Avian Demography Unit, Department of Statistical Sciences, University of Cape Town, Rondebosch 7701, South Africa; School of Biology, University of Leeds, LC Miall Building, Clarendon Way, LS2 9JT, United Kingdom
Calf, K.M., Avian Demography Unit, Department of Statistical Sciences, University of Cape Town, Rondebosch 7701, South Africa, School of Biology, University of Leeds, LC Miall Building, Clarendon Way, LS2 9JT, United Kingdom; Underhill, L.G., Avian Demography Unit, Department of Statistical Sciences, University of Cape Town, Rondebosch 7701, South Africa