Niche breadth of two lark species in the desert and the size of their geographical ranges

The crested lark Galerida cristata has a much wider geographical range than that of the desert lark Ammomanes deserti. Whereas the latter is strictly a desert species, the former inhabits both desert and non desert regions. Their niche breadths were measured in an area of sympatry in the Negev Desert, along food and habitat dimensions: seed size, and allocation of foraging time to each habitat. Both species share most seed species they consume and forage in the same habitats. But on both niche dimensions the niches were broader, and the temporal fluctuations in the breadths were higher for crested lark. -from Authors