Search results for "Fledge"
showing 10 items of 24 documents
Costs and Benefits of Experimentally Induced Changes in the Allocation of Growth versus Immune Function under Differential Exposure to Ectoparasites
2010
Background Ecological immunology has focused on the costs of investment in immunocompetence. However, understanding optimal resource allocation to immune defence requires also identification of its benefits, which are likely to occur only when parasites are abundant. Methodology We manipulated the abundance of parasitic hen fleas in blue tit (Cyanistes caeruleus) nests, and supplemented their hosts, the nestlings, with methionine (a sulphur amino acid enhancing cell-mediated immunity) during day 3–6. We found a significant interaction between these two experimental factors on the development of immune defences and growth rates. Only in parasitized nests did methionine supplementation boost …
Limitation of Reproductive Success by Food Availability and Breeding Time in Pied Flycatchers
1998
Seasonal variation in reproductive success is a common phenomenon in many taxa. In birds, the costs and benefits associated with alternative breeding dates cause variation in clutch size, which is a main cause of seasonal decline in reproductive success. An immediate cause for this might be seasonal variation in the environment, or alternatively, but not mutually exclusively, date-independent differences in the parental/territory quality of early and late parents. The predictions of these hypotheses on seasonal reduction of reproductive success were tested by manipulating the hatching date and the amount of food during the nestling period of Pied Flycatchers (Ficedula hypoleuca). Delay in t…
Life-history of two African Sylvia warblers: low annual fecundity and long post-fledging care
2004
The investigation of factors that cause differences in life-history traits between temperate and tropical birds is often hampered by a lack of knowledge about tropical species. Even within the well-known warblers of the genus Sylvia, which include resident species from temperate and tropical regions as well as migrants, there are few data from tropical species. We investigated the breeding biology of the tropical species Sylvia lugens and S. boehmi in a 2-year study in Kenya. Both species had a clutch size of 2.0 and laid c. 3.7 clutches per year. Breeding was characterized by long incubation periods (S. lugens 14.5 days, S. boehmi 15.0 days), long nestling periods (16.0 and 12.9 days, resp…
REPRODUCTIVE SUCCESS OF EURASIAN TREECREEPERS,CERTHIA FAMILIARIS,LOWER IN TERRITORIES WITH WOOD ANTS
1999
Few studies have considered the effects of interspecific competition between distantly related taxa on the reproductive success of individuals. We compared the food supply, laying date, clutch size, and breeding success of a small double-brooded passerine bird, the Eurasian Treecreeper (Certhia familiaris) between territories with or without col- onies of red wood ants (Formica rufa group) during four years. Both the wood ants and Eurasian Treecreepers forage on tree trunks and utilize the same food resources. It has been shown that the wood ants are able to depress the available food supply for the treecreepers and interfere with their foraging behavior. We found that food abundance was lo…
Seasonal changes in predator community switch the direction of selection for prey defences
2014
Insect communities consist of aposematic species with efficient warning colours against predation, as well as abundant examples of crypsis. To understand such coexistence, we here report results from a field experiment where relative survival of artificial larvae, varying in conspicuousness, was estimated in natural bird communities over an entire season. This takes advantage of natural variation in the proportion of naive predators: naivety peaks when young birds have just fledged. We show that the relative benefit of warning signals and crypsis changes accordingly. When naive birds are rare (early and late in the season), conspicuous warning signals improve survival, but conspicuousness b…
Correlates of lifetime reproductive success in three species of European ducks
2003
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 …
Evidence for an Association between Post-Fledging Dispersal and Microsatellite Multilocus Heterozygosity in a Large Population of Greater Flamingos
2013
10 pages; International audience; DISPERSAL CAN BE DIVIDED INTO THREE STAGES: departure, transience and settlement. Despite the fact that theoretical studies have emphasized the importance of heterozygosity on dispersal strategies, empirical evidence of its effect on different stages of dispersal is lacking. Here, using multi-event capture-mark-recapture models, we show a negative association between microsatellite multilocus heterozygosity (MLH; 10 loci; n = 1023) and post-fledging dispersal propensity for greater flamingos, Phoenicopterus roseus, born in southern France. We propose that the negative effects of inbreeding depression affects competitive ability and therefore more homozygous…
Clutch size and egg volume in great tits (Parus major) increase under low intensity electromagnetic fields: a long-term field study.
2012
Exposure to electromagnetic fields (EMFs) can affect a wide range of biological processes, including reproduction, growth and development. Experiments aimed at investigating the biological effects of EMFs, focused on potential harmful effects on humans, have been mostly carried out in vitro or with animal models in laboratory conditions. By contrast, studies performed on wild animals are scarce. The effects of EMFs created by an electric power line on reproductive traits of a wild great tit (Parus major) population were explored by analysing data gathered during nine breeding seasons. EMF exposure significantly increased clutch size (7%) and egg volume (3%), implying a 10% increase in clutc…
Adaptive plasticity of blue tits(Parus caeruleus)and great tits(Parus major)breeding in natural and semi‐natural insular habitats
2004
The breeding performance and foraging of blue and great tits, and the abundance of arthropods living on the trees of an oak-wood and of a coniferous reafforestation were studied in Sicily, in order to: 1) compare breeding parameters in natural and semi-natural habitats within the same area; 2) estimate the degree of overlap in peak resource and peak demand of young tits, and the overlap of nestling diet of the two species in the two habitats. Both species had earlier laying dates, laid more eggs and raised more fledglings in the oakwood than in the reafforestation; they achieved the same fledging success within the same habitat type. These differences are probably due to the earlier and hig…
Post-fledging survival of individual great tits: the effect of hatching date and fledging mass
2002
Pre-breeeding survival is one of the major sources of individual variation in lifetime reproductive success. However, very little is known about the reasons for differences in survival among individuals during this important phase of the life cycle. Some studies, using local return rates as indices of survival, have shown a relationship between post-fledging survival and fledging date and mass in birds, most of them suggesting directional selection towards heavy masses and early fledging dates. Recent development of capture-recapture models allows the separate estimate of survival and recapture probabilities, as well as the inclusion of individual covariates into the modelling process. We u…