Buteo Jamaicensis Research Articles

A long‐term assessment of raptor displacement at a wind farm

Wind energy development is advancing rapidly, but the potential ramifications of this growth on wildlife, particularly birds and bats, are not fully understood. Wind energy development may affect raptor (birds of prey) populations indirectly by displacing them from their previously occupied habitat; however, there are limited empirical data demonstrating this effect. We performed long‐term raptor surveys at a wind farm previously implicated in the displacement of resident raptors and found that the duration of displacement varied among raptor species. Abundances of turkey vultures (Cathartes aura), red‐tailed hawks (Buteo jamaicensis), and accipiters (sharp‐shinned hawks [Accipiter striatus] and Cooper's hawks [Accipiter cooperii] combined) all rebounded in years 7 and 8 of wind farm operation, while the apparent displacement of northern harriers (Circus hudsonius) and American kestrels (Falco sparverius) persisted across all post‐construction monitoring periods. Our long‐term assessment indicates not only that wind farm construction and operation may displace raptors but also that these impacts can diminish over time for certain species. This finding underscores the importance of assessing potential impacts over the operational life of a given wind farm and the need for long‐term monitoring to validate predicted impacts, particularly for raptor communities.

Effects of Broadcasting Calls on Detection Probability in Occupancy Analyses of Multiple Raptor Species

For population studies that rely on aural or visual observations of individuals, methods that induce a detectable response can greatly improve sample sizes and reduce costs. Numerous authors have reported improved detections using broadcast surveys in forested areas for various species of raptors; however, to our knowledge, none have attempted to quantify the effects of broadcast surveys on the detection probability (p) in the context of an occupancy study for multiple species. Our objective was to determine whether broadcasting conspecific and heterospecific calls (broadcast surveys) would increase p of raptor species compared to passive surveys. This comparison was accomplished by estimating p during both types of surveys using a multiscale occupancy framework. We conducted 8400 surveys for Cooper's Hawk (Accipiter cooperii), Swainson's Hawk (Buteo swainsoni), White-tailed Hawk (Geranoaetus albicaudatus), Harris's Hawk (Parabuteo unicinctus), Red-tailed Hawk (Buteo jamaicensis), and Great Horned Owl (Bubo virginianus) in 2015 and 2016 in south Texas. We conducted 10-min passive surveys in both years, 10-min broadcast surveys in 2015 including calls from each of the target hawk species, and 10-min broadcast surveys in 2016 using calls from Great Horned Owls. Our results suggest that p is improved with multiple-hawk broadcast surveys (0.16, SE 0.04) over passive surveys (0.04, SE 0.02) for Harris's Hawks; p was not affected in broadcast surveys for the other hawk species considered. Great Horned Owls had a higher p during broadcast surveys using Great Horned Owl calls (0.35, SE 0.04) than during passive surveys (0.19, SE 0.02). Our results do not support the use of broadcast surveys to improve the detection probability of multiple species of hawks. However, our results do indicate that using broadcast surveys for occupancy studies focused on Harris's Hawks or Great Horned Owls should significantly reduce the effort required over passive surveys, resulting in improved power and reduced costs.

Heterospecific information supports a foraging mutualism between corvids and raptors

Although animal social information is most commonly utilized by conspecifics, some conditions may favour heterospecific transmission. Generalists living in social groups are thought to produce information that is conspicuous and broadly useful to other species. Information may be signalled intentionally to other species when the sender benefits. We examined these predictions in a scavenger guild comprising two generalist social corvids (ravens, Corvus corax; magpies, Pica hudsonia), four raptor species and coyotes, Canis latrans. We used game cameras to monitor scavenging at 89 mule deer, Odocoileus hemionus, carcasses in Oregon and Washington, U.S.A. Corvid appearance times explained variation in golden eagle, Aquila chrysaetos, bald eagle, Haliaeetus leucocephalus, hawk (Buteo jamaicensis and Buteo lagopus) and coyote arrivals, indicating that raptors and canids use corvids to locate food. Larger numbers of magpies, but not ravens, were associated with shorter raptor appearance times, providing partial support for the importance of group size in broadcasting information to heterospecifics. We also directly observed simulated carcasses composed of a deer hide and antler. Seventy one corvids and 13 raptors appeared among 16 treatments accompanied by raven decoys and playbacks, whereas only one corvid and no raptors appeared at paired controls. The time that ravens first flew in circles above a simulated carcass explained 98% of the variation in subsequent raptor arrival time, indicating that a specific raven behaviour provides a cue of carrion. After hide-cutting raptors opened a carcass, corvids benefited by switching from feeding at the eyes and the anus to feeding on flesh. However, raptors did not arrive sooner after corvids at closed carcasses than experimentally pre-opened carcasses, suggesting that corvids do not intentionally transmit more information to raptors when a carcass requires opening, at least under these conditions. A scavenging mutualism with corvids built on carrion discovery and access, but not intentional recruitment, may facilitate winter survival of raptors.

Successful Introgressive Breeding of a Ferruginous Hawk × Red-Tailed Hawk Hybrid with a Red-Tailed Hawk

Hybridization in wild raptors is uncommon, but direct observations of successful hybridization exist. Subsequent introgressive hybridization (i.e., hybrid backcrossing), however, is less commonly reported in the raptor literature. We document (1) an interspecific Ferruginous Hawk (Buteo regalis) breeding attempt, and (2) introgressive hybridization within the genus Buteo. We found photographic evidence of a successful breeding attempt between a Ferruginous Hawk and Red-tailed Hawk (Buteo jamaicensis) in Wayne County, Utah, USA. Subsequent photographic observations in 2011 of adult and juvenile Ferruginous Hawk × Red-tailed Hawk hybrids indicate that this hybrid pair may have bred successfully multiple times. In 2017, we photographed an adult Ferruginous Hawk × Red-tailed Hawk hybrid breeding successfully with a Red-tailed Hawk near the same area where the original hybrid pair was documented. Our observations demonstrate that at least some Buteo hybrids are fertile and capable of reproduction; however, we do not know if the second-generation hybrids are fertile.

Indigenous chicken production environments, reproductive and productive performances and constraints in kaffa zone, south western Ethiopia

The main objective of this study was to describe the production systems, productive performances and associated constraints of indigenous chicken populations in Kaffa Zone. From ten districts of Kaffa Zone, three districts were purposively selected based on their potential for indigenous chicken population and accessibility. From each rural kebeles those households who possess a minimum of five mature indigenous chicken were purposively selected. Then, data on both qualitative and quantitative variables were collected from 300 purposively selected households using a semi-structured questioner. The results indicated that majority of the respondent were female (71.1%) and 56% of them were illiterate. The average family size per household was 5.86. Farmers mainly keep their chickens in the kitchen (60.7%) and main houses (30.7 %). Maize (55.7 %) and sorghum (20.3 %) were the major feed supplements provided by the households. The average chicken flock size, age at first egg (months), average egg/hen/clutch (clutch size), clutch number and annual egg/hen/year were 8.68, 6.09, 12.3, 3.6 and 44, respectively. The average hatchability was 80.5%. The major production constraints were predators (72.7 %) and diseases (27.3 %) across the studied districts. The type of predators which are commonly occurring included Buteo jamaicensis locally known as “Gace”, Helogale hirtula locally known as “Shiifoo” or “Wociwoco”, Felis silvestris locally known as “Haallaro” and Felis catus locally known as “Kubbi Kullaro” accounted about 54.6, 24.4, 15.5, and 5.5 % respectively. The effective population size and rate of inbreeding were 486 and 0.111% indicating chicken populations in the study area are not exposed to inbreeding. In conclusion, the current study indicates illiterate female farmers were mainly involved in care and managing of chickens under scavenging system. The performances of chickens were comparable with the national reports under scavenging system; however, these performances were influenced by predators and diseases. Therefore, educating and training women’s should be implemented to improve the overall socio-economic status of the family and benefit them. In addition, successful intervention strategy should be carried out to effectively utilize the existing potentials of indigenous chicken populations in line with predator and disease control programs. Again, conservation of the indigenous chicken populations should also be considered before they have been diluted with exotic breeds

Production Systems, Productive Performances, Constraints and Rate of Inbreeding of Indigenous Chicken Populations in Kaffa Zone, South Western Ethiopia

The main objective of this study was to describe the production systems, productive performances and associated constraints of indigenous chicken populations in Kaffa Zone. Data on production systems, productive performances and constraints of chickens were collected from 300 purposively selected households using a semi-structured questioner. The results indicated that majority of the respondent were female (71.1%) and 56% of the interviewed farmers were illiterate. The average family size per household was 5.86. Farmers mainly keep their chickens in the kitchen (60.7%) and main houses (30.7 %). Maize (55.7 %) and sorghum (20.3 %) were the major feed supplements provided by the households. The average chicken flock size, age at first egg (months), average egg/hen/clutch (clutch size), clutch number and annual egg/hen/year were 8.68, 6.09, 12.3, 3.6 and 44, respectively. The average hatchability was 80.5%. The major production constraints were predators (72.7 %) and diseases (27.3 %) across the studied districts. The type of predators which are commonly occurring included Buteo jamaicensis locally known as “ Gace” , Helogale hirtula locally known as “ Shiifoo” or “Wociwoco” , Felis silvestris locally known as “ Haallaro” and Felis catus locally known as “ Kubbi Kullaro” accounted about 54.6, 24.4, 15.5, and 4.58 % respectively. The effective population size and rate of inbreeding were 486 and 0.111% indicating chicken populations in the study area are not exposed to inbreeding. In conclusion, the current study indicates illiterate female farmers were mainly involved in care and managing of chickens under scavenging system. The performances of chickens were comparable with the national reports under scavenging system; however these performances were influenced by predators and diseases. Therefore, educating and training of women’s should be implemented to improve the overall socio economic status of the family and benefit them. In addition successful intervention strategy should be carried out to effectively utilize the existing potentials of indigenous chicken populations in line with predator and disease control programs. Again, conservation of the indigenous chicken populations should also be considered before they have been diluted with exotic breeds. Keywords ; Effective population size, Household Characteristics, Indigenous chicken, Productive performance, Rate of inbreeding. DOI : 10.7176/JBAH/9-5-08 Publication date :March 31 st 2019

Facultative Migration: New Insight from a Raptor

We studied migration of a female and male Red-tailed Hawk (Buteo jamaicensis) from southern California with satellite telemetry over 9.3 and 6.7 yr, respectively. Previous research suggested the migratory fraction of southern California's Red-tailed Hawk population was limited to juveniles and young adults, and that these hawks ceased migrating once they acquired a territory and mate, usually at 3 yr of age. Both hawks in this study ceased migrating at 3 yr of age, the year they both first nested, and did not migrate for the next 4 and 3 yr, respectively. However, both hawks resumed migrating in 2014, the year with the lowest recorded precipitation in California history. The male did not migrate in 2015, the last year we were able to track his movements, while the female switched between migrating (2015 and 2017) and residency (2016) over the next 3 yr. To our knowledge, our study is the first to document individual raptors displaying such switching behavior.

Confirmation of Sarcocystis jamaicensis Sarcocysts in IFN-c Gene Knockout Mice Orally Inoculated with Sporocysts from a Red-Tailed Hawk (Buteo jamaicensis)

Here, we report confirmation of sarcocysts of Sarcocystis jamaicensis in an experimental intermediate host, IFN-γ gene knockout (KO) mice orally inoculated sporocysts from its natural definitive host, a red-tailed hawk ( Buteo jamaicensis) (RTH). A RTH submitted to the Carolina Raptor Center, Huntersville, North Carolina, was euthanized because it could not be rehabilitated and released. Fully sporulated sporocysts from intestinal scrapings of the RTH were orally fed to 2 laboratory-reared outbred Swiss Webster mice (SW; Mus musculus) and to 2 KO mice. The sporocysts were infective for KO mice but not to SW mice. Both SW mice remained asymptomatic, and neither schizonts nor sarcocysts were found in their tissues when euthanized on day 54 post-inoculation (PI). The KO mice developed neurological signs and were necropsied 38-54 days PI. Schizonts/merozoites were found in both KO mice euthanized and they were confined to the brain. The predominant lesion was meningoencephalitis. Microscopic sarcocysts were found in muscles of both KO mice. When viewed with light microscopy, the sarcocyst wall appeared thin (<1 μm thick) and smooth. Ultrastructural details of sarcocysts are described.

Feather mercury concentrations in North American raptors sampled at migration monitoring stations.

We assessed total mercury (THg) concentrations in breast feathers of diurnal North American raptors collected at migration monitoring stations. For 9 species in the Pacific Flyway, we found species and age influenced feather THg concentrations whereas sex did not. Feather THg concentrations µg/g dry weight (dw) averaged (least squares mean ± standard error) higher for raptors that generally consume > 75% avian prey (sharp-shinned hawk Accipiter striatus: n = 113; 4.35 ± 0.45 µg/g dw, peregrine falcon Falco peregrinus: n = 12; 3.93 ± 1.11 µg/g dw, Cooper's hawk Accipiter cooperii: n = 20; 2.35 ± 0.50 µg/g dw, and merlin Falco columbarius: n = 59; 1.75 ± 0.28 µg/g dw) than for raptors that generally consume < 75% avian prey (northern harrier Circus hudsonius: n = 112; 0.75 ± 0.10 µg/g dw, red-tailed hawk Buteo jamaicensis: n = 109; 0.56 ± 0.06 µg/g dw, American kestrel Falco sparverius: n = 16; 0.57 ± 0.14 µg/g dw, prairie falcon Falco mexicanus: n = 10; 0.41 ± 0.13 µg/g dw) except for red-shouldered hawks Buteo lineatus: n = 10; 1.94 ± 0.61 µg/g dw. Feather THg concentrations spanning 13-years (2002-2014) in the Pacific Flyway differed among 3 species, where THg increased for juvenile northern harrier, decreased for adult red-tailed hawk, and showed no trend for adult sharp-shinned hawk. Mean feather THg concentrations in juvenile merlin were greater in the Mississippi Flyway (n = 56; 2.14 ± 0.18 µg/g dw) than those in the Pacific Flyway (n = 49; 1.15 ± 0.11 µg/g dw) and Intermountain Flyway (n = 23; 1.14 ± 0.16 µg/g dw), and Atlantic Flyway (n = 38; 1.75 ± 0.19 µg/g dw) averaged greater than the Pacific Flyway. Our results indicate that raptor migration monitoring stations provide a cost-effective sampling opportunity for biomonitoring environmental contaminants within and between distinct migration corridors and across time.

Prevalence of Sarcocysts in the Muscles of Raptors from a Rehabilitation Center in North Carolina

The life cycle of Sarcocystis species is heteroxenous (2-host), with carnivores being the definitive host and herbivores serving as intermediate hosts in predator-prey relationships. Raptors (eagles, hawks, falcons, and owls) are apex predators and are not consumed routinely by other carnivores, making the occurrence of sarcocysts in their muscles unusual. Recent reports of sarcocysts in eagles and owls with Sarcocystis encephalitis suggests that this condition may be becoming more frequent, and Sarcocystis falcatula has been implicated as the agent of encephalitis in golden ( Aquila chrysaetos) and bald eagles ( Haliaeetus leucocephalus) as well as great horned owls ( Bubo virginianus). The present study was done to determine the prevalence of sarcocysts of Sarcocystis species in the muscles of raptors from the southeastern United States. Pectoral and heart muscle from 204 raptor patients from the Carolina Raptor Center, Huntersville, North Carolina were tested for the presence of Sarcocystis species using histology. Only a few sarcocysts were seen in sections of pectoral muscle from 39 of 204 raptors (19.1%) and heart muscle from 9 that also had sarcocysts in their pectoral muscle. Two structural types of sarcocysts, thin-walled (1 μm; 62%) or thick-walled (>2 μm, 38%), were seen. Statistical analysis of raptor age and gender was done by Fisher's exact test on samples from raptors with 20 or more samples per group. The prevalence of sarcocysts by age (2 yr or more) was significant for red-shouldered hawks ( Buteo lineatus) ( P = 0.022) and Cooper's hawks ( Accipiter cooperii) ( P = 0.028). Sarcocyst prevalence in male raptors from these groups evaluated statistically were always less than in females. Prevalence in female red-tailed hawks ( Buteo jamaicensis) (42.1%) was significantly greater than in males (6.7%) using Fisher's exact test ( P = 0.047). Examination of case histories from the 39 sarcocyst-positive raptors did not reveal an association with sarcocysts in raptor pectoral or heart muscle and in a diagnosis of encephalitis. Additional studies are needed to determine the epidemiology and relationships of Sarcocystis spp. that use raptors as intermediate hosts and the importance of Sarcocystis spp. in the overall wellbeing of raptors in their natural environments.

A seasonal population matrix model of the Caribbean Red‐tailed Hawk Buteo jamaicensis jamaicensis in eastern Puerto Rico

Reliable estimates of life history parameters and their functional role in animal population trajectories are critical, yet often missing, components in conservation and management. We developed seasonal matrix population models of the Red‐tailed Hawk Buteo jamaicensis jamaicensis in the upper and lower forests of the Luquillo Mountains, Puerto Rico, to describe the influence of early life stages (nestling and clutch survival) on population growth. Modelled populations exhibited positive discrete rates of growth in forests above 400 m (λ highlands = 1.05) and in forests below 400 m (λ lowlands = 1.27) of the Luquillo Mountains. Further, adult survival was the parameter with the highest proportional effect and direct contribution to growth of the population. Besides survival of adults, our results identified that nestling survival had the second greatest influence on λ, stressing the importance of this life stage for the population growth rate of Red‐tailed Hawks in our study area. Seasonal matrices are not commonly used to describe population dynamics of birds. However, these may be a useful tool to analyse the influence of life stages in the annual cycle to better address conservation and management needs, especially for species inhabiting oceanic islands.

Enrichment Preferences of Raptors at Elmwood Park Zoo

Environmental enrichment is often offered to animals in captivity to aid in enhancing quality of life by providing appropriate environmental stimuli that improve psychological and physiological well-being. Due to the limited amount of research conducted on raptors and enrichment, I sought to determine raptor preferences of enrichment types through the observation of captive bald eagles (Haliaeetus leucocephalus) and red-tailed hawks (Buteo jamaicensis) in the education department at Elmwood Park Zoo. I predicted that the raptors would interact more with natural enrichment items compared to ones that were man-made. Although results showed only the female bald eagle to interact enough with the enrichment items to gather an adequate number of observations, she was found to interact significantly more frequently with natural enrichment items compared to ones that were man-made (p 0.0001, FET). These results are not meant to infer that all female bald eagles prefer natural enrichment items over man-made ones, or that all male bald eagles and female and male red-tailed hawks do not prefer any enrichment items. Nonetheless, they justify future research on environmental enrichment preferences involving many more individuals and many more taxa to determine more appropriate enrichment regimens for captive birds of prey.

Investigating spatial patterns of mercury and rodenticide residues in raptors collected near the Charlotte, NC, USA, metropolitan area.

Raptor population growth is dynamic and trends vary across species and by location in the United States. For those species that are declining, it is important to identify potential causes including chemical contaminants. Sampling wild raptors is problematic due to their small population sizes and role as a top predator. Therefore, we obtained liver samples (n = 56) from carcasses of several raptor species, including common species like red-tailed hawks, red-shouldered hawks, barred owls, great horned owls, and osprey that arrived dead or were euthanized from a non-profit rehabilitation center in Charlotte, North Carolina. Raptors were found or collected in South Carolina, North Carolina, and Virginia, but most samples were located near the metropolitan region of Charlotte, NC. We analyzed livers for total mercury residue (mg/kg, dry weight) and five anti-coagulant rodenticides (μg/kg wet weight). Mercury was analyzed using a direct mercury analyzer approach and rodenticides were quantified by LC-MS. Mercury residues were high in piscivorous birds (15.09mg/kg for osprey and 6.93mg/kg for great blue herons, dry weight) and relatively high in red-shouldered hawks and one eastern screech owl tested. Six of our samples exceeded a health threshold of 1mg/kg (wet weight) including three osprey and one each of great blue heron, red-shouldered hawk, and eastern screech owl. Brodifacoum was the only rodenticide consistently detected in our samples. Brodifacoum detections exceeded 75% in barred owls, great horned owls, and red-shouldered hawks. Sixty-nine percent of owl samples were within (or exceeded) a threshold of brodifacoum residue associated with a 10-20% risk of acute toxicity. Correlations between residues and human population density were not significant for either mercury or brodifacoum. Our data suggest that mercury residues for most raptors were not of significant concern with the exception of osprey and possibly red-shouldered hawks. Rodenticide exposures associated with a risk of acute toxicity appear to be common and warrant further investigation.

Responses of Blue Jays (Cyanocitta Cristata) to Raptors that Differ in Predatory Threat

Some species of birds use their vocalisations to communicate predator presence and the level of threat they pose, including two species of corvids (Corvidae), American Crows (Corvus brachyrhynchos) and Siberian Jays (Perisoreus infaustus). Our objective was to determine if Blue Jays (Cyanocitta cristata), another corvid, also use specific calls or vary the characteristics of certain calls to convey information about the level of threat posed by aerial predators. During the non-breeding seasons of 2014 and 2015, we recorded and analysed the vocal responses of Blue Jays to study skins of six species of raptors that varied in size and the level of threat they pose to Blue Jays. Experiments were conducted at seven locations in Madison County, Kentucky. The mean number of Blue Jays present during trials was 2.6, and Blue Jays uttered five different vocalisations during trials, with ditonal and monotonal jeers given most frequently. The rate at which Blue Jays uttered ditonal jeers differed among trials, with rates highest during trials with an Eastern Screech-Owl (Megascops asio) and a Sharp-shinned Hawk (Accipiter striatus). However, the characteristics of ditonal and monotonal jeers (duration, low frequency, high frequency, and peak frequency) did not differ among trials. These results suggest that Blue Jays may either perceive Eastern Screech-Owls and Sharp-shinned Hawks as the greatest threats or, alternatively, as potential, but less threatening predators, and, therefore, they were willing to take greater risks when mobbing them. In contrast, Blue Jays mobbed the other raptors, i.e. American Kestrels (Falco sparverius), Red-tailed Hawks (Buteo jamaicensis), and Great Horned Owls (Bubo virginianus), with much less intensity, likely because they posed less of a threat or, in the case of Cooper's Hawks (Accipiter cooperii) that are known predators of Blue Jays, perhaps because mobbing with greater intensity, e.g. approaching more closely, posed too great a risk. Blue Jays in our study used the same calls with the same characteristics when responding to potential predators, only calling rates differed. However, such variation in calling rates when mobbing would likely provide useful information about the presence of, and possibly the threat posed by, potential predators for conspecifics and, perhaps, heterospecifics.

Pharmacokinetics of fentanyl after intravenous administration in isoflurane-anesthetized red-tailed hawks (Buteo jamaicensis) and Hispaniolan Amazon parrots (Amazona ventralis).

OBJECTIVE To compare the disposition of fentanyl citrate after a single IV injection in isoflurane-anesthetized red-tailed hawks (Buteo jamaicensis) and Hispaniolan Amazon parrots (Amazona ventralis). ANIMALS 6 adult red-tailed hawks and 6 adult Hispaniolan Amazon parrots. PROCEDURES Anesthesia was induced and maintained with isoflurane; intermittent positive-pressure ventilation was provided. The minimum alveolar concentration of isoflurane was determined for each bird by use of the bracketing method and a supramaximal electrical stimulus. Fentanyl (20 μg/kg) was administered IV. Arterial (red-tailed hawks) or jugular venous (Hispaniolan Amazon parrots) blood samples were obtained immediately before and 1, 2, 4, 8, 15, 30, 60, 120, 180, 240, and 480 minutes (red-tailed hawks) and 1, 5, 10, 15, 30, 60, 120, and 180 minutes (Hispaniolan Amazon parrots) after fentanyl administration. RESULTS A 3-compartment and a 2-compartment model best described fentanyl pharmacokinetics in red-tailed hawks and Hispaniolan Amazon parrots, respectively. Median apparent volume of the central compartment and volume of distribution at steady state were 222 mL/kg and 987 mL/kg, respectively, for the red-tailed hawks and 5,108 mL/kg and 13,079 mL/kg, respectively, for the Hispaniolan Amazon parrots. Median clearance and elimination half-life were 8.9 mL/min/kg and 90.22 minutes, respectively, for the red-tailed hawks and 198.8 mL/min/kg and 51.18 minutes, respectively, for the Hispaniolan Amazon parrots. CONCLUSIONS AND CLINICAL RELEVANCE Pharmacokinetic results for fentanyl in isoflurane-anesthetized red-tailed hawks and Hispaniolan Amazon parrots indicated large differences and should strongly discourage extrapolation of doses between these 2 species.

Secondary Anticoagulant Rodenticide Exposure In Migrating Juvenile Red-Tailed Hawks (Buteo jamaicensis) In Relationship To Body Condition

Secondary exposure to anticoagulant rodenticides (ARs) through consumption of contaminated prey has been documented worldwide in many non-target species, especially raptors. The Red-tailed Hawk (Buteo jamaicensis), a raptor that frequents agricultural areas and eats primarily rodents, is particularly susceptible. Because there is documentation of Red-tailed Hawk exposure to ARs in California, this study aims to describe the extent to which migrating juvenile Red-tailed Hawks are exposed to ARs, as well as any sublethal effects of AR ingestion. We collected blood samples and body morphometrics from 97 juvenile Red-tailed Hawks migrating through the Marin Headlands, Marin County, CA, from August to December in 2013 and 2015, and screened samples for the presence of ARs. Eight hawks (8.2%) tested positive for some amount of ARs. We detected first-generation (diphacinone, chlorophacinone) and second-generation (brodifacoum, bromadiolone) ARs. Although some juvenile Red-tailed Hawks are exposed to ARs either along their migration route or as resident birds in the Marin Headlands, we did not find any relationship between body condition and presence of ARs. Although this method of AR sampling of live birds is novel and increases our sampling capabilities, the short half-lives of ARs in blood make it difficult to estimate population-wide exposure rates. Future studies should focus on resident raptors near agricultural areas where AR exposure can be tested over time to better understand how this technique can be used to estimate exposure rates across whole populations.

The Alaska Red-tailed Hawk

The Alaska Red-tailed Hawk

Taxonomic status of Harlan's Hawk Buteo jamaicensis harlani (Aves: Accipitriformes).

Since its description in 1830 by Audubon, Harlan's Hawk (taxon harlani) has been considered both as a species (Buteo harlani) (1830-1891 and 1944-1972) and as a subspecies of Red-tailed Hawk (B. jamaicensis harlani) (1891-1944 and 1973 to present). Both decisions making it a subspecies lacked sufficient taxonomic justification, whereas the 1944 decision to consider it a species was supported by convincing arguments. I conducted field and museum work over many years to better understand the morphology and taxonomic status of harlani and how this taxon differs from other taxa currently included in B. jamaicensis. Some hybridization between these taxa has been reported, as has been between many other species of Buteo. The taxon harlani is distinguished from all subspecies of B. jamaicensis in plumage, including the extent of feathering on the tarsus. The species occupies a breeding range parapatric, but with some overlap, to that of B. jamaicensis but occasionally breeds within a large area of the range of the latter in western Canada. It should be considered a full species based on lack of justification for considering it a subspecies, and the many differences between it and B. jamaicensis, which are greater than differences between any two subspecies of diurnal raptor.

Autumn Raptor Migration in Yellowstone National Park, 2011–2015

Raptors are wide-ranging, vagile avian predators whose populations can be difficult and costly to monitor on their breeding or winter range. However, monitoring raptors during their annual northbound or southbound migration is a cost-effective and efficient alternative to time-intensive, single-species breeding surveys. In 2010, we observed numerous Swainson’s Hawks (Buteo swainsoni) and Red-tailed Hawks (Buteo jamaicensis) migrating through the Hayden Valley in central Yellowstone National Park, prompting an investigation into raptor migration patterns in the park. Our objectives were to monitor annual autumn raptor migration in Hayden Valley from 2011 to 2015 and to determine the relative role of this undocumented migration site by comparing our observations to simultaneously collected migration data from three other sites in the Rocky Mountain Flyway. From 2011 to 2015, we observed 6441 raptors of 17 species across 170 d and 907 h of observation. Red-tailed Hawks, Swainson’s Hawks, and Golden Eagles (Aquila chrysaetos) accounted for 51% of the total individuals observed over five years. Overall counts from Hayden Valley were comparable to counts from the three migration sites in the Rocky Mountains, although abundance of individual species varied by site. Data from this study suggest that Hayden Valley may serve as a stopover site for migrating raptors and presents an opportunity for future research. By improving our understanding of where raptors migrate and the characteristics of stopover areas in the Rocky Mountains, land managers may develop effective strategies for protecting raptor populations and habitat from threats including development and climate change.

The Impacts of Native-Grassland Restoration on Raptors and their Prey on a Reclaimed Surface Mine in Kentucky

Abstract We evaluated the effects of native-grass restoration on the spatial distribution and density of raptors, vegetative characteristics, and small-mammal communities at Peabody Wildlife Management Area, a large reclaimed surface-coal mine in western Kentucky. We surveyed raptors from 2008 to 2012 via distance sampling at roadside points, and conducted vegetation and small-mammal surveys. We found no associations between total small-mammal relative abundance and native-grass restoration or vegetative characteristics. However, management for native grass positively affected the density of Circus cyaneus (Northern Harrier) and influenced the local distribution of Northern Harriers and Buteo jamaicensis (Red-Tailed Hawk). These results suggest that restoration and management of native grass on reclaimed mine lands can enhance habitat for grassland raptors, including the Northern Harrier, a species of conservation concern throughout its range.