Telomere dynamics in relation to experimentally increased locomotion costs and fitness in great tits

Evidence that telomere length (TL) and dynamics can be interpreted as proxy for 'life stress' experienced by individuals stems largely from correlational studies. We tested for effects of an experimental increase of workload on telomere dynamics by equipping male great tits (Parus major) with a 0.9 g backpack for a full year. In addition, we analysed associations between natural life-history variation, TL and TL dynamics. Carrying 5% extra weight for a year did not significantly accelerate telomere attrition. This agrees with our earlier finding that this experiment did not affect survival or future reproduction. Apparently, great tit males were able to compensate behaviourally or physiologically for the increase in locomotion costs we imposed. We found no cross-sectional association between reproductive success and TL, but individuals with higher reproductive success (number of recruits) lost fewer telomere base pairs in the subsequent year. We used the TRF method to measure TL, which method yields a TL distribution for each sample, and the association between reproductive success and telomere loss was more pronounced in the higher percentiles of the telomere distribution, in agreement with the higher impact of ageing on longer telomeres within individuals. Individuals with longer telomeres and less telomere shortening were more likely to survive to the next breeding season, but these patterns did not reach statistical significance. Whether successful individuals are characterized by losing fewer or more base pairs from their telomeres varies between species, and we discuss aspects of ecology and social organisation that may explain this variation

Empleo de análisis de datos a gran escala para evaluar rasgos de historia vital y de comportamiento: el caso de la población de cigüeñas blancas Ciconia ciconia reintroducidas en los Países Bajos

The White stork Ciconia ciconia has been the object of several successful reintroduction programmes in the last decades. As a consequence, populations have been monitored over large spatial scales. Despite these intense efforts, very few reliable estimates of life history traits are available for this species. Such general knowledge however constitutes a prerequisite for investigating the consequences of conservation measures. Using the large–scale and long–term ringing and resighting data set of White storks in the Netherlands, we investigated the variation of survival and resighting rates with age, time and previous individual resighting history, and in a second step supplementary feeding, using capture–recapture models. Providing food did not seem to affect survival directly, but may have an indirect effect via the alteration of migratory behaviour. Large–scale population monitoring is important in obtaining precise and reliable estimates of life history traits and assessing the consequences of conservation measures on these traits, which will prove useful for managers to take adequate measures in future conservation strategies.Durante las últimas décadas, la cigüeña blanca Ciconia ciconia ha sido objeto de diversos y satisfactorios programas de reintroducción, lo que ha permitido controlar poblaciones a grandes escalas espaciales. Pese a la intensidad de tales esfuerzos, se dispone de muy pocas estimaciones fiables acerca de los rasgos de la historia vital de esta especie. No obstante, estos conocimientos generales constituyen un requisito previo para investigar las consecuencias de las medidas de conservación. El empleo de datos de reavistaje y de anillamiento a largo plazo y a gran escala de las cigüeñas blancas de los Países Bajos nos ha permitido investigar la variación en las tasas de supervivencia y de reavistaje según la edad, el tiempo y la historia previa de reavistajes individuales. Asimismo, en una segunda fase, hemos analizado los efectos de la alimentación suplementaria a partir de modelos de captura–recaptura. Parece que la provisión de alimentos no incidió directamente en la supervivencia, pero es posible que tuviera un efecto indirecto como consecuencia de la alteración del comportamiento migratorio. El control de la población a gran escala es fundamental para obtener estimaciones precisas y fiables de rasgos de historia vital, así como para evaluar las consecuencias de las medidas de conservación de dichos rasgos, que resultarán de especial utilidad para los gestores a la hora de emprender iniciativas apropiadas con respecto a las estrategias de conservación futuras

S38-5 Are unseen effects of early environment negligible? Three examples in great tits (Parus major)

Abstract Three case studies failed to demonstrate impacts of early environment or maternal effects on breeding in situations where they could have been expected. This leads to a number of methodological questions about the resolving power required to detect such impacts, but above all else to the conclusion that maternal effects and homeotic control are opposites. When assessing potential maternal effects, one has to consider not only the developmental period in which they occur but also the later stage of life of concern, because, with age, maternal effects may become less and less important or disappear altogether. The only real measure that there is of the relative importance of early environment and maternal effects is their proportion in phenotypic variance in the traits of interest

Metabolic costs of bat echolocation in a non-foraging context support a role in communication

The exploitation of information is a key adaptive behavior of social animals, and many animals produce costly signals to communicate with conspecifics. In contrast, bats produce ultrasound for auto-communication, i.e., they emit ultrasound calls and behave in response to the received echo. However, ultrasound echolocation calls produced by non-flying bats looking for food are energetically costly. Thus, if they are produced in a non-foraging or navigational context this indicates an energetic investment, which must be motivated by something. We quantified the costs of the production of such calls, in stationary, non-foraging lesser bulldog bats (Noctilio albiventris) and found metabolic rates to increase by 0.021 ± 0.001 J/pulse (mean ± standard error). From this, we estimated the metabolic rates of N. albiventris when responding with ultrasound echolocation calls to playbacks of echolocation calls from familiar and unfamiliar conspecific as well as heterospecific bats. Lesser bulldog bats adjusted their energetic investment to the social information contained in the presented playback. Our results are consistent with the hypothesis that in addition to orientation and foraging, ultrasound calls in bats may also have function for active communication