Three species of birds in one nest

Abstract

Some birds build nests in which to lay eggs and rear offspring. Although occasionally associated with intra- or interspecific brood parasites, a single nest is generally occupied by the parents and offspring of one (and the same) species. However, in Xinjiang, China, we observed multiple breeding pairs of two sparrow species (saxaul sparrow [Passer ammodendri] and Spanish sparrow [Passer hispaniolensis]) inhabiting the nest of a long-legged buzzard (Buteo rufinus). On 4 April 2022, we found a long-legged buzzard's nest in a Euphrates poplar tree (Populus euphratica), near Dongdao Lake at the southern edge of the Gurbantunggut Desert in northwestern China. The nest was composed of poplar and tamarisk (Tamarix sp) branches (on the outside) and twigs (for the base). As we approached this Euphrates poplar, the buzzard was on alert. To our surprise, we detected a few holes in the middle and lower parts of the nest, in which lived several pairs of both sparrow species. According to our previous observations, neither P ammodendri nor P hispaniolensis are cavity-nesting birds, as they typically build their own cup-like nests.