Revisiting the Baltimore-Bullock's Oriole hybrid zone reveals changing plumage colour in Bullock's Orioles.

Hybrid zones are dynamic areas where populations of two or more interbreeding species may change through an influx of novel genetic material resulting from hybridization or selection on standing genetic variation. Documenting changes in populations through time, however, is challenging because repeated samples are often missing or because long-term storage can affect trait morphologies, especially colour traits that may fade through time. We document a change in carotenoid-based orange breast feathers of Bullock's Orioles ( from the Great Plains hybrid zone, USA.

Staging to join non-kin groups in a classical cooperative breeder, the Florida scrub-jay.

Why unrelated members form groups in animal societies remains a pertinent topic in evolutionary biology because benefits for group members often are not obvious. We studied subordinates that disperse to join unrelated social groups in the Florida scrub-jay Aphelocoma coerulescens, a cooperative breeding species mainly composed of kin-based groups. We evaluated potential adaptive benefits of dispersing to become an unrelated helper (staging) versus remaining home and dispersing only to pair and breed (direct dispersal) to understand why non-kin-based groups form.