Pigeon musings

A pair of Woodpigeons (Columba palumbus) provide endless interest and entertainment in our garden. The male, instantly recognisable by a deformation which results in some feathers on his upper back pointing outwards, is fiercely territorial seeing off all comers with, if necessary, wing-to-wing combat. He, surprisingly, was the offspring of the resident pair a couple of years ago. The young sometimes fall prey to the local Sparrowhawks (Accipiter nisus) (two dead in the garden so far this year).

We have four species of columbiform within walking distance. Apart from the ubiquitous Woodpigeon, there are Stock Doves (Columba oenas) in a nearby park, Collared Doves (Streptopelia decaocto) in gardens (although now less common than, say, 20 years ago) and small flocks of Rock Doves (Columba livia) on the coastal cliffs which do appear to be the wild form rather than the feral pigeons which occur in towns and country.

It was while watching the Woodpigeons doing their regular, almost constant, patrol under the bird feeders in the hope of dropped sunflower hearts, that I began to get itchy feet and think of when, with covid still in full flow in most parts of the world, we might hope to see a pigeon or dove other than in deepest Ayrshire. Columbiforms have been highly successful in reaching virtually all parts of the world and we have watched them in very different circumstances and locations—from single birds on a number of South Pacific islands to vast flocks of African Green Pigeons (Treron calvus) in the Republic of Congo. Most of my photography is video but here are a couple of photographs of pigeons we have seen in vastly different habitats and with vastly different ranges: from Bhutan in 2016, Snow Pigeons (Columba leuconota), which have a wide distribution around the Himalayas; from 2010, a Henderson Island Fruit Dove (Ptilinopus insularis) endemic to the scrub forest of that 47 square-kilometre patch of raised coral reef in the Pacific.

Pigeons usually featured in my lectures to undergraduates on lactation since they feed their young  ‘milk’ produced by the lining of crop. The mechanism of production, sloughing off whole cells, differs from mammalian milk secretion but the major hormonal control is the same. Oscar Riddle (1877-1968) not only discovered the pituitary hormone which he named prolactin but also the fact that it stimulated milk secretion by the mammary gland and the pigeon crop. As a result of this discovery in 1932, the original way to assay mammalian prolactin was by using the response of the pigeon crop sac to pituitary extracts and blood samples. In its various formats, the pigeon crop sac assay was used in physiology and medicine for 40 years until the early 1970s when it was superseded by radioimmunoassay. Kindly remember that when you next see a pigeon or dove, be it a feral pigeon scouring an inner city or a fruit dove on an exotic atoll. There is more to a pigeon than meets the eye.

Snow Pigeons, Bhutan 2016

Henderson Island Fruit Dove, 2010
Photograph by Michael Moore of the Noble Caledonia Expedition Team