A homosexual copulation, on first arrival in The Netherlands from the Cape Verde Islands

iago sparrow male on bridge of Plancius (Kees Moeliker)May 19th, 2013 was an historical moment in the history of European ornithology. Four Iago Sparrows (Passer iagoensis) arrived in The Netherlands from the Cape Verde Islands aboard a ship, named Plancius. They are the first know individuals of that species (endemic to the islands off West Africa) to have reached Europe. As the ship accommodated birdwatchers on their ‘Atlantic Odyssey’, the voyage of the sparrows is well documented. Eleven came aboard while the Plancius anchored off Raso Island on May 6th. Seven left the ship on Madeira Island, the remaining four, two pairs, continued their voyage to The Netherlands. They arrived safely.

As a sparrow enthusiast, I was among the first ornithologists to welcome the Iago Sparrows in Europe, in the late afternoon of May 19th, 2013. Although the Plancius was docked in the harbor of Hansweert, and new land was open for colonization, the sparrows remained on deck, enjoying breadcrumbs. One male (pictured above) still resided in the vessel — on the bridge, where he had become friends with the captain.

All four sparrows were timid and passive, up until the moment I released the male from his confinement on the bridge. The other male then sought the company of the Captain’s sparrow, and the two cocks started a fight on the middle deck. I observed this behavior from close quarters.

The aggressive display ended in a clear attempt to copulate. Although I could not observe direct cloacal contact, one male definitely mounted the other and tried to copulate. The male that was mounted did, however, not assume the classic submissive solicitation posture (crouched, neck drawn in, wings slightly drooped), a posture known from observation of female House Sparrows (Passer domesticus) that solicit copulation. Here are pictures that document this remarkable behavior.
two males iago sparrow on deck Plancius (Kees Moeliker)two male iago sparrow fighting on deck Plancius (Kees Moeliker)two male iago sparrows in copula on deck Plancius (Kees Moeliker)
It is striking that ‘The first case of a homosexual copulation attempt in the Iago Sparrow’ — a matter of interest to the scientific community — was observed upon first arrival of these birds in The Netherlands.

BONUS: What should happen with the Iago Sparrows in The Netherlands? [in Dutch]