Heather A. Whitlaw

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.

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.

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.

SURVIVAL OF FEMALE ELK IN NORTHERN ARIZONA

Because modeling and sound management of ungulate populations requires reliable estimates of survival and mortality, we measured survival and cause-specific mortality rates for 43 yearling and 197 adult, radiocollared female elk (Cervus elaphus) in hunted and unhunted areas of northern Arizona during 1985-93, and for 18 adult radiocollared females from the moderately hunted White Mountain Tribal Reservation (1983- 85). Hunting-related causes were the largest source (62%) of adult mortality. Annual survival was highest in the unhunted segment of the population (0.969). Elk survival rates in northern Arizona are representative of an expanding elk population with few limiting factors, and our data provides baseline information for Mexican wolf (Canis lupus baileyi) reintroductions.

Survival and cougar predation of translocated bighorn sheep in Arizona

We estimated survival and cause-specific mortality of 395 translocated bighorn sheep (Ovis canadensis) in Arizona, USA, from May 1979 to November 1997. To investigate regional and temporal trends, we compared survival among disjunct populations in 4 regions in Arizona (Northwest, Southeast, Southwest, Central) during 3 time periods: 1979-1985, 1986-1991, and 1992-1997. Survival did not differ among periods in the Northwest (P= 0.50) and Southeast (P= 0.78) regions, and ranged from 0.80 to 0.88 and 0.76 to 0.82, respectively. In contrast, survival decreased in the Southwest (P < 0.01) and Central (P< 0.01) regions, and ranged from 0.44 to 0.79 and 0.42 to 0.83, respectively. Cougar (Puma concolor) predation was the most important source of mortality (66%). Our results suggest that recent increases in cougar predation in most areas of Arizona may be responsible for declining bighorn sheep numbers. Recent population declines in mule deer (Odocoileus hemionus), the primary prey of cougars, may be responsible for recent increases of cougar predations on bighorn sheep in Arizona and other areas of western North America.

Age Structure, Survival, and Mortality of Mountain Lions in Southeastern Arizona

Reliable estimates of survival and mortality rates for mountain lions (Puma concolor) have been difficult to obtain because of their low densities and secretive behavior. We estimated annual survival and cause-specific mortality rates for a heavily exploited mountain lion population in southeastern Arizona from February 1991 to April 1994. We monitored 24 adult radio-collared mountain lions weekly. We used MICROMORT to determine daily, annual, and overall survival rates. Radio-collared mountain lions had low annual survival (0.62). Depredation control was the leading cause of mortality. Survival rates of female (0.67) and male (0.58) lions did not differ. Because of the high mortality in the area of depredation control, this area may represent a mor-

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.

Interactions of Raptors and Lesser Prairie-Chickens at Leks in the Texas Southern High Plains

Abstract We examined behavioral interactions of raptors, Chihuahuan Ravens (Corvus cryptoleucus), and Lesser Prairie-Chickens (Tympanuchus pallidicinctus) at leks in the Texas Southern High Plains. Northern Harriers (Circus cyaneus) and Swainsons Hawks (Buteo swainsoni) were the most common raptors observed at leks. Only 15 of 61 (25%) raptor encounters at leks (0.09/hr) resulted in a capture attempt (0.02/hr). Mean (± SD) time for Lesser Prairie-Chickens to return to lekking behavior following a raptor encounter was 4.2 ± 5.5 min suggesting the disturbance had little influence on lekking behaviors. Lesser Prairie-Chickens engaged in different escape behaviors depending on raptor species and, generally, did not respond to ravens suggesting they are able to assess different predation risks. The raptors in our study area posed little predation risk to lekking prairie-chickens. Behavioral disturbance at leks appears minimal due to the lack of successful predation events, low raptor encounter rates, and short time to return to lekking behavior.

Sexual Selection and Mating Chronology of Lesser Prairie-Chickens

Abstract Little is known about mate selection and lek dynamics of Lesser Prairie-Chickens (Tympanuchus pallidicinctus). We collected data on male territory size and location on leks, behavior, and morphological characteristics and assessed the importance of these variables on male Lesser Prairie-Chicken mating success during spring 2008 and 2009 in the Texas Southern High Plains. We used discrete choice models and found that males that were less idle were chosen more often for mating. Our results also suggest that males with smaller territories obtained more copulations. Morphological characteristics were weaker predictors of male mating success. Peak female attendance at leks occurred during the 1-week interval starting 13 April during both years of study. Male prairie-chickens appear to make exploratory movements to, and from, leks early in the lekking season; 13 of 19 males banded early (23 Feb–13 Mar) in the lekking season departed the lek of capture and were not reobserved (11 yearlings, 2 adults). Thirty-three percent (range  =  26–51%) of males on a lek mated (yearlings  =  44%, adults  =  20%) and males that were more active experienced greater mating success.