30±0.04; Ŝ±SE, n=102 bobwhites) and wet period (0.60± 0.06; n=71 bobwhites; P≤0.001) during fall-winter (Sep–Feb). A lower proportion of hens nested during the dry period (95% CI: 52.6±22.5 %; n=19 hens) compared to the wet period (100%; n=15 hens). Of hens that nested, the dry period exhibited a lower nesting rate (95% CI: 1.2±0.3 nests/hen) compared to the wet period (95% CI: 2.3±0.5 nests/hen). The dry period also experienced a shorter nesting season (69 days) compared to wet period (159 days). Lastly, percent juveniles (Nov–Feb) was lower during the dry period (95% CI: 69.3±0.3 %; n=740 harvested bobwhites) compared to wet period (95% CI: 78.3±2.1%; n=1,415 harvested bobwhites). Our field study highlights 4 demographic variables (i.e., survival, percentage of hens nesting, nesting rate, and nesting-season length) that warrant further research to identify causal factors responsible for the boom-and-bust phenomenon in bobwhites. Further, our data suggest that drought negatively impacts bobwhite reproductive effort such that harvest should be reduced or ceased during drought (e.g., <50 cm annual precipitation).

DISPERSAL BY YEARLING MALE WHITE-TAILED DEER AND IMPLICATIONS FOR MANAGEMENT

Abstract The scale at which populations use the landscape influences ecological processes and management decisions. Dispersal and home-range size define the scale of landscape use for many large-mammal species. We measured dispersal and home-range size of yearling male white-tailed deer (Odocoileus virginianus) in southern Texas, and compared our results to values from the literature to understand the implications of dispersal in management of deer populations. We used radiotelemetry to monitor 22 yearling deer on 1 study site from October 1998 to October 1999, and 27 yearling deer on a second study site from October 1999 to October 2000. On the 2 study sites, 68% and 44% of yearling deer established new areas of use 4.4±1.0 km and 8.2±4.3 km, respectively, from the center of their autumn home range. Yearling males with spike antlers (2 points) were less likely to disperse than yearlings with fork antlers (> 2 points) on 1 study site. Computer simulation showed that the scale at which deer use the landscape is large compared to property sizes in southern Texas and probably in other areas of the white-tailed deers range. Differences in scale between land ownership patterns and landscape use by deer may result in a failure to meet management objectives and conflict among managers. High harvest rates for male deer occur in part because deer movements are large relative to property size, creating a “tragedy of the commons.” Cooperative management groups are beneficial if all landowners in an area agree on management objectives. Otherwise, deer-proof fences often are erected to reduce conflicts among property owners.

Bed-site characteristics of pronghorn fawns

We examined microhabitat factors associated with bedding sites of pronghorn fawns in the Trans-Pecos Region of Texas. We marked 101 fawns during 3 consecutive fawning seasons, April-June 1990-92. We measured and compared 11 microhabitat characteristics of 127 and 489 bed sites from surviving (n = 11) and non-surviving (n = 89) fawns and compared these characteristics to 225 sites we selected randomly. Differences occurred between fawn-selected bed sites and random sites for shrub cover (P = 0.04), shrub density (P = 0.01), grass cover (P = 0.03), nearest concealing cover (NCC; P = 0.0001), rock cover (P = 0.008), and bed slope (P = 0.0001). Shrub cover, shrub density, and grass cover at bed sites of surviving fawns were more similar to that found at random sites than to bed sites of non-surviving fawns. Bed sites of survivors and non-survivors differed in rock cover (P = 0.03), slope (P = 0.008), and bed slope (P = 0.001) characteristics. Fawn age class appeared to influence preference for particular microhabitat characteristics; shrub density was greater (P = 0.027) and grass cover less (P = 0.0001) in young-age fawn bed sites. Environmental features that provided adequate concealment, but that also provided increased long-range visibility of the area surrounding the bed site, appeared to be favored for bedding. Overall, important microhabitat variables were shrub cover, shrub density, grass cover, NCC, and bed slope, and to a lesser extent rock cover, terrain slope, overstory height, and understory height. Management that encourages increased grass and forb production will provide necessary hiding cover for fawns.

Botanical composition and nutritional quality of alpaca diets in two Andean rangeland communities.

Our objectives were to measure alpaca (Lamapacos) diet quality and botanical composition seasonally on 2 high elevation rangesites (bofedal and Altiplano) in the Andes Mountains of Peru. The bofedal site was a perennially green sedge and forb community located at 5,000 m elevation. The Altiplano site, located at 3,190 m, was predominately bunchgrass. We collected diets from freeranging, esophageally fistulated alpacas at each site. Alpaca diets at both sites were highest in grasses during the wet and early dry season. As the dry season progressed, bofedal alpaca diets were comprised largely of sedges and reeds (78%) while Altiplano diets remained predominantly grasses (68%). Forb consumption varied annually between 8 and 29%o of the diet on both sites. Crude protein (CP) in bofedal diets (12.3%) averaged higher than on the Altiplano (10.2%). Values were lowest during August (6.1%) on the Altiplano and in July (8.0%Io) on the bofedal. In vitro organic matter digestibility (IVOMD) of alpaca diets on the bofedal (63%) was similar to the Altiplano site (64%) when averaged for all seasons. IVOMD was lowest during August (49%) at the Altiplano site and in October (50%0) on the bofedal. Low dietary CP and IVOMD during the late dry season (Aug.-Oct.) denote this period as nutritionally critical for both sites. Alpacas are important fiberand meat-producing livestock for highland inhabitants of the Andes mountains of southern Peru and northern Bolivia (Reiner and Bryant 1983). Approximately 2.5 million alpacas graze high-elevation grassland in Peru and Bolivia (Fernandez Baca 1975). Alpacas are physiologically adapted for life at high elevation and are able to graze much of the Andean range where sheep and cattle production is unprofitable. Alpaca grazing sites are primarily chosen in response to forage availability and tradition. Range management in the form of grazing systems or diet supplementation is rare. Little is known about nutritional quality and botanical composition of alpaca diets on the varied range sites they graze. Implementing effective grazing systems or diet supplementation schemes requires this knowledge. We describe the botanical composition and nutritional quality of alpaca diets relative to seasonal forage availability for 2 important rangeland sites (bofedal and Altiplano) in southern Peru. High-elevation rangeland in southern Peru is characterized by 2 major grassland zones: the Altiplano (high plains) of the Lake Titicaca basin (3,100 m elevation) and the mountains surrounding the basin. Mountain rangeland occasionally exceeds 5,800 m. The Altiplano is primarily a zone of sheep production although alpaca numbers are increasing due to a favorable market for alpaca wool. The mountain zone is grazed primarily by alpacas. The wet growing season occurs in November through April in southern Peru. During the rest of the year, there is no precipitation and little forage production. Alpacas grazing in the mountains during the dry season are herded to perennially green, tundra-like Authors are research assistant, Mississippi State University, Department of Wildlife and Fisheries, P.O. Drawer LW, Mississippi State 39762 and associate professor, Department of Range and Wildlife Management, Texas Tech University, Lubbock 79409. This research was carried out as part of the United States Agency for International Development, Title XII, Small Ruminant Collaborative Research Support Program, under Grant DSAN/ XII-G-0049, in collaboration with Instituto Nacional Investigacion y Promocion Agropecuaria, Peru. This is Texas Tech University College of Agricultural Science Publication No. T-9-000. The authors wish to thank Susan Rikert and Timoteo Huisa for laboratory and field assistance. We also thank Universidad Nacional Mayor de San Marcos for their support. Manuscript accepted 27 January 1986. pastures called bofedales. Bofedales are scarce on the Altiplano and are often over-grazed. Physiological differences between alpaca and sheep preclude adapting established sheep management techniques for alpaca. For example, the gestation period for alpacas is almost 1 year (345 days). Females are bred and give birth during January when nutritious forage is available. Alpacas survive the nutritionally stressful dry season while in the late stages of lactation and supporting gestation (Sumar 1983). Weight loss, impaired wool production, and low fertility have been attributed to inadequate dry season nutrition (West 1981).

An Evaluation of Survey Methods for Estimating Northern Bobwhite Abundance in Southern Texas

Abstract Distance sampling has been identified as a reliable and well-suited method for estimating northern bobwhite (Colinus virginianus) density. However, distance sampling using walked transects requires intense sampling to obtain precise estimates, thus making the technique impractical for large acreages. Researchers have addressed this limitation by either resorting to the use of indices (e.g., morning covey-call surveys) or incorporating the use of aerial surveys with distance sampling. Both approaches remain relatively untested. Our objectives were to 1) compare density estimates among morning covey-call surveys, helicopter transects, and walked transects; 2) test a critical assumption of distance sampling pertinent to helicopter surveys (i.e., all objects on line are detected); and 3) evaluate the underlying premise of morning covey-call surveys (i.e., that the no. of calling coveys correlates with bobwhite density). Our study was conducted on 3 study sites in Brooks County, Texas, USA, during October to December, 2001 to 2005. Comparisons between walked transects and morning covey-call surveys involved the entire 5-year data set, whereas helicopter transects involved only the latter 2 years. Density estimates obtained from helicopter transects were similar to walked transect estimates for both years. We documented a detection probability on the helicopter transect line of 70 ± 10.2% (% ± SE; n = 20 coveys). Morning covey-call surveys yielded similar density estimates to walked transect estimates during only 2 of 5 years, when walked transect estimates were the least accurate and precise. We detected a positive relationship (R2 = 0.51; 95% CI for slope: 29.5–53.1; n = 63 observations) between covey density and number of coveys heard calling. We conclude that helicopter transects appear to be a viable alternative to walked transects for estimating density of bobwhites. Morning covey-call surveys appear to be a poor method to estimate absolute abundance and to depict general population trajectories.

Observations on white-tailed deer and habitat response to livestock grazing in south Texas.

Since short duration grazing (SDG) was introduced to Texas, concern for white-tailed deer (Odocoileus virginianus) has magnified because they are a species of major economic importance to ranchers. The objective of this study was to observe the effects of SDG and continuous yearlong grazing (CG) on home ranges and movement indices of female deer, and on forage availability. The study was conducted on the Rob and Bessie Welder Wildlife Refuge, near Sinton, Texas. The study area included a 10-pasture SDG cell and a CG pasture, each stocked at 2.8 ha/auy. Cattle grazed each SDG paddock 2 to 8 days; paddocks were rested 32 to 47 days. A total of 3,961 radio-fixes from 11 does was collected over an 11-month study period in 1983. Monthly and annual home ranges of does were similar (P > 0.05) between SDG (207 ha) and CG (229 ha). However, white-tailed deer traveled 35% more (P & 0.05) between fixes in SDG (449 m) than in CG (332 m) from May to August, a time of greatest physiological and nutritional stress for female deer in south Texas. Also, does avoided (P & 0.05) cattle during 2 cycles of the SDG rotation. The primary trend observed was for the deer under SDG to avoid cattle concentrations by alternating between preferred habitats rather than a predictable paddock-to-paddock movement. In general, there were few differences in total grass and forb cover between SDG and CG. However, several forage species important to deer were less frequent (P & 0.05) under SDG than CG.

A Population Model to Simulate Northern Bobwhite Population Dynamics in Southern Texas

ABSTRACT Models are important tools that can help managers and researchers understand the population dynamics of a species and how different habitat or population management scenarios impact that species. We used radio-telemetry data from northern bobwhites (Colinus virginianus) in southern Texas from 2000 to 2005 to develop a stochastic simulation model for bobwhite populations. Our model is based on difference equations, with stochastic variables drawn from normal and Weibull distributions. We simulated bobwhite populations to 100 yr and evaluated our model by comparing results with independent estimates of 4 population parameters (spring and fall density, finite rate of increase in the fall population [&lgr;], and winter juv:ad age ratios). Using a quasi-extinction criterion of ≤40 birds (density = ≤0.05 birds/ha), probability of persistence to 100 yr was 88.3% (106 of 120 simulations) for the spring population and 96.7% (116 of 120 simulations) for the fall population. Using a less restrictive quasi-extinction criteria (≤ 14 birds), probability of persistence was 93.3% (112 of 120 simulations) for the spring population and 98.3% (118 of 120 simulations) for the fall population. Simulated population parameters were similar to independent estimates for 4 of 4 population parameters. Winter age ratios differed between our model ( = 4.98 juv:ad, n = 120, SE = 0.32) and empirical age ratios from harvested bobwhites on our study area ( = 2.85 juv:ad, n = 25, SE = 0.24). However, when we corrected harvest age ratios for bias in juvenile harvest ( = 3.85 juv:ad, n = 25, SE = 0.32) simulated and empirical estimates were similar. Our model appears to be a reliable predictor of bobwhite populations in the southern Texas. Our simulation results indicate that bobwhite hunters and managers can expect excellent bobwhite hunting (fall populations ≥2.2 birds per ha) in about one of 10 yr.