The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
David E Swayne - One of the best experts on this subject based on the ideXlab platform.
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homo and heterosubtypic low pathogenic avian influenza exposure on h5n1 highly pathogenic avian influenza virus infection in wood ducks Aix Sponsa
PLOS ONE, 2011Co-Authors: Taiana P Costa, David E Stallknecht, Elizabeth W Howerth, Justin Brown, David E SwayneAbstract:Wild birds in the Orders Anseriformes and Charadriiformes are the natural reservoirs for avian influenza (AI) viruses. Although they are often infected with multiple AI viruses, the significance and extent of acquired immunity in these populations is not understood. Pre-existing immunity to AI virus has been shown to modulate the outcome of a highly pathogenic avian influenza (HPAI) virus infection in multiple domestic avian species, but few studies have addressed this effect in wild birds. In this study, the effect of pre-exposure to homosubtypic (homologous hemagglutinin) and heterosubtypic (heterologous hemagglutinin) low pathogenic avian influenza (LPAI) viruses on the outcome of a H5N1 HPAI virus infection in wood ducks (Aix Sponsa) was evaluated. Pre-exposure of wood ducks to different LPAI viruses did not prevent infection with H5N1 HPAI virus, but did increase survival associated with H5N1 HPAI virus infection. The magnitude of this effect on the outcome of the H5N1 HPAI virus infection varied between different LPAI viruses, and was associated both with efficiency of LPAI viral replication in wood ducks and the development of a detectable humoral immune response. These observations suggest that in naturally occurring outbreaks of H5N1 HPAI, birds with pre-existing immunity to homologous hemagglutinin or neuraminidase subtypes of AI virus may either survive H5N1 HPAI virus infection or live longer than naive birds and, consequently, could pose a greater risk for contributing to viral transmission and dissemination. The mechanisms responsible for this protection and/or the duration of this immunity remain unknown. The results of this study are important for surveillance efforts and help clarify epidemiological data from outbreaks of H5N1 HPAI virus in wild bird populations.
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filter feeding bivalves can remove avian influenza viruses from water and reduce infectivity
Proceedings of The Royal Society B: Biological Sciences, 2009Co-Authors: Christina L Faust, David E Stallknecht, David E Swayne, Justin C BrownAbstract:Avian influenza (AI) viruses are believed to be transmitted within wild aquatic bird populations through an indirect faecal‐oral route involving contaminated water. This study examined the influence of filterfeeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water. Clams were placed into individual flasks with distilled water inoculated 1:100 with a low pathogenic (LP) AI virus (A/Mallard/MN/190/99 (H3N8)). Viral titres in water with clams were significantly lower at 24 and 48 h post-inoculation compared to LPAI-infected water without clams. To determine whether clams affected the infectivity of AI viruses, 18 wood ducks (Aix Sponsa) were divided into test groups and inoculated with a variety of treatments of clam supernatants, whole clams and water exposed to a high pathogenic (HP) AI (A/whooper swan/Mongolia/244/05 (H5N1)). None of the wood ducks inoculated with HPAI-infected water that was filtered by clams or that was inoculated with or fed tissue from these clams exhibited morbidity or mortality. All wood ducks exposed to either HPAI-infected water without clams or the original viral inoculum died. These results indicate that filter-feeding bivalves can remove and reduce the infectivity of AI viruses in water and demonstrate the need to examine biotic environmental factors that can influence AI virus transmission.
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susceptibility of north american ducks and gulls to h5n1 highly pathogenic avian influenza viruses
Emerging Infectious Diseases, 2006Co-Authors: Justin C Brown, David E Stallknecht, Joan R Beck, David L Suarez, David E SwayneAbstract:Since 2002, H5N1 highly pathogenic avian influenza (HPAI) viruses have been associated with deaths in numerous wild avian species throughout Eurasia. We assessed the clinical response and extent and duration of viral shedding in 5 species of North American ducks and laughing gulls (Larus atricilla) after intranasal challenge with 2 Asian H5N1 HPAI viruses. Birds were challenged at ≈10 to 16 weeks of age, consistent with temporal peaks in virus prevalence and fall migration. All species were infected, but only wood ducks (Aix Sponsa) and laughing gulls exhibited illness or died. Viral titers were higher in oropharyngeal swabs than in cloacal swabs. Duration of viral shedding (1–10 days) increased with severity of clinical disease. Both the hemagglutination-inhibition (HI) and agar gel precipitin (AGP) tests were able to detect postinoculation antibodies in surviving wood ducks and laughing gulls; the HI test was more sensitive than the AGP in the remaining 4 species
David E Stallknecht - One of the best experts on this subject based on the ideXlab platform.
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wood ducks Aix Sponsa as potential reservoirs for avian influenza and avian paramyxoviruses
Avian Pathology, 2015Co-Authors: Whitney M Kistler, David E Stallknecht, Samantha E J Gibbs, Michael J YabsleyAbstract:Influenza A viruses (IAVs) and avian paramyxoviruses (APMVs) are important pathogens of poultry worldwide, and both commonly occur in wild waterfowl, especially ducks in the family Anatidae. Although wood ducks (Aix Sponsa) are members of the Anatidae, their behaviour differs from most other species in this family, which could affect the transmission of IAVs and APMVs. We collected cloacal and oropharyngeal swab and blood samples from more than 700 wood ducks across nine states in the eastern United States of America. No IAVs were isolated, and based on blocking enzyme-linked immunoassay ELISA results, antibodies to IAVs were only detected in 0.2% of samples. In contrast, 23 (3%) APMVs were isolated (22 Newcastle disease virus and 1 APMV-6), and antibodies to multiple serotypes of APMVs were detected in more than 60% of the samples. After-hatch-year birds were more likely to be antibody positive for APMV-4 and APMV-6 compared to hatch-year birds. Female birds were more likely to be antibody positive for A...
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variation in viral shedding patterns between different wild bird species infected experimentally with low pathogenicity avian influenza viruses that originated from wild birds
Avian Pathology, 2011Co-Authors: T P Costa, J. D. Brown, Elizabeth W Howerth, David E StallknechtAbstract:The prevalence of infection with avian influenza (AI) virus varies significantly between taxonomic Orders and even between species within the same Order. The current understanding of AI infection and virus shedding parameters in wild birds is limited and largely based on trials conducted in mallards (Anas platyrhynchos). The objective of the present study was to provide experimental data to examine species-related differences in susceptibility and viral shedding associated with wild bird-origin low-pathogenicity avian influenza (LPAI) viruses in multiple duck species and gulls. Thus mallards, redheads (Aythya americana), wood ducks (Aix Sponsa), and laughing gulls (Leucophaeus atricilla) were inoculated experimentally with three wild mallard-origin LPAI viruses representing multiple subtypes. Variation in susceptibility and patterns of viral shedding associated with LPAI virus infection was evident between the duck and gull species. Consistent with the literature, mallards excreted virus predominantly via...
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homo and heterosubtypic low pathogenic avian influenza exposure on h5n1 highly pathogenic avian influenza virus infection in wood ducks Aix Sponsa
PLOS ONE, 2011Co-Authors: Taiana P Costa, David E Stallknecht, Elizabeth W Howerth, Justin Brown, David E SwayneAbstract:Wild birds in the Orders Anseriformes and Charadriiformes are the natural reservoirs for avian influenza (AI) viruses. Although they are often infected with multiple AI viruses, the significance and extent of acquired immunity in these populations is not understood. Pre-existing immunity to AI virus has been shown to modulate the outcome of a highly pathogenic avian influenza (HPAI) virus infection in multiple domestic avian species, but few studies have addressed this effect in wild birds. In this study, the effect of pre-exposure to homosubtypic (homologous hemagglutinin) and heterosubtypic (heterologous hemagglutinin) low pathogenic avian influenza (LPAI) viruses on the outcome of a H5N1 HPAI virus infection in wood ducks (Aix Sponsa) was evaluated. Pre-exposure of wood ducks to different LPAI viruses did not prevent infection with H5N1 HPAI virus, but did increase survival associated with H5N1 HPAI virus infection. The magnitude of this effect on the outcome of the H5N1 HPAI virus infection varied between different LPAI viruses, and was associated both with efficiency of LPAI viral replication in wood ducks and the development of a detectable humoral immune response. These observations suggest that in naturally occurring outbreaks of H5N1 HPAI, birds with pre-existing immunity to homologous hemagglutinin or neuraminidase subtypes of AI virus may either survive H5N1 HPAI virus infection or live longer than naive birds and, consequently, could pose a greater risk for contributing to viral transmission and dissemination. The mechanisms responsible for this protection and/or the duration of this immunity remain unknown. The results of this study are important for surveillance efforts and help clarify epidemiological data from outbreaks of H5N1 HPAI virus in wild bird populations.
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filter feeding bivalves can remove avian influenza viruses from water and reduce infectivity
Proceedings of The Royal Society B: Biological Sciences, 2009Co-Authors: Christina L Faust, David E Stallknecht, David E Swayne, Justin C BrownAbstract:Avian influenza (AI) viruses are believed to be transmitted within wild aquatic bird populations through an indirect faecal‐oral route involving contaminated water. This study examined the influence of filterfeeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water. Clams were placed into individual flasks with distilled water inoculated 1:100 with a low pathogenic (LP) AI virus (A/Mallard/MN/190/99 (H3N8)). Viral titres in water with clams were significantly lower at 24 and 48 h post-inoculation compared to LPAI-infected water without clams. To determine whether clams affected the infectivity of AI viruses, 18 wood ducks (Aix Sponsa) were divided into test groups and inoculated with a variety of treatments of clam supernatants, whole clams and water exposed to a high pathogenic (HP) AI (A/whooper swan/Mongolia/244/05 (H5N1)). None of the wood ducks inoculated with HPAI-infected water that was filtered by clams or that was inoculated with or fed tissue from these clams exhibited morbidity or mortality. All wood ducks exposed to either HPAI-infected water without clams or the original viral inoculum died. These results indicate that filter-feeding bivalves can remove and reduce the infectivity of AI viruses in water and demonstrate the need to examine biotic environmental factors that can influence AI virus transmission.
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susceptibility of north american ducks and gulls to h5n1 highly pathogenic avian influenza viruses
Emerging Infectious Diseases, 2006Co-Authors: Justin C Brown, David E Stallknecht, Joan R Beck, David L Suarez, David E SwayneAbstract:Since 2002, H5N1 highly pathogenic avian influenza (HPAI) viruses have been associated with deaths in numerous wild avian species throughout Eurasia. We assessed the clinical response and extent and duration of viral shedding in 5 species of North American ducks and laughing gulls (Larus atricilla) after intranasal challenge with 2 Asian H5N1 HPAI viruses. Birds were challenged at ≈10 to 16 weeks of age, consistent with temporal peaks in virus prevalence and fall migration. All species were infected, but only wood ducks (Aix Sponsa) and laughing gulls exhibited illness or died. Viral titers were higher in oropharyngeal swabs than in cloacal swabs. Duration of viral shedding (1–10 days) increased with severity of clinical disease. Both the hemagglutination-inhibition (HI) and agar gel precipitin (AGP) tests were able to detect postinoculation antibodies in surviving wood ducks and laughing gulls; the HI test was more sensitive than the AGP in the remaining 4 species
Justin C Brown - One of the best experts on this subject based on the ideXlab platform.
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filter feeding bivalves can remove avian influenza viruses from water and reduce infectivity
Proceedings of The Royal Society B: Biological Sciences, 2009Co-Authors: Christina L Faust, David E Stallknecht, David E Swayne, Justin C BrownAbstract:Avian influenza (AI) viruses are believed to be transmitted within wild aquatic bird populations through an indirect faecal‐oral route involving contaminated water. This study examined the influence of filterfeeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water. Clams were placed into individual flasks with distilled water inoculated 1:100 with a low pathogenic (LP) AI virus (A/Mallard/MN/190/99 (H3N8)). Viral titres in water with clams were significantly lower at 24 and 48 h post-inoculation compared to LPAI-infected water without clams. To determine whether clams affected the infectivity of AI viruses, 18 wood ducks (Aix Sponsa) were divided into test groups and inoculated with a variety of treatments of clam supernatants, whole clams and water exposed to a high pathogenic (HP) AI (A/whooper swan/Mongolia/244/05 (H5N1)). None of the wood ducks inoculated with HPAI-infected water that was filtered by clams or that was inoculated with or fed tissue from these clams exhibited morbidity or mortality. All wood ducks exposed to either HPAI-infected water without clams or the original viral inoculum died. These results indicate that filter-feeding bivalves can remove and reduce the infectivity of AI viruses in water and demonstrate the need to examine biotic environmental factors that can influence AI virus transmission.
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susceptibility of north american ducks and gulls to h5n1 highly pathogenic avian influenza viruses
Emerging Infectious Diseases, 2006Co-Authors: Justin C Brown, David E Stallknecht, Joan R Beck, David L Suarez, David E SwayneAbstract:Since 2002, H5N1 highly pathogenic avian influenza (HPAI) viruses have been associated with deaths in numerous wild avian species throughout Eurasia. We assessed the clinical response and extent and duration of viral shedding in 5 species of North American ducks and laughing gulls (Larus atricilla) after intranasal challenge with 2 Asian H5N1 HPAI viruses. Birds were challenged at ≈10 to 16 weeks of age, consistent with temporal peaks in virus prevalence and fall migration. All species were infected, but only wood ducks (Aix Sponsa) and laughing gulls exhibited illness or died. Viral titers were higher in oropharyngeal swabs than in cloacal swabs. Duration of viral shedding (1–10 days) increased with severity of clinical disease. Both the hemagglutination-inhibition (HI) and agar gel precipitin (AGP) tests were able to detect postinoculation antibodies in surviving wood ducks and laughing gulls; the HI test was more sensitive than the AGP in the remaining 4 species
Gary R. Hepp - One of the best experts on this subject based on the ideXlab platform.
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Laying sequence interacts with incubation temperature to influence rate of embryonic development and hatching synchrony in a precocial bird
2018Co-Authors: Gary R. Hepp, Robert A KennamerAbstract:Incubation starts during egg laying for many bird species and causes developmental asynchrony within clutches. Faster development of late-laid eggs can help reduce developmental differences and synchronize hatching, which is important for precocial species whose young must leave the nest soon after hatching. In this study, we examined the effect of egg laying sequence on length of the incubation period in Wood Ducks (Aix Sponsa). Because incubation temperature strongly influences embryonic development rates, we tested the interactive effects of laying sequence and incubation temperature on the ability of late-laid eggs to accelerate development and synchronize hatching. We also examined the potential cost of faster development on duckling body condition. Fresh eggs were collected and incubated at three biologically relevant temperatures (Low: 34.9°C, Medium: 35.8°C, and High: 37.6°C), and egg laying sequences from 1 to 12 were used. Length of the incubation period declined linearly as laying sequence advanced, but the relationship was strongest at medium temperatures followed by low temperatures and high temperatures. There was little support for including fresh egg mass in models of incubation period. Estimated differences in length of the incubation period between eggs 1 and 12 were 2.7 d, 1.2 d, and 0.7 d at medium, low and high temperatures, respectively. Only at intermediate incubation temperatures did development rates of late-laid eggs increase sufficiently to completely compensate for natural levels of developmental asynchrony that have been reported in Wood Duck clutches at the start of full incubation. Body condition of ducklings was strongly affected by fresh egg mass and incubation temperature but declined only slightly as laying sequence progressed. Our findings show that laying sequence and incubation temperature play important roles in helping to shape embryo development and hatching synchrony in a precocial bird.
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plasticity of incubation behaviors helps wood ducks Aix Sponsa maintain an optimal thermal environment for developing embryos
The Auk, 2014Co-Authors: Maureen E Mcclintock, Gary R. Hepp, Robert A KennamerAbstract:ABSTRACT Optimal development of avian embryos occurs within a narrow range of incubation temperatures. Most parents that physically incubate their eggs through direct contact are challenged to balance their time on the nest with taking foraging recesses to satisfy their energetic requirements. To explore the costs and investment strategies of incubating female Wood Ducks (Aix Sponsa), we manipulated the microclimate of nests by reducing down insulation from the typical 4.0 g to 0.5 g. Cooling rates of clutches during morning recesses increased when down insulation was reduced, especially at low ambient temperatures. Females with reduced down responded to increased cooling rates by shortening morning recesses and increasing daily incubation constancy, and these behavioral changes were independent of their body mass at the start of incubation. Females in both treatment groups responded similarly to changes in ambient temperature and spent less time incubating as ambient temperatures increased. Clutch temper...
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thermal challenge severity differentially influences wound healing in wood duck Aix Sponsa ducklings
Journal of Experimental Zoology, 2013Co-Authors: Amanda W Carter, Gary R. Hepp, Sarah E Durant, William A HopkinsAbstract:Environmental conditions during early development can profoundly influence an individual's phenotype. Development requires simultaneous maturation and orchestration of multiple physiological systems creating the potential for interaction among key systems and requiring substantial resources. We investigated the influence of thermoregulation on immunocompetence in Wood Duck ducklings (Aix Sponsa). At both 1 and 2 days post hatch (dph) we evaluated ducklings' abilities to thermoregulate during a thermal challenge at one of four temperatures (36 [thermoneutral controls], 20, 10, or 5°C). At 3 dph, ducklings received a superficial wound, which was monitored until full recovery to quantify wound healing ability, an ecologically relevant, integrative measure of immune function. We demonstrated that duckling body temperature decreased with increasing thermal challenge severity, thermoregulatory ability increased with age, and thermoregulation had temperature-dependent effects on the immune system. Specifically, a more severe thermal challenge (5°C) resulted in decreased immune performance when compared to a mild challenge (20°C). We conclude that early thermoregulatory experiences are influential in shaping immune responses early in development. Furthermore, our results emphasize that future studies of environmental stressors need to consider multiple physiological endpoints since interaction among systems can result in competing physiological demands. J. Exp. Zool. 319A: 422–429, 2013. © 2013 Wiley Periodicals, Inc.
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effects of nest reuse and onset of incubation on microbial growth and viability of wood duck eggs
The Condor, 2012Co-Authors: Johnathan G Walls, Gary R. Hepp, Lori G EckhardtAbstract:Abstract. In many birds, egg viability declines the longer that eggs remain unincubated (i.e., incubation delay), possibly because of increased levels of microbial infection. Reuse of nests is common in cavity-nesting species and may also increase exposure of eggs to microbes. Starting incubation before the clutch is complete may help protect early-laid eggs from microbial infection. In this study, we tested the effects of nest cleaning, length of incubation delay, and onset of night incubation on growth of microbes on Wood Duck (Aix Sponsa) eggshells and examined the effect of microbial infection on hatching success. We used nest boxes that had been cleaned or not cleaned of previous nesting materials and sampled microbes on eggshells during early and mid egg laying and after the start of night incubation. We detected levels of eggshell microbes (101 colony forming units [CFU] egg-1) lower than at more tropical locations (103–4 CFU egg-1). Levels of heterotrophic bacteria were 2.2 times greater in unclea...
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warm is better incubation temperature influences apparent survival and recruitment of wood ducks Aix Sponsa
PLOS ONE, 2012Co-Authors: Gary R. Hepp, Robert A KennamerAbstract:Avian parents that physically incubate their eggs must balance demands of self-maintenance with providing the proper thermal environment for egg development. Low incubation temperatures can lengthen the incubation period and produce changes in neonate phenotype that may influence subsequent survival and reproduction. We artificially incubated wood duck (Aix Sponsa) eggs at three temperature regimes (low, 35.0; mid, 35.9; and high, 37.3°C) that are within the range of temperatures of naturally-incubated nests. We tested the effect of incubation temperature on duckling body composition, fledging success, the probability that females were recruited to the breeding population, and their subsequent reproductive success. Incubation period was inversely related to incubation temperature, and body mass and lipid mass for newly-hatched ducklings incubated at the lowest temperature were lower than for ducklings produced at higher temperatures. In 2008, ducklings (n = 412) were individually marked and broods (n = 38) containing ducklings from each temperature treatment were placed with wild foster mothers within 24 hrs of hatching. Ducklings incubated at the lowest temperature were less likely to fledge from nest sites than ducklings incubated at the higher temperatures. We recaptured female ducklings as adults when they were either prospecting for nest sites (n = 171; 2009–2011) or nesting (n = 527; 2009–2012). Female ducklings incubated at the lowest temperature were less likely to survive and be recruited to the breeding population than females incubated at higher temperatures. Reproductive success of surviving females also was greater for females that had been incubated at warmer temperatures. To our knowledge, this is the first avian study to link developmental conditions experienced by neonates during incubation with their survival and recruitment to the breeding population, and subsequent reproductive success. These results advance our understanding of incubation as an important reproductive cost in birds and support the potential significance of incubation in influencing the evolution of avian life histories.
Robert A Kennamer - One of the best experts on this subject based on the ideXlab platform.
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Laying sequence interacts with incubation temperature to influence rate of embryonic development and hatching synchrony in a precocial bird
2018Co-Authors: Gary R. Hepp, Robert A KennamerAbstract:Incubation starts during egg laying for many bird species and causes developmental asynchrony within clutches. Faster development of late-laid eggs can help reduce developmental differences and synchronize hatching, which is important for precocial species whose young must leave the nest soon after hatching. In this study, we examined the effect of egg laying sequence on length of the incubation period in Wood Ducks (Aix Sponsa). Because incubation temperature strongly influences embryonic development rates, we tested the interactive effects of laying sequence and incubation temperature on the ability of late-laid eggs to accelerate development and synchronize hatching. We also examined the potential cost of faster development on duckling body condition. Fresh eggs were collected and incubated at three biologically relevant temperatures (Low: 34.9°C, Medium: 35.8°C, and High: 37.6°C), and egg laying sequences from 1 to 12 were used. Length of the incubation period declined linearly as laying sequence advanced, but the relationship was strongest at medium temperatures followed by low temperatures and high temperatures. There was little support for including fresh egg mass in models of incubation period. Estimated differences in length of the incubation period between eggs 1 and 12 were 2.7 d, 1.2 d, and 0.7 d at medium, low and high temperatures, respectively. Only at intermediate incubation temperatures did development rates of late-laid eggs increase sufficiently to completely compensate for natural levels of developmental asynchrony that have been reported in Wood Duck clutches at the start of full incubation. Body condition of ducklings was strongly affected by fresh egg mass and incubation temperature but declined only slightly as laying sequence progressed. Our findings show that laying sequence and incubation temperature play important roles in helping to shape embryo development and hatching synchrony in a precocial bird.
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relating climatological patterns to wetland conditions and wood duck production in the southeastern atlantic coastal plain
Wildlife Society Bulletin, 2016Co-Authors: Robert A KennamerAbstract:Efforts to index annual population size and recruitment of the wood duck (Aix Sponsa) on a geographic scale sufficiently large to be useful in managing this species have met with mixed results. A general relationship between climatic factors and wood duck produc- tion has been the most economical and promising approach, particularly in the South- east, though further refinement or understanding of factors mediating the relationship has been lacking. Development of climate-based models that predict wetland hydrologic conditions during the wood duck breeding season can be a useful step to index recruit- ment and may provide useful insights into population dynamics. In this study, I illustrate the concept's potential by developing a robust deterministic model of wetland water con- ditions on the 78,000-ha Savannah River Site (SRS) in west-central South Carolina over a 13-year period (1984-1996). During 6 years (1982-1987) when more than 90% of all hatched ducklings were marked before leaving nest boxes on the SRS, production of female ducklings was related positively to estimated female recruitment into the popula- tion the following year (combined breeding and nonbreeding yearling population seg- ments; rs=0.90, P=0.015), indicating that duckling production was a reasonable proxy for recruitment. The return of females initially marked as ducklings suggested that deferred yearling breeding was highest in dry years that were preceded by wetter years, thereby contributing to lower productivity in such years. Annual wetland condition indices were related to 15 years of duckling production from SRS nest boxes. Productiv- ity of wood ducks was positively associated with wetland hydrologic conditions. In wet years, an average of 9.8?0.7 (SE) ducklings was produced by each female in the breed- ing population, but only 8.6?0.5 (SE) ducklings/female were produced in dry years. Greater productivity in wet years was attributed in part to longer breeding seasons, which allowed more females in the population to produce second broods, and to reduced pre- dation rates. Additional insights gained through application of the method are discussed.
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plasticity of incubation behaviors helps wood ducks Aix Sponsa maintain an optimal thermal environment for developing embryos
The Auk, 2014Co-Authors: Maureen E Mcclintock, Gary R. Hepp, Robert A KennamerAbstract:ABSTRACT Optimal development of avian embryos occurs within a narrow range of incubation temperatures. Most parents that physically incubate their eggs through direct contact are challenged to balance their time on the nest with taking foraging recesses to satisfy their energetic requirements. To explore the costs and investment strategies of incubating female Wood Ducks (Aix Sponsa), we manipulated the microclimate of nests by reducing down insulation from the typical 4.0 g to 0.5 g. Cooling rates of clutches during morning recesses increased when down insulation was reduced, especially at low ambient temperatures. Females with reduced down responded to increased cooling rates by shortening morning recesses and increasing daily incubation constancy, and these behavioral changes were independent of their body mass at the start of incubation. Females in both treatment groups responded similarly to changes in ambient temperature and spent less time incubating as ambient temperatures increased. Clutch temper...
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warm is better incubation temperature influences apparent survival and recruitment of wood ducks Aix Sponsa
PLOS ONE, 2012Co-Authors: Gary R. Hepp, Robert A KennamerAbstract:Avian parents that physically incubate their eggs must balance demands of self-maintenance with providing the proper thermal environment for egg development. Low incubation temperatures can lengthen the incubation period and produce changes in neonate phenotype that may influence subsequent survival and reproduction. We artificially incubated wood duck (Aix Sponsa) eggs at three temperature regimes (low, 35.0; mid, 35.9; and high, 37.3°C) that are within the range of temperatures of naturally-incubated nests. We tested the effect of incubation temperature on duckling body composition, fledging success, the probability that females were recruited to the breeding population, and their subsequent reproductive success. Incubation period was inversely related to incubation temperature, and body mass and lipid mass for newly-hatched ducklings incubated at the lowest temperature were lower than for ducklings produced at higher temperatures. In 2008, ducklings (n = 412) were individually marked and broods (n = 38) containing ducklings from each temperature treatment were placed with wild foster mothers within 24 hrs of hatching. Ducklings incubated at the lowest temperature were less likely to fledge from nest sites than ducklings incubated at the higher temperatures. We recaptured female ducklings as adults when they were either prospecting for nest sites (n = 171; 2009–2011) or nesting (n = 527; 2009–2012). Female ducklings incubated at the lowest temperature were less likely to survive and be recruited to the breeding population than females incubated at higher temperatures. Reproductive success of surviving females also was greater for females that had been incubated at warmer temperatures. To our knowledge, this is the first avian study to link developmental conditions experienced by neonates during incubation with their survival and recruitment to the breeding population, and subsequent reproductive success. These results advance our understanding of incubation as an important reproductive cost in birds and support the potential significance of incubation in influencing the evolution of avian life histories.
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date of nest initiation mediates incubation costs of wood ducks Aix Sponsa
The Auk, 2011Co-Authors: Gary R. Hepp, Robert A KennamerAbstract:ABSTRACT. Incubation has a significant reproductive cost in birds that can limit both current and future reproductive success. We manipulated the incubation period of Wood Ducks (Aix Sponsa) to examine how female body mass, incubation behavior, and nest temperature responded to changes in incubation costs. We found no relationships between the length of the incubation period and either the percent loss of body mass or the body mass at the end of incubation. However, females that initiated nests early in the season lost more body mass than females that nested later. The number of daily recesses increased slightly with longer incubation periods, but incubation constancy over the full incubation period and during the last week of incubation was not affected by incubation-period length. Variation in incubation constancy was explained best by nest initiation date. Incubation constancy was greatest for early-nesting females and declined for females that nested later. There also was a weak positive relationship ...
