Turdus merula

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Norbert Nowotny - One of the best experts on this subject based on the ideXlab platform.

Ben J. Hatchwell - One of the best experts on this subject based on the ideXlab platform.

  • characterization of 38 microsatellite loci in the european blackbird Turdus merula turdidae aves
    Molecular Ecology Resources, 2009
    Co-Authors: Michelle Simeoni, Lisette Coiffait, Kirsten Wolff, Kevin J. Gaston, Deborah A Dawson, L K Gentle, Karl L. Evans, Ben J. Hatchwell
    Abstract:

    : We characterized 38 microsatellite loci in the European blackbird, Turdus merula. Thirty-seven loci were identified by testing 242 loci that had been originally isolated in other avian species. One additional locus was isolated from a European blackbird genomic library. All loci were characterized in 20-29 blackbirds from a population in the Czech Republic and displayed between two and 16 alleles, with observed heterozygosity ranging from 0.04 to 1.00. Thirty-seven loci could be assigned a chromosome location in the zebra finch (Taeniopygia guttata) genome based on sequence homology.

  • effects of urbanisation on disease prevalence and age structure in blackbird Turdus merula populations
    Oikos, 2009
    Co-Authors: Karl L. Evans, Michelle Simeoni, Kevin J. Gaston, Stuart P Sharp, Andrew Mcgowan, Ben J. Hatchwell
    Abstract:

    Despite increasing interest in urban ecology most attention has focussed on describing changes in assemblage composition and structure along urbanisation gradients, whilst relatively little research has focussed on the mechanisms behind these changes. Ecological theory predicts that alterations in biotic interactions are particularly likely to arise, especially with regard to disease risk. Here, we report on differences in prevalence of avian malaria and tick infection and intensity in 11 paired urban and rural blackbird Turdus merula populations from across the western Palearctic. We find large and consistent reductions in tick prevalence and intensity in urban areas. There are also large reductions in the prevalence of avian malaria in many, but not all, urban areas. The proportion of first year birds in urban populations is significantly lower than that in rural ones, and across the more natural rural sites southerly populations contain fewer first years than northern ones. These patterns are expected to arise if survival rates are higher in urban areas, and are negatively correlated with latitude.

  • The reproductive success of Blackbirds Turdus merula in relation to habitat structure and choice of nest site
    Ibis, 2008
    Co-Authors: Ben J. Hatchwell, Dan E Chamberlain, Christopher M. Perrins
    Abstract:

    The reproductive success of a population of Blackbirds Turdus merula occupying farmland and woodland was studied over 3 years to investigate the effects of habitat on breeding success. Territory distribution was patchy in both farmland and woodland; some areas were unoccupied, while other areas were occupied at variable densities. Habitat structure appeared to influence occupation: the index of habitat complexity (“cover score”) was higher in occupied areas than in unoccupied areas and high-density territories had higher cover scores than low-density territories. However, habitat structure had no significant effect on reproductive success because the cover scores of territories where pairs were successful did not differ significantly from those of territories where there were no successful breeding attempts. There was no evidence of differential mortality rates in adults according to habitat. The height, bulk and exposure of c. 430 nests were measured to determine the effect of nest and nest-site characteristics on reproductive success. Nest exposure was the only feature that differed between successful and failed nests, successful nests being less exposed than failed nests. The major cause of breeding failure was nest predation, but the effect of nest exposure operated only during the laying and incubation period and not during the nestling period. The significance of habitat structure for variation in population densities between habitats is discussed.

  • importance of feeding ecology to the reproductive success of blackbirds Turdus merula nesting in rural habitats
    Ibis, 2008
    Co-Authors: Dan E Chamberlain, Ben J. Hatchwell, Christopher M. Perrins
    Abstract:

    The feeding ecology of Blackbirds Turdus merula breeding in contiguous woodland and farmland habitats was studied over three years. The aim of the study was to investigate how reproductive success was influenced by nestling diet and the provisioning rates of parents feeding nestlings. Parental provisioning rates increased with brood size, and consequently individual nestlings were no lighter in larger broods. None of the environmental factors measured had strong effects on parental provisioning rate. The nestling diet was dominated by caterpillars and earthworms, the former occurring in a short period in the middle of the breeding season. The availability of earthworms was higher in woodland and was dependent on rainfall in farmland. Nestling mass and provisioning rates were marginally higher under predominantly earthworm diets. Nestling mass increased with rainfall in farmland only, and was higher in farmland than in woodland or woodland-edge, although it is doubtful whether this result is of any significance for fledgling survival. Overall, Blackbirds were able to provision their nestlings adequately throughout the breeding season across a range of conditions. There was no evidence to suggest that reproductive success was constrained by aspects of feeding ecology within the natural range of brood size.

  • The haematozoan parasites of Common Blackbirds Turdus merula: associations with host condition
    Ibis, 2001
    Co-Authors: Ben J. Hatchwell, Dan E Chamberlain, Matthew J.a. Wood, M. Ali Anwar, Christopher M. Perrins
    Abstract:

    A population of European Blackbirds Turdus merula was studied to investigate the relationships between blood parasitism and host morphometrics, a putative sexually-selected trait, and reproductive parameters. The prevalence of haematozoa was extremely high and infection was negatively associated with adult morphometrics: adults infected with Leucocytozoon were in relatively poor body condition and had shorter wings than uninfected birds. There was also a negative relationship between blood parasite infection and traits associated with reproduction. The bill colour of males (a putative sexually-selected trait) infected with Plasmodium was duller than that of uninfected males, and in females Haemoproteus infection was significantly positively associated with bill colouration. Haematozoan infection was unrelated to reproductive parameters, and there was no relationship between blood parasite infection and the provision of parental care.

Will Cresswell - One of the best experts on this subject based on the ideXlab platform.

  • body mass change strategies in blackbirds Turdus merula the starvation predation risk trade off
    Journal of Animal Ecology, 2005
    Co-Authors: Ross Macleod, P. Barnett, Jacquie A. Clark, Will Cresswell
    Abstract:

    Summary 1. It is theoretically well established that body mass in birds is the consequence of a trade-off between starvation risk and predation risk. There are, however, no studies of mass variation from sufficiently large wild populations to model in detail the range of diurnal and seasonal mass change patterns in natural populations and how these are linked to the complex environmental and biological variables that may affect the trade-off. 2. This study used data on 17 000 individual blackbirds Turdus merula to model how mass changes diurnally and seasonally over the whole year and over a wide geographical area. Mass change was modelled in respect of temperature, rainfall, day length, geographical location, time of day and time of year and the results show how these mass changes vary with individual size, age and sex. 3. The hypothesis that seasonal mass is optimized over the year and changes in line with predictors of foraging uncertainty was tested. As theory predicts, reduced day length and reduced temperature result in increased mass and the expected seasonal peak of mass in midwinter. 4. The hypothesis that diurnal mass gain is optimized in terms of starvation‐predation risk trade-off theory was also tested. The results provide the first empirical evidence for intraspecies seasonal changes in diurnal mass gain patterns. These changes are consistent with shifts in the relative importance of starvation risk and predation risk and with the theory of mass-dependent predation risk. 5. In winter most mass was gained in the morning, consistent with reducing starvation risk. In contrast, during the August‐November non-breeding period a bimodal pattern of mass gain, with increases just after dawn and before dusk, was adopted and the majority of mass gain occurred at the end of the day consistent with reducing massdependent predation risk. The bimodal diurnal mass gain pattern described here is the first evidence that bird species in the wild gain mass in this theoretically predicted pattern.

  • Body mass change strategies in blackbirds Turdus merula: the starvation–predation risk trade‐off
    Journal of Animal Ecology, 2005
    Co-Authors: Ross Macleod, P. Barnett, Jacquie A. Clark, Will Cresswell
    Abstract:

    Summary 1. It is theoretically well established that body mass in birds is the consequence of a trade-off between starvation risk and predation risk. There are, however, no studies of mass variation from sufficiently large wild populations to model in detail the range of diurnal and seasonal mass change patterns in natural populations and how these are linked to the complex environmental and biological variables that may affect the trade-off. 2. This study used data on 17 000 individual blackbirds Turdus merula to model how mass changes diurnally and seasonally over the whole year and over a wide geographical area. Mass change was modelled in respect of temperature, rainfall, day length, geographical location, time of day and time of year and the results show how these mass changes vary with individual size, age and sex. 3. The hypothesis that seasonal mass is optimized over the year and changes in line with predictors of foraging uncertainty was tested. As theory predicts, reduced day length and reduced temperature result in increased mass and the expected seasonal peak of mass in midwinter. 4. The hypothesis that diurnal mass gain is optimized in terms of starvation‐predation risk trade-off theory was also tested. The results provide the first empirical evidence for intraspecies seasonal changes in diurnal mass gain patterns. These changes are consistent with shifts in the relative importance of starvation risk and predation risk and with the theory of mass-dependent predation risk. 5. In winter most mass was gained in the morning, consistent with reducing starvation risk. In contrast, during the August‐November non-breeding period a bimodal pattern of mass gain, with increases just after dawn and before dusk, was adopted and the majority of mass gain occurred at the end of the day consistent with reducing massdependent predation risk. The bimodal diurnal mass gain pattern described here is the first evidence that bird species in the wild gain mass in this theoretically predicted pattern.

Tamas Bakonyi - One of the best experts on this subject based on the ideXlab platform.

Zdeněk Hubalek - One of the best experts on this subject based on the ideXlab platform.

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