Time spent grooming is a labile trait in waterfowl that varies with foraging ecology but not sociality

Abstract

Grooming serves many purposes in animals including removing ectoparasites and thermoregulation. Time spent grooming varies to a large extent among species and often represents a large component of the time budget. Nevertheless, few comparative analyses have been carried to determine the ecological correlates of grooming in animals. Time spent grooming was analysed in a sample of 78 species of waterfowl using a phylogenetic framework and the raw data. The phylogenetic analysis revealed no relationship between time spent grooming and ecological factors such as body mass, latitude and foraging group size. The raw data analysis indicated that time spent grooming varied mostly within rather than among species, suggesting that the phylogenetic signal may be weak for this trait in waterfowl. In a sample of 153 time budgets, time spent grooming increased with body mass, decreased with latitude, was smaller in browsing species, in migratory species and in species with no access to agricultural food. However, time spent grooming was not related to sociality in the breeding and non-breeding seasons. The effect of latitude, agricultural food and foraging technique is probably related to time constraints, which are relaxed at lower latitudes, when extra food is available and when animals do not browse allowing more time to grooming. However, ectoparasite burden is also known to vary in relation to these ecological factors and disentangling the relative contribution of ectoparasite burden and time constraints remains a challenge.