Very short delays prior to escape from potential predators may function efficiently as adaptive risk-assessment periods
Source: Behaviour, Volume 146, Number 6, 2009 , pp. 795-813(19)
Abstract:Periods between predator detection and an escape response (escape delays) by prey upon attack by a predator often arise because animals trade-off the benefits such a delay gives for assessing risk accurately with the costs of not escaping as quickly as possible. We tested whether freezing behaviour (complete immobility in a previously foraging bird) observed in chaffinches before escaping from an approaching potential threat functions as a period of risk-assessment, and whether information on predator identity is gained even when time available is very short. We flew either a model of a sparrowhawk (predator) or a woodpigeon (no threat) at single chaffinches. Escape delays were significantly shorter with the hawk, except when a model first appeared close to the chaffinch. Chaffinches were significantly more vigilant when they resumed feeding after exposure to the sparrowhawk compared to the woodpigeon showing that they were able to distinguish between threats, and this applied even when time available for assessment was short (an average of 0.29 s). Our results show freezing in chaffinches functions as an effective economic risk assessment period, and that threat information is gained even when very short periods of time are available during an attack.
Document Type: Research article
Affiliations: 1: Bute Building, School of Biology, University of St. Andrews, St. Andrews, Fife KY16 9TS, UK;, Email: email@example.com 2: Centre for Agri-Environment Research, School of Agriculture, Policy & Development, University of Reading, Reading RG6 6AR, UK 3: Division of Biology, School of Biology and Psychology, Ridley Building, University of Newcastle, Newcastle-Upon-Tyne NE1 7RU, UK 4: Edward Grey Institute, Zoology Department, South Parks Road, Oxford OX1 3PS, UK
Publication date: 2009-06-01