Tony W. Mong

USING FECAL GLUCOCORTICOIDS FOR STRESS ASSESSMENT IN MOURNING DOVES

Abstract Fecal glucocorticoid assays provide a potentially useful, noninvasive means to study physiological responses of wildlife to various stressors. The objective of our study was to validate a method for measuring glucocorticoid metabolites in Mourning Dove (Zenaida macroura) feces. We validated the assay using standard procedures (e.g., parallelism, recovery of exogenous corticosterone) to demonstrate that the assay accurately and precisely measured glucocorticoid metabolites in Mourning Dove fecal extracts. We conducted adrenocorticotropin (ACTH) challenge experiments to validate the assays ability to determine biologically important changes in fecal glucocorticoids. Fecal glucocorticoid levels increased significantly approximately 2–3 hr after administration of ACTH at 50 IU per kg body mass to wild Mourning Doves held in captivity. In contrast, fecal glucocorticoid metabolites did not increase in control birds, birds that received saline injections, or a lower dose of ACTH (1 IU per kg body mass). Variation in overall fecal glucocorticoid metabolite levels may have been influenced by season and the length of time birds were held in captivity. Noninvasive fecal glucocorticoid metabolite analyses, in combination with demographic information, may have considerable utility for monitoring the effects of natural and anthropogenic disturbances on Mourning Dove populations. Uso de Glucocorticoides Fecales Para Evaluar el Estrés en Zenaida macroura Resumen. Las evaluaciones de glucocorticoides fecales representan un medio no invasor potencialmente útil para estudiar las respuestas fisiológicas de los animales silvestres ante agentes causantes de estrés. El objetivo de nuestro estudio fue validar un método para medir metabolitos glucocorticoides en heces de palomas Zenaida macroura. Validamos el método mediante procedimientos estándar (e.g., paralelismo, recuperación de corticosterona exógena) para demostrar que éste mide con exactitud y precisión los metabolitos glucocorticoides en extractos fecales de Z. macroura. Realizamos experimentos de desafío con adrenocorticotropina (ACTH) para validar la habilidad que tenía el método para determinar cambios biológicamente importantes en los glucocorticoides fecales. Los niveles de glucocorticoides fecales aumentaron de forma significativa aproximadamente 2–3 hr después de la administración de ACTH a 50 IU por kg de peso corporal a palomas silvestres mantenidas en cautiverio. En contraste, los metabolitos glucocorticoides fecales no aumentaron en aves control, ni en aves que recibieron inyecciones salinas o una menor dosis de ACTH (1 IU por kg de peso corporal). La variación en los niveles generales de metabolitos glucocorticoides fecales podría haber sido influenciada por la estación y la longitud del período de tiempo en que las aves fueron mantenidas en cautiverio. Los análisis no invasores de metabolitos glucocorticoides, en combinación con información demográfica, podrían ser de considerable utilidad para monitorear los efectos de los disturbios naturales y antropogénicos sobre las poblaciones de Z. macroura.

Survival and Body Condition of Captive-Reared Juvenile Ozark Hellbenders (Cryptobranchus alleganiensis bishopi) Following Translocation to the Wild

We used radiotelemetry and recapture to monitor survival and body condition of 36 captive-reared Ozark Hellbenders (Cryptobranchus alleganiensis bishopi) released at two sites on the North Fork of the White River, Missouri, from May 2008 to August 2009. At the end of our study 16 salamanders were alive, 13 had died, and the fate of seven could not be determined. Captive-reared hellbenders released at a site with densely arranged boulders exhibited approximately 1.5-fold higher annual survival (0.7467; daily survival  =  0.9992 ± 0.0004 95% CI) than hellbenders released at a site where boulders were patchily distributed (0.4816; daily survival  =  0.9980 ± 0.0007 95% CI). When compared to log-transformed length–mass relationships developed for wild hellbenders from the same river in the 1970s, mean body condition of hellbenders at the patchy boulder site was about average at the end of the study (mean residual distance  =  −0.0273 ± 0.0234 SE, n  =  7; range  =  −0.1375–0.0486), while mean body condition of hellbenders at the dense boulder site was above average (mean residual distance  =  0.0423 ± 0.0402 SE; n  =  8; range  =  −0.0374–0.1088). In addition to lower survivorship and body condition, a greater proportion of hellbenders at the patchy site accrued physical abnormalities (6 of 13 vs. 2 of 14), carried leech parasites (9 of 16 vs. 4 of 14), and carried the fungus Batrachochytrium dendrobatidis (3 of 11 vs. 1 of 13). A ‘site only’ model of survival was most supported, though additional supported models suggested increased mass at release may have increased daily survivorship. While more work is needed to determine the impact of translocation on long-term population dynamics of Ozark Hellbenders, our study demonstrated that about half of a translocated population of captive-reared hellbenders can survive while maintaining or increasing in body condition during their first year post-release, given release sites are well selected.

Physiological effects of radiotransmitters on mourning doves

Abstract It is critical to understand how radiotransmitters and their attachment techniques impact marked individuals. Many studies of transmitter effects assess only overt, deleterious effects. However, physiological effects caused by attachment techniques might compromise the integrity of resulting information. Our objectives, therefore, were to assess the efficacy of subcutaneous implants and determine the physiological effects on mourning doves (Zenaida macroura) using heterophil: lymphocyte (H:L) ratios, and fecal glucocorticoid measures. We conducted 2 trials with 60 mourning doves; 1 in summer-autumn (trial #1) and 1 in autumn-winter (trial #2). For each trial we assigned 15 male and 15 female doves to either a subcutaneous implant treatment or a control group. During the 2 trials, we observed no differences in body masses, H:L ratios or fecal corticosterone levels between mourning doves with subcutaneous implants and the control group. Given the ultimate use of the information obtained from telemetry projects and cost of the resulting initiatives, expenditures associated with rigorous experimental evaluations can only improve the basis of reliable knowledge used in making resource management decisions

Eastern Spotted Skunk (Spilogale putorius) Survival and Cause-specific Mortality in the Ouachita Mountains, Arkansas

Abstract Survival and cause-specific mortality of eastern spotted skunks (Spilogale putorius) was assessed for a radio-monitored population in the Ouachita Mountains of westcentral Arkansas, USA. We monitored 33 eastern spotted skunks over a 23 mo period. Mean annual survival was 0.354 (0.339–0.368, 95% CI), and survival estimates were similar across age and sex categories. Survival increased for males as measures of body condition index increased. This pattern was reversed for females, although interpretation of the patterns is potentially confounded by female reproductive status. Of 19 mortality events, 63% (12) were caused by avian predators, most likely great horned owls (Bubo virginianus), 26% (5) were caused by mammalian predators, and 11% (2) were due to unknown causes. Although eastern spotted skunks are known to avoid open areas and forested areas where the understory is less dense and the canopy more open, 11 of 12 avian-caused deaths occurred in mature shortleaf pine stands with an open canopy and herbaceous understory.

Survival and Cause-Specific Mortality of Pronghorn in Southwestern North Dakota

Abstract In many pronghorn populations there exists uncertainty about which factors most affect survival rates. Also, although pronghorn within the same population might exhibit both migratory and non-migratory behaviors, few studies have assessed whether migration status affects survival rates. We determined cause-specific mortality for 134 adult, radio-tagged pronghorn in southwestern North Dakota, 2004–2008, estimated survival rates, and examined support for 11 a priori models containing combinations of year, age, sex, season, and migration status. We documented 102 deaths (52 females, 50 males) of radio-collared pronghorn. Over half of the observed mortality was due to hunter harvest (58%). Migration status was not an important determinant of pronghorn survival when compared to other factors. A model containing a season × sex interaction was most supported. Seasonal survival rates were >0.90 for males and females except in fall when female survival rates were reduced to 0.8, and male survival was less than half (0.42), which was due to hunting mortality. Survival rates were highest in winter, which might have been facilitated by mild winter weather during our study. Given the important role of harvest on pronghorn survival, biologists can best manipulate pronghorn abundance, and reduce landowner conflicts, through hunting license allocation.

Adult Pronghorn (Antilocapra americana) Survival and Cause-specific Mortality in Custer State Park, S.D

Abstract Although understanding natural mortality rates of ungulate populations is essential for effective management, published data on adult survival from unharvested pronghorn (Antilocapra americana) populations in the Northern Great Plains is limited. We estimated seasonal adult survival rates and cause-specific mortality of an unharvested pronghorn population in Custer State Park, S.D. We assessed the relative importance of sex, age, year, and season in explaining pronghorn survival rates using an information-theoretic approach. We captured and radio-collared 26 male and 24 female adult pronghorn from fall 2005 through spring 2008. We observed higher predation rates and lower survival of adult pronghorn in CSP compared to other populations in the region, but similar to the pronghorn population in Yellowstone National Park. We documented 23 deaths (10 females, 13 males) of the 50 radio-collared pronghorn from Nov. 2005–Nov. 2008. Predation by mountain lions (Puma concolor) and coyotes (Canis latrans) accounted for 69.5% of all mortalities. The season model received the greatest support although there also was strong support for the season × sex model. Seasonal survival for males and females was >0.90 for the winter-grouping and breeding seasons but fell to 0.791(95% CI 0.644–0.887) and 0.837 (95% CI 0.706–0.916) for females and males, respectively, during the small group – parturition season. A dense predator population, as well as a higher vulnerability to predation when pronghorn are solitary or in small groups, may explain the lower survival during these time periods. If population estimates fall below management goals, management actions aimed at reducing predator cover may be beneficial to adult pronghorn. Managers of pronghorn populations near forested and rugged areas and that are sympatric with dense predator populations should consider adult survival may be lower than observed in Great Plains populations.