Matthew J. Butler

Commentary: Wildlife ranching in North America— arguments, issues, and perspectives

Abstract The term “wildlife ranching” has been used to describe many commercial activities associated with wildlife recreation and products. We discuss the advantages and drawbacks of 2 of those activities: fee-hunting and wildlife farming and husbandry. Perhaps the greatest advantage of fee-hunting programs is economic return to the private landowner, which, in turn, provides the landowner incentive and resources to conserve wildlife and wildlife habitat. The greatest drawback is privatization of the North American wildlife resource. Many individuals from the general public as well as professional wildlife biologists fear that commercial activities associated with wildlife recreation and products ultimately will allow a shift from public to private ownership of wildlife, resulting in diminished public interest in wildlife. The advantages of wildlife farming and husbandry include greater productivity of food animals, healthy alternative food sources, product diversification, and economic gains to private landowners. Because wildlife farming and husbandry activities typically focus on exotic big game, many drawbacks have been suggested. Drawbacks include disease introduction, competition and hybridization with native wildlife, range degradation, and pest problems. However, adequate research in many of those areas is lacking. Ultimately, wildlife is a product of the land, subsidized at the expense of the private landowner. Perhaps revenues from wildlife ranching can provide positive incentives to private landowners, resulting in increased wildlife and wildlife habitat conservation and preservation.

The relationship of Rio Grande wild turkey distributions to roads

Wildlife Society Bulletin 2005, 33(2):745–748 Peer refereed Distance sampling from roads is a common population estimation technique used for many wildlife species (Brennan and Block 1986, DeYoung and Priebe 1987, Borralho et al. 1996, Dahlheim et al. 2000). A critical assumption of the distance sampling technique is that the distribution of animals is not influenced by the transect, but this assumption may be violated if the transect is a road (Burnham et al. 1980, Buckland et al. 2001, Williams et al. 2001). Attraction of target animals to the transect will result in inflated population estimates, and withdrawal from the transect will bias the estimates low (Verner 1985,Thompson et al. 1998, Buckland et al. 2001). Many authors have suggested line transects should not be positioned along roadways unless individuals are randomly distributed across the landscape (Burnham et al. 1980, Buckland et al. 2001, Williams et al. 2001). Male Rio Grande wild turkeys (Meleagris gallopavo intermedia) likely use roads as display sites in south Texas; thus, population surveys using roads should be conducted outside of the breeding season to reduce the probability of wild turkeys being attracted to roads (DeYoung and Priebe 1987). Eastern wild turkeys (M. g. silvestris) in Virginia used areas >450 m from roads more than expected and areas <150 m from roads in proportion to availability (McDougal et al. 1990). In Arizona, male Merriam’s wild turkeys (M. g. merriami) used areas <200 m from roads less than expected (Rogers et al. 1999). However, none of those studies examined the relationship of roads to wild turkey distributions during specific seasons and time periods. Our objectives were to quantify the association of male and female Rio Grande wild turkeys to roads according to season and time of day, and examine the potential biases of using roads as transects for distance sampling. We conducted this research in order to help develop appropriate protocols for distance sampling of Rio Grande wild turkeys from roads.

Road-Based Surveys for Estimating Wild Turkey Density in the Texas Rolling Plains

Abstract Line-transect–based distance sampling has been used to estimate density of several wild bird species including wild turkeys (Meleagris gallopavo). We used inflatable turkey decoys during autumn (Aug–Nov) and winter (Dec–Mar) 2003–2005 at 3 study sites in the Texas Rolling Plains, USA, to simulate Rio Grande wild turkey (M. g. intermedia) flocks. We evaluated detectability of flocks using logistic regression models. Our modeling effort suggested that distance to a flock and flock size played important roles in flock detectability. We also conducted surveys from roads for wild turkeys during November 2004–January 2006. The detection probability of decoy flocks was similar to wild turkey flocks during winter (decoy flock, 69.3 ± 6.2% [x̄ ± 95% CI]; wild turkey flock, 62.2 ± 18.3%) and autumn (decoy flock, 44.1 ± 5.1%; wild turkey flock, 44.7 ± 25.6%), which suggested that using decoys was appropriate for evaluating detectability of wild turkey flocks from roads. We conducted computer simulations to evaluate the performance of line-transect–based distance sampling and examined the power to detect trends in population change. Simulations suggested that population density may be underestimated by 12% during winter and 29% during autumn. Such bias occurred because of incomplete detectability of flocks near roads. Winter surveys tended to have less bias, lower relative variability, and greater power than did autumn surveys. During winter surveys, power was sufficient (≥0.80) to detect a 10–25% change in population density in 8–12 years using ≥100 16-km transects or ≥80 32-km transects. We concluded line-transect–based distance sampling from roads is an efficient, effective, and inexpensive technique for monitoring Rio Grande wild turkey populations across large scales.

Aerial Surveys for Estimating Wild Turkey Abundance in the Texas Rolling Plains

Abstract Aerial surveys have been used to estimate abundance of several wild bird species including wild turkeys (Meleagris gallopavo). We used inflatable turkey decoys at 3 study sites in the Texas Rolling Plains to simulate Rio Grande wild turkey (M. g. intermedia) flocks. We evaluated detectability of flocks and errors in counting flock size during fixed-wing (Cessna 172) aerial surveys using logistic and linear regression models. Flock detectability was primarily influenced by flock size and vegetative cover, and errors in counting flock size were primarily influenced by size of flocks. We conducted computer simulations to evaluate the accuracy and precision of fixed-wing aerial surveys and examined power to detect trends in population change. Our simulations suggested abundance estimates from fixed-wing aerial surveys may be underestimated by 10–15% (2.0–4.8% CV). Power analyses suggested that fixed-wing aerial surveys can provide sufficient power (≥0.80) to detect a population change of 10–25% over a 4–5-year period. We concluded fixed-wing aerial surveys are feasible on ecoregion scales.

Possible Vector Dissemination by Swift Foxes following a Plague Epizootic in Black-tailed Prairie Dogs in Northwestern Texas

To determine whether swift foxes (Vulpes velox) could facilitate transmission of Yersinia pestis to uninfected black-tailed prairie dog (Cynomys ludovicianus) colonies by acquiring infected fleas, ectoparasite and sero-logic samples were collected from swift foxes living adjacent to prairie dog towns during a 2004 plague epizootic in northwestern Texas, USA. A previous study (1999–2001) indicated that these swift foxes were infested almost exclusively with the flea Pulex irritans. Black-tailed prairie dogs examined from the study area harbored only Pulex simulans and Oropsylla hirsuta. Although P. irritans was most common, P. simulans and O. hirsuta were collected from six swift foxes and a single coyote (Canis latrans) following the plague epizootic. Thus, both of these canids could act as transport hosts (at least temporarily) of prairie dog fleas following the loss of their normal hosts during a plague die-off. All six adult swift foxes tested positive for antibodies to Y. pestis. All 107 fleas from swift foxes tested negative for Y. pestis by mouse inoculation. Although swift foxes could potentially carry Y. pestis to un-infected prairie dog colonies, we believe they play only a minor role in plague epidemiology, considering that they harbored just a few uninfected prairie dog fleas (P. simulans and O. hirsuta).

Detectability of Lesser Prairie-Chicken Leks: A Comparison of Surveys from Aircraft

ABSTRACT Lesser prairie-chickens (Tympanuchus pallidicinctus) are traditionally monitored by spring roadbased lek surveys and counts of males attending leks. Several weaknesses exist with ground-based monitoring methods such as the bias of restricting surveys to roads, unknown probability of lek detection, and man-hours required to survey large tracts of habitat. We evaluated aerial surveys to locate lesser prairie-chicken leks in Texas and New Mexico using a Cessna 172 airplane (C172), R-22 Beta II helicopter (R-22), and R-44 Raven II helicopter (R-44) during spring 2007–2008. We determined lek activity during surveys with remote cameras placed on leks and cross-referenced time on the photo frame to time on our Global Positioning System flight log. From remote cameras we found that 305 leks were available for detection during survey flights. We determined lek detectability was 32.7% (95% CI = 20.3–47.1%) in the C172, 72.3% (64.50– 79.14%) in the R-22, and 89.8% (82.0–95.0%) in the R-44. We created 16 a priori logistic regression models incorporating aircraft platform, distance to lek, survey date, lek size, and lek type to explain lek detection from aerial surveys. Our top ranked model included platform, distance, and lek type (model weight; w1 = 0.288). We had four competitive models and model averaged to draw inferences. Model averaging showed that detectability was generally greatest with the R-44, followed by the R-22, and lowest with the C172, with a slight deviation from this ranking at increased distances. Within our transect width, model averaging also suggested that detectability decreased as distance from the transect to the lek increased during helicopter surveys, and detectability increased as distance from the transect to the lek increased during C172 surveys. Furthermore, man-made leks were more likely to be detected than natural leks and large leks were more likely to be detected than medium or small leks. Aerial surveys effectively locate new leks and monitor lek density, and alleviate weaknesses associated with ground-based monitoring. We recommend using the R-44 to conduct lek surveys while flying at an altitude of 15 m at a speed of 60 km/hr on sunny mornings.

Monitoring Whooping Crane Abundance Using Aerial Surveys: Influences on Detectability.

The whooping crane (Grus americana), an endangered species, has been counted on its winter grounds in Texas, USA, since 1950 using fixed-wing aircraft. Many shortcomings of the traditional survey technique have been identified, calling into question its efficacy, defensibility, repeatability, and usefulness into the future. To improve and standardize monitoring effort, we began investigating new survey techniques. Here we focus on efficacy of line transect-based distance sampling during aerial surveys. We conducted a preliminary test of distance sampling during winter 2010–2011 while flying the traditional survey, which indicated that detectability within 500 m of transects was 0.558 (SE = 0.031). We then used an experimental decoy survey to evaluate impacts of observer experience, sun position, distance from transect, and group size on detectability. Our results indicated decoy detectability increased with group size and exhibited a quadratic relationship with distance likely due to pontoons on the aircraft. We found that detectability was 2.704 times greater when the sun was overhead and 3.912 times greater when the sun was at the observers back than when it was in the observers eyes. We found that an inexperienced observer misclassified non-target objects more often than an experienced observer. During the decoy experiment we used marks on the struts to categorize distances into intervals, but we found that observers misclassified distances 46.7% of the time (95% CI = 37.0–56.6%). Also, we found that detectability of individuals within detected groups was affected by group size and distance from transect. We discuss how these results inform design and implementation of future whooping crane monitoring efforts. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Rio Grande Wild Turkey Habitat Selection in the Southern Great Plains

Abstract We recorded telemetry locations from 1,129 radiotagged turkeys (Meleagris gallopavo intermedia) on 4 study areas in the Texas Panhandle and southwestern Kansas, USA, from 2000 to 2004. Analyses of telemetry locations indicated both sexes selected riparian vegetative zones. Females did not select grazed or nongrazed pastures for daily movements. However, females did select nongrazed pastures for nest sites on 2 study areas and males selected for grazed pastures at one study area during the breeding season. We compared nest sites (n = 351) to random sites using logistic regression, which indicated height of visual obstruction, percent canopy cover, and percent bare ground provided the highest predictive power (P ≤ 0.003) for characteristics describing nest-site selection. Nest-site vegetative characteristics between vegetative zones differed primarily in composition: upland zone nest sites had more (P ≤ 0.001) shrubs and riparian zone nest sites had more (P ≤ 0.001) grass. There were no differences in measured nest-site vegetative characteristics between pasture types, but there were differences between available nesting cover in grazed and nongrazed pastures. Random plots in grazed pastures had less grass cover (P ≤ 0.001) and more bare ground (P = 0.002). Because of cattle impacts on average grass height and availability, grazing would likely have the highest impact on nesting in riparian zones due to turkey use of grass as nesting cover. An appropriate grazing plan to promote Rio Grande turkey nesting habitat would include grazing upland zones in the spring, when it likely has little impact on nesting-site selection, and grazing riparian zones following breeding season completion. Grazing at light to moderate intensities with periods of rest did not affect male turkey pasture use and may have continued to maintain open areas used by male turkeys for displaying purposes.

Sound Intensity of Booming in Lesser Prairie-Chickens

Abstract Wildlife managers traditionally monitored lesser prairie-chicken (Tympanuchus pallidicinctus) populations using road-based lek surveys and assumed booming can be heard ≥1.6 km from a lek. To assess this assumption, we measured sound intensity (decibels) of booming lesser prairie-chickens. Our results indicated sound intensity 1.6 km from a lek would be less than or equal to the sound intensity of a whisper. Thus, 1.6 km is probably too great a distance for audible detection of booming in many conditions.

Assessing range-wide habitat suitability for the Lesser Prairie- Chicken

Population declines of many wildlife species have been linked to habitat loss incurred through land-use change. Incorporation of conservation planning into development planning may mitigate these impacts. The threatened Lesser Prairie- Chicken (Tympanuchus pallidicinctus) is experiencing loss of native habitat and high levels of energy development across its multijurisdictional range. Our goal was to explore relationships of the species occurrence with landscape characteristics and anthropogenic effects influencing its distribution through evaluation of habitat suitability associated with one particular habitat usage, lekking. Lekking has been relatively well-surveyed, though not consistently, in all jurisdictions. All five states in which Lesser Prairie-Chickens occur cooperated in development of a Maxent habitat suitability model. We created two models, one with state as a factor and one without state. When state was included it was the most important predictor, followed by percent of land cover consisting of known or suspected used vegetation classes within a 5000 m area around a lek. Without state, land cover was the most important predictor of relative habitat suitability for leks. Among the anthropogenic predictors, landscape condition, a measure of human impact integrated across several factors, was most important, ranking third in importance without state. These results quantify the relative suitability of the landscape within the current occupied range of Lesser Prairie-Chickens. These models, combined with other landscape information, form the basis of a habitat assessment tool that can be used to guide siting of development projects and targeting of areas for conservation.