Generalists, specialists and opportunists: niche metrics of Poicephalus parrots in southern Africa

Abstract

There are distinct differences in the way in which Poicephalus parrots utilise food resources within their distributional range. Our study evaluated the niche metrics of all Poicephalus parrots studied thus far for evidence of linkages between body mass, distributional range and niche breadth. We calibrated the degree of dietary specialisation of Meyer's Parrots in the Okavango Delta, Botswana, over 12 months using a modified Hurlbert's expanded and standardised niche breadth index, and for comparison using Levins's niche breadth, with the food item calendars of the other Poicephalus parrots in southern Africa. Our study showed that Meyer's Parrot has the widest niche breadth of any Poicephalus parrot studied thus far, which likely plays a role in their wide distributional range. In addition, degree of dietary specialisation was inversely correlated with body mass, whereby the narrower the trophic niche, the larger the body size.