Mass, Reproductive Biology, and Nonrandom Pairing in Cooper's Hawks

Rosenfield, Robert N.; Bielefeldt, John

doi:10.2307/4089346

Cited by 35 publications

(40 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We found the same trend for body condition, but it was not significant. This result is similar to those reported for other species of birds (Choudhury et al 1992;Heitmeyer 1995;Rosenfield and Bielefeldt 1999;Wagner 1999). However, body mass is usually an unreliable measurement in birds because it tends to fluctuate throughout the breeding cycle (Moreno 1989).…”

Section: Discussionsupporting

confidence: 90%

Phenotypic assortative mating and within-pair sexual dimorphism and its influence on breeding success and offspring quality in Magellanic penguins

Forero¹,

Tella²,

Donázar³

et al. 2001

Can. J. Zool.

View full text Add to dashboard Cite

We examined within-pair sexual dimorphism and phenotypic assortative mating in Magellanic penguins (Spheniscus magellanicus) breeding in six colonies located on the Patagonian coast (Argentina). All measured phenotypic traits except the number of pectoral spots differed between the sexes; bill depth and flipper length were the most and least dimorphic traits, respectively. We found assortative mating by bill depth and body mass. The similarity in body condition within pairs was close to significant. When we performed separate correlations for birds that bred successfully, i.e., raised one or two offsprings, and birds that did not attempt to breed or bred unsuccessfully, only the successful breeders showed assortative mating by body mass. In addition, we attempted to relate the body size of each member of the pair and the degree of sexual dimorphism within pairs to the breeding performance of individuals, which was measured as brood size, and body condition and immunocompetence of offspring. We found that pairs that were less dimorphic in flipper length raised more offspring. This effect was due to female flipper length per se and not to the relative difference in flipper length between members of the pair. Females with larger flippers had a higher probability of raising two chicks. No effects of body measurements or degree of sexual dimorphism on body condition or T-cell-mediated immune response of offspring were found. We discuss these results in the context of potential factors responsible for the maintenance of sexual size dimorphism in this species.Résumé : Nous avons étudié le dimorphisme sexuel et le choix d'un partenaire en fonction du phénotype chez des couples de Manchots de Magellan (Spheniscus magellanicus) dans six colonies reproductrices de la côte de la Patagonie (Argentine). Tous les caractères phénotypiques mesurés différaient chez le mâle et la femelle d'un même couple, à l'exception du nombre de taches pectorales; la hauteur du bec était le caractère le plus dimorphe, la longueur des ailerons, le caractère le moins dimorphe. Le choix d'un partenaire se faisait en fonction de la profondeur du bec et de la masse corporelle. La similarité de la condition physique chez le mâle et la femelle d'un couple était presque significative. En faisant des corrélations séparées chez les oiseaux à reproduction réussie et chez les oiseaux non reproducteurs ou les oiseaux qui avaient raté leur reproduction, seuls les oiseaux à reproduction réussie (i.e., qui avaient élevé un ou deux petits) avaient choisi leur partenaire en fonction de sa masse corporelle. Nous avons également tenté de relier la taille de chaque partenaire du couple et l'importance du dimorphisme sexuel au sein du couple avec la performance reproductrice individuelle en mesurant la taille des couvées, la condition physique et la compétence immunitaire des rejetons. Ce sont les couples les moins dimorphes quant à la longueur des ailerons qui ont élevé le plus de petits. Cet effet est attribuable à la longueur per se des ailerons de la femelle et n...

show abstract

Section: Discussionsupporting

confidence: 90%

Phenotypic assortative mating and within-pair sexual dimorphism and its influence on breeding success and offspring quality in Magellanic penguins

Forero¹,

Tella²,

Donázar³

et al. 2001

Can. J. Zool.

View full text Add to dashboard Cite

show abstract

“…Difficult forging conditions may also have contributed to the high Cooper's hawk mortality rates in 1998, but other factors were also likely involved. Rosenfield and Bielefeldt (1999) noted that breeding male Cooper's hawks in Wisconsin declined in mass over the course of the breeding season. Although Rosenfield and Bielefeldt (1999) observed no interyear variation in male body mass in their study, it seems logical that declines in mass might be greatest in years when foraging is particularly difficult.…”

Section: Survival and Causes Of Mortalitymentioning

confidence: 99%

“…Rosenfield and Bielefeldt (1999) noted that breeding male Cooper's hawks in Wisconsin declined in mass over the course of the breeding season. Although Rosenfield and Bielefeldt (1999) observed no interyear variation in male body mass in their study, it seems logical that declines in mass might be greatest in years when foraging is particularly difficult. We hypothesize that this may have occurred in our study in 1998, and that low prey resources that year may have required those male Cooper's hawks that did breed that year to exert more effort in foraging than usual, which in turn resulted in more males being in low condition and vulnerable to disease and other mortality factors after the breeding season.…”

Section: Survival and Causes Of Mortalitymentioning

confidence: 99%

“…We hypothesized that these factors would affect measures of reproductive success in our study populations, and that poor reproductive conditions would be associated with larger home-range sizes because of the need for foraging adults to cover more area to find sufficient food, and lower annual survival of breeding adults because of negative effects on body condition from increased foraging (see Rosenfield and Bielefeldt 1999). We also hypothesized that observed variation in reproduction and ranging behavior would be reflected by differences in diet and foraging behavior.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ecology of the Cooper's Hawk in North Florida

Millsap

Breen

Phillips

2013

North American Fauna

View full text Add to dashboard Cite

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.

show abstract

“…Body mass has been used extensively as an index of size in intra-and interspecific studies of raptors (e.g., Snyder and Wiley 1976, Mueller 1986, Rosenfield et al 2009). In Wisconsin and British Columbia, after an age of 2 years, both sexes of Cooper's hawk vary negligibly in body mass, as measured annually when their young are nestlings (Rosenfield and Bielefeldt 1999;R. N. Rosenfield and A. C. Stewart, unpubl.…”

mentioning

confidence: 99%

Comparative Morphology of Northern Populations of Breeding Cooper's Hawks

Rosenfield

Bielefeldt

et al. 2010

Condor

Self Cite

View full text Add to dashboard Cite

Resumen. Pocos estudios han caracterizado la variación intraespecífica en la morfología de halcones de áreas arboladas del género Accipiter a una escala geográfica amplia. Entre 1999 y 2007, investigamos la variación morfológica en muestras grandes de individuos vivos de la especie A. cooperii que se encontraban anidando en cuatro áreas de estudio: bosques de coníferas alrededor de Victoria, British Columbia, Canadá; bosques caducifolios aislados en medio de praderas de pastos cortos en el noroeste de North Dakota; poblados y bosques caducifolios rurales a lo largo de la frontera entre North Dakota y Minnesota; y paisajes mixtos urbanos y rurales, caducifolios y de coníferas en Wisconsin. Estos sitios abarcan 2660 m a través de la parte norte del área de distribución reproductiva de la especie. Medimos la masa corporal (i.e., el tamaño), la cuerda alar, la longitud de la cola, el diámetro del tarso, la longitud del hálux y la longitud del culmen de adultos reproductivos, y encontramos que existe variación significativa y clinal en la masa corporal (o el tamaño). Las aves más pequeñas y con menor dimorfismo sexual se encontraron en British Columbia y en el oeste de North Dakota, aves más grandes a lo largo de la frontera entre North Dakota y Minnesota y las más grandes de todas en Wisconsin. Varios rasgos adicionales variaron significativamente tras utilizar la masa como una covariable. La variación entre sitios de estudio en índices promedio de dimorfismo sexual en el tamaño fue despreciable y no siginificativa. Especulamos que las diferencias morfológicas que encontramos son, en parte, el resultado del aislamiento geográfico, debido a que la dieta, el comportamiento migratorio y las características estructurales de los ambientes de anidación varían entre tipos de paisaje.Abstract. few studies at a broad geographical scale have characterized intraspecific variation in morphology of woodland hawks in the genus Accipiter. from 1999 to 2007 we investigated morphological variation in large samples of live Cooper's hawks (A. cooperii) nesting in four study areas: coniferous woodland around Victoria, British Columbia, Canada, isolated deciduous woodlands in short-grass prairies of northwestern North Dakota, towns and rural deciduous woodlands along the border of North Dakota and Minnesota, and urban and rural mixed deciduous and coniferous landscapes of Wisconsin. These sites span 2660 km across the northern part of the species' breeding range. We measured body mass (i.e., size), wing chord, tail length, tarsus diameter, hallux length, and culmen length of breeding adults, finding significant and clinal variation in body mass (or size). The smallest and most similar-sized birds occurred in British Columbia and western North Dakota, larger birds along the border between North Dakota and Minnesota, and the largest birds in Wisconsin. Several other characters varied significantly when mass was used as a covariate. Variation by study site in mean indices of sexual size dimorphism was negligible and not significant. We spec...

show abstract

Mass, Reproductive Biology, and Nonrandom Pairing in Cooper's Hawks

Cited by 35 publications

References 15 publications

Phenotypic assortative mating and within-pair sexual dimorphism and its influence on breeding success and offspring quality in Magellanic penguins

Phenotypic assortative mating and within-pair sexual dimorphism and its influence on breeding success and offspring quality in Magellanic penguins

Ecology of the Cooper's Hawk in North Florida

Comparative Morphology of Northern Populations of Breeding Cooper's Hawks

Contact Info

Product

Resources

About