West Nile Virus Devastates an American Crow Population

Caffrey, Carolee; Smith, Shauna C. R.; Weston, Tiffany J.

doi:10.1093/condor/107.1.128

Cited by 28 publications

(42 citation statements)

References 13 publications

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“…Despite the buffering capacity of cooperative breeding, if the severe outbreaks like those documented here and in other areas (Yaremych et al 2003, Caffrey et al 2005) occur repeatedly over several years, they must cause drastic population reduction unless resistance evolves rapidly. There is, as yet, little evidence of increasing resistance.…”

Section: Discussionmentioning

confidence: 74%

“…1), but the normal rate of mortality for juveniles during the August-October period, computed for the decade 1990-1999, is >4x that for adults (Table 2) West Nile virus killed all Ithaca crows without regard to age, sex, or breeding status, as it did in Oklahoma and Illinois (Yaremych et al 2004, Caffrey et al 2005). Overall mortality from the end of July through the first week of October was elevated by a factor of -4.5 and exceeded total normal annual mortality.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of West Nile Virus Mortality on Social Structure of an American Crow (Corvus brachyrhynchos) Population in Upstate New York

Clark¹,

Robinson²,

McGowan³

2006

Ornithological Monographs

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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. . University of California Press and AmericanOrnithologists' Union are collaborating with JSTOR to digitize, preserve and extend access to Ornithological Monographs.Abstract.-In a marked population of cooperatively breeding American Crows (Corvus brachyrhynchos) studied for 17 years in Ithaca, New York, the effect of West Nile virus (WNV) was local but dramatic during 2002-2003. In two consecutive years, >35% of American Crows in well-known families died or disappeared between late July and early October, the primary WNV season in the state of New York. West Nile virus was confirmed as the cause of death in nearly all tested birds. Risk of mortality did not differ with age, sex, or breeding status of birds, but adult mortality increased 10-fold and juvenile mortality 3-fold above normal levels for this population as measured during 1990-1998. Four times as many breeders died during August-October as disappeared during an entire year between 1995 and 1998. Social effects were assessed by comparing changes from 2001, before WNV was present, through 2005, two years after the high mortality of 2003. Although no significant decreases in group size, frequency of helping, average age of breeders, or territory density were observed after two years of WNV presence, the direction of most changes suggested that repeated years of WNV presence would likely affect social structure. Unusual social events, including female territory-budding and adoption of and subsequent helping by unrelated juveniles, were documented in 2004-2005. American Crows filled territory vacancies very slowly. The presence of breeding-age auxiliaries on territories may counter rapid social change and breeding declines in cooperatively breeding crow populations, but repeated years of such high mortality are likely to cause both significant social disruption and severe population declines among American Crows. Resumen.-El efecto de el virus del Oeste del Nilo (VON) fue especifico pero dramatico durante el 2002-2003, en una poblacion marcada de Corvus brachyrhynchos que presentabanreproduccion cooperativa la cual fue estudiada durante 17 anos en Ithaca, Nueva York. En dos afios consecutivos mas del 35% de Corvus brachyrhynchos pertenecientes a familias conocidas murieron o desaparecieron entre finales de Julio y principios de Octubre, coincidiendo con la primera temporada del VON en el estado de Nueva York. Se confirmo que el virus del Oeste del Nilo fue la causa de mortalidad e casi todas las aves examinadas. El riego de mortalidad no fue diferente con la edad, sexo o estado de apareamiento de las aves, pero la mortalidad de adultos y juveniles se incremento diez y tres veces, respectivamente, arriba de los niveles normale...

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Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Effects of West Nile Virus Mortality on Social Structure of an American Crow (Corvus brachyrhynchos) Population in Upstate New York

Clark¹,

Robinson²,

McGowan³

2006

Ornithological Monographs

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“…For example, native populations frequently are depleted after the first wave of an invasion. In a case involving West Nile virus, 72%, including 82% of juveniles, of an Oklahoma population of American crows ( Corvus brachyrhynchos ) died in a single year (Caffrey et al. 2005).…”

Section: When Adaptive Evolutionary Responses By Natives To Biologicamentioning

confidence: 99%

Evolutionary responses of natives to introduced species: what do introductions tell us about natural communities?

2006

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Biological invasions dramatically affect the distribution, abundance and reproduction of many native species. Because of these ecological effects, exotic species can also influence the evolution of natives exposed to novel interactions with invaders. Evolutionary changes in natives in response to selection from exotics are usually overlooked, yet common responses include altered anti-predator defenses, changes in the spectrum of resources and habitats used, and other adaptations that allow native populations to persist in invaded areas. Whether a native population is capable of responding evolutionarily to selection from invaders will depend on the demographic impact of the invader, the genetic architecture and genetic variability of the native population and potentially the history of previous invasions. In some cases, natives will fail to evolve or otherwise adapt, and local or global extinction will result. In other cases, adaptive change in natives may diminish impacts of invaders and potentially promote coexistence between invaders and natives. Here, we review the evidence for evolutionary responses of native species to novel community members. We also discuss how the effects of introduced species may differ from those caused by natural range expansions of native species. Notably, introduced species may come from remote biotas with no previous evolutionary history with the native community. In addition, the rate of addition of introduced species into communities is much greater than all but the most extreme cases of historical biotic exchange. Understanding the evolutionary component of exotic/ native species interactions is critical to recognizing the long-term impacts of biological invasions, and to understanding the role of evolutionary processes in the assembly and dynamics of natural communities. KeywordsAnti-predator behavior, character displacement, community ecology, evolutionary ecology, natural selection, phylogenetics, plasticity, rapid evolution.Ecology Letters (2006) 9: 357-374Human transport over the past five centuries has augmented rates of biotic exchange among the Earth's realms far beyond pre-industrial norms (Elton 1958;Perrings et al. 1992). Non-indigenous organisms may become invasive, meaning that they naturalize, i.e. become numerically and ecologically prominent, and are often capable of dominating native populations and communities (Crooks 2002). Owing to time-lags common in the establishment of non-native species, the impacts of many prior introductions are just now beginning to become manifest (Kowarik 1995). Invasive species participate in ecological webs as predators, pathogens or parasites of natives, as competitors with natives for space and other resources, and as mutualists or hosts (Schiffman 1994). The subdiscipline of invasion biology has developed to address our lack of knowledge regarding the capacity of invasives to alter native communities, as well as the attributes leading to vulnerability in native communities and the characteristics that make some invading...

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“…Species within the family Corvidae are most severely affected, with lethality ranging from 100% among American crows Corvus brachyrhynchos and Black‐billed magpies Pica hudsonia , to between 55% and 75% among Fish crows Corvus ossifragus , Jungle crows Corvus macrorhynchos , Blue jays Cyanocitta cristata and Western scrub‐jays Aphelocoma californica (Komar et al ., ; Shirafuji et al ., ; Nemeth et al ., ; Wheeler et al ., ). In addition, an estimated 65% of a well‐studied free‐ranging American crow population was lost to WNV in Oklahoma in 2003 (Caffrey et al ., ). Species in the family Phasianidae exhibit varied responses to infection, with 100% fatality among experimentally infected Greater sage‐grouse Centrocercus urophasianus to subclinical infection with 100% survival among Ring‐necked pheasants Phasianus colchicus (Clark et al ., ).…”

Section: Susceptibility and Scope Of Wnv Infection Among Avian Speciesmentioning

confidence: 97%

West Nile virus from an avian conservation perspective

Nemeth

Oesterle

2013

International Zoo Yearbook

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West Nile virus (WNV) is a widespread and ecologically adaptable virus for which birds are major amplifying hosts. Its unexpected arrival to North America in 1999 gained worldwide attention, in part because of the resulting mortality in birds. The virus is now endemic in North America, and sporadic outbreaks continue in Africa, the Middle East, as well as Europe and Russia. Avian taxa vary in their susceptibility to WNV‐associated disease, with North American corvids being the most severely affected. Recent North American and European WNV strains have experimentally induced morbidity and mortality in birds; however, avian deaths have not been a prominent feature of WNV epidemiology outside of the United States and Canada. Bird species experiencing population declines include the Yellow‐billed magpie Pica nuttalli, American crow Corvus brachyrhynchos and Blue jay Cyanocitta cristata. The American robin Turdus migratorius is noteworthy for its important role in transmission. Methods to reduce WNV transmission range from screened enclosures to aerial pesticide spraying. In addition, numerous vaccines have been administered to birds with unreliable but occasionally encouraging results. Avian conservation efforts will continue to be challenged with controlling WNV spread and transmission owing to the wide geographic range of the virus, diversity and abundance of mosquito vectors and global climatic trends.

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West Nile Virus Devastates an American Crow Population

Cited by 28 publications

References 13 publications

Effects of West Nile Virus Mortality on Social Structure of an American Crow (Corvus brachyrhynchos) Population in Upstate New York

Effects of West Nile Virus Mortality on Social Structure of an American Crow (Corvus brachyrhynchos) Population in Upstate New York

Evolutionary responses of natives to introduced species: what do introductions tell us about natural communities?

West Nile virus from an avian conservation perspective

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