Why are American Kestrel (Falco sparverius) Populations Declining in North America? Evidence from Nest-Box Programs

Smallwood, John A.; Causey, Mark F.; Mossop, David; Klucsarits, James R.; Robertson, Bob; Robertson, Sue; Mason, Joey; Maurer, Michael; Melvin, Richard J.; Dawson, Russell D.; Bortolotti, Gary R.; Parrish, John W.; Breen, T.; Boyd, Kenneth

doi:10.3356/jrr-08-83.1

Cited by 101 publications

(121 citation statements)

References 11 publications

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“…Cooper's hawk predation has been identified as a possible factor in the decline of American kestrels in North America (Farmer et al 2006). Although Smallwood et al (2009) found no direct statistical relationship between negative population trends in American kestrels and population increases in Cooper's hawks in Breeding Bird Survey data, our findings provide empirical evidence that in at least some settings, Cooper's hawks can and do target kestrel nest boxes as sources of prey. Given this, nest box programs may increase the vulnerability of American kestrels to predation by Cooper's hawks.…”

Section: Diet and Foraging Habitsmentioning

confidence: 43%

Ecology of the Cooper's Hawk in North Florida

Millsap

Breen

Phillips

2013

North American Fauna

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We studied adult Cooper's hawks Accipiter cooperii on two study areas in north Florida from 1995 to 2001, an area dominated by large plantations managed for northern bobwhite Colinus virginianus and an area of mixed farmland and woods with no direct bobwhite management. We monitored 76 Cooper's hawk nesting attempts at 31 discrete nest areas, and radio-tagged 19 breeding males and 30 breeding females that we radio-tracked for up to 5 y. Nesting density (565 to 1,494 ha per occupied nest area) was comparable but productivity (1.8 and 2.8 young fledged per occupied and successful nest area, respectively) was lower than for the species elsewhere. Prey may have been more limiting than in other areas studied because chipmunks Tamias striatus, an important prey elsewhere, were absent. Annual Cooper's hawk survival averaged 84% for males and 81% for females, except in 1998 when survival was substantially lower. Average annual home-range size for male Cooper's hawks was 15.3 km2 inclusive of one nesting area. Female annual ranges averaged 30.3 km2, and included from three to nine nesting areas. Daily space use was similar between the sexes, but females had separate breeding and nonbreeding ranges whereas males were sedentary. Females used the same nonbreeding areas among years, but switched nesting areas 68% of the time compared with only 17% for males. Birds comprised 88% of the breeding and 98% of the nonbreeding season diet of Cooper's hawks by frequency. Important prey species all year were mourning doves Zenaida macroura, blue jays Cyanocitta cristata, and northern bobwhite; during summer, cattle egrets Bubulcus ibis, northern mockingbirds Mimus polyglottos and northern cardinals Cardinalis cardinalis were also important; and during autumn and winter, killdeer Charadrius vociferus, yellow-billed cuckoos Coccyzus americanus, and chickens were important. Female Cooper's hawks took larger prey than males; females were responsible for most cattle egret and chicken kills; whereas, males took most blue jays, killdeer, northern mockingbirds, and northern cardinals. Of avian prey brought to nests, 64% were nestling birds. Most adult male Cooper's hawks were adept at raiding bird nest boxes. Male Cooper's hawks captured 85% of the prey fed to nestlings. Female Cooper's hawks relied on males for food from early March until young were ≥12 d old, and 6 of 10 breeding females monitored intensively were never observed foraging for their broods. Most prey brought to nestling Cooper's hawks was captured within 2 km of nests, and foraging effort was consistent throughout the day. During the nonbreeding season, most prey captures occurred before 0900 hours or at dusk. Northern bobwhite made up 2% of male and 6% of female Cooper's hawk prey annually by frequency; this extrapolated to 18 bobwhite/year/adult Cooper's hawk on both study areas, 59% of which were captured between November and February. Outside the breeding season, male Cooper's hawks foraged evenly over their home range whereas females tended to focus on prey concentrations. Because female Cooper's hawks were so adept at finding and exploiting prey hotspots, perhaps the best strategy for reducing predation on bobwhite is habitat management that produces an even distribution of bobwhite across the landscape.

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Section: Diet and Foraging Habitsmentioning

confidence: 43%

Ecology of the Cooper's Hawk in North Florida

Millsap

Breen

Phillips

2013

North American Fauna

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“…We also provide evidences that the largest cavity nesters, such as the biggest hawks, might have limited nesting possibilities in mid-seccessional stage areas. Management strategies currently used to overcome these problems involve the distribution of nest boxes and the enlargement of the entrances of part of the available cavities (Kuniy et al 2006, Smallwood et al 2009, Olah et al 2014. In face of the evidences provided here, we suggest that these strategies might be considered for the preservation of the guild of Atlantic Forest cavity-nester birds in areas classified in mid-or lower successional stages.…”

Section: Discussionmentioning

confidence: 99%

Successional stage effect on the availability of tree cavities for cavity-nesting birds in an Atlantic Forest park from the state of São Paulo, Brazil

et al. 2017

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The availability of suitable cavities and substrate for hole construction can limit the populations of birds that rely on tree hollows to reproduce. Several studies have focused on the effects of types of habitats, and types of human disturbances on cavities abundance, but the effect of successional stages in the Atlantic Forest has been poorly addressed. In this study we aimed to compare the availability and biometric characteristics of tree cavities between primary and mid-successional stage sites in an Atlantic Forest area from southeastern Brazil. Based on nest characteristics described in the literature, we inferred if hollows present in secondary sites could harbor the large secondary-nester Atlantic Forest birds, with special attention to toucans and hawks. From September 2016 to April 2017, 96 cavities were sampled, 67 in the primary, and 29 in the secondary plots. Our data revealed that the communities of cavity-nester birds in mid-successional stage areas may be more affected by the reduced cavity availability than by cavities quality, as the number of cavities in these sites was less than half than that found in mature forests. We also provide evidences that the largest cavity nesters, such as the biggest hawks, might have limited nesting possibilities in mid-successional stage areas especially due to small cavity entrances, which may have important reflects in conservation strategies. Keywords

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“…Para anidar, utiliza cavidades naturales en árboles así como cavidades construidas por pájaros carpinteros, huecos en construcciones, huecos en rocas y en bancos de tierra (Baicich & Harrison 2005). Recientemente se ha documentado que sus poblaciones en Norteamérica, tanto reproductoras como migratorias, están disminuyendo (Sullivan & Wood 2005, Sauer et al 2008, Farmer & Smith 2009, Smallwood et al 2009, Ruelas et al 2010. Entre las causas principales de su disminución se sugiere la pérdida del hábitat.…”

Section: Introductionunclassified

“…Entre las causas principales de su disminución se sugiere la pérdida del hábitat. Aunque aún existe controversia de cuál es la verdadera causa de su disminución, se ha sugerido que probablemente el problema se encuentre en las áreas donde sus poblaciones pasan la temporada de migración o a lo largo de sus rutas migratorias (Farmer & Smith 2009, Smallwood et al 2009). …”

Section: Introductionunclassified

Efectos de la fragmentación del matorral desértico sobre poblaciones del aguililla cola-roja y el cernícalo americano en Baja California Sur, México

Tinajero¹,

Rodríguez‐Estrella²

2012

AZM

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Tinajero, R. & R. Rodríguez-Estrella. 2012. Efectos de la fragmentación del matorral desértico sobre poblaciones del aguililla cola-roja y el cernícalo americano en Baja California Sur, México. Acta Zoológica Mexicana (n. s.), 28(2): 427-446. RESUMEN. Para evaluar el efecto de la fragmentación del desierto sobre especies de poblaciones residentes y migratorias, durante 2008 y 2009 se realizaron muestreos mensuales de dos especies de aves rapaces, el aguililla cola-roja Buteo jamaicensis y el cernícalo americano Falco sparverius. Los muestreos se realizaron en áreas naturales continuas y en áreas fragmentadas por actividad agrícola en el matorral desértico de Baja California Sur. En total se registraron en 1,806 ocasiones las dos especies. La más común fue el cernícalo americano con 1,164 (64.4%) registros (los cuales fueron 51% en área fragmentada y 49% área natural) y el aguililla cola-roja con 642 registros (35.6%) (70% en área fragmentada y 30% en área natural). Se estimaron las abundancias relativas y la densidad, las cuales no variaron durante la primavera y verano para el aguililla cola-roja, pero sus abundancias y densidades fueron mayores en las áreas fragmentadas durante otoño e invierno. Por otro lado, la abundancia del cernícalo americano fue similar entre áreas en todas las temporadas del año, mientras que la densidad fue similar en primavera, verano e invierno, pero fue mayor en el área fragmentada durante el otoño. Se encontró que el matorral desértico y sus áreas fragmentadas dentro de una matriz agrícola en Baja California Sur es un hábitat importante para las poblaciones migratorias de ambas especies de rapaces. Se discute sobre la tolerancia de las dos especies en función de su tamaño y selección de hábitat para anidar y forrajear, así como los efectos de la fragmentación del desierto sobre su abundancia y densidad en el sur de la península de Baja California.

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Why are American Kestrel (Falco sparverius) Populations Declining in North America? Evidence from Nest-Box Programs

Cited by 101 publications

References 11 publications

Ecology of the Cooper's Hawk in North Florida

Ecology of the Cooper's Hawk in North Florida

Successional stage effect on the availability of tree cavities for cavity-nesting birds in an Atlantic Forest park from the state of São Paulo, Brazil

Efectos de la fragmentación del matorral desértico sobre poblaciones del aguililla cola-roja y el cernícalo americano en Baja California Sur, México

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