Optimal foraging - mixed species flock of redwings and blackbirds foraging on berries

Animals can forage more optimally by joining a social group with others (including individuals from other species). In this example, redwings (Turdus iliacus) a thrush that is a winter migrant to the UK forages on berries with resident blackbirds (Turdus merula). However, there are trade-offs to this foraging behaviour, such as competition for resources and aggression.