Survival of House Sparrows and House Finches in Kern County, California

Milby, M. M.; Wright, M.

doi:10.2307/4512211

Cited by 6 publications

(4 citation statements)

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“…This mortality may have contributed to the survivorship differences seen between seropositive and negative birds. Interestingly, although calculated differently, our survivorship estimates were greater than those for a smaller cohort of House Finches and House Sparrows banded and recaptured in Kern County [34] when they were infected at a low level with WEEV and SLEV [35] . Similar to our data, they found that House Finches lived longer than House Sparrows, and that some especially long-lived birds were recaptured 55 and 66 months after banding, respectively.…”

Section: Discussionmentioning

confidence: 99%

Antecedent Avian Immunity Limits Tangential Transmission of West Nile Virus to Humans

2012

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BackgroundWest Nile virus (WNV) is a mosquito-borne flavivirus maintained and amplified among birds and tangentially transmitted to humans and horses which may develop terminal neuroinvasive disease. Outbreaks typically have a three-year pattern of silent introduction, rapid amplification and subsidence, followed by intermittent recrudescence. Our hypothesis that amplification to outbreak levels is contingent upon antecedent seroprevalence within maintenance host populations was tested by tracking WNV transmission in Los Angeles, California from 2003 through 2011.MethodsPrevalence of antibodies against WNV was monitored weekly in House Finches and House Sparrows. Tangential or spillover transmission was measured by seroconversions in sentinel chickens and by the number of West Nile neuroinvasive disease (WNND) cases reported to the Los Angeles County Department of Public Health.ResultsElevated seroprevalence in these avian populations was associated with the subsidence of outbreaks and in the antecedent dampening of amplification during succeeding years. Dilution of seroprevalence by recruitment resulted in the progressive loss of herd immunity following the 2004 outbreak, leading to recrudescence during 2008 and 2011. WNV appeared to be a significant cause of death in these avian species, because the survivorship of antibody positive birds significantly exceeded that of antibody negative birds. Cross-correlation analysis showed that seroprevalence was negatively correlated prior to the onset of human cases and then positively correlated, peaking at 4–6 weeks after the onset of tangential transmission. Antecedent seroprevalence during winter (Jan – Mar) was negatively correlated with the number of WNND cases during the succeeding summer (Jul–Sep).ConclusionsHerd immunity levels within after hatching year avian maintenance host populations <10% during the antecedent late winter and spring period were followed on three occasions by outbreaks of WNND cases during the succeeding summer. Because mosquitoes feed almost exclusively on these avian species, amplification was directly related to the availability of receptive non-immune hosts.

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Section: Discussionmentioning

confidence: 99%

Antecedent Avian Immunity Limits Tangential Transmission of West Nile Virus to Humans

2012

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“…(2002); 7, Goddard et al . (2003); 8, Griffith & Turner (1996); 9, Hayes & Hsi (1975); 10, Hickey & Brittingham (1991); 11, Milby & Wright (1976); 12, Mpho et al . (2002); 13, Oda et al .…”

Section: Core Modelmentioning

confidence: 98%

Transmission assumptions generate conflicting predictions in host–vector disease models: a case study in West Nile virus

Wonham¹,

Lewis²,

et al. 2006

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This review synthesizes the conflicting outbreak predictions generated by different biological assumptions in host-vector disease models. It is motivated by the North American outbreak of West Nile virus, an emerging infectious disease that has prompted at least five dynamical modelling studies. Mathematical models have long proven successful in investigating the dynamics and control of infectious disease systems. The underlying assumptions in these epidemiological models determine their mathematical structure, and therefore influence their predictions. A crucial assumption is the hostvector interaction encapsulated in the disease-transmission term, and a key prediction is the basic reproduction number, R 0 . We connect these two model elements by demonstrating how the choice of transmission term qualitatively and quantitatively alters R 0 and therefore alters predicted disease dynamics and control implications. Whereas some transmission terms predict that reducing the host population will reduce disease outbreaks, others predict that this will exacerbate infection risk. These conflicting predictions are reconciled by understanding that different transmission terms apply biologically only at certain population densities, outside which they can generate erroneous predictions. For West Nile virus, R 0 estimates for six common North American bird species indicate that all would be effective outbreak hosts.

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“…Most of the analyses of passerines is of crude annual adult mortality taking the beginning of life as the initial 1 January. For small passerines, the data suggest a mean longevity (expectation of further life), for individuals that have reached January, of between 1 and 2 yr with most values being < 1.5 yr (summarized in Farner 1949, Franks 1975, Milby and Wright 1976.…”

Section: Discussionmentioning

confidence: 99%

Demography of White-Crowned Sparrows (Zonotrichia Leucophrys Nuttalli)

Baker¹,

Mewaldt²,

Stewart³

1981

Ecology

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Analysis of a White-crowned Sparrow population in coastal California resulted in estimates of the magnitude of variation in longevity (a) among cohorts in the same breeding season, (b) between sexes, and (c) between years. Mean longevity calculated from early juvenile life averaged = 13 mo whereas mean longevity calculated from the egg stage was =6 mo. Survival of fledglings to 1 January was generally lower and more variable among cohorts than survival beyond January as adults. Reproductive information from a sample of known-age females indicated that clutch size and number of nestlings increased with female age. Age-specific longevity and clutch size were combined to calculate the net reproductive rates of two female cohorts. These were 1.042 and 1.025, respectively. A combination of survival information from five cohorts and information on the numbers of males and females in reproductive condition suggested an effective sex ratio of one male per 1.2 females. This departure from strict monogamy reduces the genetically effective population size by 10%.

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Survival of House Sparrows and House Finches in Kern County, California

Cited by 6 publications

References 0 publications

Antecedent Avian Immunity Limits Tangential Transmission of West Nile Virus to Humans

Antecedent Avian Immunity Limits Tangential Transmission of West Nile Virus to Humans

Transmission assumptions generate conflicting predictions in host–vector disease models: a case study in West Nile virus

Demography of White-Crowned Sparrows (Zonotrichia Leucophrys Nuttalli)

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