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Gerald Heckel - One of the best experts on this subject based on the ideXlab platform.
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temporal genetic structure and relatedness in the Tufted Duck aythya fuligula suggests limited kin association in winter
Ibis, 2013Co-Authors: Gerald Heckel, Irene KellerAbstract:Conspecific aggregation of waterfowl in winter is a common example of animal flocking behaviour, yet patterns of relatedness and temporal substructure in such social groups remain poorly understood even in common species. A previous study based on mark-recapture data showed that Tufted Ducks Aythya fuligula caught on the same day were re-caught together in subsequent winters more often than expected by chance, suggesting stable assortments of ‘socially familiar’ individuals between wintering periods. The genetic relationships within these social groups were not clear. Based on 191 individuals genotyped at 10 microsatellite markers, we investigated the temporal genetic structure and patterns of relatedness among wintering Tufted Ducks at Lake Sempach, Switzerland, in two consecutive winters. We found no evidence of genetic differentiation between temporal groups within or between winters. The average levels of relatedness in temporal groups were low and not higher than expected in random assortments of individuals. However, Mantel tests performed for each sex separately revealed significant negative correlations between the pairwise relatedness coefficients and the number of days between the capture dates of pairs of wintering Tufted Duck in males and females. This pattern suggests the presence of a small number of co-migrating same-sex sibling pairs in wintering flocks of Tufted Ducks. Our findings provide one of the first genetic analyses of a common Duck species outside the breeding season and contribute to the understanding of social interactions in long-distance migratory birds.
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breeding site fidelity and winter admixture in a long distance migrant the Tufted Duck aythya fuligula
Heredity, 2012Co-Authors: Irene Keller, Gerald HeckelAbstract:Long-distance migrants are, by definition, highly mobile but it is poorly understood if this leads to high rates of gene flow and an essentially panmictic global population structure. Genetic divergence in migratory species could be promoted, for example, by fidelity to distinct migratory pathways. In this study, we investigate the population genetic structure of Tufted Duck (Aythya fuligula), a long-distance migrant with a largely continuous breeding distribution across Eurasia. Distinct, longitudinally oriented flyways have been postulated based on geographically disjunct wintering areas and are supported by evidence from ringing data. We generated sequences of the mitochondrial control region and multi-locus microsatellite genotypes for several hundreds of samples from the European and Asian breeding and wintering grounds including some individuals infected with highly pathogenic avian influenza virus H5N1. Significant differentiation between breeding sites was observed for both marker types, but FST values were approximately 10 times higher for maternally inherited mitochondrial DNA than for biparentally transmitted nuclear markers. The genetic differentiation between the postulated European and Asian flyways was similar to that observed within continents and, in general, genetic divergence was not associated with geographic distance. Neither marker type showed evidence of genetic substructure among aggregations on the European wintering grounds. Our results suggest some breeding site fidelity, especially in females, but extensive population admixture on the wintering grounds. Several scenarios may explain the observed lack of genetic divergence between Europe and Asia including non-equilibrium conditions following a recent range expansion or contemporary gene flow across the postulated migratory divides.
Leif Nilsson - One of the best experts on this subject based on the ideXlab platform.
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Hanöbukten, ett viktigt övervingringsområde för sjöfåglar i södra Sverige
2020Co-Authors: Leif Nilsson, Mats OlssonAbstract:Hanobukten in SE Sweden (including Blekinge archi-pelago) is an important wintering and staging area for a number of waterbird species. The inshore parts have been covered by counts from the shore during the International Waterbird Counts (IWC) since 1969. In the present study we analyze these counts for the period 1969–2014. When the counts started the total number of wintering waterbirds varied between 20 000 and 40 000 per year. However, from the early 1990s the number doubled, reaching 60 000 to 80 000 birds per year. All species with the exception of the Long-tailed Duck Clangula hyemalis showed similar increase. The area had a high proportion of the Swedish wintering population of Pochard Aythya ferina and Smew Mergellus albellus. Large numbers of Tufted Duck Aythya fuligula also wintered in the area, and some parts of the archipelago had internationally important concentrations of Tufted Duck and Smew. The increase in numbers in the study area showed the same pattern as in all Sweden and was most probably a result of milder winters in recent years.
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Changes in numbers and distribution of wintering waterbirds at the south coast of Scania, Sweden, during 55 winters, 1964–2018
Ornis Svecica, 2020Co-Authors: Leif NilssonAbstract:THE SOUTH COAST of Scania, southernmost Sweden, has long been an important wintering and staging area for waterbirds. A large part of the coast was surveyed annually as a part of the international midwinter counts for 55 years (1964–2018). The total number of wintering waterbirds showed an increasing trend but there was much variation between years. Common Goldeneye Bucephala clangula, followed by Mallard Anas platyrhynchos, Tufted Duck Aythya fuligula and—during the early years—Long-tailed Duck Clangula hyemalis, dominated the community. Great Cormorant Phalacrocorax carbo, Mallard, Common Goldeneye and Eurasian Coot Fulica atra increased in numbers, reflecting the national and international trends related to milder winters and a northward shift of the winter distribution. Eurasian Wigeon Mareca penelope and Great Crested Grebe Podiceps cristatus established wintering traditions in the area during the study period. Tufted Duck and Common Merganser Mergus merganser decreased locally due to a northward shift of the wintering distribution northwards within the country. The Long-tailed Duck was an important winter guest in the first years but was only seen in very small numbers in later years, reflecting the general and large-scale decrease of the Baltic wintering population. (Less)
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Hanöbukten, an important wintering area for waterbirds in South Sweden
Ornis Svecica, 2017Co-Authors: Leif Nilsson, Mats OlssonAbstract:Hanobukten in SE Sweden (including Blekinge archipelago) is an important wintering and staging area for a number of waterbird species. The inshore parts have been covered by counts from the shore during the International Waterbird Counts (IWC) since 1969. In the present study we analyze these counts for the period 1969–2014. When the counts started the total number of wintering waterbirds varied between 20,000 and 40,000 per year. However, from the early 1990s the number doubled, reaching 60,000 to 80,000 birds per year. All species with the exception of the Long-tailed Duck Clangula hyemalis showed similar increase. The area had a high proportion of the Swedish wintering population of Pochard Aythya ferina and Smew Mergellus albellus. Large numbers of Tufted Duck Aythya fuligula also wintered in the area, and some parts of the archipelago had internationally important concentrations of Tufted Duck and Smew. The increase in numbers in the study area showed the same pattern as in all Sweden and was most probably a result of milder winters in recent years.
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Long-term trends and Changes in numbers and distribution of some wintering waterfowl species along the Swedish Baltic coast.
Acta Zoologica Lituanica, 2012Co-Authors: Leif NilssonAbstract:Regular counts of wintering waterfowl have been undertaken as a part of the International Waterfowl Census (IWC) and the National Swedish Environmental Monitoring Program since 1964. After the first years, a network of annually surveyed sites was established for the calculation of annual indices. Country-wide surveys (also including aerial counts) were undertaken 1971–1974, 1987–1989, 1992–1993 (partial) and 2004. During the survey period, increasing trends were found in Mallard (Anas platyrhynchos), Tufted Duck (Aythya fuligula), Pochard (Aythya ferina), Goldeneye (Bucephala clangula), Red-breasted Merganser (Mergus serrator), Mute Swan (Cygnus olor) and Cormorant (Phalacrocorax carbo). Some of these trends reflect genuine population changes; others are related to changing winter conditions, e.g. the establishment of a new wintering tradition for Wigeon (Anas penelope). Tufted Duck and Goldeneye decreased in the south and increased in the northern part of the coast. Mallard, on the other hand, increased ...
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wintering diving Duck populations in the oresund southern sweden in relation to available food resources
Wildfowl; 55 pp 61-76 (2005), 2005Co-Authors: Leif NilssonAbstract:Intensive surveys of staging and wintering diving Ducks in the Oresund area,southern Sweden, were undertaken during the winters 1995/96, 1996/97 and1997/98 as a part of the Environmental Impact Assessment (EIA) related to theestablishment of a Fixed Link (bridge–tunnel–artificial island) between Swedenand Denmark. Monitoring of the benthic fauna made it possible to compare thecalculated food requirements of the diving Duck populations with their foodresources. Overall, the diving Ducks (mainly Tufted Duck Aythya fuligula, ScaupAythya marila and Goldeneye Bucephala clangula) consumed between 2.6% and4.6 % of the standing crop of suitable food organisms. It is, however, probable that higher proportions of the prey are consumed in the shallowest areas compared to areas with deeper water. A prolonged period of ice cover during one of the study years made a large proportion of the feeding areas unavailable, but the main mussel beds were still free of ice because of strong currents so this had only limited impact on the food availability for the Ducks.
P J Butler - One of the best experts on this subject based on the ideXlab platform.
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the effect of elevated levels of thyroxine on the aerobic capacity of locomotor muscles of the Tufted Duck aythya fuligula
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 1995Co-Authors: Charles M Bishop, P J Butler, N M AtkinsonAbstract:Following extended periods of relative inactivity, or prior to migration, birds are able to increase the aerobic capacity of their locomotory muscles. Thyroid hormones may influence this process. A preliminary study was undertaken to assess the ability of elevated levels of thyroxine to increase the aerobic capacity of the locomotory and cardiac muscles of adult Tufted Ducks. Administration of thyroxine in the food for 8 weeks had little effect on body mass or on the masses of the pectoralis, semitendinosus and iliofibularis muscles, although there were increases in resting oxygen consumption and in the mass of the cardiac ventricles. The maximum activity of the aerobic enzyme, citrate synthase, was significantly greater in the left ventricle, liver, and iliofibularis muscles (P<0.005) of treated birds. However, while there was clearly no difference in activity in the semimembranosus leg muscle, that of the pectoralis was not quite significant (P=0.078). It is concluded that addition of supra-physiological levels of exogenous thyroxine may induce a differential increase in the maximum activity of citrate synthase in the locomotor muscles of the Tufted Duck, which is correlated with the fibre type composition of these muscles. These results are consistent with those found in studies on rats, with slow oxidative fibres being the most sensitive, and fast glycolytic fibres the least sensitive, to thyroxine treatment.
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Arterial blood pressure during voluntary diving in the Tufted Duck, Aythya fuligula
Journal of Comparative Physiology B, 1994Co-Authors: R M Bevan, P J ButlerAbstract:Arterial blood pressure was monitored in voluntarily diving Tufted Ducks. Mean arterial blood pressure while diving increased during the pre-dive tachycardia, fell to resting levels on submersion, then gradually increased before peaking on surfacing. Estimated total peripheral resistance fell during the pre-dive and post-dive tachycardia, presumably to allow the oxygen stores to be loaded and replenished respectively and/or for carbon dioxide levels to be reduced. Changes in mean arterial blood pressure and total peripheral resistance suggest that peripheral vasoconstriction occurs in some vascular beds during a dive. An increase in arterial blood pressure (and therefore perfusion pressure) may be employed to increase blood flow and oxygen delivery to the active leg muscles.
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cardiac output and blood flow distribution during swimming and voluntary diving of the Tufted Duck aythya fuligula
The Journal of Experimental Biology, 1992Co-Authors: R M Bevan, P J ButlerAbstract:Cardiac output ( V b) and blood flow distribution were continuously measured in the Tufted Duck when diving voluntarily. Blood flows through pulmonary, ischiadic, carotid and brachiocephalic arteries were recorded using miniature pulsed Doppler flow probes. By measuring these flows, cardiac output and blood flow to the leg muscles and to the flight muscles could be calculated. Heart rate and V b were well correlated, making the former a very good indicator of any changes in the latter. Blood flow to the leg muscles increased substantially during both swimming and diving to five times the resting rate. Cardiac output, though, was lower during the later portions of a dive than it was during swimming. A consequence of this lower V b was that the proportion of V b supplying the leg muscles was much greater during diving than it was whilst the Duck was swimming. This indicates that more extensive peripheral vasoconstriction was occurring during diving. The blood flow to the wing muscles during diving was found to be significantly lower than that at rest but there was no net change in blood flow through the brachiocephalic arteries as the blood flow to the head increased. Peripheral vasoconstriction must, therefore, have been occurring in other parts of the body during diving, possibly within the vascular beds supplying the gastrointestinal tract, the skin and the respiratory muscles. This study supports the prediction that voluntary diving in Tufted Ducks is a compromise between the physiological response to involuntary submergence and that to exercise in air, but with the bias towards the latter.
Irene Keller - One of the best experts on this subject based on the ideXlab platform.
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temporal genetic structure and relatedness in the Tufted Duck aythya fuligula suggests limited kin association in winter
Ibis, 2013Co-Authors: Gerald Heckel, Irene KellerAbstract:Conspecific aggregation of waterfowl in winter is a common example of animal flocking behaviour, yet patterns of relatedness and temporal substructure in such social groups remain poorly understood even in common species. A previous study based on mark-recapture data showed that Tufted Ducks Aythya fuligula caught on the same day were re-caught together in subsequent winters more often than expected by chance, suggesting stable assortments of ‘socially familiar’ individuals between wintering periods. The genetic relationships within these social groups were not clear. Based on 191 individuals genotyped at 10 microsatellite markers, we investigated the temporal genetic structure and patterns of relatedness among wintering Tufted Ducks at Lake Sempach, Switzerland, in two consecutive winters. We found no evidence of genetic differentiation between temporal groups within or between winters. The average levels of relatedness in temporal groups were low and not higher than expected in random assortments of individuals. However, Mantel tests performed for each sex separately revealed significant negative correlations between the pairwise relatedness coefficients and the number of days between the capture dates of pairs of wintering Tufted Duck in males and females. This pattern suggests the presence of a small number of co-migrating same-sex sibling pairs in wintering flocks of Tufted Ducks. Our findings provide one of the first genetic analyses of a common Duck species outside the breeding season and contribute to the understanding of social interactions in long-distance migratory birds.
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breeding site fidelity and winter admixture in a long distance migrant the Tufted Duck aythya fuligula
Heredity, 2012Co-Authors: Irene Keller, Gerald HeckelAbstract:Long-distance migrants are, by definition, highly mobile but it is poorly understood if this leads to high rates of gene flow and an essentially panmictic global population structure. Genetic divergence in migratory species could be promoted, for example, by fidelity to distinct migratory pathways. In this study, we investigate the population genetic structure of Tufted Duck (Aythya fuligula), a long-distance migrant with a largely continuous breeding distribution across Eurasia. Distinct, longitudinally oriented flyways have been postulated based on geographically disjunct wintering areas and are supported by evidence from ringing data. We generated sequences of the mitochondrial control region and multi-locus microsatellite genotypes for several hundreds of samples from the European and Asian breeding and wintering grounds including some individuals infected with highly pathogenic avian influenza virus H5N1. Significant differentiation between breeding sites was observed for both marker types, but FST values were approximately 10 times higher for maternally inherited mitochondrial DNA than for biparentally transmitted nuclear markers. The genetic differentiation between the postulated European and Asian flyways was similar to that observed within continents and, in general, genetic divergence was not associated with geographic distance. Neither marker type showed evidence of genetic substructure among aggregations on the European wintering grounds. Our results suggest some breeding site fidelity, especially in females, but extensive population admixture on the wintering grounds. Several scenarios may explain the observed lack of genetic divergence between Europe and Asia including non-equilibrium conditions following a recent range expansion or contemporary gene flow across the postulated migratory divides.
Peter Blums - One of the best experts on this subject based on the ideXlab platform.
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Individual quality, survival variation and patterns of phenotypic selection on body condition and timing of nesting in birds
Oecologia, 2005Co-Authors: Peter Blums, James D Nichols, James E. Hines, Mark S. Lindberg, Aivars MednisAbstract:Questions about individual variation in “quality” and fitness are of great interest to evolutionary and population ecologists. Such variation can be investigated using either a random effects approach or an approach that relies on identifying observable traits that are themselves correlated with fitness components. We used the latter approach with data from 1,925 individual females of three species of Ducks (Tufted Duck, Aythya fuligula ; common pochard, Aythya ferina ; northern shoveler, Anas clypeata ) sampled on their breeding grounds at Engure Marsh, Latvia, for over 15 years. Based on associations with reproductive output, we selected two traits, one morphological (relative body condition) and one behavioral (relative time of nesting), that can be used to characterize individual females over their lifetimes. We then asked whether these traits were related to annual survival probabilities of nesting females. We hypothesized quadratic, rather than monotonic, relationships based loosely on ideas about the likely action of stabilizing selection on these two traits. Parameters of these relationships were estimated directly using ultrastructural models embedded within capture-recapture-band-recovery models. Results provided evidence that both traits were related to survival in the hypothesized manner. For all three species, females that tended to nest earlier than the norm exhibited the highest survival rates, but very early nesters experienced reduced survival and late nesters showed even lower survival. For shovelers, females in average body condition showed the highest survival, with lower survival rates exhibited by both heavy and light birds. For common pochard and Tufted Duck, the highest survival rates were associated with birds of slightly above-average condition, with somewhat lower survival for very heavy birds and much lower survival for birds in relatively poor condition. Based on results from this study and previous work on reproduction, we conclude that nest initiation date and body condition covary with both reproductive and survival components of fitness. These associations lead to a positive covariance of these two fitness components within individuals and to the conclusion that these two traits are indeed correlates of individual quality.
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Correlates of lifetime reproductive success in three species of European Ducks.
Oecologia, 2004Co-Authors: Peter Blums, Robert G. ClarkAbstract:Number of breeding attempts is a strong correlate of lifetime reproductive success (LRS) in birds, but the relative importance of potentially interacting factors affecting LRS has rarely been fully evaluated. We considered simultaneously five main factors hypothesized to influence LRS (age at first breeding, nesting date, number of breeding attempts, female traits, brood parasitism) by analyzing with path analysis 22-year data sets for 1,279 individually marked females and their offspring in Tufted Duck (Aythya fuligula), common pochard (A. ferina) and northern shoveler (Anas clypeata). We recaptured marked offspring as breeding adults (n=496 females) and obtained more complete estimates of LRS by incorporating information about banded Ducklings of both sexes shot by hunters ≥12 months after banding (n=138). In Tufted Ducks and especially pochard (both diving Duck species), late-hatched females tended to delay nesting until 2-years old. Most females (Tufted Duck, 74%; pochard, 71%; shoveler, 59%) apparently produced no breeding-age offspring. Number of breeding attempts (i.e., longevity) was the strongest correlate of LRS in all species, after controlling effects of age at first breeding, relative nest initiation date, wing length and body mass. Percentage of females producing recruits increased gradually with number of breeding attempts for all three species. Also, as expected, females nesting early in the breeding season had higher LRS than late-nesting individuals. In shoveler, female-specific characteristics of relatively longer wings and heavier late incubation body mass had positive effects on LRS, the latter feature being more common in 2-year-old nesters. In diving Ducks, no relationships were detected between LRS and female-specific traits like wing length or body mass, and nor did acceptance of parasitic eggs have any deleterious impact on fitness estimates. Overall, number of fledged Ducklings and LRS were related in Tufted Duck, weakly associated in pochard and unrelated in shoveler, implying that fledging success is not always a reliable measure of LRS.
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Patterns of reproductive effort and success in birds: path analyses of long-term data from European Ducks
Journal of Animal Ecology, 2002Co-Authors: Peter Blums, Robert G. Clark, Aivars MednisAbstract:Summary 1 We tested ecological hypotheses about timing of breeding and reproductive effort in birds, by analysing > 15-year data sets for individually marked females in three species of Latvian Ducks (northern shoveler, Tufted Duck, common pochard). 2 Duckling survival and recruitment declined with advancing hatch date in pochard and Tufted Duck, after controlling for effects of female age and other factors with path analysis, a novel finding which indicates that fitness advantages associated with early hatching extended beyond the prefledging period. Logistic regression analysis suggested further that individual Duckling prefledging survival was moderate in the earliest phase of the breeding season, greatest in mid-season and lowest later on. 3 However, selection acting against early hatched Ducklings was surpassed by strong directional selection favouring recruitment of the earliest hatching females. The absolute and relative numbers of female recruits produced by a breeding female declined sharply with advancing hatch date in all species. 4 Unlike previous studies, an hypothesized intraspecific trade-off between Duckling mass and brood size was detected, being very robust in two of three species. 5 Unexpectedly, female age effects on recruitment were manifested only indirectly by several pathways, the most important being the earlier hatching dates of older females. Size-adjusted body mass (i.e. condition index) was positively related to reproductive success, and was 2–8-fold more influential than female size (indexed by wing length). 6 Overall, fecundity-independent variables (e.g. hatching date, weather, indices of Duckling production and habitat quality) generally had 2–10 times greater influence on recruitment rates than did fecundity-dependent variables such as female size or condition, Duckling mass and brood size, suggesting a critical role for external environmental factors vs. individual female-specific traits in the recruitment process.
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Effect of Conspecific Brood Parasitism on Host Fitness for Tufted Duck and Common Pochard
The Auk, 2001Co-Authors: B D Dugger, Peter BlumsAbstract:Abstract Brood parasitism occurs disproportionately in birds with precocial young and is particularly common in Anseriformes. In part, that pattern may result because precocial hosts, relative to altricial species, incur relatively few costs when caring for precocial eggs. Empirical data do not consistently support that hypothesis, and some parameters have not been adequately compared between parasitized and nonparasitized nests or females. We used a combination of experimentation (egg and Duckling additions) and analysis of a larger observational data set to compare reproductive parameters, recruitment, and adult survival between parasitized and nonparasitized female Common Pochard (Aythya ferina) and Tufted Ducks (A. fuligula). Addition of three eggs to nests during the host's laying cycle had no effect on host clutch size, host egg hatch success, or nest success for either species. Nest success was not affected by parasitism intensity for pochards, but we did detect a small drop in nest success for Tufted Duck nests parasitized with >6 eggs. Recruitment probability did not differ between parasitized and nonparasitized nests for either species, and parasitism had no negative effect on adult survival. Between-year nest initiation dates were later for parasitized Tufted Ducks, although the biological consequences of that difference (3.8 days) seem negligible. Moderate levels of parasitism do not negatively affect hosts for these two species.
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effect of conspecific brood parasitism on host fitness for Tufted Duck and common pochard
The Auk, 2001Co-Authors: B D Dugger, Peter BlumsAbstract:Abstract Brood parasitism occurs disproportionately in birds with precocial young and is particularly common in Anseriformes. In part, that pattern may result because precocial hosts, relative to altricial species, incur relatively few costs when caring for precocial eggs. Empirical data do not consistently support that hypothesis, and some parameters have not been adequately compared between parasitized and nonparasitized nests or females. We used a combination of experimentation (egg and Duckling additions) and analysis of a larger observational data set to compare reproductive parameters, recruitment, and adult survival between parasitized and nonparasitized female Common Pochard (Aythya ferina) and Tufted Ducks (A. fuligula). Addition of three eggs to nests during the host's laying cycle had no effect on host clutch size, host egg hatch success, or nest success for either species. Nest success was not affected by parasitism intensity for pochards, but we did detect a small drop in nest success for Tuf...
