From hardy cliff dwellers to darling pets to the ancestor of emails✉️, and now a reviled pest, the feral pigeon🕊️, 𝘊𝘰𝘭𝘶𝘮𝘣𝘢 𝘭𝘪𝘷𝘪𝘢 𝘥𝘰𝘮𝘦𝘴𝘵𝘪𝘤𝘢 Gmelin, 1789, is a bird with a long, rich, and complex relationship to humans. As the Hong Kong government, urged by Health Authorities, looks to further clamp down on the age-old pastime of pigeon feeding, we ask, how much do you know about the feral pigeon?
A member of the Columbidae family, which includes about 340 species of pigeons and doves, urban feral pigeons are descendants of domestic pigeons, which are in turn ancestors of the wild Rock Dove, 𝘊𝘰𝘭𝘶𝘮𝘣𝘢 𝘭𝘪𝘷𝘪𝘢. What is the difference between a dove and a pigeon you may ask? Pigeons can refer to larger and heftier members, while doves to smaller ones. There is no real scientific distinction, however, between the two, and the terms can often be used interchangeably depending on where you live and the language spoken. Although the Rock Dove’s native range spans North Africa, Southern Europe, and West Asia, its descendants have been introduced worldwide, often voluntarily, with the migration of humans. In the wild, the lifespan of these birds is 3-5 years, while in captivity they can live up to 15 years and even as long as 35 years for some!
While Rock Doves are granivorous, meaning they eat grains and seeds🌾, their feral descendants have a broader appetite that includes small insects🐛, bread🍞, and food scraps scavenged from human trash. As you can imagine, this makes us, humans, very attractive neighbours. You may also have noticed that feral pigeons are very gregarious creatures, living in flocks of 50 to 500 individuals, depending on the availability of food. Speaking of food, these pigeons have a secret in their lower esophagus called a crop. This is where they can store food that they have scavenged to be digested at a later time. And that’s not all the crop is useful for. Did you know that pigeons can produce “milk”? Well, it’s not actually milk🥛, as true milk is something only mammals can produce. Instead, this is crop milk, produced from secretions from the lining of the crop. The crop milk is semi-solid, and said to resemble “pale yellow cottage cheese” with a high content in protein and fat, but produced by both male and female birds which can regurgitate it to feed their babies👶🏻.
Domestication of Rock Doves may have begun as long as 5,000 years ago, as recorded on Mesopotamian tablets and Egyptian hieroglyphs for ceremonial and culinary purposes. Other research suggests the practice goes back further still, and the Rock Doves may have been revered by Early Near East cultures. This captive breeding continued on, and today over 350 breeds have been derived from the humble Rock Dove. Pigeon breeding even played a part in the development of Darwin’s Theory of Evolution🕰️, citing the practice in several of his works as a domestic example of the power of selection in developing desired traits through successive generations. Yet the human-Rock Dove relationship was not built on aesthetics alone. 𝘊. 𝘭𝘪𝘷𝘪𝘢 has incredible homing instincts, are fast fliers, and can carry up to 10% of their body weight. These skills have been relied upon across the world and across ages to relay important messages such as the results of ancient Roman chariot races or to covert communications during the World Wars. Apart from the domestication of Rock Dove, they were consumed as a type of poultry. Tracing back to archeological evidence, pigeons were consumed as a food source 🍴as early as the Pleistocene, around 10,000 years ago!
In Hong Kong, the first record of 𝘊. 𝘭𝘪𝘷𝘪𝘢 dates from 1953, although they were likely introduced as much as 100 years earlier with the establishment of the British colony as escaped or released domesticated birds. Pigeon racing became a popular sport among local Hong Kongers. However, since the 80s, successive ordinances to limit the rearing of livestock, better regulate sanitation within the city, and increased controversy over animal welfare, have led to the sport falling out of favour. Over time, urban feral colonies were established, particularly in the large urban parks and city centers such as Victoria Park, Tsim Sha Tsui, and Tseung Kwan O, to name a few. But why have they been so successful at colonizing city centers? Believe it or not, urban environments provide a lot that somewhat resembles the Rock Dove’s native habitat. Our skyscrapers and other tall structures are much like cliffs, with ledges and overhangs providing ideal places for roosting. Even the urban island heating effect, the tendency for urbanized spaces to be hotter than surrounding natural environments, can reduce cold stress and provide a climate that better resembles the high temperatures of their natural range. But perhaps the most attractive of all is the boundless supplies of food, whether scavenged or voluntarily offered by humans. The city center is thus a much more attractive home than rural areas.
Despite their hallowed history, the feral pigeons of today have drawn much ire, with concerns over property damage and health. While it is true that feral pigeons can be perceived as reservoirs of human pathogenic organisms🦠, direct transmission between the birds and humans, however, is relatively rare, with a study reporting less than 180 cases globally over a six-decade period. It is undoubtedly that feral pigeons harbour pathogens and have the potential to represent, although infrequently, health risks to us. Results showed, however, that the risk is very low, even for people engaging in professionals who are close to pigeons, such as cleaning droppings. Instead, immunocompromised patients have a higher risk of getting disease from feral pigeons and their excreta. But perhaps the most vexing is the droppings, which can not only cover the sidewalks, cars, and buildings, but the pH of which, over time, can cause corrosion of those structures.
Due to these nuisances, authorities have tried several methods to reduce feral pigeon populations, but with limited success. Attempts at culling were particularly ineffective, because reduced bird numbers meant less competition for food, allowing for an eventual later boom in population or emigration from individuals from nearby populations. The most effective by far, is limiting available food. Conserving and establishing healthy and suitable populations are important for biodiversity. Artificial breeding should also be considered to provide shelter and food sources for pigeons. Nevertheless, education is equally important, no matter the ecology of pigeons or the potential health risks brought by pigeons. Visit the Hong Kong Biodiversity Museum to appreciate this little cute creature👍!
Text: Deidra Wirakusumah, Lydia Chang
Photo credit: Gotcritters, modified
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