Repeated Successful Nest Sharing and Cooperation between Western
Kingbirds (Tyrannus verticalis) and a Female Western Kingbird x
Scissor-tailed Flycatcher (T. forficatus) Hybrid
Abstract
Nest sharing by birds, or the phenomenon where multiple individuals of
different species contribute genetically and parentally to a single
nest, is a rare form of cooperative breeding that has only occasionally
been reported in socially monogamous birds. Here we describe, both
behaviorally and genetically, the unique case of two female birds, a
western kingbird (Tyrannus verticalis) and a western kingbird x
scissor-tailed flycatcher (T. forficatus) hybrid simultaneously
occupying (and likely co-incubating) a brood in a single nest. Both
females provisioned nestlings, and they did this in two consecutive
years (producing four fledglings each year). Genomic data from the
females revealed that they were unrelated and parentage analyses
revealed that both females contributed genetically to at least one of
the offspring, and at least two fathers were involved. In total, this is
the first reported case of nest sharing involving a hybrid individual
and the first case within the family Tyrannidae.