Warren B. Ballard

Accuracy and precision of estimating age of gray wolves by tooth wear

We evaluated the accuracy and precision of tooth wear for aging gray wolves (Canis lupus) from Alaska, Minnesota, and Ontario based on 47 known-age or known-minimum-age skulls. Estimates of age using tooth wear and a commercial cementum annuli-aging service were useful for wolves up to 14 years old. The precision of estimates from cementum annuli was greater than estimates from tooth wear, but tooth wear estimates are more applicable in the field. We tended to overestimate age by 1-2 years and occasionally by 3 or 4 years. The commercial service aged young wolves with cementum annuli to within ±1 year of actual age, but under estimated ages of wolves ≥9 years old by 1-3 years. No differences were detected in tooth wear patterns for wild wolves from Alaska, Minnesota, and Ontario, nor between captive and wild wolves. Tooth wear was not appropriate for aging wolves with an underbite that prevented normal wear or severely broken and missing teeth.

Pathogens, Nutritional Deficiency, and Climate Influences on a Declining Moose Population

Abstract Several potential proximate causes may be implicated in a recent (post-1984) decline in moose (Alces alces andersoni) numbers at their southern range periphery in northwest Minnesota, USA. These causes include deleterious effects of infectious pathogens, some of which are associated with white-tailed deer (Odocoileus virginianus), negative effects of climate change, increased food competition with deer or moose, legal or illegal hunting, and increased predation by gray wolves (Canis lupus) and black bears (Ursus americanus). Long-standing factors that may have contributed to the moose decline include those typically associated with marginal habitat such as nutritional deficiencies. We examined survival and productivity among radiocollared (n = 152) adult female and juvenile moose in northwest Minnesota during 1995–2000, and assessed cause of death and pathology through carcass necropsy of radiocollared and non-radiocollared animals. Aerial moose surveys suggested that hunting was an unlikely source of the numerical decline because the level of harvest was relatively low (i.e., approx. 15% / 2 yr) and the population usually grew in years following a hunt. The majority of moose mortalities (up to 87% of radiocollared moose [n = 76] and up to 65% of non-radiocollared moose [n = 84]) were proximally related to pathology associated with parasites and infectious disease. Liver fluke (Fascioloides magna) infections apparently constituted the greatest single source of mortality and caused significant pathology in the liver, thoracic and peritoneal cavities, pericardial sac, and lungs. Mortality due to meningeal worm (Parelaphostrongylus tenuis) was less prevalent and was manifested through characteristic neurological disease. Several mortalities apparently were associated with unidentified infectious disease, probably acting in close association with malnutrition. Bone-marrow fat was lower for moose dying of natural causes than those dying of anthropogenic factors or accidents, implying that acute malnutrition contributed to moose mortality. Blood profiles from live-captured animals indicated that those dying in the subsequent 18 months were chronically malnourished. Relative to other populations, average annual survival rates for adult females (0.79 [0.74–0.84; 95% CI]) and yearlings (0.64 [0.48–0.86]) were low, whereas those for calves (0.66 [0.53–081]) were high. Pregnancy (48%) and twinning (19%) rates were among the lowest reported for moose, with reproductive senescence among females being apparent as early as 8 years. Pregnancy status was related to indices of acute (i.e., bone-marrow fat) and chronic (i.e., blood condition indices) malnutrition. Opportunistic carcass recovery indicated that there likely were few prime-aged males (>5 yr old) in the population. Analysis of protein content in moose browse and fecal samples indicated that food quality was probably adequate to support moose over winter, but the higher fecal protein among animals that died in the subsequent 18 months could be indicative of protein catabolism associated with malnutrition. Trace element analysis from moose livers revealed apparent deficiencies in copper and selenium, but there was limited evidence of direct association between trace element concentrations and moose disease, pathology, or mortality. Time-series analysis of regional moose counts (1961–2000) indicated that annual population growth rate was related negatively to mean summer temperature, with winter and summer temperatures increasing by an average of 6.8 and 2.1 C, respectively, during the 40-year period. This change may have increased moose thermoregulatory costs and disrupted their energy balance, and thereby reduced their fitness. Time-series analysis failed to show a relationship between annual population growth rate and moose or deer abundance, indicating that food limitation via resource competition was unlikely. Population viability analyses, using count data (1961–2000) and demographic data collected during this study, suggested that the northwest Minnesota moose population likely would not persist over the next 50 years. More broadly, we conclude that the southern distribution of moose may become restricted in areas where climate and habitat conditions are marginal, especially where deer are abundant and act as reservoir hosts for parasites.

Predation and survival of white-tailed deer fawns in northcentral New Brunswick

Identification of mortality sources of white-tailed deer (Odocoileus virginianus), particularly predation and survival rates, is important for effective management. We captured, radiocollared, and monitored 78 white-tailed deer fawns in northcentral New Brunswick to determine survival and cause-specific mortality from February 1994 through May 1997. Of 50 fawns captured as neonates, 22 died by 30 November 1994-96. Predation by coyotes (Canis latrans; n = 9), black bears (Ursus americanus; n = 5), domestic dogs (Canis familiaris; n = 3), and bobeats (Felis rufus; n = 2) was the largest cause of fawn mortality during summer and autumn, Coyotes were the primary cause of mortality of fawns >7 months old (11 of 15). Fawn survival was lowest during summer (0.47). increased during autumn (0.86) and early winter (0.95), and then declined during late winter (0.76) and spring (0.81). Our results support the hypothesis that coyotes have replaced gray wolves (Canis lupus) in northeastern North America, with survival and mortality rates being comparable between New Brunswick and other areas where wolves and coyotes are sympatric.

Viewpoint: Benefits and impacts of wildlife water developments

Resource managers in the western United States have long assumed that water was a key limiting factor on wildlife populations in arid habitats. Beginning in the 1940s-1950s, state and federal resource management agencies initiated water development programs intended to benefit game species and other wildlife. At least 5,859 such developments have been built in 11 western states. Most state wildlife management agencies in the western United States have ongoing wildlife water development programs that vary greatly in extent. Ranchers and range managers also have developed water sources for livestock, many of which also are used by wildlife. Recently, critics have suggested that wildlife water developments have not yielded expected benefits, and may negatively impact wildlife by increasing predation, competition, and disease transmission. Based upon a comprehensive review of scientific literature, we conclude that wildlife water developments have likely benefitted many game and non-game species, but not all water development projects have yielded expected increases in animal distribution and abundance. Hypothesized negative impacts of water developments on wildlife are not supported by data and remain largely speculative. However, our understanding of both positive and negative effects of wildlife water developments is incomplete, because of design limitations of previous research. Long-term, experimental studies are needed to address unanswered questions concerning the efficacy and ecological effects of water developments. We also recommend that resource managers apply more rigorous planning criteria to new developments, and expand monitoring efforts associated with water development programs.

Impacts of coyotes on swift foxes in Northwestern Texas

The distribution of swift foxes (Vulpes velox) in the western Great Plains has been dramatically reduced since historical times. Because coyotes (Canis latrans) have been identified as the main cause of mortality in swift fox populations, we studied the impacts of coyotes on swift foxes in northwestern Texas, USA. We radiomarked and monitored 88 swift foxes and 29 coyotes at 2 study sites from 1998 to 2000. On site 1, coyotes had relatively high abundance (41 ± 6.8 scats/2 km) and survival (0.90), whereas swift foxes had low survival (0.47), low density (0.24-0.31 foxes/km 2 ), and low recruitment (0.25 young/adult), and killings by coyotes (n = 8) were the major cause of death. On site 2, coyotes had relatively low abundance (19 ± 4.9 scats/2 km) and survival (0.54) due to greater human persecution, whereas swift foxes had relatively high survival (0.69), high density (0.68-0.77 foxes/km 2 ), and high recruitment (1.3 young/adult), and few (n = 2) were killed by coyotes. Our initial results -. suggested that swift foxes benefited from lower coyote numbers. To test this hypothesis, we removed 227 coyotes on site 1 during the final year of our study. Subsequently, coyote abundance decreased (18 ± = 4.5 tcats/2 km), whereas swift foxes had increased survival (0.63), increased density (0.68 foxes/km 2 ), arid increased recruitment (1.2 young/adult), and few (n = 3) were killed by coyotes. All parameters remained consistent on site 2. Our results indicate that coyotes can suppress swift fox populations, and that reductions in coyote numbers can change a swift fox population from a sink to a source.

Causes of Neonatal Moose Calf Mortality in South Central Alaska

During spring 1977 and 1978, 136 moose (Alces alces gigas) calves were radio-collared in the Nelchina and Susitna river basins of south central Alaska in an effort to determine causes of mortality. Thirteen calves (9.5%) died as a result of collaring activities. Of 123 remaining calves exhibiting normal cow-calf bonds, contact with 3 calves was lost and 66 (55%) died of natural causes. Predation by brown bears (Ursus arctos) was the most important cause of mortality, accounting for 79% of the deaths. Timing of the deaths of radio-collared calves was similar to that of uncollared calves of radio-collared adults, which indicated that collaring did not predispose the calves to predation. Ninety-four percent of the natural mortality occurred before 19 July each year. Little scavenging of either abandoned or predatorkilled calves was observed. Radio-collared brown bears were observed on 78 kills during 1978, averaging 1 ungulate kill/6.1 observation days. Moose of all age-classes comprised 87% of the kills and calves were the most common prey (57%). Identification of brown bear as a significant predator of moose complicates attempts to understand and manage ungulate-carnivore relationships. J. WILDL. MANAGE. 45(2):335-342 The Nelchina and upper Susitna river basins of south central Alaska have been important areas for moose hunting in recent years, accounting for 18% of the annual statewide harvest. The moose population peaked in 1960, and began declining after the severe winter of 196162. Severe winters also occurred in 196566 and 1971-72. Severe winters were thought to have precipitated the decline, but factors such as predation, range deterioration, hunting, and low bull:cow ratios were also thought to have contributed (Bishop and Rausch 1974). During this decline the moose population began exhibiting low calf recruitment, reflected by moose sex and age composition counts (Alaska Department of Fish and Game [ADFG severe winters were thought to be the controlling factor (Bishop and Rausch 1974). In the mid-1970s, the population again declined and wolf predation was suspected of preventing the population from recovering (Gasaway et al. 1977). Several studies were initiated in an effort to identify the reasons for the moose population declines. Several approaches were used, as described by Franzmann and Bailey (unpubl. rep., Alaska Dep. Fish and Game, Fed. Aid Proj. W-17-9, 1977), Oldemeyer et al. (1977), Gasaway J. Wildl. Manage. 45(2):1981 335 This content downloaded from 157.55.39.95 on Sat, 11 Jun 2016 06:28:55 UTC All use subject to http://about.jstor.org/terms 336 MOOSE CALF MORTALITY IN ALASKA* Ballard et al. et al. (1977), Stephenson (unpubl. rep., Alaska Dep. Fish and Game Fed Aid Proj. W-17-8, 1978), and Ballard and Spraker (unpubl. rep., Alaska Dep. Fish and Game Fed. Aid Proj. W-17-9 and 10, 1979). The Tanana Flats and Nelchina Basin studies evaluated the effects of wolf predation on moose calf survival in part by reducing wolf densities. All study approaches attempted to enumerate predator and prey densities by using radiotelemetry and aerial surveys. In the Nelchina study, food habit studies of the gray wolf indicated that moose comprised the bulk of the year-round diet, but rates of predation on calves were not sufficient to cause the low moose calf:cow ratios in the basin (Ballard and Spraker, unpubl. rep., Alaska Dep. Fish and Game Fed. Aid Proj. W17-9 and 10, 1979). A preliminary analysis of moose population data indicated either small or no increases in numbers of calves/100 cows following reduction in wolf densities. Evaluation of several blood parameters, used by Franzmann and LeResche (1978) to assess the physical condition of Alaskan moose populations, revealed that Nelchina Basin moose rated high in comparison to other populations, and indicated that deteriorating range conditions probably were not the cause. Moose pregnancy rates determined by rectal palpation were normal (88%), and thus low initial calf production due to low bull:cow ratios was ruled out (Ballard and Taylor, unpubl. rep., Alaska Dep. Fish and Game Fed. Aid Proj. W-17-9 and 10, 1978). As a result of these studies, it became apparent that a more direct method of determining causes of moose calf mortality was needed. In Idaho, newborn elk (Cervis elaphus) calves were fitted with radio-collars and monitored to determine the causes of mortality (Schlegel 1976). Schlegels technique was adapted to newborn moose calves concurrently for both this study and a study on the Kenai Peninsula (Franzmann et al. 1980). The objectives were to identify specific causes of moose calf mortality between parturition and November, when fall sex and age counts are conducted. This paper reports results of the Nelchina calf mortality study and brown bear predation studies, and discusses their management implications. These studies and the Kenai Peninsula moose calf mortality study (Franzmann et al. 1980) were conducted concurrently during 1977 and 1978. These studies were supported in part by Alaska Federal Aid to Wildlife Restoration Projects W-17-R. We acknowledge the fieldwork conducted by S. Eide, T. Balland, and L. Metz, ADF&G. R. Barret, Alaska State-Federal Laboratory, Palmer, performed all the necropsies. We especially thank M. Schlegel, Idaho Department Fish and Game, for sharing his radio-collar design with us and for making many suggestions. K. B. Schneider and D. E. McKnight, ADF&G, reviewed early drafts of the manuscript and made many suggestions.

Migration behavior of white-tailed deer under varying winter climate regimes in New Brunswick

White-tailed deer (Odocoileus virginianus) exhibit a variety of migration strategies across northern portions of their range. Factors reported as being responsible for migration initiation have shown no consistent pattern. We monitored 186 radiocollared white-tailed deer from 1994 to 1998 in 2 areas of New Brunswick: a southern area with moderate and variable winter climate and a northern area with consistently severe winter climate. We determined that deer in the south contained a large proportion of conditional migrators (individuals that may or may not migrate to winter range in a given year, and may or may not remain until spring), whereas deer in the north consisted almost entirely of obligate migrators (those that annually migrate to winter range for the duration of winter). Occurrence of conditional migration appeared to be a function of climate variability, although distribution of the behavior among individual deer was influenced by migration distance. Initiation of autumn migration in the south was related to snow depth for most deer and represented a response to the proximate cue of the onset of limiting conditions. Autumn migration in the north appeared to be a response to seasonal cues, and the direct influence of snow depth was reduced. Initiation of spring migration in the 2 study areas showed a similar pattern. Migration distance may represent a factor influencing distribution of migrational cues among individual deer within a population. The effect of winter climate variability on deer migration behavior may account for the disparity in behavior reported in the literature. The differences in migration behavior have implications for deer management surveys in northern areas where deer yarding occurs. Managers have assumed that deer observed during winter surveys were on winter range, hut this may not be a reasonable assumption in areas with variable winter climates.

THE INFLUENCE OF MOUNTAIN LION PREDATION ON BIGHORN SHEEP TRANSLOCATIONS

Abstract We studied the effects of mountain lion (Puma concolor) predation on 2 translocated populations of bighorn sheep (Ovis canadensis) in New Mexico, USA. During 1993, 32 Rocky Mountain bighorn sheep (O. c. canadensis) were translocated to Wheeler Peak Wilderness Area in northern New Mexico, and during 1992–1993, 31 desert bighorn sheep (O. c. mexicana) were translocated to Sierra Ladron in central New Mexico. We monitored both populations from release through 2000 using fixed-wing aircraft and ground and/or helicopter surveys. We determined cause of mortality for radiomarked individuals (n = 26) and calculated survival rates, cause-specific mortality rates, exponential growth rates, and lamb:ewe ratios. The post-lambing population estimates in 2000 were 180 in Wheeler Peak and 21 in Sierra Ladron. Annual adult survival was higher (P < 0.005) in the Wheeler Peak population (0.955) than in the Sierra Ladron population (0.784). Annual lamb:ewe ratios also were higher (P < 0.001) in the Wheeler Peak population (66.7 vs. 29.8). Mean annual exponential growth rate (r) in the Wheeler Peak population was 0.25 compared to −0.01 for the Sierra Ladron population. Predation by mountain lions was the primary proximate cause (75%) of 16 known-cause mortalities of radiomarked bighorn sheep in the Sierra Ladron population, while we did not document any predation in Wheeler Peak. The annual cause-specific mortality rates due to mountain lion predation in Sierra Ladron were 0.13 for males, 0.09 for females, and 0.11 for all adult bighorn sheep. Mountain lion predation may have limited the Sierra Ladron bighorn sheep population and could be imposing a destabilizing inverse density-dependent mortality. Mountain lions preyed on domestic cattle in the Sierra Ladron area and throughout desert bighorn sheep habitat in New Mexico; we therefore hypothesize that cattle “subsidized” the diets of mountain lions (i.e., reduced or eliminated natural starvation). The ultimate cause of mortality for these desert bighorn sheep may be related to subsidized mountain lion populations that do not appear to decline following native ungulate population decreases. In addition, the encroachment of woody vegetation may increase the hunting success of ambush predators like mountain lions. High mountain lion predation may require mitigation for the successful restoration of bighorn sheep.

Survival and cause-specific mortality rates of adult white-tailed deer in New Brunswick

Survival and cause-specific mortality rates between yarded and nonyarded white-tailed deer populations have not beer previously studied with the use of radiotelemetry, We captured, radiocollared, and monitored the survival of 103 adult male and female white-tailed deer (Odocoileus virginianus) in northern and southern New Brunswick from February 1994 through May 1997. Annual survival rates for adult does in northern New Brunswick were higher than those for females in the south but were not different for adult males between the 2 study areas. Six of 37 adult female mortalities in the northern, yarded population died as a result of coyote (Canis latrans) predation (0.098); doe harvest was illegal in this portion of the province, However, in the southern population, where a limited number of antlerless permits were issued but deer did not concentrate in traditional deeryards, 9 of 21 adult female mortalities were from hunting-related causes (0.114). Mortality rates for adult females as a result of predation did not differ between the 2 study areas (0.098 for north, 0.058 for south), and mortality rates of northern females (0.151) did not differ from hunting-related mortality rates for does in the south (0.128). A majority of adult males in northern New Brunswick died as a result of predation and hunting-related causes, while most (5 of 10) mortality in the southern study area resulted from legal harvest. There were no differences in adult male mortality rates among seasons or between study areas (P > 0.05), Annual survival of adult white-tailed deer in New Brunswick, where deer exist on the northern edge of their North American distribution, appeared dependent on either legal harvest rates in those populations that were exploited, or on coyote predation. Our results did not support the hypothesis that yarded white-tailed deer have higher winter survival rates than nonyarded populations.

HABITAT USE, HOME RANGES, AND SURVIVAL OF SWIFT FOXES IN A FRAGMENTED LANDSCAPE: CONSERVATION IMPLICATIONS

Abstract Habitat loss might be one of the primary reasons for the decline of the swift fox (Vulpes velox) in the western Great Plains of North America. From 1998 to 2001, we monitored 42 swift foxes in a landscape interspersed with native short-grass prairies, nonnative grasslands enrolled in the Conservation Reserve Program, irrigated agricultural fields, and dry-land agricultural fields. Survival estimates ranged from 0.52 to 0.66 for both adults and juveniles, and the primary causes of death were vehicle collisions (42% deaths) and coyote (Canis latrans) predation (33%). Annual home-range size was similar for males and females (10.8 and 10.5 km2, respectively). Within the study area, swift foxes selected only short-grass prairies and had lower-than-expected use or complete avoidance of all other habitat types. Our results indicate swift foxes are more specialized in habitat selection than other North American canids; thus, protection of native short-grass prairies might be necessary for their long-term existence.