Brian D. Jansen

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.

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.

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

Infectious Keratoconjunctivitis in Bighorn Sheep, Silver Bell Mountains, Arizona, USA

An infectious keratoconjunctivitis (IKC) epizootic in bighorn sheep (Ovis canadensis) occurred in the Silver Bell Mountains, Arizona, USA, from 1 December 2003 to 31 March 2004. We used standard culture methods and polymerase chain reaction (PCR) amplification of the 16S rRNA gene to test for the causative agents of IKC and other diseases reported to be associated with bighorn sheep populations. All bighorn sheep and domestic goat test results were negative except for Mycoplasma spp. and Branhamella spp. The culture and PCR results differed. Conjunctival swabs from four of 19 IKC-affected bighorn sheep tested by culture were positive for Mycoplasma spp., whereas 22 of 22 bighorn sheep samples tested by PCR were positive for Mycoplasma spp. None of 13 domestic goats tested positive by culture for Mycoplasma spp., whereas five of 16 tested positive by PCR. Three of 16 domestic goats and seven of 24 IKC-affected bighorn sheep tested positive for Branhamella spp. by culture. Bighorn sheep began showing clinical signs of IKC between 21 and 28 days following initial detection of domestic goats in bighorn sheep habitat. The IKC epizootic lasted 122 days, and individual bighorn sheep were blind for an average of 38.4 days. Given the clear potential for disease transmission to bighorn sheep, we recommend that land managers not allow the pasturing of domestic goats near occupied bighorn sheep habitat.

INFLUENCE OF MINING ON BEHAVIOR OF BIGHORN SHEEP

Abstract Mining has been cited as detrimental to bighorn sheep (Ovis canadensis), but little research exists that has demonstrated those effects. We compared behavior of bighorn sheep while individuals were inside and outside of an active copper mine to determine if individual animals were altering their behavior relative to the active mine. We conducted this study in the Silver Bell Mountains, Arizona, from December 2003 to January 2005. We observed 3 radiocollared subadult males, 4 adult males, and 5 females, and recorded behavior throughout the daylight period. After accounting for differences by sex-age class (i.e., subadult male, adult male, female) and season (i.e., breeding, non-breeding), bighorn sheep fed less (6%) while inside the mine perimeter. Other behaviors (e.g., bedding, standing, alert, and interacting) were observed for similar amounts of time while within and outside the mine perimeter. Within sex-age classes, there were few differences in behavior. Subadult males fed less (mean difference  =  −18.6%, 95% C.I.  =  −43.1–6.0) and bedded more (mean difference  =  14.3%, 95% C.I.  =  −40.9–69.4) while inside the mine. During the breeding season, adult males were alert less and interacted less (alert, mean difference  =  4.1%, 95% C.I.  =  −1.63–9.9; interacting, mean difference  =  3.1%, 95% C.I.  =  −5.7–11.9) while inside the mine. Females interacted more (mean difference  =  0.37%; 95% C.I.  =  −0.01–0.8) while inside the mine area. Elements of modern mining activity (e.g., vehicular traffic, humans afoot near vehicles, sounds) might be predictable to bighorn sheep allowing them to habituate to those human activities.

Bighorn Sheep Selection of Landscape Features in an Active Copper Mine

Abstract Bighorn sheep (Ovis canadensis) and Dalls sheep (O. dalli) use mining areas despite high human activity. We studied bighorn sheep selection of landscape features within a mine in a desert environment to determine those important for bighorn sheep and to enhance reclamation efforts of mines in desert environments. We collared and observed 8 male and 6 female bighorn sheep from December 2003 to January 2005 in the Silver Bell Mountains, Arizona, USA. We classified 13 unique features within a mine landscape based on topography, hydrology, and vegetation. Subadult male, adult male, and female bighorn sheep used desert islands (54, 76, and 54%, respectively) followed by highwalls (14, <10, and 11%, respectively). Subadult male, adult male, and female bighorn sheep selected for desert islands, and subadult males and females also selected for highwalls, whereas adult males did not. We did not observe bighorn sheep using leach ponds, pit bottoms, or tailings dumps. Bighorn sheep behavior while on desert islands was similar to behavior recorded when outside the mine perimeter. Subadult male and female bighorn sheep fed and were alert less and socially interacted more on highwalls than they did while outside the mine perimeter. Bighorn sheep in mines select areas similar to conspecifics outside of mined areas. In areas where mining and bighorn sheep are in proximity, mining engineers and wildlife biologists should work together to design reclamation plans that benefit bighorn sheep. In places where revegetation is difficult (i.e., deserts), mine engineers should design infrastructure (i.e., roadways, waste dumps, buildings) to minimize the unnecessary destruction of native slopes and vegetation.

Population Dynamics and Behavior of Bighorn Sheep with Infectious Keratoconjunctivitis

Abstract Introduced disease is a major mortality factor in some populations of bighorn sheep (Ovis canadensis). Epizootics of infectious keratoconjunctivitis (IKC) and contagious ecthyma occurred in bighorn sheep in the Silver Bell Mountains of south-central Arizona, USA, from 1 December 2003 to 31 March 2004. Our objectives were to 1) investigate the influence of the epizootic on abundance and demographics and 2) examine how IKC affected the mortality, behavior, and movements of clinically affected animals. Morbidity was 39%, and all sex and age classes were affected. The population declined 23%, with most mortality in the adult female (1 M, 11 F) segment of the population. Of the diseased animals that were marked (n = 27), 44% recovered and 44% died. Predation (50%) and starvation (33%) were the primary causes of mortality of diseased bighorn sheep. Bighorn sheep that were infected spent less time feeding and moved less than noninfected animals during the epizootic. Managers might be able to minimize losses of infected animals through predator control. To minimize losses to starvation, managers should refrain from any activity that disturbs infected animals (including treatment) because disturbances increase energy expenditures and expose infected animals to injury.

Surface mining and ecology of desert bighorn sheep.

Abstract Understanding how mining operations influence use of habitat and movements by bighorn sheep (Ovis canadensis) is critical to long-term management of populations that inhabit areas in and around mining operations. We studied responses of a population of desert bighorn sheep to a surface-mining operation in the Silver Bell Mountains, Pima County, Arizona. We incorporated two study periods with different levels of activity at the mine: closure (1993–1995) and operation (2003–2005). We captured and radiocollared ≥22 bighorn sheep in each period and monitored size of home ranges, size of core areas, and use of the mine. Home ranges and core areas of adult males during the breeding season were larger during closure than during operation. During the non-breeding season, there was evidence that home ranges of adult males were larger during closure compared to when the mine was in operation. Core areas of adult males were similar in size during the non-breeding season of both periods. During the breeding season, adult males used the mine more while the mine was in operation than during closure. During the non-breeding season, however, adult males did not use the mine more during either period. Home ranges and core areas of females were not different in size during both seasons and periods of closure and operation of the mine. During both seasons, females used the mine more during operation than during closure. Overall, the population of desert bighorn sheep used an active mine more than it did when the mine was closed.

TREE SWALLOW ENTANGLED ON TEDDY BEAR CHOLLA SPINES

Abstract Avian collisions with human-made objects are relatively common; however, documented avian collisions with naturally occurring objects are rare in scientific literature. On 22 April 2002, we observed a tree swallow (Tachycineta bicolor) entangled in the spines of a teddy bear cholla (Opuntia bigelovii) in the Tule Mountains, Cabeza Prieta National Wildlife Refuge, Arizona. Two possible causes of this incident include the swallow flying into the teddy bear cholla, possibly being blown by a gust of wind, or being placed there by a loggerhead shrike (Lanius ludovicanus). Because of the flying abilities of swallows and documented diets of loggerhead shrikes, either would be unusual.

SAGUARO SPINE PENETRATED BIGHORN SHEEP SKULL

Abstract Animals that inhabit vegetative communities where thorns and spines are common should be capable of moving while avoiding injury from thorns and spines. On 21 December 2003, we found that a saguaro cactus (Carnegiea gigantea) spine had penetrated the lacrimal bone into the orbit of a desert bighorn sheep (Ovis canadensis) in south-central Arizona. The animal was observed with clinical infectious keratoconjunctivitis and was blind for 3 weeks prior to death. It is likely that the animal collided with a saguaro cactus after she became blinded by disease.