Causes and consequences of expanding American Crow populations

Marzluff, John M.; McGowan, Kevin J.; Donnelly, Roarke; Knight, Richard L.

doi:10.1007/978-1-4615-1531-9_16

Cited by 96 publications

(81 citation statements)

References 20 publications

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“…Additionally, the raw number of WNVpositive carcasses collected in the winter (18) was only marginally larger than the number collected between July and August of 2013 (13) despite the change in local crow population size. In the fall, as the winter roost is established, the Davis population of crows expands, most likely due to an influx of migrants (Marzluff et al 2001). In conjunction, these two observations indicate a decrease in overall WNV infection rates during the winter.…”

Section: Discussionmentioning

confidence: 93%

West Nile Virus Activity in a Winter Roost of American Crows (Corvus brachyrhynchos): Is Bird-To-Bird Transmission Important in Persistence and Amplification?

et al. 2015

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Since its emergence in North America, West Nile virus (WNV) has had a large impact on equines, humans, and wild bird communities, yet gaps remain in our understanding of how the virus persists at temperate latitudes when winter temperatures preclude virus replication and host-seeking activity by mosquito vectors. Bird-to-bird transmission at large communal American Crow roosts could provide one mechanism for WNV persistence. Herein, we describe seasonal patterns of crow and Culex mosquito abundance, WNV infection rates, and the prevalence of WNV-positive fecal samples at a winter crow roost to test the hypothesis that bird-to-bird transmission allows WNV to persist at winter crow roosts. Samples were collected from large winter crow roosts in the Sacramento Valley of California from January 2013 until August 2014, encompassing two overwintering roost periods. West Nile virus RNA was detected in local crow carcasses in both summer [13/18 (72% WNV positive)] and winter [18/44 (41% WNV positive)] 2013-2014. Winter infections were unlikely to have arisen by recent bites from infected mosquitoes because Culex host-seeking activity was very low in winter and all Culex mosquitoes collected during winter months tested negative for WNV. Opportunities existed for fecal-oral transfer at the overwintering roost: most carcasses that tested positive for WNV had detectable viral RNA in both kidney and cloacal swabs, suggesting that infected crows were shedding virus in their feces, and >50% of crows at the roost were stained with feces by mid-winter. Moreover, 2.3% of fecal samples collected in late summer, when mosquitoes were active, tested positive for WNV RNA. Nevertheless, none of the 1,119 feces collected from three roosts over two winters contained detectable WNV RNA. This study provided evidence of WNV infection in overwintering American crows without mosquito vector activity, but did not elucidate a mechanism of WNV transmission during winter.

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Section: Discussionmentioning

confidence: 93%

West Nile Virus Activity in a Winter Roost of American Crows (Corvus brachyrhynchos): Is Bird-To-Bird Transmission Important in Persistence and Amplification?

et al. 2015

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“…However, despite all the above, relatively few intensive studies have centred on these 'synanthropic' urban exploiters (e.g. Marzluff et al 2001;Parker and Nilon 2012).…”

Section: Introductionmentioning

confidence: 99%

Habitat selection by an avian top predator in the tropical megacity of Delhi: human activities and socio-religious practices as prey-facilitating tools

et al. 2017

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Research in urban ecology is growing rapidly in response to the exponential growth of the urban environment. However, few studies have focused on tropical megacities, and on the interplay between predators' habitat selection and human socio-economic aspects, which may mediate their resilience and coexistence with humans. We examined mechanisms of breeding habitat selection by a synanthropic raptor, the Black Kite Milvus migrans, in Delhi (India) where kites mainly subsist on: (1) human refuse and its associated prey-fauna, and (2) ritualised feeding of kites, particularly practised by Muslims. We used mixed effects models to test the effect of urban habitat configuration and human practices on habitat selection, site occupancy and breeding success. Kite habitat decisions, territory occupancy and breeding success were tightly enmeshed with human activities: kites preferred areas with high human density, poor waste management and a road configuration that facilitated better access to resources provided by humans, in particular to Muslim colonies that provided ritual subsidies. Furthermore, kites bred at 'clean' sites with less human refuse only when close to Muslim colonies, suggesting that the proximity to ritual-feeding sites modulated the suitability of other habitats. Rather than a nuisance to avoid, as previously portrayed, humans were a keenly-targeted foraging resource, which tied a predator's distribution to human activities, politics, history, socio-economics and urban planning at multiple spatio-temporal scales. Many synurbic species may exploit humans in more subtle and direct ways than was previously assumed, but uncovering them will require greater integration of human socio-cultural estimates in urban ecological research.

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“…Bird feeders attract cowbirds from great distances and support populations to the extent that reducing bird feeding during the breeding season is one management recommendation for decreasing the risk of brood parasitism and nest predation by cowbirds (Coker andCapen 1995, Chace et al 2003). Crows are also known to heavily exploit supplementary foods associated with human habitation, and such foods are thought to promote both high densities and reproductive success of crows in suburbs (Marzluff et al 2001, McGowan 2001, Marzluff and Neatherlin 2006. Although crows are not strongly associated with bird feeders in some regions, they are common visitors to feeders in Ohio, where they are reported at 16-30% of bird feeders included in the FeederWatch citizen science project (feederwatch.org).…”

Section: Discussionmentioning

confidence: 99%

“…These supplementary foods, provided through both intentional means such as bird feeders and unintentional means such as poor refuse management, often make patchy resources more continuously available in space and time (Beckmann and Berger 2003, Bozek et al 2007, Robb et al 2008. Relationships between breeding birds and their nest predators in developed landscapes may be especially influenced by supplementary foods because both songbirds and generalist predators readily exploit these resources, and thus congregate in the same areas (Marzluff et al 2001, Robb et al 2008, Theimer et al 2015. However, despite many studies on avian reproduction in urban landscapes, no clear pattern has emerged regarding the effect of urbanization and associated supplementary foods on the relationship between predators and nest survival (Chamberlain et al 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Collectively, these 6 predator species accounted for the majority of predation events on both robin and cardinal nests in our system (74% and 66%, respectively ;Malpass 2015). The diets of Brown-headed Cowbirds, American Crows, Common Grackles, Blue Jays, and eastern gray squirrels incorporate anthropogenic foods, including birdseed from feeders in suburban neighborhoods (Lowther 1993, Bowers and Breland 1996, Peer and Bollinger 1997, Marzluff et al 2001, Verbeek and Caffrey 2002, Marzluff and Neatherlin 2006, Parker and Nilon 2008, Smith et al 2013.…”

Section: Introductionmentioning

confidence: 99%

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Species-dependent effects of bird feeders on nest predators and nest survival of urban American Robins and Northern Cardinals

2017

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Causes and consequences of expanding American Crow populations

Cited by 96 publications

References 20 publications

West Nile Virus Activity in a Winter Roost of American Crows (Corvus brachyrhynchos): Is Bird-To-Bird Transmission Important in Persistence and Amplification?

West Nile Virus Activity in a Winter Roost of American Crows (Corvus brachyrhynchos): Is Bird-To-Bird Transmission Important in Persistence and Amplification?

Habitat selection by an avian top predator in the tropical megacity of Delhi: human activities and socio-religious practices as prey-facilitating tools

Species-dependent effects of bird feeders on nest predators and nest survival of urban American Robins and Northern Cardinals

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