Comparative Breeding Ecology of Cooper's Hawks in Urban and Exurban Areas of Southeastern Arizona

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Abstract: One step in assessing the quality of an urban environment as habitat for a species is to compare its breeding ecology and productivity in urban and exurban (i.e., undeveloped, natural) areas. We studied Cooper's hawks (Accipiter cooperii) in Tucson, Arizona, and in exurban areas in southeastern Arizona, 1994-96. Urban pairs nested earlier (P < 0.001) and had larger clutches (P = 0.085) than exurban pairs. Nestling mortality was greater among urban nests (50.3%) than exurban nests (4.9%). The primary cause of death among urban nestlings was trichomoniasis (79.9%), which was a consistent mortality factor among years (P = 0.402). An overall failure rate among urban nests (52.6%) was greater than at exurban nests (20.5%; P < 0.001). Although the role of bird feeding in the spread of trichomoniasis remains unclear, promoting "dove-proof" feeders or abstinence from bird feeding may minimize the spread of the disease among prey species, thereby reducing mortality of nestling Cooper's hawks. The greatest cause of mortality among free-ranging Cooper's hawks in the urban area was collisions (69.8%), primarily with windows. Techniques to decrease window collisions should be promoted to reduce window-strike mortalities among both Cooper's hawks and their prey. Cooper's hawks also are occasionally aggressive when defending their nests from perceived threats, which may lead to fear and persecution by city residents. Hence, environmental education may be an important component of managing this species in urban settings. JOURNAL OF WILDLIFE MANAGEMENT 63(1):77-84

The breeding performance of raptors in urban landscapes: a review and meta-analysis

“…This finding is similar to that found in passerines, and is hypothesised to be induced by the year-round abundance of food (Solonen and Ursin 2008;Chamberlain et al 2009). Similarly, the year-round availability of prey in urban environments may allow earlier raptor broods to survive (Lin et al 2015) and may also promote year-round pair bonds, triggering earlier nesting in raptor species (Boal and Mannan 1999). However, the species studied here were largely resident in the location of study and thus these findings may differ in migratory species who are not influenced by year-round food availability.…”

“…2) (Kettel et al unpublished data). Cooper's Hawks also showed a positive response to urbanisation, laying on average 0.44 more eggs in urban areas, but this difference was not significant in the study (Boal and Mannan 1999). However, other findings for Cooper's Hawks showed no difference in clutch size between the habitats when looking at cross-study comparisons (Rosenfield et al 1996(Rosenfield et al , 2000.…”

“…The literature reported that Cooper's Hawks, Crested Goshawks (Accipiter trivirgatus) and Tawny Owls (Strix aluco) all began breeding significantly earlier in urban environments (Boal and Mannan 1999;Solonen 2014;Lin et al 2015). The biggest difference was found in Crested Goshawks, where breeding began over a month earlier in urban nesters ( Fig.…”

“…5). Conversely, Burrowing Owls, Cooper's Hawks, Eurasian Kestrels, Lesser Kestrels and Swainson's Hawks were less successful in urban habitats (England et al 1995;Tella et al 1996;Boal and Mannan 1999;Conway et al 2006;Charter et al 2007) (Fig. 5) and American Kestrels showed a negative correlation between nest success and urban cover in an urban-gradient study (Strasser and Heath 2013).…”

“…Barn Owls, Cooper's Hawks and Northern Goshawks (Accipiter gentilis) produced brood sizes of 0.28-0.6 more chicks in urban nests (Fig. 3) (Boal and Mannan 1999;Salvati et al 2002;Solonen 2008) but Bald Eagles (Haliaeetus leucocephalu) produced only 0.02 more chicks in urban habitats (Millsap et al 2004). Differences were only significant for Peregrine Falcons and Northern Goshawks, despite relatively large sample sizes in the majority of studies (Fig.…”