Can Great Tits (Parus major) Acquire Search Images?

Abstract

A 'search image' is said to be acquired when there is change in the ability of a pred'ator to detect cryptic familiar Young great tits Parus major were presented with 'cryptic' and 'conspicuous' artificial prey on bark backgrounds. The results showed that eleven captive great tits had more difficulty detecting cryptic prey than conspicuous prey. Detailed analysis of video recordings revealed two types of search behaviour in response to cryptic prey: (1) the birds sighted (and successfully flew in to take) the prey from vantage points 0.5 m and further away, or (2) they alighted on the bark and then searched over the bark surface in detail. Search images seem to have been acquired when behaviour (1) was used but there was little evidence for search images when behaviour (2) was used. There was a striking difference in the ability of each bird to locate cryptic prey at first as measured by unsuccessful search, overlooking prey, background-directed pecks, followed by accidental discovery, and its ability to detect them as efficiently as conspicuous prey towards the end of its test.