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Grünau im Almtal, Austria

Ludwig S.C.,Institute of Avian Research Vogelwarte Helgoland | Ludwig S.C.,Konrad Lorenz Research Station | Becker P.H.,Institute of Avian Research Vogelwarte Helgoland
Ibis | Year: 2012

Mating between close relatives can have deleterious effects on reproductive success or offspring fitness, which should favour the evolution of active or passive inbreeding avoidance mechanisms. In birds, evidence for active inbreeding avoidance by kin-discriminative mate choice is scarce; many studies describe random mating in relation to kinship and thus support passive inbreeding avoidance by natal dispersal. However, most studies were conducted in island populations of short-lived passerines with fast alternation of generations. In this study, we present inbreeding estimates based on pedigree data from a 16-year study in a coastal colony of Common Terns Sterna hirundo, a long-lived seabird with delayed sexual maturation and low rates of extra-pair paternity. Incestuous mating was rare (four of 2387 pairs), even if partially accounting for incomplete pedigrees. Although the average relatedness of observed pairs was lower than would be expected from random pairing, the inbreeding coefficient did not differ from random mating. Hence, we found no clear evidence for active inbreeding avoidance by kin-discriminative mate choice, and the low level of inbreeding seems to be related to the high immigration rate in the colony and thus to be maintained passively by dispersal. © 2011 The Authors. Ibis © 2011 British Ornithologists' Union.

Sim I.M.W.,RSPB Scotland | Sim I.M.W.,University of Aberdeen | Ludwig S.C.,RSPB Scotland | Ludwig S.C.,Konrad Lorenz Research Station | And 4 more authors.
Ibis | Year: 2013

Recent studies indicate that variation in juvenile survival may be particularly important in driving avian population dynamics. The quality of habitats available to inexperienced juveniles of migrant species is critical to their survival because they must obtain enough food to build up fat reserves for migration, while avoiding predation. We radiotracked 110 juvenile Ring Ouzels Turdus torquatus, a species of high conservation concern in the UK, to quantify for the first time seasonal patterns in foraging habitat and food abundance during this potentially key life-history period. Key attributes of foraging plots were compared with those on control plots (representing the broad habitat types selected by foraging juveniles) during 2007-08. Birds foraged on invertebrates in grass-rich plots during June to mid-July and then shifted to foraging mainly on moorland berries in higher-altitude, heather-rich plots during mid-July to early-September. Juveniles selected invertebrate foraging plots with low soil acidity, and increasingly selected plots with high earthworm (an important food) biomass and grass cover, but low grass and all vegetation height as the season progressed. In contrast, earthworm biomass and grass cover remained constant, and grass and all vegetation height increased, on control plots. Juveniles selected berry foraging plots with higher abundance of ripe Bilberries Vaccinium myrtillus and Crowberries Empetrum nigrum than found on control plots. Juvenile Ring Ouzels thus appear to require access to short, grass- and invertebrate-rich habitat during early summer, and taller, heather-dominated and berry-rich areas in late summer. The use of two distinct habitat types during the pre-migratory period illustrates the need for a detailed understanding of the requirements of juvenile birds. © 2012 British Ornithologists' Union.

Martinez-Padilla J.,CSIC - National Museum of Natural Sciences | Martinez-Padilla J.,University of Aberdeen | Vergara P.,CSIC - National Museum of Natural Sciences | Vergara P.,University of Aberdeen | And 10 more authors.
Biology Letters | Year: 2011

In many species, females display brightly coloured and elaborate traits similar to those that males use in intra- and inter-sexual selection processes. These female characters are sometimes related to fitness, and might function as secondary sexual characteristics that have evolved through sexual selection. Here, we used descriptive data from 674 females in 10 populations and an experimental removal of Trichostrongylus tenuis parasites in four populations, to examine the effects of season, age, condition, and parasites on the size of supraorbital combs displayed by female red grouse Lagopus lagopus scoticus. We found that comb size (i) was greater during the breeding than the non-breeding season, (ii) was greater in adult than in young females, (iii) was positively correlated with body condition, and (iv) negatively correlated with parasite abundance. Experimentally, we showed that comb size increased proportionally to the number of worms removed after parasite dosing. Our findings provide a better understanding of proximate mechanisms behind the expression of a male-like trait in females, and we discuss its possible function as a female ornament. © 2010 The Royal Society.

Gonzlez-Jaramillo M.,Colegio de Mexico | Schloegl C.,Konrad Lorenz Research Station | Schloegl C.,University of Vienna | De La Cueva H.,Research Center Cientifica ucacion Superior Of Ensenada
Southwestern Naturalist | Year: 2012

We induced three adoptions during the period of biparental care by placing orphaned chicks of magnificent frigatebirds (Fregata magnificens) into nests of foster parents whose chick had died. Indirect parent-offspring recognition seemed to occur during the period of biparental care. A chick was adopted in one of our three trials; thus, adoption of orphaned chicks potentially could be used as a conservation strategy.

Schloegl C.,Konrad Lorenz Research Station | Schloegl C.,University of Vienna
Journal of Comparative Psychology | Year: 2011

Choice by exclusion, that is, the ability to base the choice of a target on the rejection of potential alternatives, is becoming increasingly interesting for comparative cognition research. Recently, ravens have been shown to solve an exclusion task and it had been suggested that this ability might benefit ravens in a food-caching context. To investigate this possibility, the raven study was replicated with a closely related, but noncaching, species, the jackdaw (Corvus monedula). In the first test, the birds had to find food hidden in one of two differently shaped tubes. The results suggest that the jackdaws found the food through intensive search behavior, with little evidence for exclusion abilities. In a follow-up experiment, the tubes were replaced by cups, and before the birds made a choice, one of the cups was lifted to inform them about its content. In a final task, this procedure was modified to control for the influence of local enhancement. In both experiments, the jackdaws were successful only if they had seen the food before. These findings are in contrast to the previous results on ravens and support the idea that exclusion abilities may have evolved as specific adaptations to food caching. © 2011 American Psychological Association.

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