Point counts are a standard sampling procedure for many bird species, but lingering concerns stil... more Point counts are a standard sampling procedure for many bird species, but lingering concerns still exist about the quality of information produced from the method. It is well known that variation in observer ability and environmental conditions can influence the detection probability of birds in point counts, but many biologists have been reluctant to abandon point counts in favor of more intensive approaches to counting. However, over the past few years a variety of statistical and methodological developments have begun to pro- vide practical ways of overcoming some of the prob- lems with point counts. We describe some of these ap- proaches, and show how they can be integrated into standard point count protocols to greatly enhance the quality of the information. Several tools now exist for estimation of detection probability of birds during counts, including distance sampling, double observer methods, time-depletion (removal) methods, and hyb- rid methods that combine these approac...
The availability of a validated commercial assay is an asset for any wildlife investigation. Howe... more The availability of a validated commercial assay is an asset for any wildlife investigation. However, commercial products are often developed for use in livestock and are not optimized for wildlife. Consequently, it is incumbent upon researchers and managers to apply commercial products appropriately to optimize program outcomes. We tested more than 800 serum samples from mallards for antibodies to influenza A virus with the IDEXX AI MultiS-Screen Ab test to evaluate assay performance. Applying the test per manufacturer's recommendations resulted in good performance with 84% sensitivity and 100% specificity. However, performance was improved to 98% sensitivity and 98% specificity by increasing the recommended cut-off. Using this alternative threshold for identifying positive and negative samples would greatly improve sample classification, especially for field samples collected months after infection when antibody titers have waned from the initial primary immune response. Furth...
Following a 2008 outbreak of North American low-pathogenic H5N8 influenza A virus at an upland ga... more Following a 2008 outbreak of North American low-pathogenic H5N8 influenza A virus at an upland gamebird farm, we sero-sampled rock doves (pigeons, Columba livia) at the outbreak site and conducted experimental inoculations of wild-caught pigeons using the H5N8 virus and another low-pathogenic virus (H4N6). While 13Â % of pigeons at the outbreak site were seropositive, none were positive for exposure to H5, and one was positive for N8. Challenged pigeons exhibited low susceptibility and limited viral RNA excretion for both viruses tested, but at least one individual had RNA loads indicative of the potential for viral transmission to other birds.
Friday, August 7, 2009 - 9:50 AM Epidemiological implications of virus shedding characteristics o... more Friday, August 7, 2009 - 9:50 AM Epidemiological implications of virus shedding characteristics of mallards infected with Low-Pathogenic Avian Influenza (LPAI) Viruses. Susan A. Shriner, Kaci K. VanDalen, Nicole L. Mooers, Heather J. Sullivan, and Alan B. Franklin. ...
Background/Question/Methods Avian influenza viruses are known to productively infect a number of ... more Background/Question/Methods Avian influenza viruses are known to productively infect a number of mammal species, several of which are commonly found on or near poultry and gamebird farms. While control of rodent species is often used to limit avian influenza virus transmission within and among agricultural operations, few studies have investigated the potential role of these species in outbreak dynamics. We used three approaches to evaluate whether small mammals pose a transmission risk during an avian influenza outbreak. First, we trapped and sampled synanthropic mammals on a gamebird farm in Idaho, USA that had recently experienced a low pathogenic avian influenza outbreak. Second, we trapped mammals on a virus-free farm in Colorado, USA in spring, summer, and fall to characterize the synanthropic mammal community. We used these data to develop population estimates for different species on the farm and on an adjacent field. Finally, we experimentally infected groups of naïve Norwa...
Point counts are a standard sampling procedure for many bird species, but lingering concerns stil... more Point counts are a standard sampling procedure for many bird species, but lingering concerns still exist about the quality of information produced from the method. It is well known that variation in observer ability and environmental conditions can influence the detection probability of birds in point counts, but many biologists have been reluctant to abandon point counts in favor of more intensive approaches to counting. However, over the past few years a variety of statistical and methodological developments have begun to pro- vide practical ways of overcoming some of the prob- lems with point counts. We describe some of these ap- proaches, and show how they can be integrated into standard point count protocols to greatly enhance the quality of the information. Several tools now exist for estimation of detection probability of birds during counts, including distance sampling, double observer methods, time-depletion (removal) methods, and hyb- rid methods that combine these approac...
The availability of a validated commercial assay is an asset for any wildlife investigation. Howe... more The availability of a validated commercial assay is an asset for any wildlife investigation. However, commercial products are often developed for use in livestock and are not optimized for wildlife. Consequently, it is incumbent upon researchers and managers to apply commercial products appropriately to optimize program outcomes. We tested more than 800 serum samples from mallards for antibodies to influenza A virus with the IDEXX AI MultiS-Screen Ab test to evaluate assay performance. Applying the test per manufacturer's recommendations resulted in good performance with 84% sensitivity and 100% specificity. However, performance was improved to 98% sensitivity and 98% specificity by increasing the recommended cut-off. Using this alternative threshold for identifying positive and negative samples would greatly improve sample classification, especially for field samples collected months after infection when antibody titers have waned from the initial primary immune response. Furth...
Following a 2008 outbreak of North American low-pathogenic H5N8 influenza A virus at an upland ga... more Following a 2008 outbreak of North American low-pathogenic H5N8 influenza A virus at an upland gamebird farm, we sero-sampled rock doves (pigeons, Columba livia) at the outbreak site and conducted experimental inoculations of wild-caught pigeons using the H5N8 virus and another low-pathogenic virus (H4N6). While 13Â % of pigeons at the outbreak site were seropositive, none were positive for exposure to H5, and one was positive for N8. Challenged pigeons exhibited low susceptibility and limited viral RNA excretion for both viruses tested, but at least one individual had RNA loads indicative of the potential for viral transmission to other birds.
Friday, August 7, 2009 - 9:50 AM Epidemiological implications of virus shedding characteristics o... more Friday, August 7, 2009 - 9:50 AM Epidemiological implications of virus shedding characteristics of mallards infected with Low-Pathogenic Avian Influenza (LPAI) Viruses. Susan A. Shriner, Kaci K. VanDalen, Nicole L. Mooers, Heather J. Sullivan, and Alan B. Franklin. ...
Background/Question/Methods Avian influenza viruses are known to productively infect a number of ... more Background/Question/Methods Avian influenza viruses are known to productively infect a number of mammal species, several of which are commonly found on or near poultry and gamebird farms. While control of rodent species is often used to limit avian influenza virus transmission within and among agricultural operations, few studies have investigated the potential role of these species in outbreak dynamics. We used three approaches to evaluate whether small mammals pose a transmission risk during an avian influenza outbreak. First, we trapped and sampled synanthropic mammals on a gamebird farm in Idaho, USA that had recently experienced a low pathogenic avian influenza outbreak. Second, we trapped mammals on a virus-free farm in Colorado, USA in spring, summer, and fall to characterize the synanthropic mammal community. We used these data to develop population estimates for different species on the farm and on an adjacent field. Finally, we experimentally infected groups of naïve Norwa...
Oral and external dosing methods replicating field exposure were developed using the double crest... more Oral and external dosing methods replicating field exposure were developed using the double crested cormorant (DCCO) to test the toxicity of artificially weathered Deepwater Horizon Mississippi Canyon 252 oil. The majority of previous oil dosing studies conducted on wild-caught birds used gavage methods to dose birds with oil and determine toxicity. However, rapid gut transit time of gavaged oil likely reduces oil absorption. In the present studies, dosing relied on injection of oil into live feeder fish for oral dosing of these piscivorous birds, or applying oil to body contour feathers resulting in transdermal oil exposure and oral exposure through preening. Both oral and external oil dosing studies identified oil-related toxicity endpoints associated with oxidative stress such as hemolytic anemia, liver and kidney damage, and immuno-modulation or compromise. External oil application allowed for controlled study of thermoregulatory stress as well. Infrared thermal images indicated significantly greater surface temperatures and heat loss in treated birds following external oil applications; however, measurements collected by coelomically implanted temperature transmitters showed that internal body temperatures were stable over the course of the study period. Birds exposed to oil externally consumed more fish than control birds, indicating metabolic compensation for thermal stress. Conversely, birds orally dosed with oil experienced hypothermia and consumed less fish compared to control birds.
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