Travis L. Booms

Time-lapse video system used to study nesting Gyrfalcons

Abstract We used solar-powered time-lapse video photography to document nesting Gyrfalcon (Falco rusticolus) food habits in central West Greenland from May to July in 2000 and 2001. We collected 2677.25 h of videotape from three nests, representing 94, 87, and 49% of the nestling period at each nest. The video recorded 921 deliveries of 832 prey items. We placed 95% of the items into prey categories. The image quality was good but did not reveal enough detail to identify most passerines to species. We found no evidence that Gyrfalcons were negatively affected by the video system after the initial camera set-up. The video system experienced some mechanical problems but proved reliable. The system likely can be used to effectively document the food habits and nesting behavior of other birds, especially those delivering large prey to a nest or other frequently used site.

GYRFALCON DIET IN CENTRAL WEST GREENLAND DURING THE NESTING PERIOD

Abstract We studied food habits of Gyrfalcons (Falco rusticolus) nesting in central west Greenland in 2000 and 2001 using three sources of data: time-lapse video (3 nests), prey remains (22 nests), and regurgitated pellets (19 nests). These sources provided different information describing the diet during the nesting period. Gyrfalcons relied heavily on Rock Ptarmigan (Lagopus mutus) and arctic hares (Lepus arcticus). Combined, these species contributed 79–91% of the total diet, depending on the data used. Passerines were the third most important group. Prey less common in the diet included waterfowl, arctic fox pups (Alopex lagopus), shorebirds, gulls, alcids, and falcons. All Rock Ptarmigan were adults, and all but one arctic hare were young of the year. Most passerines were fledglings. We observed two diet shifts, first from a preponderance of ptarmigan to hares in mid-June, and second to passerines in late June. The video-monitored Gyrfalcons consumed 94–110 kg of food per nest during the nestling period, higher than previously estimated. Using a combination of video, prey remains, and pellets was important to accurately document Gyrfalcon diet, and we strongly recommend using time-lapse video in future diet studies to identify biases in prey remains and pellet data. Dieta de Falco rusticolus durante el Período de Nidificación en el Centro-Oeste de Groenlandia Resumen. Estudiamos los hábitos alimenticios de Falco rusticolus durante la época de nidificación en el centro-oeste de Groenlandia durante los años 2000 y 2001. Utilizamos tres fuentes de datos: registros en lapsos de tiempo con cámaras de video (nidos en los árboles), restos de presas (22 nidos) y egagrópilas (19 nidos). Esto permitió describir la dieta durante el período de nidificación con base en la información diferente provista por cada fuente. F. rusticolus dependió fuertemente de las presas Lagopus mutus y Lepus arcticus. En forma combinada, estas dos especies contribuyeron en un 79–91% de la dieta total, dependiendo de los datos utilizados para el análisis. Las aves paserinas fueron el tercer grupo más importante. Las presas menos comunes presentes en la dieta fueron aves acuáticas, cachorros de zorro (Alopex lagopus), aves playeras, gaviotas, álcidos y halcones. Todos los individuos de L. mutus fueron adultos y todos excepto un individuo de L. arcticus fueron juveniles nacidos ese mismo año. La mayoría de las aves paserinas fueron volantones. Observamos dos cambios en la dieta, primero de preponderancia de L. mutus a L. articus a mediados de junio, y el segundo a aves paserinas a fines de junio. Los individuos monitoreados con cámaras de video consumieron 94–110 kg de alimento por nido durante el período con polluelos, una cantidad mayor a la estimada previamente. La utilización combinada de registros de cámaras de video, restos de presas y egagrópilas fue importante para documentar la dieta de F. rusticolus con precisión, y recomendamos fuertemente utilizar cámaras de video con registros intermitentes en estudios futuros sobre la dieta para poder identificar los sesgos en los datos obtenidos a partir de restos de presas y egagrópilas.

Detection Probability of Cliff-Nesting Raptors During Helicopter and Fixed-Wing Aircraft Surveys in Western Alaska

Abstract We conducted repeated aerial surveys for breeding cliff-nesting raptors on the Yukon Delta National Wildlife Refuge (YDNWR) in western Alaska to estimate detection probabilities of Gyrfalcons (Falco rusticolus), Golden Eagles (Aquila chrysaetos), Rough-legged Hawks (Buteo lagopus), and also Common Ravens (Corvus corax). Using the program PRESENCE, we modeled detection histories of each species based on single species occupancy modeling. We used different observers during four helicopter replicate surveys in the Kilbuck Mountains and five fixed-wing replicate surveys in the Ingakslugwat Hills near Bethel, AK. During helicopter surveys, Gyrfalcons had the highest detection probability estimate (;  =  0.79; SE 0.05), followed by Golden Eagles (  =  0.68; SE 0.05), Common Ravens (  =  0.45; SE 0.17), and Rough-legged Hawks (  =  0.10; SE 0.11). Detection probabilities from fixed-wing aircraft in the Ingakslugwat Hills were similar to those from the helicopter in the Kilbuck Mountains for Gyrfalcons and Golden Eagles, but were higher for Common Ravens (  =  0.85; SE 0.06) and Rough-legged Hawks (  =  0.42; SE 0.07). Fixed-wing aircraft provided detection probability estimates and SEs in the Ingakslugwat Hills similar to or better than those from helicopter surveys in the Kilbucks and should be considered for future cliff-nesting raptor surveys where safe, low-altitude flight is possible. Overall, detection probability varied by observer experience and in some cases, by study area/aircraft type.

Survival Rates and Lifetime Reproduction of Breeding Male Cooper's Hawks in Wisconsin, 1980–2005

Abstract There are few published data on annual survival and no reports of lifetime reproduction for breeding Coopers Hawks (Accipiter cooperii). Breeding males (n  =  105) in central and southeastern Wisconsin had an annual mortality rate of 19%, or a survival rate of 81% for birds ≤10 years of age. We did not detect significant differences in mortality rates between urban and rural habitats, nor between the earlier 13 years and later 13 years of this study. Male Coopers Hawks produced from zero to 32 nestlings during their lifetimes. Body mass or size appeared unrelated to annual survivorship and lifetime reproduction, although lifetime reproduction was correlated strongly with longevity of breeding males. Fifteen of 66 males (23%) produced most (53%) of the nestlings. Our studies occurred in an area where breeding populations may be increasing with some of the highest reported productivity indices and nesting densities for this species. Habitat used for nesting on our Wisconsin study areas may be less important for survivorship and lifetime reproduction than acquisition of a nesting area in which a male will breed throughout his life.

Life-History Trade-Offs of Breeding in One-Year-Old Male Cooper'S Hawks

Abstract. Life-history theory suggests that delayed maturation is beneficial to birds when costs of breeding early in life are high. We compared selected aspects of the biology of male Coopers Hawks (Accipiter cooperii) that began breeding at 1 year of age (SY males) vs. males that began breeding ≥2 years of age (ASY males) in an effort to elucidate what renders breeding of SY males rare. Of the 732 males of known age whose breeding we studied over 32 years (1980–2011) 13 (2%) were SY and 719 (98%) were ASY During this period, the incidence of breeding of SY males changed markedly, as 12 of the instances of breeding of SY males were recorded in the first half of our study, only 1 in the latter half. We suggest that SY males could acquire nest sites more readily in the first half of the study when the breeding population of ASY males was apparently lower. Males breeding in their second year were on average similar in size to ASY males but were molting more extensively than were ASY males. ASY males lived longer than males breeding in their second year, and maximum lifetime production of young was greater, so SY males may have sacrificed greater longevity for breeding early. A strategy of facultative breeding in response to the constraints of higher numbers of older breeding males and restraints of trade-offs in energy allocation may explain why SY male Coopers Hawks rarely breed.

Preening Behavior of Adult Gyrfalcons Tagged with Backpack Transmitters

Comportamiento de Acicalamiento de Halcones Falco rusticolus Adultos Marcados Con Transmisores de Mochila Realizamos observaciones continuas o muestreos de observacion instantanea para documentar el comportamiento de acicalamiento de dos hembras adultas reproductivas de Falco rusticolus con transmisores satelitales de 30 g y de sus companeros libres de transmisores en el Refugio Delta Yukon de Vida Silvestre, en Alaska, (61.5°N, 164°W) a partir del 20 de mayo hasta el 6 de julio de 2005. Los transmisores fueron fijados a las aves usando arneses tipo mochila hechos de una cinta de nylon de 5 mm recubierta por teflon, siguiendo las recomendaciones publicadas para halcones. Los transmisores pesaron menos de 2% de la masa corporal de cada ave y se colocaron en las aves durante el final del periodo de incubacion o a principios del periodo de polluelos. El tiempo dedicado a acicalarse oscilo entre 0% y 50% del tiempo total observado durante las observaciones de las hembras con transmisores y de 0% a 8% en las o...

Body Mass of Female Cooper's Hawks is Unrelated to Longevity and Breeding Dispersal: Implications for the Study of Breeding Dispersal

La Masa Corporal de Hembras de Accipiter cooperii No Esta Relacionada Con la Longevidad y la Dispersion Reproductiva: Implicaciones Para El Estudio de la Dispersion Reproductiva Capturamos, marcamos individualmente y pesamos 271 hembras reproductoras de segundo ano de Accipiter cooperii durante la epoca de cria en dos areas de estudio principales en Wisconsin durante el periodo comprendido entre 1980 y 2007. Luego recapturamos o volvimos a avistar a algunas de las aves utilizando prismaticos o telescopios y las identificamos a traves del color de sus anillas. Para analizar la relacion de la longevidad de la hembra con el tamano, examinamos la masa corporal de adultos reproductores recapturados o avistados nuevamente por categoria de edad relativa durante el ultimo ano de deteccion. Encontramos que la masa corporal (o tamano) en esta especie no estuvo relacionada con la longevidad ni con la dispersion reproductiva entre, o la fidelidad con, las areas de nidificacion en Wisconsin. Aunque previamente demostr...

Molted-Feather Persistence and Aging in a Sub-Arctic Environment: Implications for Noninvasive Genetic Sampling

Abstract We investigated molted-feather persistence and aging in a sub-Arctic environment by placing marked feathers at historical Gyrfalcon (Falco rusticolus) nesting areas and returning a year later to collect and inspect remaining feathers. After one year, only 14% of marked feathers remained and were collected during primary searches; small, body feathers were significantly less likely to persist than large or flight feathers. No differences in trends were detected between feathers from perch and below-nest locations. All recovered feathers displayed at least one of three signs of aging (matted and separated barbs, fungal growth, or algal growth) that reliably distinguished them from fresh feathers. We show that collection efforts should focus on small, body feathers to ensure that collected feathers are freshly molted and suggest feather persistence and aging be directly addressed in other studies using feathers for noninvasive genetic sampling. Doing so should reduce potential genotyping and data interpretation errors, help meet capture-mark-recapture assumptions, and increase confidence in results.

Use of a Net Gun to Safely Capture Short-eared Owls in Mid-flight from a Helicopter

USO DE UNA PISTOLA DE RED PARA CAPTURAR DE MODO SEGURO A INDIVIDUOS DE ASIO FLAMMEUS EN VUELO DESDE UN HELICOPTERO Probamos una tecnica novedosa de captura que consiste en disparar desde un helicoptero una red sobre individuos de Asio flammeus en vuelo, para colocar transmisores satelitales en esta especie en disminucion. Capturamos 18 buhos (10 machos, 8 hembras) durante 17 horas de vuelo y colocamos transmisores en 12 aves que cumplieron con nuestro criterio de uso de transmisores. Desplegamos 2.5 ± 1.0 redes por captura exitosa, con una moda de una red por captura. Las persecuciones duraron 4.0 ± 4.1 min. No se mato ningun buho y no se detectaron heridas considerables como huesos rotos, abrasiones o contusiones. Todas las aves a las que se les colocaron los transmisores sobrevivieron al menos tres semanas luego de la captura; 10 de las 12 aves migraron hasta 5500 km. Hemos demostrado, por primera vez, el uso seguro de redes disparadas desde helicopteros para capturar aves en vuelo. Recomendamos el uso ...