Is the Hamerkop Scopus umbretta a neocolonist or an opportunist nester?

Abstract

We report two cases of large aggregations of Hamerkop Scopus umbretta nests in relatively small areas; the first had a maximum of 639 nests in 2004, all within an area of about 8 km2 near to Entebbe, Uganda. However, in recent years there were far fewer nests, with less than a hundred in 2012. The reasons for this decline are unclear. The second site, in Queen Elizabeth National Park, had 56 nests in 2004. There are very few previous records of such gregarious behaviour in this species. Even though a pair may build more than one nest, it implies the presence of a large concentration of birds, which must therefore require rich food sources.