Cactus wrens Two species squabble over territory.
And both species are thought to be imperiled. Despite all they have in common, the two species don't seem to get along very well. Cactus wrens are robust, colorful birds with a harsh, insect-like call, and have been known to puncture the eggs of other bird species in nearby nests. They may even prey on gnatcatcher eggs. In any case, the gnatcatchers don't like them.