Temporal avoidance as a means of reducing competition between sympatric species

Abstract

Human activity has modified the availability of natural resources and the abundance of species that rely on them, potentially changing interspecific competition dynamics. Here, we use large-scale automated data collection to quantify spatio-temporal competition among species with contrasting population trends. We focus on the spatial and temporal foraging behaviour of subordinate marsh tits Poecile palustris among groups of socially and numerically dominant blue tits Cyanistes caeruleus and great tits Parus major . The three species exploit similar food resources in mixed groups during autumn–winter. Using 421 077 winter recordings of individually marked birds at 65 automated feeding stations in Wytham Woods (Oxfordshire, UK), we found that marsh tits were less likely to join larger groups of heterospecifics, and they accessed food less frequently in larger groups than in smaller ones. Marsh tit numbers within groups declined throughout the diurnal and winter periods, while the number of blue and great tits increased. However, sites that attracted larger groups of these heterospecifics also attracted more marsh tits. The results suggest that subordinate species exhibit temporal avoidance of socially and numerically dominant heterospecifics, but have limited ability for spatial avoidance, indicating that behavioural plasticity enables only a partial reduction of interspecific competition.

Alloparenting by Helpers in Striped Hyena (Hyaena hyaena)

“…Our observations confirm that during the breeding period, the adult female at the den is solitary, elusive, and not exclusively nocturnal. This also raises the question of differences in habitats, resources, and other life cycle parameters to reduce inter- or intra-specific competition [ 49 ] to maximize fitness. However, we are unable to determine the activities of the females when away from the den daily for several hours, potentially socializing with other adults at a distance; this remains to be studied.…”

“…The fact that no other studies have definitively reported—except for the one unpublished observation [ 25 ]—the relatively high occurrence of alloparenting by helpers in striped hyenas may be because it is, in general, a rare phenomenon across the species range. However, one must also take into account that the number of studies on breeding in striped hyenas is negligible to non-existent; most studies address the ecology—that is, food/prey [ 48 , 49 , 50 ], den locations [ 51 ], physiology [ 52 ], distribution and densities [ 53 , 54 ], threats and conservation [ 55 , 56 ], social interactions [ 45 , 57 ], population trends [ 26 ], human-hyena conflict [ 58 ], etc.…”