Non-breeding habitat selection of a sandy shore obligate shorebird

Abstract

The temporal partitioning of species' life history phases according to seasonal environmental variation is pervasive, yet most habitat selection studies have focused on breeding rather than non-breeding periods. Using remote-sensing data and previously collected information on occurrence, this study explores the habitat selection of a non-breeding, resident shorebird (the hooded plover Thinornis cucullatus) on southern hemisphere, high energy beaches exposed to the southern ocean (Victoria, Australia). While many beaches are used for breeding, non-breeding or both, some beaches are never used. These usage patterns may reflect site attributes, which could effectively define non-breeding habitat for the species. We identified and described differences in beachscapes between four distinct types of non-breeding habitat occupation: 1) flocking sites, 2) year-round territories, 3) breeding season only territories, and 4) sites on beaches not occupied by hooded plovers (“no bird” sites). Potentially important habitat variables (36) were measured using a Geographic Information System (GIS) and analysed using multinomial regression following variable selection (Least Absolute Shrinkage and Selection Operator; LASSO). This enabled us to characterise the different site types. Flocking sites were characterised by having southerly aspects and were closer to the nearest breeding territory (hereafter ‘nearest neighbour’) than no bird sites, and year-round territories had closer nearest neighbours than no bird sites and typically were at southwest facing beaches. Breeding territories that were unoccupied during the non-breeding period had less available swash area, were further from nearest neighbours than year-round territories, and typically were southwest facing. No bird sites were further from nearest neighbours than occupied sites and typically were southeast facing. These differences are likely driven by social and ecological factors (i.e. foraging habitat and ecological productivity). This study has identified sites, beach types and habitat features that warrant priority protection from threats such as development, disturbance, marine pollution events and sea level rise.