I am currently studying coevolutionary relationships between Cuckoo Finches Anomalospiza imberbis and Greater Honeyguides Indicator indicator and their respective hosts, in the Choma District of southern Zambia.

Cuckoo Finches (also known as Parasitic Weavers) parasitise a range of warbler (Prinia and Cisticola) species, some of which have extraordinarily polymorphic eggs (right) which appear to have evolved as a defence against Cuckoo Finch parasitism.Together with Martin Stevens (University of Cambridge), I am investigating how coevolution between host and parasite has been shaped by visual perception.

In collaboration with the late John Colebrook-Robjent, I have also been studying brood parasitism in Greater (right) and Lesser Honeyguides (Indicatoridae) parasitising different host species. In particular, we have been examining egg size and shape specialisation in females parasitising different host species, and exploring the coevolutionary consequences of egg puncturing by the Greater Honeyguide (see 15). Together with Michael Sorenson and Katie Stryjewski (Boston University, USA) we are also studying the mode of inheritance of host-specific adaptations in honeyguides.

Photo copyright www.nigeldennis.com

COSTS AND BENEFITS OF SOCIALITY

My PhD research (2002-2005), supervised by Nick Davies, partly involved a detailed field study of a colonial, communal and cooperatively-breeding bird, the Sociable Weaver Philetairus socius. This is a remarkable bird of the Kalahari and Namib deserts of south-western Africa, where it builds enormous haystack-like communal nests in Acacia trees (see below)

Predation by snakes attracted by the size of weaver colonies appears to be a major cost of extreme sociality in this species. I showed that individuals in colonies of different sizes differ with respect to morphology and reproductive investment (see 16), and carried out various field experiments to attempt to distinguish whether these among-colony differences could be explained by adaptive life-history divergence in colonies of different sizes and hence predation risk (see 22).

Further to predation, parasitism and disease are also potential costs of sociality. If so, then we would expect cooperatively breeding birds that live in groups to invest more in immune defence than pair breeding species. I carried out a comparative study of South African and Malawian birds and found that this was so, at least with respect to one measure of immunity (see 18).

SEXUAL SELECTION AND BIRD MIGRATION

Migratory birds arrive as early as possible on their breeding grounds not only because of its naturally selected advantages, but also because females prefer early-arriving males as mates. Anders Pape Møller and I showed that this could generate the latitudinal trend that is observed in rates of extra-pair paternity in birds, which are higher in the north-temperate zone where many species are migratory (see 7). But spring conditions are not remaining constant, and as the world's climate warms many migratory birds are arriving earlier and earlier on their breeding grounds. However, the degree of such change varies greatly among species - why is this so? Anders Tøttrup, Tim Coppack and I showed that these differences in species's responses to climate change might be explained by female choice, since in strongly sexually selected species there is the most incentive to arrive earlier as conditions become milder (see 12; also 10). Nicola Saino and I have just written a review chapter on the potential relationships between sexual selection and climate change, to appear in a forthcoming OUP book, Effects of Climate Change on Birds.

• Spottiswoode, C.N., Wondafrash, M, Gabremichael, M.N., Dellelegn, Y., Mwangi, M.K., Collar, N.J., Dolman, P.M. (2009) Rangeland degradation is poised to cause Africa’s first recorded avian extinction. Animal Conservation 12: 249-257.
• Spottiswoode, C.N. (2009) Fine-scale life-history variation in Sociable Weavers in relation to colony size. Journal of Animal Ecology 78: 504-512
• Spottiswoode, C.N. (2008) Cooperative breeding and immunity: a comparative study of PHA response in African birds. Behavioral Ecology and Sociobiology 62: 963-974
• Spottiswoode, C.N. & Colebrook-Robjent, J.F.R. (2007) Egg puncturing by the brood parasitic Greater Honeyguide and potential host counteradaptations. Behavioral Ecology 18: 792-799.
• Spottiswoode, C.N., Tøttrup, A.P. & Coppack, T. (2006) Sexual selection predicts advancement of avian spring migration in response to climate change. Proceedings of the Royal Society of London Series B 273: 3023-3029

Birding books:

• Cohen, C. & Spottiswoode, C. (2000) Essential Birding in Western South Africa. Struik Publishers, Cape Town.
• Cohen, C., Spottiswoode, C. & Rossouw, J. (2006) Southern African Birdfinder: Where to find 1400 bird species in southern Africa and Madagascar. Struik Publishers, Cape Town.