Plains Gerbils (Gerbilliscus robusta) as food of the Barn Owl (Tyto alba) in the Serengeti Plains (Tanzania): Thirty-Six Years Later

Abstract

The barn owl (Tyto alba (Blyth 1862) roosts and nests in crevices and caves of kopjes (rock outcrops) of the Serengeti plains. Its major food in the 1970’s was found to be Gerbilliscus robusta (Cretschmer 1826) which inhabits the expansive grasslands surrounding the kopjes. In October 2012, pellets of the owl were collected from one of its roosting cave in the Gol Kopjes at the plains; the roosting cave was the same as one where a 1976 pellet collection was made. Collected intact and disintegrated pellets were weighed and sorted to identify and enumerate their contents. Morphometrics of sorted out bony remains from the pellets were measured to assist in identifying the taxonomic status of the pellet contents and in determining the size ranges (including lengths and widths) of bone pieces ingested by the owls. Pellet contents of the 2012 collection were found to be of similar sizes and types as those of 1976 suggesting that species composition of the pellet contents was similar over the 36 year period. Skull and other bone contents were mostly (about 90%) of Gerbilliscus robusta, suggesting this rodent to still be an important food item of the barn owl in the Serengeti short grassland plains.

Key words: Serengeti plains, kopjes, Barn Owl, plains gerbil