An inordinate fondess for seabirds: how to explain patterns in abundance and diversity of albatrosses and petrels across the Southern Ocean

Brief summary:

The project will examine the role of habitat availability and preference in explaining occurrence and abundance of different species, and in structuring seabird communities

Importance of the area of research concerned:

Explaining why some seabirds number in millions and others are naturally rare, and some are single-island endemics and others widespread, is not easy. Potential mechanisms include allochrony, differences in distribution or foraging behavior. These determine the intensity of competition for resources, resilience in the face of environmental variability and, over time, population sizes and trends. In the Southern Ocean, many predator communities are highly speciose. Although albatrosses and petrels can access vast areas of ocean, tracking has revealed considerable habitat specialization. Yet, surprisingly few studies have examined consistency in habitat use and preferences across populations, whether foraging habitat might explain why particular species are absent, much more or less abundant at some sites than others, or have an ecological analogue better adapted to local conditions. This knowledge is invaluable for explaining patterns in abundance and diversity, and the structure of communities. It also helps tease apart natural and anthropogenic drivers of population dynamics in these often threatened species, and has major implications for designation of marine protected areas.

Project summary :

How seabirds co-exist, particularly during breeding, has fascinated researchers keen to understand niche partitioning. The recent exponential increase in tracking offers unprecedented opportunities for research on their distribution, ecology and evolution. Knowledge of key habitat variables allows species distribution models (SDMs) to be built, but adjacent colonies can show spatial segregation, and SDMs often perform poorly when applied to other populations. This project will use extensive tracking data from albatrosses and petrels at different island groups to: compare habitat use and feeding behavior across the annual cycle; test predictive performance of SDMs; determine the role of accessibility and preference in explaining habitat use across populations; examine convergence in habitat preference by ecologically-similar species at different sites and its role in community structure

What will the student do?:

The student will apply the latest techniques for analyzing spatial data. This will include incorporating location error, reconstructing paths, defining behavioural states (e.g. foraging/resting/transit), and other approaches to movement analysis. The ultimate focus will be to compare habitat use and preference among species to understand community structure, potentially using GAMs, GLMMs, Hidden Markov Models, State Space Models, Expectation‐maximization Binary Clustering, Random Forest and other approaches. The student will have access to extensive distribution and at-sea activity (immersion) data available for 11 species of albatrosses and petrels at South Georgia, including >3000 tracks collected using satellite-transmitters, GPS or GLS loggers. Most tracks are from individuals of known age, sex and breeding history. Comparable datasets exist from other island groups and have been offered by long-standing collaborators. Habitat use and preference will be modelled in terms of satellite remote-sensed environmental datasets, including sea surface temperature (SST), SST anomalies, chlorophyll a concentrations, sea level height anomalies, ice coverage, wind and precipitation