The effects of food availability and distance to protective cover on the winter foraging behaviour of tits (Aves: Parus)

B. Walther, A. Gosler

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

To maximize fitness, many animals must trade off their need to forage efficiently against their need to avoid predators. We studied such a trade-off in four species of tits (Paridae) in a forest near Oxford, UK. During winter, tits form flocks which increase feeding efficiency and reduce predation risk. These flocks feed extensively on beech (Fagus sylvatica) seeds, the abundance of which may be critical for winter survival. Because these seeds drop to the ground, where birds are exposed to sparrowhawk (Accipiter nisus) attack, tits need to trade off their need to find seeds against the proximity to protective cover, provided by dense clusters of hawthorn (Crataegus spp.). The quality of the beech crop differs markedly between trees and years. During a year of abundant beechmast, most tits searched for seeds close to protective cover. This 'safety-first' strategy precluded visits to superabundant food patches if they were too far from protective cover. Among beech trees near to cover, tits tended to prefer those with high seed density. Tits benefited from foraging under trees with high seed density because this correlated significantly with seed mass per square metre and because mean search times decreased with increasing seed density. Finally, we show experimentally that great tits, Parus major, can discriminate between edible (viable) and inedible (empty) seeds.

Original languageEnglish
Pages (from-to)312-320
Number of pages9
JournalOecologia
Volume129
Issue number2
DOIs
Publication statusPublished - 2001
Externally publishedYes

Keywords

  • Anti-predator behaviour
  • Discrimination experiment
  • Optimal foraging
  • Winter flocks

ASJC Scopus subject areas

  • Ecology

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