Unlike their eastern or western relatives, Mountain Bluebirds rarely eat seeds or berries. Mountain Bluebirds also differ from other bluebirds in that they often hover while foraging. Similar Species Bluebirds and other small thrushes. Pair Formation and Territoriality Males return to the breeding grounds before the females and establish territories. This happens in late march in the south but not until early April in the North.
Females arrive several days to a few weeks later.
Initially, pairs aggressively defend a large area around their nest site, but as the breeding season progresses, the size of the defended area decreases and becomes more localized around the nest. Mountain Bluebirds defend territories against others of the own species, as well as against other bluebird species in areas where their breeding ranges overlap. Mountain Bluebirds are basically monogamous. But, as with other bluebirds, both males and females sneak copulations with individuals that are not their mates. For this reason, males guard their mates from the time a pair forms until the female lays her eggs.