Floating behaviour and singing activity in the great tit Parus major

Abstract

The dawn chorus of songbirds is among the most conspicuous phenomena the animal world has to offer in temperate zones. The biological function of this peak of singing before sunrise, however, is still much debated. In a long-term study on the nightingale (Luscinia megarhynchos), I showed that territory-searching males prospect nightingale territories only during the hour before sunrise. This was a hint that dawn singing may be important to defend the territory against such prospecting males (so-called floaters).

For a generalization of the results, however, it seems necessary to study a second species that does not, like the nightingale, sing at night. A classic dawn chorus study species is the great tit (Parus major), which breeds in easily accessible nestboxes in the surroundings of Oslo. I will investigate whether singing activity of male great tits is most intense at dawn and how it varies with the stages of the breeding cycle. The patterns of singing activity in unmanipulated great tits will then be compared with those of cross-fostered great tits and of blue tits (Parus caeruleus).

Furthermore, I will translocate radio-tagged great tits from one area to another, to observe their territory prospecting behaviour during 48 hours. Since, in contrast to the nightingale, both male and female great tits are present in their territory for several weeks before they start breeding, I will also be able to study how translocated females behave in the hour before sunrise. Should they stay stationary at dawn, while the males prospect other territories, I would have found further evidence that dawn singing of resident males serves to defend the territory but is less important to attract territory-searching females.

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