Home-ranges of tropical Red-capped Larks are influenced by breeding rather than vegetation, rainfall or invertebrate availability

Home-range studies have received considerable attention from ecologists but are greatly skewed towards the north temperate areas. Tropical areas offer an ideal setting to tease apart hypotheses about weather, food availability and social interactions as important factors influencing home-range. In this study, we investigated home-range and movement patterns of the tropical Red-capped Lark Callandrella cineria, a year-round breeding bird with a dynamic social structure. We tracked 56 individuals using radiotransmitters and colour-ring readings over a 23-month period. Our objective was to understand year-round variation in home-range size in the context of the highly aseasonal and unpredictable variation in weather and resources typical of many equatorial habitats, in addition to the birds? changing social structure and year-round breeding. The mean composite monthly home-range of Red-capped Larks was 58.0 ha, and the mean individual home-range size was 19.9 ha, but this varied considerably between individuals. The total number of nests found per month (breeding intensity) best predicted home-range size of non-breeding birds, and of breeding and non-breeding birds combined. We show for the first time that breeding intensity decreases the home-range size of non-breeding individuals. Our study also underlines the relevance of conducting more studies in aseasonal tropical areas in order to disentangle effects of weather, food availability and breeding that vary in parallel, peaking simultaneously in most seasonal areas.