Sindal, Denmark
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Moller A.P.,University Paris - Sud | Nielsen J.T.,Espedal 4
Current Zoology | Year: 2015

The level of genetic variation among individuals may affect performance by reducing the ability of prey to detect and escape from predators if lack of genetic variation reduces flight ability directly or indirectly through reduced parasite resistance. We investigated vulnerability of common avian prey species to predation by the sparrowhawk Accipiter nisus and the goshawk A. gentilis in relation to an index of genetic similarity among adults of potential prey species. We estimated a prey vulnerability index that reflects the abundance of prey relative to the expected abundance according to local population density, and related this index to band sharing coefficients based on analyses of minisatellites for adults in local breeding populations. The prey vulnerability index was positively correlated with the band sharing coefficient in both predators, even when controlling for potentially confounding variables. These findings indicate that prey species with high band sharing coefficients, and hence low levels of genetic variation, are more readily caught by avian predators. Therefore, predation may constitute a major cost of low levels of genetic variation in extant populations of prey © 2015 Current Zoology.


Moler A.P.,University Paris - Sud | Moler A.P.,Center for Advanced Study | Nielsen J.T.,Espedal 4
Ethology Ecology and Evolution | Year: 2010

Fear screams are calls emitted by prey just before or during capture by a predator, and the evolution of such calls has been attributed to the fitness benefits of escape from a predator due to interference by a secondary, kleptoparasitic predator or interference by conspecifics. If fear screams had beneficial effects on individuals carrying the same genes (in terms of learnt avoidance of a predator by related individuals, or predators avoiding future capture attempts of difficult prey), then fear screams should be more prevalent in species with little genetic variation and hence a high degree of shared alleles. In a comparative analysis of 71 species of birds, the proportion of individuals emitting fear screams in different species increased with the degree of genetic similarity among adults in local populations, as reflected by the band-sharing coefficient for neutral minisatellite markers. Furthermore, the proportion of individuals emitting fear screams in different species increased with the degree of preference by a common avian predator, the goshawk Accipiter gentilis, but not by the sparrowhawk Accipiter nisus, showing that individuals belonging to species that suffered disproportionately from predation were more likely to emit fear screams. Finally, the proportion of individuals emitting fear screams in different species increased with the proportion of individuals that were tail-less, thus having successfully escaped a predator. These results suggest that genetic variation has played a role in the evolution of fear screams, and that the frequency of fear screams is related to the risk of predation and the probability of successful escape. © 2010 Dipartimento di Biologia Evoluzionistica dell'Universitá.


Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Erritzoe J.,Taps Old Rectory | Tottrup Nielsen J.,Espedal 4
Functional Ecology | Year: 2010

Summary: 1. The uropygial gland of birds produces chemical substances with antimicrobial properties that have been shown to reduce the abundance of feather degrading bacteria and other microorganisms. These microorganisms would affect the flight capabilities of birds and, consequently, a relationship between size of uropygial glands and probability of capture by aerial predators should exist. 2. We tested this hypothesis by estimating the susceptibility of 56 species of prey of the goshawk Accipiter gentilis Linnaeus to predation as the observed abundance of prey relative to the expected abundance from mean population density. 3. In a comparative analysis of the relationship between relative size of the uropygial gland and susceptibility to predation we found a strong negative relationship accounting for 16% of the variance. This relationship was present in analyses that accounted for similarity due to common phylogenetic descent, the fact that prey of intermediate size were preferred, and that larger prey species have larger uropygial glands. 4. These observations are consistent with uropygial glands being under strong selection from aerial predators that are likely mediated by the effect of uropygial glands on feather degrading bacteria and therefore on flight capabilities of birds. © 2009 The Authors. Journal compilation © 2009 British Ecological Society.


Moller A.P.,University Paris - Sud | Nielsen J.T.,Espedal 4
Behavioral Ecology | Year: 2014

Animals with parental care defend their offspring with an intensity reflecting parental investment. Parental investment theory predicts that parents should take risks relative to their residual reproductive value. Therefore, parental defense should change consistently with age reaching a peak at middle age, and it should vary consistently with age at start and end of reproduction. We recorded the intensity of parental defense of offspring in 410 female goshawks Accipiter gentilis throughout their lives, ranging from timid females that barely approached a human intruder at the nest to aggressive females that physically attacked the human. Females were consistent in their level of defense throughout life, and aggressive females were mated to aggressive males. Investment in reproduction as reflected by laying date, clutch size, and brood size showed a bell-shaped relationship with age. Females that started to breed at a young age were less aggressive than females that started late. Likewise, females that finished reproduction at a young age behaved less aggressively than females that finished at an old age. The intensity of defense of offspring peaked at an intermediate age followed by a decrease into old age and senescence. Females that started to breed early during the season were more aggressive than late breeders. These findings are consistent with the hypothesis that the intensity of parental defense of their offspring reflects parental investment and patterns of aging. © 2014 International Society for Behavioral Ecology. All rights reserved.


Moller A.P.,University Paris - Sud | Peralta-Sanchez J.M.,CSIC - Estación Experimental De Zonas Áridas | Nielsen J.T.,Espedal 4 | Lopez-Hernandez E.,CSIC - Estación Experimental De Zonas Áridas | Soler J.J.,CSIC - Estación Experimental De Zonas Áridas
Journal of Animal Ecology | Year: 2012

Predators often prey on individuals that are sick or otherwise weakened. Although previous studies have shown higher abundance of parasites in prey, whether prey have elevated loads of micro-organisms remains to be determined. We quantified the abundance of bacteria and fungi on feathers of woodpigeons Columba palumbus L., jays Garrulus glandarius L. and blackbirds Turdus merula L. that either fell prey to goshawks Accipiter gentilis L. or were not depredated. We found an almost three-fold increase in bacterial load of prey compared with non-prey, while there was no significant difference between prey and non-prey in level of fungal infection of the plumage. The results were not confounded by differences in size or mass of feathers, date of collection of feathers, or date of analysis of feathers for micro-organisms. These findings suggest a previously unknown contribution of bacteria to risk of predation, with important implications for behaviour, population ecology and community ecology. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society.


Kruger O.,Bielefeld University | Chakarov N.,Bielefeld University | Nielsen J.T.,Espedal 4 | Looft V.,University of Kiel | And 3 more authors.
Journal of Animal Ecology | Year: 2012

The habitat heterogeneity (HHH) and individual adjustment (IAH) hypotheses are commonly proposed to explain a decrease in reproduction rate with increasing population density. Higher numbers of low-quality territories with low reproductive success as density increases lead to a decrease in reproduction under the HHH, while more competition at high density decreases reproduction across all territories under the IAH. We analyse the influence of density and habitat heterogeneity on reproductive success in eight populations of long-lived territorial birds of prey belonging to four species. Sufficient reliability in distinguishing between population-wide, site-specific and individual quality effects on reproduction was granted through the minimal duration of 20years of all data sets and the ability to control for individual quality in five of them. Density increased in five populations but reproduction did not decrease in these. Territory occupancy as a surrogate of territory quality correlated positively with reproductive success but only significantly so in large data sets with more than 100 territories. Reproductive success was always best explained by measures of territory quality in multivariate models. Direct or delayed (t-1) population density entered very few of the best models. Mixed models controlling for individual quality showed an increasing reproductive performance in older individuals and in those laying earlier, but measures of territory quality were also always retained in the best models. We find strong support for the habitat heterogeneity hypothesis but weak support for the individual adjustment hypothesis. Both individual and site characteristics are crucial for reproductive performance in long-lived birds. Proportional occupancy of territories enables recognition of high-quality territories as preferential conservation targets. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society.


Moller A.P.,University Paris - Sud | Nielsen J.T.,Espedal 4
Oecologia | Year: 2015

Many animals build extravagant nests that exceed the size required for successful reproduction. Large nests may signal the parenting ability of nest builders suggesting that nests may have a signaling function. In particular, many raptors build very large nests for their body size. We studied nest size in the goshawk Accipiter gentilis, which is a top predator throughout most of the Nearctic. Both males and females build nests, and males provision their females and offspring with food. Nest volume in the goshawk is almost three-fold larger than predicted from their body size. Nest size in the goshawk is highly variable and may reach more than 600 kg for a bird that weighs ca. 1 kg. While 8.5 % of nests fell down, smaller nests fell down more often than large nests. There was a hump-shaped relationship between nest volume and female age, with a decline in nest volume late in life, as expected for senescence. Clutch size increased with nest volume. Nest volume increased during 1977–2014 in an accelerating fashion, linked to increasing spring temperature during April, when goshawks build and start reproduction. These findings are consistent with nest size being a reliable signal of parental ability, with large nest size signaling superior parenting ability and senescence, and also indicating climate warming. © 2015 Springer-Verlag Berlin Heidelberg


Moller A.P.,University Paris - Sud | Moller A.P.,Center for Advanced Study | Flensted-Jensen E.,Cypresvej 1 | Klarborg K.,Skovvej 28 | And 2 more authors.
Journal of Animal Ecology | Year: 2010

1. The duration of the reproductive season may depend on the duration of the growing season, with recent amelioration in spring temperatures allowing earlier start of reproduction. Earlier start of reproduction may allow a longer breeding season because of more broods a longer interval between broods for multi-brooded species. 2. We analysed extensive long-term data sets on timing of breeding in 20 species of birds from Denmark, based on records of over 100 000 individual offspring, showing considerable heterogeneity among species in temporal change in duration of the breeding season. 3. Multi-brooded species increased the duration of their breeding season by 0·43 days year-1 while single-brooded species decreased the duration of their breeding season by 0·44 days year-1. This implies that recent climate change has allowed more broods or better temporal spacing of broods in multi-brooded species, while the time window for reproduction has become narrower in single-brooded species. 4. The single-most important predictor of change in duration of the breeding season was change in the date breeding started; there was no change in the date of end of breeding. Species advancing their breeding date the most also expanded the duration of the breeding season. In contrast, longdistance migration and generation time did not predict change in duration of the breeding season. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.


Herfindal I.,Norwegian University of Science and Technology | van de Pol M.,Australian National University | van de Pol M.,Netherlands Institute of Ecology | Nielsen J.T.,Espedal 4 | And 2 more authors.
Journal of Animal Ecology | Year: 2015

Environmental variation can induce life-history changes that can last over a large part of the lifetime of an organism. If multiple demographic traits are affected, expected changes in climate may influence environmental covariances among traits in a complex manner. Thus, examining the consequences of environmental fluctuations requires that individual information at multiple life stages is available, which is particularly challenging in long-lived species. Here, we analyse how variation in climatic conditions occurring in the year of hatching of female goshawks Accipiter gentilis (L.) affects age-specific variation in demographic traits and lifetime reproductive success (LRS). LRS decreased with increasing temperature in April in the year of hatching, due to lower breeding frequency and shorter reproductive life span. In contrast, the probability for a female to successfully breed was higher in years with a warm April, but lower LRS of the offspring in these years generated a negative covariance among fecundity rates among generations. The mechanism by which climatic conditions generated cohort effects was likely through influencing the quality of the breeding segment of the population in a given year, as the proportion of pigeons in the diet during the breeding period was positively related to annual and LRS, and the diet of adult females that hatched in warm years contained fewer pigeons. Climatic conditions experienced during different stages of individual life histories caused complex patterns of environmental covariance among demographic traits even across generations. Such environmental covariances may either buffer or amplify impacts of climate change on population growth, emphasizing the importance of considering demographic changes during the complete life history of individuals when predicting the effect of climatic change on population dynamics of long-lived species. © 2014 The Authors.


Moller A.P.,French National Center for Scientific Research | Flensted-Jensen E.,Cypresvej 1 | Nielsen J.T.,Espedal 4
Oecologia | Year: 2016

Predators account for lethal effects in their prey, but importantly also for non-lethal indirect effects through the presence and the activity of predators. Such non-lethal effects include altered timing of reproduction, incidence of reproduction, clutch size and quality of offspring produced. We investigated the effects of goshawks Accipiter gentilis on reproduction of the stock dove Columba oenas in 1723 breeding events during 2006–2015 in Northern Denmark, while simultaneously accounting for effects of climate on reproduction of stock doves. Stock doves were consumed by goshawks 36 times less frequently than expected from their abundance, showing that lethal effects of predation were negligible. Laying date advanced at higher temperatures and stronger winds. Laying was delayed when the population size of goshawks increased, and the effects of goshawks interacted wind speed. The frequency of eggs that did not hatch increased with the population size of goshawks, and with increasing temperatures. Recruitment rate of stock doves decreased with increasing population size of goshawks and stock doves. These findings show that indirect effects of predation by goshawks on stock doves were much larger than direct lethal effects and that climate change interacted with predator–prey interactions. © 2016 Springer-Verlag Berlin Heidelberg

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