Influence of the physical environment and conspecific aggression on the spatial arrangement of breeding grey seals

1 2 Understanding the habitat requirements of a species for breeding is essential for its 3 conservation, particularly if the availability of suitable habitat is a limiting factor for 4 population growth. This is postulated to be the case for grey seals, one of the more 5 abundant marine apex predators in northern European waters. In common with similar 6 studies that have investigated the habitat preferences of breeding grey seals, we use 7 abiotic (topographical, climatological) attributes but, unlike previous work, we also 8 incorporate behavioural variables, particularly the occurrence of aggressive 9 interactions between females and the presence of neighbouring seals. We used two 10 generalized additive models (GAM) in a sequential and iterative fashion. The first 11 model links the occurrence of aggression at particular points in the colony to local 12 topography derived from a Geographical Information System (GIS), presence of 13 neighbouring seal pups and the day of the breeding season. The output of this GAM is 14 used as one of the explanatory variables in a GAM of daily variation in the spatial 15 distribution of births. Although proximity of a birth site to a water source and the 16 presence of neighbouring seal pups both had significant influences on the distribution 17 of newborn pups over time and space, at the scale of the study site it was found that 18 simple rules could predict pup distribution more efficiently than a complex individual-19 based simulation model. 20 21