New research led by the Department of Zoology has found that the production of food-related vocalisations made by wintering songbirds decreases progressively throughout the day, as foraging group sizes increase.
Wintering songbirds have to find food while avoiding predators. Previous research has demonstrated that birds benefit by forming groups: they use information from others to find food sources while per-capita predation risk decreases through dilution. However, much less is known about in what way birds produce information about food availability, e.g. calls which attract others. Attracting others to food decreases per-capita risk of predation, but increases competition. However, these costs and benefits do not covary linearly with group size, and the effect of recruiting an additional group member is not constant.
Friederike Hillemann, lead author on the paper, said: 'Using a combined observational and experimental approach, we show that wintering songbirds make economic decisions about when to produce information about food availability: As the day progresses and foraging group sizes increase, the costs of producing calls that attract others outweigh the benefits, causing a decrease in vocal activity into the afternoon.'
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Read the paper, published in the Proceedings of the Royal Society B, here: 'Diurnal variation in the production of vocal information about food supports a model of social adjustment in wild songbirds'.
