Drivers of individual foraging/behaviour specialisation in a model seabird: The Falkland Islands shag

This PhD will investigate how intra-specific competition and environmental variation influence individual specialisation in foraging behaviours by studying the Falkland Island shag (Leucocarbo atriceps albiventer). This species is part of a Southern Ocean complex of poorly known species/subspecies, many of which, including the Falkland Island shag, have not been studied in detail. However, as a widely-distributed resident seabird, it offers a model system to not only follow individuals from colonies of varying size and with access to different oceanographic environments; but to examine these contrasts year-round. Such characteristics make this species an excellent model to run a 'natural experiment' across gradients of competition (colony size) and environmental conditions (inshore and offshore colonies and seasonal variation in productivity and daylength) through which to examine drivers of individual variation in foraging/behavioural specialization.

Individual variation is increasingly recognised as being central to our understanding of ecological and evolutionary processes, and has important implications for species conservation. In particular, the relevance and extent of consistent behavioural differences ('personality'), and the degree of plasticity or specialisation shown by individuals, has important consequences for a range of key traits including survival and reproductive success. These translate into population level impacts because they influence the susceptibility of individuals to anthropogenic threats. While behavioural variation among individuals is often clear, what is less well understood empirically is what drives individuals to generalise or specialise across contexts. Classical niche theory suggests that increased intra-specific competition (i.e. top-down effects) drives increasing levels of individual specialisation. However, environmental opportunity and resource availability (i.e. bottom-up effects), also vary temporally and spatially, for example as a result of anthropogenic impacts and seasonality, and represent an independent gradient with important consequences for niche divergence.

This multidisciplinary project will collect novel information from multiple colonies around the Falkland Islands on 1)at-sea behaviour via biologging devices (e.g. GPS, accelerometry and dive-depth tags) 2)foraging preferences using stable isotope, DNA metabarcoding and regurgitate analysis, and 3)will combine it through state of the art statistical modelling. Ultimately, this project will allow us to make important scientific and applied contributions through:
- Empirical testing of ecological niche theory.
- Informing proposed Falkland Islands Marine Managed Areas and improving environmental impact assessments for current, and future, extractive industries through building baseline data on an important but poorly known nearshore predator.