PhD student Nina Bircher and Master student Hongye Zhang perform measurements on the great tits. Photo: Marc Naguib.
Professor Marc Naguib and colleagues from the NIOO have been studying the behaviour of great tits for many years. Usually the males have been at the centre of attention but the new study focuses on the females. Everything we know so far about their sexual selection behaviour has been learned in the lab, says Naguib. ‘We know which song attracts females and which colours they like, but we know nothing about their actual selection behaviour in the field. Their options are limited in the lab: it could be that the man of their dreams just isn’t there. Do females stick with the first partner who comes along, or do they go looking? And what is the role of song and of personality in this?
Great tits are given to extramarital shopping around. In about one quarter of the nests at least one of the young has a different father than the mother’s steady partner. This is known from genetic analysis of the young by Kees van Oers of the NIOO. How that choice by the female comes about is what the new study aims to shed light on. Swiss researcher Nina Bircher at the NWO is going to study this.
In the Westerheide forest near Arnhem, a permanent research location for Naguib and the NIOO, 80 great tits have been fitted with transmitters. More than 130 nesting boxes have been hung up around the woods with receivers that register the birds’ spatial behaviour. The song of the male is recorded by programmed song recorders.
The receivers make it possible to identify precisely which territories – and therefore which males – the females frequent. A genetic analysis of the young can then determine whether these visits were fruitful. Linking these data to the personality tests done by the NIOO on the great tits can lead to interesting conclusions about the sexual preferences of female great tits and the functioning of animal populations.