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Wild Bird Populations (wild + bird_population)
Selected AbstractsAvian influenza surveillance in wild birds in the European Union in 2006INFLUENZA AND OTHER RESPIRATORY VIRUSES, Issue 1 2009Uta Hesterberg Abstract Background, Infections of wild birds with highly pathogenic avian influenza (AI) subtype H5N1 virus were reported for the first time in the European Union in 2006. Objectives, To capture epidemiological information on H5N1 HPAI in wild bird populations through large-scale surveillance and extensive data collection. Methods, Records were analysed at bird level to explore the epidemiology of AI with regard to species of wild birds involved, timing and location of infections as well as the applicability of different surveillance types for the detection of infections. Results, In total, 120,706 records of birds were sent to the Community Reference Laboratory for analysis. Incidents of H5N1 HPAI in wild birds were detected in 14 EU Member States during 2006. All of these incidents occurred between February and May, with the exception of two single cases during the summer months in Germany and Spain. Conclusions, For the detection of H5N1 HPAI virus, passive surveillance of dead or diseased birds appeared the most effective approach, whilst active surveillance offered better detection of low pathogenic avian influenza (LPAI) viruses. No carrier species for H5N1 HPAI virus could be identified and almost all birds infected with H5N1 HPAI virus were either dead or showed clinical signs. A very large number of Mallards (Anas platyrhynchos) were tested in 2006 and while a high proportion of LPAI infections were found in this species, H5N1 HPAI virus was rarely identified in these birds. Orders of species that appeared to be very clinically susceptible to H5N1 HPAI virus were swans, diving ducks, mergansers and grebes, supporting experimental evidence. Surveillance results indicate that H5N1 HPAI virus did not establish itself successfully in the EU wild bird population in 2006. [source] Interactive effects of environmental stress and inbreeding on reproductive traits in a wild bird populationJOURNAL OF ANIMAL ECOLOGY, Issue 6 2006A. B. MARR Summary 1Conservation biologists are concerned about the interactive effects of environmental stress and inbreeding because such interactions could affect the dynamics and extinction risk of small and isolated populations, but few studies have tested for these interactions in nature. 2We used data from the long-term population study of song sparrows Melospiza melodia on Mandarte Island to examine the joint effects of inbreeding and environmental stress on four fitness traits that are known to be affected by the inbreeding level of adult birds: hatching success, laying date, male mating success and fledgling survival. 3We found that inbreeding depression interacted with environmental stress to reduce hatching success in the nests of inbred females during periods of rain. 4For laying date, we found equivocal support for an interaction between parental inbreeding and environmental stress. In this case, however, inbred females experienced less inbreeding depression in more stressful, cooler years. 5For two other traits, we found no evidence that the strength of inbreeding depression varied with environmental stress. First, mated males fathered fewer nests per season if inbred or if the ratio of males to females in the population was high, but inbreeding depression did not depend on sex ratio. Second, fledglings survived poorly during rainy periods and if their father was inbred, but the effects of paternal inbreeding and rain did not interact. 6Thus, even for a single species, interactions between the inbreeding level and environmental stress may not occur in all traits affected by inbreeding depression, and interactions that do occur will not always act synergistically to further decrease fitness. [source] Parasitism and developmental plasticity in Alpine swift nestlingsJOURNAL OF ANIMAL ECOLOGY, Issue 4 2003Pierre Bize Summary 1Development plasticity is a common evolutionary and phenotypic response to poor growth condition, in particular in organisms with determinate growth such as most birds and mammals. Because various body structures can contribute differently to overall fitness, natural selection will adjust the degree of plasticity of each structure to its proportionate contribution to fitness at a given life stage. 2Two non-mutually exclusive mechanisms can account for plasticity in the growth of offspring to compensate for the effect of parasites. First, if parasite infestation levels fluctuate over the nestling period, parasitized young may show reduced growth until peak parasite infestation, and accelerated growth once the conditions improve (the accelerated growth hypothesis). Secondly, if the period of tissue maturation is not fixed in time, hosts may grow slower than parasite-free hosts but for a longer period of time (the delayed maturation hypothesis). 3To test whether hosts compensate for the effects of parasites on their development, the load of the blood-sucking louse-fly Crataerina melbae Rondani in the nests of Alpine swifts, Apus melba Linnaeus, was increased or decreased experimentally. Parasite prevalence was 100% in both treatments, but intensity (no. of parasites per nestling) was significantly lower for deparasitized nestlings. In both treatments, parasite intensity increased up to halfway through the rearing period (i.e. 30 days of age) and decreased afterwards. 4In line with the accelerated growth hypothesis, wings of parasitized nestlings grew at a lower rate than those of deparasitized ones before the peak of parasite infestation, but at a greater rate after the peak. Louse-flies had no significant effect on the growth of body mass. In agreement with the delayed-maturation hypothesis, wings of parasitized nestlings grew for 3 additional days and were of similar size at fledging as in deparasitized birds. 5In summary, the present study shows in a wild bird population that nestling hosts can compensate for the effect of parasitism on their phenotype. It emphasizes the need to take the dynamics of parasite populations into account in studies of host,parasite relationships, and to investigate the effect of parasites on host development over the entire growing period rather than only at fledging, as employed traditionally. [source] Evidence that plumage bacteria influence feather coloration and body condition of eastern bluebirds Sialia sialisJOURNAL OF AVIAN BIOLOGY, Issue 4 2009Alex R. Gunderson Parasites influence the expression of secondary sexual traits and the health of infected individuals. We set out to test the influence of reputed exogenous parasites, plumage bacteria, including feather-degrading bacteria (FDB), on secondary sexual characteristics and body condition of wild adult eastern bluebirds Sialia sialis. Previous work has shown that FDB alter the coloration of structurally-colored bluebird feathers in vitro (Shawkey et al. 2007). In a correlational study of how bacteria affect birds in the wild, we found that female plumage got duller with increasing FDB intensity. Males tended to get brighter with increasing FDB intensity, but the relationship was not significant. We also found significant associations between plumage bacteria intensity and body condition, but, again, with gender-based differences. Female body condition was negatively associated with plumage bacteria intensity, while male body condition was positively associated with plumage bacteria intensity. Interestingly, plumage bacteria intensity of males and females in nesting pairs was significantly positively correlated. We also report the highest prevalence of FDB measured in a wild bird population, with FDB detected on 67/68 (99%) of individuals. Further work is needed to fully understand the relationships between plumage bacteria and birds, but our data indicate that plumage bacteria may have sex-dependent effects on multiple phenotypic traits. [source] Physiological response to stress in fledgling Lesser Kestrels Falco naumanni: the role of physical condition, sex and individual genetic diversityIBIS, Issue 3 2009JOAQUÍN ORTEGO Exposure to chronic stress early on during development has important deleterious consequences later in life, reducing important components of individual fitness such as survival and future reproduction. In this study, we evaluate the factors associated with physiological response to stress in fledgling Lesser Kestrels Falco naumanni, paying particular attention to the potential role of individual genetic diversity. For this purpose, we used heterophil/lymphocyte ratios (H/L ratio) as a haematological stress indicator and typed the analysed individuals at 11 highly polymorphic microsatellite loci, which allowed us to estimate their genetic diversity. We found that the H/L ratio decreases with fledgling physical condition, suggesting that this parameter is a good indicator of nutritionally based physiological stress. Physiological response to stress was higher in males than in females and this effect was independent of physical condition, suggesting that the observed pattern is due to inherent sexual differences in the factors influencing H/L ratios. Finally, the H/L ratio was positively associated with the genetic diversity of offspring. Previous experimental studies have found that individuals with higher genetic diversity show increased levels of circulating glucocorticoids, which in turn are directly responsible for increasing H/L ratios. On this basis, we suggest that a positive effect of genetic diversity on corticosterone levels may explain the observed association between H/L ratios and individual heterozygosity. Overall, this study highlights the utility of leucocyte profiles to study stress in wild bird populations and poses an interesting question about the effects of individual genetic diversity on haematological response to stress. [source] Adult sex ratios in wild bird populationsIBIS, Issue 4 2007PAUL F. DONALD Offspring sex ratios in wild bird populations, and the extent to which they vary from the equality expected by random genotypic sex determination, have received much recent attention. Adult sex ratios (ASRs) in wild birds, on the other hand, remain very poorly described, and many of the questions about them posed by Ernst Mayr in 1939 remain unanswered. This review assesses population-level sex ratio patterns in wild bird populations, with an emphasis on the ASR. A quantitative assessment of over 200 published estimates of ASR, covering species from a wide range of taxa, regions and habitats, supported Mayr's assertion that skewed ASRs are common in wild bird populations. On average, males outnumbered females by around 33%, and 65% of published estimates differed significantly from equality. In contrast, population-level estimates of offspring sex ratio in birds did not generally differ from equality, and mean ASR across a range of wild mammal species was strongly female-skewed. ASR distortion in birds was significantly more severe in populations of globally threatened species than in non-threatened species, a previously undescribed pattern that has profound implications for their monitoring and conservation. Higher female mortality, rather than skewed offspring sex ratio, is the main driver of male-skewed ASRs in birds, and the causes and implications of this are reviewed. While estimates of ASR in wild bird populations may be subject to a number of biases, which are discussed, there is currently no quantitative evidence that an ASR of one male to one female represents the norm in birds. A better understanding and reporting of ASRs in wild bird populations could contribute greatly to our understanding of population processes and could contribute much to theoretical and applied research and conservation. [source] Avian influenza surveillance in wild birds in the European Union in 2006INFLUENZA AND OTHER RESPIRATORY VIRUSES, Issue 1 2009Uta Hesterberg Abstract Background, Infections of wild birds with highly pathogenic avian influenza (AI) subtype H5N1 virus were reported for the first time in the European Union in 2006. Objectives, To capture epidemiological information on H5N1 HPAI in wild bird populations through large-scale surveillance and extensive data collection. Methods, Records were analysed at bird level to explore the epidemiology of AI with regard to species of wild birds involved, timing and location of infections as well as the applicability of different surveillance types for the detection of infections. Results, In total, 120,706 records of birds were sent to the Community Reference Laboratory for analysis. Incidents of H5N1 HPAI in wild birds were detected in 14 EU Member States during 2006. All of these incidents occurred between February and May, with the exception of two single cases during the summer months in Germany and Spain. Conclusions, For the detection of H5N1 HPAI virus, passive surveillance of dead or diseased birds appeared the most effective approach, whilst active surveillance offered better detection of low pathogenic avian influenza (LPAI) viruses. No carrier species for H5N1 HPAI virus could be identified and almost all birds infected with H5N1 HPAI virus were either dead or showed clinical signs. A very large number of Mallards (Anas platyrhynchos) were tested in 2006 and while a high proportion of LPAI infections were found in this species, H5N1 HPAI virus was rarely identified in these birds. Orders of species that appeared to be very clinically susceptible to H5N1 HPAI virus were swans, diving ducks, mergansers and grebes, supporting experimental evidence. Surveillance results indicate that H5N1 HPAI virus did not establish itself successfully in the EU wild bird population in 2006. [source] An overlooked DNA source for non-invasive genetic analysis in birdsJOURNAL OF AVIAN BIOLOGY, Issue 1 2005Márton B. Horváth Non-invasive sampling is a useful tool for genetic analyses of endangered and/or elusive species, but it is often inapplicable due to the low quality and quantity of the DNA obtained. In this study we show that the blood clot located in the superior umbilicus of the feather shaft is a better source of DNA than the previously used tip samples from moulted feathers. We found that feather clots from museum specimens provided results nearly as good as footpad and better than those from the more commonly used museum skin snips. Feather clots proved to be a good source of DNA for genetic analysis that will significantly facilitate genetic monitoring of wild bird populations. [source] Early maternal, genetic and environmental components of antioxidant protection, morphology and immunity of yellow-legged gull (Larus michahellis) chicksJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2006D. RUBOLINI Abstract Maternal effects mediated by egg quality are important sources of offspring phenotypic variation and can influence the course of evolutionary processes. Mothers allocate to the eggs diverse antioxidants that protect the embryo from oxidative stress. In the yellow-legged gull (Larus michahellis), yolk antioxidant capacity varied markedly among clutches and declined considerably with egg laying date. Analysis of bioptic yolk samples from clutches that were subsequently partially cross-fostered revealed a positive effect of yolk antioxidant capacity on embryonic development and chick growth, but not on immunity and begging behaviour, while controlling for parentage and common environment effects. Chick plasma antioxidant capacity varied according to rearing environment, after statistically partitioning out maternal influences mediated by egg quality. Thus, the results of this study indicate that egg antioxidants are important mediators of maternal effects also in wild bird populations, especially during the critical early post-hatching phase. [source] | ||||||||||