The increasingly urban status of the Cattle Egret Bubulcus ibis in Uganda, with some observations on its variable breeding seasons and associated species

Abstract

Cattle Egrets Bubulcus ibis, long known for their expanding geographical range, have in recent years also become increasingly urbanized in Kampala, a city with over 1.5 million people, and elsewhere. First recorded roosting in Kampala over 15 years ago, their numbers now exceed 16 000, spread across several sites, at most of which they have also been breeding for several years. However, the numbers nesting are far lower than might be expected from those that come nightly to roost. Breeding in Kampala shows bimodal peaks, perhaps because some birds breed twice a year—which would partly explain their rapid increase in numbers. Timing of breeding is linked to rainfall, but shows more variation between sites and between years than might be expected. Some birds may always have fed in the area that is now Kampala. Today, some feed at the city’s main land-fill site, but most go to the countryside where their consumption of bush-crickets, grasshoppers and other insects is presumably beneficial to farmers. Overall, for breeding and roosting, and to some extent feeding, Cattle Egrets can now be considered as urbanized in this near-equatorial city.