Data from: Isodars unveil asymmetric effects on habitat use caused by competition between two endangered species

In order for competing species to coexist, segregation on some ecological
niche component is required and is often mediated by differential habitat
use. When unequal competitors are involved, the dominant species tends to
displace the subordinate one to its less preferred habitat. Here, we use
habitat isodars, an approach which reflects evolutionary stable strategies
of habitat selection, to evaluate whether interspecific competition
between two competing species with distinct habitat preferences, the
little bustard Tetrax tetrax and the great bustard Otis tarda, modulates
their habitat use. Field data on these endangered species demonstrate that
unequal competitors can coexist without completely segregating on their
preferred habitats. The negatively sloped isodar of the subordinate little
bustard unveils its competition with the dominant great bustard.
Interference from great bustards in secondary cereal habitats reinforces
use of preferred natural habitat by little bustards. Studies of
density-dependent habitat selection by a single-species can thus aid in
identifying the effects of competition on community composition, and guide
the conservation of at-risk species. Isodars, in particular, represent a
promising method to gain clear knowledge on interspecific competition for
species in which experimental manipulations are not feasible.