James C. Cathey

INTROGRESSIVE HYBRIDIZATION AND NONCONCORDANT EVOLUTIONARY HISTORY OF MATERNAL AND PATERNAL LINEAGES IN NORTH AMERICAN DEER

Introgressive hybridization between mule deer (Odocoileus hemionus) and white‐tailed deer (O. virginianus) was studied using sequence analysis of the paternally inherited, Y‐linked, Zfy gene. The distribution of Zfy genotypes indicate that male white‐tailed deer disperse into the range of mule deer and successfully breed with mule deer does. In western Texas, F1 hybrids are rare, but a relatively high proportion of backcross individuals was observed. Phylogenetic analysis of Zfy among white‐tailed, mule, and black‐tailed deer was consistent with traditional systematic placement of the latter two being sister‐taxa, whereas previous mtDNA studies suggested mule and white‐tailed deer were sister taxa.

Distribution and interspecies contact of feral swine and cattle on rangeland in south Texas: implications for disease transmission.

The last outbreak of foot-and-mouth disease (FMD) in the United States occurred in 1929. Since that time, numbers and distribution of feral swine (Sus scrofa) have increased greatly, especially in the southern states. This creates a potential risk to livestock production because swine are susceptible to, and can be carriers of, several economically harmful diseases of livestock. Most importantly, swine are potent amplifiers of FMD virus. In this study, global positioning system (GPS) collars were placed on rangeland cattle (Bos indicus × taurus) and feral swine to determine shared habitat use by these species on a large ranch in south Texas from 2004 to 2006. The aim was to identify locations and rates of interspecies contact that may result in effective transfer of FMD virus, should an outbreak occur. In shrubland and riparian areas, animals were dispersed, so contacts within and between species were relatively infrequent. Indirect contacts, whereby cattle and feral swine used the same location (within 20 m) within a 360-min period, occurred primarily at water sources, and seasonally in irrigated forage fields and along ranch roads. Direct contacts between species (animals <20 m apart and within 15 min) were rare and occurred primarily at water sources. Changes in ranch management practices are suggested to reduce interspecies contact should an FMD disease outbreak occur. This information can also be used to improve current epidemiologic models to better fit free-ranging animal populations.

Managing Yaupon in the Post Oak Savannah

Yaupon can be effectively managed during March or June, with individual plant treatments of triclopyr and diesel, which can be an effective tool for restoring fragmented grassland savannahs. DOI:10.2458/azu_rangelands_v28i3_cathey

A box-trap design to capture alligators in forested wetland habitats

Abstract Although much work has been conducted on coastal populations of the American alligator (Alligator mississippiensis), less is known about the population dynamics and ecology of alligators in inland habitats. This paucity of knowledge may relate to the difficulty in capturing alligators within inland locations, as traditional methods of capture often are compromised by the heterogeneous habitat. To circumvent these problems, we developed an alternative method for capturing alligators that allows researchers to sample forested wetlands using a simple box-trap design. We set traps for 273 trap-nights, resulting in 45 captures. Twenty-nine of these were adults (183–287 cm total length), 9 were juveniles (100–183 cm total length), and 7 were recaptures. Inland population surveys and demographic data sets collected using this capture method can be integrated into more sound alligator management strategies that encompass varying population life histories.

Role of free-ranging mammals in the deposition of Escherichia coli into a Texas floodplain

Abstract Context. The role of wildlife in faecal pollution of water bodies (deposition of Escherichia coli (E. coli)) is not well understood. Current water-quality and land-use planning research largely relies on unreliable wildlife data (e.g. poor sourcing of abundance estimates, population density estimates applied to multiple fundamentally different areas, suspect or insufficiently described data collection techniques) Aims. Our goal for the present research was to investigate deposition of E. coli into a floodplain by free-ranging mammals. Objectives of the research were to determine the density of important free-ranging meso- and large mammals in the study area, determine faecal E. coli loads for each species, and evaluate spatial data on species-specific faecal deposition. Methods. We conducted our research in south-eastern Texas, USA, on two cattle ranches bisected by Cedar Creek (44-km long). Cedar Creek has elevated E. coli concentrations. We conducted mark–recapture and mark–resight population density estimates (2008/09) for meso- and large mammals in the study areas. We collected faecal samples from all captured wildlife. We also conducted transects through the study area to determine faecal-deposition patterns. Key results. We found that raccoons (Procyon lotor), wild pigs (Sus scrofa), Virginia opossums (Didelphis virginiana) and white-tailed deer (Odocoileus virginianus) all had substantial faecal E. coli loads and population densities, thus implying an important role in E. coli deposition into the study floodplain. All species were widely distributed through the floodplain. Conclusions. Free-ranging mammals contribute E. coli to floodplains and potentially affect water quality. We determined that four species commonly found in floodplains throughout North America all contributed E. coli to the study floodplain, thus implying mammal E. coli contributions in many locations and this is potentially important for E. coli management. Implications. Improved locally specific mammal population estimates and estimates of locally derived E. coli concentration will improve floodplain and water-quality models that often depend on data of various quality. Additionally, our analyses demonstrated the need for continued research into the role of wildlife in E. coli deposition.

Influence of rainfall, type of range, and brush management on abundance of northern bobwhites (Colinus virginianus) in southern Texas.

Abstract Assessing numerical response of northern bobwhites (Colinus virginianus) to habitat improvement in semi-arid rangeland often is confounded by responses of populations to highly variable patterns of rainfall. During 2 years of above-average rainfall, we investigated abundance of northern bobwhites relative to type of range and treatments to reduce brush on seven ranches in southern Texas. We expected response of populations to treatment of land to be more evident when northern bobwhites were released from constraints of low precipitation. However, main factors dominating abundance were rainfall during the previous growing season and type of range. Greatest numbers of calls were in mid-productivity rangeland (potential production of forage 2,000–3,900 kg/ha), especially sandy loam, clay loam, sandy, and gravelly ridge. Treatments to reduce brush increased abundance of northern bobwhites to a limited extent and were most effective when large blocks of land were treated. Techniques that kill brush (root-plowing) were more successful in increasing populations than top-removal methods (roller-chopping). Leaving strips or mottes (large clumps of living brush and trees) in cleared areas did not enhance populations, although we caution that retaining some brush cover may be important to survival of northern bobwhites in drier years and in situations where herbaceous cover is less abundant.

Video-Scale: A Novel Device to Measure Supplemental Feed Consumption by Wildlife

Abstract We present a novel technique using a video serial interface to link a motion-activated, infrared video camera and a weigh-scale to measure supplemental feed consumption by wildlife. This “video-scale” allows us to quantify consumption of various feeds by individual animals to an accuracy of 5 g and to record feeding duration to the second. Using intake rate and total time spent feeding, we calculated comparative use of supplemental feed by animals categorized by species, age, and sex. We present preliminary data on feed consumption and intake rates of wild and tame white-tailed deer (Odocoileus virginianus) and raccoons (Procyon lotor) eating shelled corn, pelleted supplement, and whole cottonseed. Other uses and limitations of the video-scale are discussed.

Managing Yaupon With Fire and Herbicides in the Texas Post Oak Savannah

Yaupon invasion into historic grassland savannahs can be effectively reduced with prescribed burning and herbicides. DOI:10.2458/azu_rangelands_v27i5_mitchell

A model for assessing mammal contribution of Escherichia coli to a Texas floodplain

Abstract Context. Free-ranging mammals contribute to faecal pollution in United States water bodies. However, research into wildlife impact on water quality is dependent upon unreliable data (e.g. data uncertainty, unknown importance of parameters). Aims. Our goal was to determine the potential impacts of common free-ranging mammal species and their management on Escherichia coli in the study floodplain. Our objectives for this research were to construct a model from study area- and literature-derived data, determine important species for E. coli deposition, and conduct sensitivity analyses on model parameters to focus future research efforts. Methods. We constructed a model that incorporated parameters for four wildlife species known to contribute E. coli in central Texas: raccoons (Procyon lotor), white-tailed deer (Odocoileus virginianus), Virginia opossums (Didelphis virginiana), and wild pigs (Sus scrofa). These parameters were (1) population density estimates, (2) defaecation rates, (3) defaecation areas, (4) E. coli concentration in faecal material estimates, and (5) E. coli survival. We conducted sensitivity analyses on the model parameters to determine relative importance of each parameter and areas for additional study. Key results. We found that adjustment of raccoon and Virginia opossum population densities had higher impacts on E. coli in the floodplain than similar changes in other species across all spatial and seasonal variations. We also found that the changes in E. coli survival, E. coli concentration in raccoon faecal material, and defaecation rates had the highest impacts on E. coli in the floodplain. Conclusions. Our sensitivity analyses indicated that the largest impacts to projected E. coli loads were from changes in defaecation rates followed by E. coli concentration in faecal material and E. coli survival. Watershed planners, ranchers, and regulators must be cautioned that faecal deposition patterns are location specific and could significantly impact which species are considered the most important contributors. Implications. Although all parameters require more research, we recommend that researchers determine defaecation rates for contributing species due to their relatively large impacts on E. coli in comparison to the other parameters. We also suggest additional research in free-ranging wildlife faecal morphology (form and structure) and area of deposition. Finally, species-specific E. coli survival studies for free-ranging wildlife should be conducted.