Abstract: Externally attached remote-sensing devices used to study animals in their environment are a possible source of disturbance, notably in terms of drag, for diving species. The aim of the present study was to assess the possible effect of device-induced drag on the diving performance of great cormorants Phalacrocorax carbo. Based on wind-tunnel measurements, we assessed the effect of device size on drag and derived a formula to predict how drag changes as a function of both swim speed and device cross-sectional area. Tests on captive cormorants indicated that drag had an effect on the energy expenditure (using dynamic body acceleration as a proxy) during the dive. Wind tunnel-derived drag metrics were combined with data from the literature to construct a model predicting the power consumption of diving cormorants according to device size. Applying the model to dive data from 6 free-living great cormorants (recorded using implanted time-depth recorders) indicated that a device constituting only ca. 3% of the bird’s cross-sectional area could cause a 1.7% increase in power consumption when swimming. However, if a bird maintains constant power underwater, e.g. by decreasing foraging speed with increasing drag, this would result in a 7.1% reduction in the distance travelled during the bottom (active hunting) phase of the dive. Device-related increases in drag are also likely to reduce the maximum speeds achievable by these pursuit predators. The present study highlights the interaction between both drag coefficient and swim speed for diving animals with externally attached devices.

Abstract: Invited talk
University of British Columbia, Vancouver, Canada, July 2015

Abstract: Growing evidence suggests that telomeres, non-coding DNA sequences that shorten with age and stress, are related in an undefined way to individual breeding performances and survival rates in several species. Short telomeres and elevated shortening rates are typically associated with life stress and low health. As such, telomeres could serve as an integrative proxy of individual quality, describing the overall biological state of an individual at a given age. Telomere length could be associated with the decline of an array of physiological traits in age-controlled individuals. Here, we investigated the links between individuals’ relative telomere length, breeding performance and various physiological (body condition, natural antibody levels) and life history (age, past breeding success) parameters in a long-lived seabird species, the king penguin Aptenodytes patagonicus. While we observed no link between relative telomere length and age, we found that birds with longer telomeres arrived earlier for breeding at the colony, and had higher breeding performances (i.e. the amount of time adults managed to maintain their chicks alive, and ultimately breeding success) than individuals with shorter telomeres. Further, we observed a positive correlation between telomere length and natural antibody levels. Taken together, our results add to the growing evidence that telomere length is likely to reflect individual quality difference in wild animal.