James W. Cain

Mechanisms of Thermoregulation and Water Balance in Desert Ungulates

Abstract Desert ungulates must contend with high solar radiation, high ambient temperatures, a lack of water and cover, unpredictable food resources, and the challenges these factors present for thermoregulation and water balance. To deal with the conflicting challenges of maintaining body temperature within acceptable limits and minimizing water loss, desert ungulates use a variety of physiological, morphological, and behavioral mechanisms. The mechanisms involved in thermoregulation and water balance have been studied in many domestic and wild African and Middle Eastern ungulates; studies involving ungulates inhabiting North American deserts are limited in comparison. Our objectives were to review available scientific literature on thermoregulation, water balance, and the effects of dehydration in desert ungulates. We discuss the physiological, morphological, and behavioral mechanisms used by ungulates to maintain temperature and water balance in arid environments, and the implications for research and management of desert ungulates in western North America.

Influence of topography and GPS fix interval on GPS collar performance

Abstract Topography, vegetation, and animal behavior may influence the performance of Global Positioning System (GPS) telemetry collars, affecting fix success rates and location error. We reviewed the scientific literature published from 1995 to June 2004 to determine the fix intervals used and fix success rates obtained in studies using GPS telemetry. We also programmed GPS telemetry collars with 6 different fix intervals and placed them at fixed locations of varying topography in the Cabeza Prieta National Wildlife Refuge, Arizona from August 2003–May 2004. Fix interval affected fix success rates both in our field study (99, 98, 96, 94, 93, 92% fix success rate for 0.25, 0.5, 1, 4, 6, and 13-hour fix intervals, respectively) and in our analysis of data obtained from scientific literature (r2=0.531, P≤0.001), with shorter fix intervals being associated with higher fix success rates. Topography affected the fix success rate (F2, 77=12.017, P≤0.001), location error (F2, 77=6.76, P=0.002), and proportion of 3-dimensional (3-D) fixes (F2,77=10.184, P≤0.001), resulting in lower fix success rates and larger location errors in areas with more rugged topography. The influence of topography and fix interval on location error and fix success rates may bias GPS location data, resulting in misclassification of habitat use and under-sampling certain areas used by animals. Location error and missing data can increase type II error and may result in incorrect inferences in some studies. These biases need to be assessed and steps should be taken to minimize their influence on results of studies of habitat selection and other aspects of animal ecology.

Developed Waters for Wildlife: Science, Perception, Values, and Controversy

Abstract Human-made or -modified water sources (i.e., catchments) are widely used for wildlife management in the arid western United States, where thousands of such catchments have been built to enhance wildlife populations and mitigate for the loss of natural water sources. For decades, the need for and value of catchments to wildlife was unquestioned. Recently, however, the use of catchments has become controversial, particularly on public lands. Impacts to wildlife populations and wildlife habitats have been central to the debate, which has, in large part, been fueled by a paucity of scientific information. Value-based conflicts over management practices on public lands also have played a significant role.

Predator activity and nest success of willow flycatchers and yellow warblers

Willow flycatchers (Empidonax traillii) and yellow warblers (Dendroica petechia) are riparian-dependent species that have declined throughout much of their former range in California, USA. These declines have been primarily associated with the loss of riparian breeding habitat, increases in brood parasitism, and increases in nest predation. We (1) identified potential nest predators using inactive yellow warbler nests; (2) determined the relationship of meadow wetness, meadow size, and amount of edge to predator activity; (3) determined the association between potential nest predator activity and nest success; and (4) determined how proximity to forest edge and isolated trees was related to nest success. We used automatic cameras to monitor inactive yellow warbler nests baited with zebra finch (Taeniopygia guttata) eggs to identify nest predators. We used track plates (mammalian), point counts (avian), and time-constrained searches (reptilian) to assess the activity of potential nest predators. We photographed short-tailed weasel (Mustela erminea), Douglas squirrel (Tamiasciurus douglasii), lodgepole chipmunk (Tamias speciosus), deer mouse (Peromyscus maniculatus), and unidentified chipmunks (Tamias spp.) depredating yellow warbler nests baited with finch eggs. The amount of meadow covered with water was negatively associated with the activity of chipmunks and Douglas squirrels. Meadow size was negatively associated with Douglas squirrel activity. The amount of edge was positively associated with the activity of Douglas squirrels, chipmunks, Stellers jays (Cyanocitta stelleri), and brown-headed cowbirds (Molothrus ater). Nest predation was the major cause of nest failure in our study. However, only short-tailed weasels, Douglas squirrels, Clarks nutcrackers (Nucifraga columbiana), Stellers jays, Coopers hawks (Accipiter cooperii), and brown-headed cowbirds had activity indices that were negatively associated with nest success of either species. The distance to isolated trees was associated with willow flycatcher nest success, whereas the distance to both isolated trees and to the forest edge was associated with yellow warbler nest success-nests located closer to isolated trees and the forest edge were more likely to be parasitized and/or depredated. Our results suggest that flooding portions of meadows may restrict meadow access to forest-edge-associated nest predators.

Potential Effects of the United States-Mexico Border Fence on Wildlife

Security infrastructure along international boundaries threatens to degrade connectivity for wildlife. To explore potential effects of a fence under construction along the U.S.-Mexico border on wildlife, we assessed movement behavior of two species with different life histories whose regional persistence may depend on transboundary movements. We used radiotelemetry to assess how vegetation and landscape structure affect flight and natal dispersal behaviors of Ferruginous Pygmy-Owls (Glaucidium brasilianum), and satellite telemetry, gene-flow estimates, and least-cost path models to assess movement behavior and interpopulation connectivity of desert bighorn sheep (Ovis canadensis mexicana). Flight height of Pygmy-Owls averaged only 1.4 m (SE 0.1) above ground, and only 23% of flights exceeded 4 m. Juvenile Pygmy-Owls dispersed at slower speeds, changed direction more, and had lower colonization success in landscapes with larger vegetation openings or higher levels of disturbance (p < or = 0.047), which suggests large vegetation gaps coupled with tall fences may limit transboundary movements. Female bighorn sheep crossed valleys up to 4.9 km wide, and microsatellite analyses indicated relatively high levels of gene flow and migration (95% CI for F(ST)=0.010-0.115, Nm = 1.9-24.8, M =10.4-15.4) between populations divided by an 11-km valley. Models of gene flow based on regional topography and movement barriers suggested that nine populations of bighorn sheep in northwestern Sonora are linked by dispersal with those in neighboring Arizona. Disruption of transboundary movement corridors by impermeable fencing would isolate some populations on the Arizona side. Connectivity for other species with similar movement abilities and spatial distributions may be affected by border development, yet mitigation strategies could address needs of wildlife and humans.

Responses of Desert Bighorn Sheep to Removal of Water Sources

Abstract In arid regions of the southwestern United States, water is often considered a primary factor limiting distribution and productivity of desert ungulates, including desert bighorn sheep (Ovis canadensis mexicana). Thus, wildlife management agencies and sportsmens organizations have invested substantial time and resources in the construction and maintenance of water catchments. Although the availability of freestanding water sources is believed to influence many aspects of the ecology of desert bighorn sheep, the efficacy of these water sources has been questioned and has not been examined experimentally. We used a before-after–control-impact study design to determine if removal of water catchments changed diet, characteristics of foraging areas used by female desert bighorn sheep, home-range size, movement rates, distance to catchments, adult mortality, productivity, or juvenile recruitment in 2 mountain ranges on the Cabeza Prieta National Wildlife Refuge, Arizona, USA. During pretreatment (2002–2003), we ensured that water catchments were available to desert bighorn sheep in both mountain ranges; during posttreatment (2004–2005), we drained all water catchments in the treatment range. We measured diet composition, characteristics of foraging areas, 50% and 95% kernel home ranges, movement rates, and distance to water catchments seasonally from 2002 to 2005. We also estimated adult survival, lamb:female, and yearling:female ratios from 2002 to 2005. We predicted that removal of water catchments would result in 1) increased use of foraging areas with more vegetation cover, more thermal cover, and higher succulent abundance; 2) increased consumption of cacti and other succulents; 3) an increase in home-range size, movement rates, and distance to nearest catchment; and 4) a decrease in adult survival, productivity, and juvenile recruitment. Removal of water catchments in the treatment range did not result in predicted changes in diet, foraging area selection, home-range size, movement rates, mortality, productivity, or recruitment. Female desert bighorn sheep did use areas with more thermal cover during the summer after removal of water catchments, but other characteristics of foraging areas used by bighorn sheep and their diet did not change appreciably with removal of water catchments. We did not document changes in home-range area, movement rates, or distance sheep were from water during hotter months; we only documented changes in home-range area, movement rates, and distance to water catchments during winter and autumn. There were 10 desert bighorn sheep mortalities in the treatment range and 8 in the control range; 7 mortalities in each mountain range were during pretreatment. Twelve of the 18 total mortalities occurred during summer. Survival rate was lower during pretreatment than posttreatment in both mountain ranges. We did not document increased mortality or a change in lamb:female or yearling:female ratios after removal of water catchments. Home-range area and movement rates declined with increasing precipitation. Annual survival rates increased with increases in the current years total precipitation and total precipitation during the previous year; annual survival rates declined with increases in average daily temperature during winter. There was a severe drought during pretreatment and abnormally wet conditions during posttreatment. The increase in precipitation that coincided with removal of water sources improved forage conditions during posttreatment and may have provided adequate water for female desert bighorn sheep. The lack of change in home-range size, movement rates, and distance to the nearest water catchment during hot, dry seasons after removal of water sources suggests that forage conditions played a greater role in determining home-range area and movement rates than did the presence of water catchments. Higher mortality rates during the drought of the pretreatment period indicates that during droughts as severe as that of 2002, presence of water catchments was not sufficient to prevent mortalities of desert bighorn sheep and a lack of forage quality and quantity was likely the primary limiting factor of the population during this time. Improving forage conditions during posttreatment, increases in forage moisture content, and availability of naturally occurring sources of free water in the treatment range likely minimized any impact of removing water catchments on survival rates and lamb:female and yearling:female ratios. However, due to the climatic conditions during the study we were unable to assess how the treatment population would have responded to a lack of water sources during a drought period. The influence of anthropogenic water catchments, if any, on desert bighorn sheep populations may be strongest during years with weather conditions that are neither drought nor wet periods. Given the high interannual variability in precipitation in many areas of the arid Southwest, it is important for wildlife managers to determine if and when water is the primary limiting factor for populations of desert bighorn sheep in order to make the most efficient use of agency time and resources.

Influence of Mammal Activity on Nesting Success of Passerines

Abstract For many avian species, predation is the leading cause of nest failure. However, relationships between predator abundance and nest predation often differ across spatial scales. We examined the relationship between environmental characteristics in meadows and mammalian predator activity, the relationship between predator activity at 2 spatial scales, and the probability of nest predation of willow flycatchers (Empidonax traillii), dusky flycatchers (Empidonax oberholseri), and yellow warblers (Dendroica petechia) in the central Sierra Nevada Mountains, California, USA. Environmental characteristics associated with the detection of nest predators varied depending on species. Douglass squirrel (Tamiasciurus douglasii) and chipmunks (Tamias spp.) were associated with characteristics common along edges of meadows; short-tailed weasels (Mustela erminea) were associated with willows, whereas mice (Peromyscus maniculatus, Reithrodontomys megalotis, and Microtus spp.) and long-tailed weasels (Mustela frenata) were distributed throughout the meadows. The probability of predation of willow and dusky flycatcher nests increased with increasing short-tailed weasel activity, and the probability of predation of yellow warbler nests increased with increasing activity of chipmunks and short-tailed weasels. Variation in the occurrence of predator species in different areas of the meadows likely influences the probability of nest predation by each species and the nesting success of birds. Identifying factors that influence the distribution and abundance of common nest predators will likely be integral to the development of conservation efforts to increase the reproductive success of some bird species.

Neck lesions in ungulates from collars incorporating satellite technology

Wildlife Society Bulletin 2004, 32(3):987–991 Peer edited Investigators have used marking collars and telemetry collars to enhance knowledge about movements of ungulates for many decades. Technological advances have provided increasingly dependable and sophisticated equipment (Fancy et al. 1988; Mourao and Merdi 2002), and methods of collar attachment have evolved substantially, particularly with respect to juvenile ungulates (Smith et al. 1998, Bleich and Pierce 1999). Nevertheless, recent observations of mule deer (Odocoileus hemionus) and mountain sheep (Ovis canadensis) fitted with telemetry collars that incorporate Global Positioning Systems (GPS) and other satellite technology indicate those collars may cause injury to the study animal. The intent of investigators should be to minimize injuries and effects of marking on the behavior of animals (White and Garrott 1990), but our observations suggest lack of compliance in some cases with existing guidelines (Committee on Acceptable Field Methods 1987, Institutional Animal Use and Care Committee [Powell and Proulx 2003]). We placed collars incorporating GPS receivers and very high frequency (VHF) transmitters (Telonics, Mesa, Ariz.; and Posrec, TVP Positioning AB, Lindesberg, Sweden) on mule deer and mountain sheep. We collared female deer in Round Valley, Inyo, and Mono counties, California during March (n=12) and November 2002 (n=1). Four of 6 deer recaptured in November 2002, 2 of 3 recaptured in January 2003, and 2 of 2 recaptured in March 2003 (1 of which was collared in November 2002) exhibited all stages of ulcer formation except bone involvement. Patchy alopecia, nonblanchable erythema, induration, and edema of the intact skin surrounding ulceration were present. In some deer there was only partial skin loss and the ulcers were superficial; others revealed skin loss to the subcutaneous layer resembling a deep abrasion. The most severely affected deer had skin loss with extensive destruction of muscle on the dorsal aspect of the neck (Figure 1). Affected areas varied from 4–100 cm2 and extended from 4–8 cm distal of the occiput or jaw to the mid-cervical region on the dorsal and ventral surfaces of the neck, respectively; lateral surfaces were not involved. We removed collars from the 6 deer that exhibited lesions in November 2002 and January 2003. Three of those animals were recaptured in March 2003, and all lesions had healed completely. As part of long-term ecological investigations (Pierce et al. 2000a,b), we placed VHF collars from 3 manufacturers on 113 juvenile ( 500 adult mule deer of both sexes since 1992. We From the Field: Neck lesions in ungulates from collars incorporating satellite technology

Forage selection of sable antelope in Pilanesberg Game Reserve, South Africa

Concern about the habitat requirements of sable antelope (Hippotragus niger) has increased due to population declines shown in some protected areas. Our study was prompted by the lack of initial increase by the sable antelope introduced into the Pilanesberg Game Reserve in North West Province, South Africa; 67 animals released between 1979 and 1983 had only grown to approximately 70 animals by 1988. We recorded forage selection by sable antelope within the context of the landscape units favoured in different seasons. Chrysopogon serrulatus, Panicum maximum, Heteropogon contortus, and Themeda triandra contributed most to the diet of sable antelope. Faecal crude protein content did not drop below 6.6% of dry matter during the dry season, with use of burnt grassland by sable contributing to an elevation in faecal protein levels at the beginning of the wet season. The sable population had increased to 127 animals by 1991, suggesting that the earlier lack of population growth had been due to below-average rainfall, lack of burns providing green regrowth during the dry season, or a delay in learning to exploit available forage resources efficiently.

Nesting Ecology of the Black-Capped Vireo in Southwest Texas

Abstract There is little information about nesting ecology of the federally endangered Black-capped Vireo (Vireo atricapilla) in the southern and western region of its breeding range, which is characterized by xeric thornscrub and patchy low-growing vegetation. We mapped territories and monitored 119 Black-capped Vireo nests across seven study sites in 2009 and 2010 in Val Verde County, Texas in the Devils River region on the western edge of the Edwards Plateau. We observed 69 nests with cameras to identify nest predators. Clutch size was significantly smaller in 2009 (3.4 ± 0.82) than in 2010 (3.8 ± 0.43). Both nest depredation and parasitism by Brown-headed Cowbirds (Molothrus ater) were >10% higher in 2009 than in 2010. There was a large diversity of nest predators identified including Brown-headed Cowbird (n  =  4), snakes (n  =  4), and Greater Roadrunner (Geococcyx californianus) (n  =  3). Species identified that have not been previously observed as Black-capped Vireo nest predators were bobcat (Lynx rufus), common raccoon (Procyon lotor), Greater Roadrunner, and the greater arid-land katydid (Neobarrettia spinosa). Productivity of Black-capped Vireos in the Devils River area appeared to be heavily influenced by weather, particularly precipitation during the breeding season.