Derek Craighead

Blood Lead Levels of Common Ravens With Access to Big-Game Offal

Abstract Despite increased knowledge about environmental toxins and changes in lead use (i.e., the mandated use of nonlead paint, gasoline, and shotgun pellets used for hunting waterfowl on federal lands), lead poisoning continues to occur in terrestrial birds. The degree of exposure and its demographic effect, however, continue to be described, emphasizing the growing concern over lead exposure. We examined 302 blood samples from common ravens (Corvus corax) scavenging on hunter-killed large ungulates and their offal piles to determine if lead rifle-bullet residuum was a point source for lead ingestion in ravens. We took blood samples during a 15-month period spanning 2 hunting seasons. Of the ravens tested during the hunting season, 47% exhibited elevated blood lead levels (≥10 μg/dL) whereas 2% tested during the nonhunting season exhibited elevated levels. Females had significantly higher blood lead levels than did males. Our results confirm that ravens are ingesting lead during the hunting season and ...Abstract Despite increased knowledge about environmental toxins and changes in lead use (i.e., the mandated use of nonlead paint, gasoline, and shotgun pellets used for hunting waterfowl on federal lands), lead poisoning continues to occur in terrestrial birds. The degree of exposure and its demographic effect, however, continue to be described, emphasizing the growing concern over lead exposure. We examined 302 blood samples from common ravens (Corvus corax) scavenging on hunter-killed large ungulates and their offal piles to determine if lead rifle-bullet residuum was a point source for lead ingestion in ravens. We took blood samples during a 15-month period spanning 2 hunting seasons. Of the ravens tested during the hunting season, 47% exhibited elevated blood lead levels (≥10 μg/dL) whereas 2% tested during the nonhunting season exhibited elevated levels. Females had significantly higher blood lead levels than did males. Our results confirm that ravens are ingesting lead during the hunting season and are likely exposed to lead from rifle-shot big-game offal piles.

Seasonal Foraging Ecology of Non-Migratory Cougars in a System with Migrating Prey

We tested for seasonal differences in cougar (Puma concolor) foraging behaviors in the Southern Yellowstone Ecosystem, a multi-prey system in which ungulate prey migrate, and cougars do not. We recorded 411 winter prey and 239 summer prey killed by 28 female and 10 male cougars, and an additional 37 prey items by unmarked cougars. Deer composed 42.4% of summer cougar diets but only 7.2% of winter diets. Males and females, however, selected different proportions of different prey; male cougars selected more elk (Cervus elaphus) and moose (Alces alces) than females, while females killed greater proportions of bighorn sheep (Ovis canadensis), pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus) and small prey than males. Kill rates did not vary by season or between males and females. In winter, cougars were more likely to kill prey on the landscape as: 1) elevation decreased, 2) distance to edge habitat decreased, 3) distance to large bodies of water decreased, and 4) steepness increased, whereas in summer, cougars were more likely to kill in areas as: 1) elevation decreased, 2) distance to edge habitat decreased, and 3) distance from large bodies of water increased. Our work highlighted that seasonal prey selection exhibited by stationary carnivores in systems with migratory prey is not only driven by changing prey vulnerability, but also by changing prey abundances. Elk and deer migrations may also be sustaining stationary cougar populations and creating apparent competition scenarios that result in higher predation rates on migratory bighorn sheep in winter and pronghorn in summer. Nevertheless, cougar predation on rare ungulates also appeared to be influenced by individual prey selection.

Lead exposure in bald eagles from big game hunting, the continental implications and successful mitigation efforts.

Studies suggest hunter discarded viscera of big game animals (i.e., offal) is a source of lead available to scavengers. We investigated the incidence of lead exposure in bald eagles in Wyoming during the big game hunting season, the influx of eagles into our study area during the hunt, the geographic origins of eagles exposed to lead, and the efficacy of using non-lead rifle ammunition to reduce lead in eagles. We tested 81 blood samples from bald eagles before, during and after the big game hunting seasons in 2005–2010, excluding 2008, and found eagles had significantly higher lead levels during the hunt. We found 24% of eagles tested had levels indicating at least clinical exposure (>60 ug/dL) during the hunt while no birds did during the non-hunting seasons. We performed driving surveys from 2009–2010 to measure eagle abundance and found evidence to suggest that eagles are attracted to the study area during the hunt. We fitted 10 eagles with satellite transmitters captured during the hunt and all migrated south after the cessation of the hunt. One returned to our study area while the remaining nine traveled north to summer/breed in Canada. The following fall, 80% returned to our study area for the hunting season, indicating that offal provides a seasonal attractant for eagles. We fitted three local breeding eagles with satellite transmitters and none left their breeding territories to feed on offal during the hunt, indicating that lead ingestion may be affecting migrants to a greater degree. During the 2009 and 2010 hunting seasons we provided non-lead rifle ammunition to local hunters and recorded that 24% and 31% of successful hunters used non-lead ammunition, respectively. We found the use of non-lead ammunition significantly reduced lead exposure in eagles, suggesting this is a viable solution to reduce lead exposure in eagles.

EVALUATION OF TECHNIQUES FOR ATTACHING TRANSMITTERS TO COMMON RAVEN NESTLINGS

Abstract We assessed 4 methods of attaching transmitters to nestling Common Ravens (Corvus corax) in Grand Teton National Park, Wyoming, in preparation for a larger telemetry study. The attachment types included backpack style with a cross-chest harness, rump mount (“figure-8”), necklace, and tarsal mounts. We tested 2 to 5 transmitters of each attachment type and recorded the ease of attachment, agitation of the ravens (from the nestling stage through the post-fledging dependence period) caused by the transmitters, and any noticeable abrasions caused by the attachment. We preferred the tarsal mount attachment because the transmitters can be placed on the bird early in the nestling stage and 1 person can attach it quickly. We did not prefer the other methods. The necklace mount became “bridled” between the birds upper and lower mandible and/or fell off. Backpack and rump mounts required extensive fitting time, and we felt they should not be used until the nestlings had attained maximum growth, reducing the window of time for attachment.

Habitat Selection and Factors Influencing Nest Survival of Golden Eagles in South-Central Montana

Abstract Golden Eagle (Aquila chrysaetos) population trends in the western United States are unclear, but an increase in future threats is causing concern for the species. Understanding the resource requirements of Golden Eagles will be essential to the creation of an effective management approach. Yet, we currently lack sufficient information on the basic habitat requirements of Golden Eagles, which hinders creation of a successful conservation plan. We took a multiscaled approach to identify factors influencing habitat selection of breeding Golden Eagles in south-central Montana. In addition, we tested environmental factors we predicted would influence daily nest survival rates to understand environmental influences on breeding success. From the 2010–2013 nesting seasons, we located 45 nesting territories and identified 115 apparent nest initiations (defined as nests where eggs have apparently been laid). We collected 15,182 telemetry locations from 12 breeding Golden Eagles. We found that Golden Eagles selected home ranges based on the percent of intermixed shrub and grassland and terrain ruggedness. At the within-home range scale, Golden Eagles selected areas based on aspect, distance to their nest, and an interaction between proximity to prey habitat and terrain ruggedness. Despite Golden Eagle selection of rugged topography, daily nest survival was negatively influenced by topographic ruggedness. Based on our results, we suggest that to maintain breeding pairs of Golden Eagles in areas similar to our study area, management should focus on preserving adequate prey habitat in areas with rugged topography. However, territories with higher ruggedness may not be as productive; therefore, management goals should be clear and environmental factors influencing both habitat selection and reproductive success should be considered when possible.

Using Morphometrics To Determine the Sex of Common Ravens

Abstract We tried using morphometrics to determine sex for a population of Common Ravens (Corvus corax) in northwestern Wyoming. We attempted to correlate 13 external measurements to sex using discriminant function analyses. Sex was verified with a DNA test that identified females with 2 PCR-amplified gene copies (1 each from the W and Z chromosomes) and males with 1 gene copy (only Z chromosome). We created a predictive model of sex of ravens for easy field use. We found that by using 2 separate discriminant functions with footpad length and body mass measurements simultaneously, we were able to correctly classify 97% of female samples, 91% of male samples, and had an unknown category that included 15% of samples.

Migratory Pathways, Timing, and Home Ranges of Southern Greater Yellowstone Osprey

Rutas Migratorias, Tiempos y Area de Campeo de Pandion haliaetus En El Sur de Yellowstone Durante el periodo 2010–2012 documentamos los movimientos migratorios y estacionales de 11 individuos de Pandion haliaetus que se reproducen o que nacieron en el Parque Nacional Grand Teton, Wyoming. Seguimos los movimientos de los individuos de P. haliaetus con emisores de telemetria satelital a traves de Argos, documentando un total de 13 migraciones otonales y cinco migraciones primaverales. Las fechas de partida promedio durante el otono fueron el 19 de septiembre y el 23 de septiembre para los adultos y juveniles, respectivamente, y los individuos viajaron un promedio de 225 km/d. Los individuos de P. haliaetus presentaron areas de invernada dispersas, generalmente en los alrededores del Golfo de Mexico. La fecha de partida promedio en la primavera fue el 2 de abril y los individuos adultos viajaron un promedio de 269 km/d. Los adultos presentaron un area de campeo en promedio de 176 y 199 ha, considerando el mi...

Apparent Adoption of Orphaned Cougars (Puma concolor) in Northwestern Wyoming

Abstract. Cougars (Puma concolor) are widely distributed throughout the western portion of North America and are generally described as solitary carnivores. Most cougar social interactions have been described as instances of parental care, intraspecific strife, or breeding. We report an apparent case of an adoption of orphaned juveniles in a wild cougar population. We used radiotelemetry and direct visual observations to document an adult female, her 3 dependent offspring, and 2 orphaned juvenile males physically interacting, sharing bed sites, and sharing kills in the late winter of 2007/2008. We consider the potential benefits and/or negative effects of these social interactions, and the role that relatedness and/or familiarity may play in the motivation for developing such associations.

Multiple anthropogenic interventions drive puma survival following wolf recovery in the Greater Yellowstone Ecosystem

Abstract Humans are primary drivers of declining abundances and extirpation of large carnivores worldwide. Management interventions to restore biodiversity patterns, however, include carnivore reintroductions, despite the many unresolved ecological consequences associated with such efforts. Using multistate capture–mark–recapture models, we explored age‐specific survival and cause‐specific mortality rates for 134 pumas (Puma concolor) monitored in the Greater Yellowstone Ecosystem during gray wolf (Canis lupus) recovery. We identified two top models explaining differences in puma survivorship, and our results suggested three management interventions (unsustainable puma hunting, reduction in a primary prey, and reintroduction of a dominant competitor) have unintentionally impacted puma survival. Specifically, puma survival across age classes was lower in the 6‐month hunting season than the 6‐month nonhunting season; human‐caused mortality rates for juveniles and adults, and predation rates on puma kittens, were higher in the hunting season. Predation on puma kittens, and starvation rates for all pumas, also increased as managers reduced elk (Cervus elaphus) abundance in the system, highlighting direct and indirect effects of competition between recovering wolves and pumas over prey. Our results emphasize the importance of understanding the synergistic effects of existing management strategies and the recovery of large, dominant carnivores to effectively conserve subordinate, hunted carnivores in human‐dominated landscapes.

Migration of Red-tailed Hawks (Buteo jamaicensis) from northwest Wyoming

ABSTRACT While a common species throughout most of the United States, little is known on the migration habits of Red-tailed Hawks (Buteo jamaicensis). From 1999–2002, we tracked 16 adult Red-tailed Hawks from their breeding grounds in northwest Wyoming using Argos PTT transmitters. Our objectives were to identify dates and duration of migratory movements, stopover sites, and identify migration routes and wintering areas. We found the mean migration initiation date from the breeding area was 13 October, mean fall migration duration including stopovers was 23.3 days, mean distance of fall migration was 2489.6 km, and mean end date of fall migration was 5 November. Wintering locations were in Mexico and ranged from the southern Mexican state of Chiapas north to Sonora and Chihuahua. The mean number of days spent on the wintering grounds by tracked hawks was 133.1. The mean departure date from wintering grounds to breeding areas was 17 March, mean spring migration duration including stopovers was 22.1 days, mean end date of spring migration was 8 April, and mean distance of spring migration was 2 490.3 km. Most birds made stopovers during both fall and spring migration which varied in location and duration. Using satellite telemetry, we identified wintering locations of Red-tailed Hawks breeding in northwest Wyoming and confirmed a leapfrog migration pattern with no concentrated migration routes from the breeding area to non-breeding areas.