Components of fitness in a sexually selected trait in the blue tit

The tit populations at Wytham Woods, Oxfordshire, have been studied since the 1940's. Wytham Wood is owned and managed by the University of Oxford.

A blue tit on a bird feeder.
Eurasian blue tit (Cyanistes caeruleus)

Wytham Woods is a mixed woodland with many different trees, including stands of beech, oak, hazel and pine. It supports a wide range of species from hares to sparrowhawks to moth caterpillars and fungi.

There is a population of approximately 350 breeding pairs of Blue tits (Parus caeruleus) that nest in concrete nestboxes. This study is part of collaboration between the University of Sheffield and the University of Oxford involving Dr Ben Sheldon, Dr Simon Griffith, Dr Louise Rowe and Iain Barr.

The team is looking at sexual selection and fitness traits of the blue tits. Sexual selection occurs when male reproductive success is non-random compared to certain phenotypic traits. Two examples could be that very colourful males or good singers may get more offspring than bad singers or dull males.

Previous studies have highlighted potential traits of males on which sexual selection may act, the U.V reflectance of feather patches on the head and wings, the length and structure of dawn songs, male size and age.

We analyse samples taken from birds in our population to determine levels of extra-pair paternity. This is a method by which a male can increase his reproductive success and overall "fitness". These data can be compared between males losing and gaining paternity and with their phenotypic traits to see where selection is occurring.

We used microsatellite markers to determine paternity, by running gels on the ABI 377 sequencing machine here at Sheffield. From this, the blue tit chicks can be assigned to their correct genetic parents

We also recorded and analysed dawn songs of male blue. The songs vary in their length, the number of notes use, time of singing in relation to dawn and the length of the entire dawn chorus. You can see below two example sonograms of two males songs that are very different. We hope to correlate these song characteristics with the phenotypic traits and my extra-pair paternity data.

Sonogram 1 (top) and Sonogram 2 (bottom)

Blue tit sonogram

Background references

Andersson, M. 1994. Sexual selection. Princetown University Press.

Andersson, M. & Iwasa, Y. 1996. Sexual Selection. TREE (11) 53-58

Andersson, S et al.1998. Ultraviolet sexual dimorphism and assortative mating in blue tits. Proc. R. Soc. Lond. B (265) 445-450.

Birkhead, T. R. & Moller , A.P. 1998. Sperm competition and sexual selection. Academic Press. 826pp.

Hunt, S. et al.1998. Blue tits are ultraviolet tits. Proc. R. Soc. Lond. B. (265), 451-455.

Kempenaers, B et al. 1997. Extrapair paternity in the Blue Tit (Parus caeruleus) : female choice, male characteristics, and offspring quality. Behavioural Ecology (8) 481-492.

Krokene, C. Rigstad, K., Dale M. Lifjeld, J.T. 1998. The function of extrapair paternity in blue tits and great tits: Good genes or fertility insurance? Behavioural Ecology 9, 649-656.

Poesel A, Foerster K, Kempenaers B 2001The dawn song of the blue tit Parus caeruleus and its role in sexual selection Ethology 107(6) 521-531.

Sheldon, B.C., Andersson, S. Griffith, S.C., Ornborg, J., Sendecka, J. 1999. Ultraviolet colour variation influences blue tit sex ratios. Nature 402, 874-877.


Mr Iain Barr (2000-2005)


Professor Terry Burke
Dr Simon Griffith


European blue tit research collaboration including:

Blue tit genotyping methodology

Molecular Ecology in the blue tit
Fifteen microsatellite loci for the blue tit and PCR conditions (collected and compiled by Simon Griffith.

Dawson DA, Hanotte O, Greig C, Stewart IRK, Burke T (2000) Polymorphic microsatellites in the blue tit Parus caeruleus and their cross-species utility in 20 songbird families. Molecular Ecology9, 1941-1944.

This project is funded by the Natural Environment Research Council.

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