Due to increased persecution and anti-bird architecture in British cities, which has drastically reduced available nesting sites, some of the UK’s feral pigeon populations no longer build nests or lay eggs and instead give birth to a single chick. The new behaviour has been witnessed mostly in London since 2018 and has now been confirmed in Bristol and Exeter.
During gestation of 21 days, the female pigeon becomes virtually flightless due to the weight of the growing chick inside her. When born, the squab – as young pigeons are known – is already able to walk and can fly within 11 days. Previously it was typical for feral pigeons to lay two eggs but the extra demands of pregnancy mean the female now only bears a single offspring.
The rock dove, the wild ancestor of the urban pigeon and found now on a few coastal sites around the west coast has not exhibited any change of behaviour.
Ornothologist Dr Irma Turtledove of Severn University has been studying live birth in pigeons near her home in Bristol during the Covid lockdowns and she told BBC Countryfile Magazine: “Viviparacity [live birth] in birds is unknown. This astonishing phenomena reveals how quickly some animals can adapt to the environmental pressures that we humans inflict on their lives.”
While the new behaviour has astonished ornithologists, Michelle Cracken of the National Egg-Layers Union (NELU) expressed concern that this behaviour couple leap species and impact on the chicken industry. "There has already been a shortage of eggs this past winter due to a variety of supply factors but if chickens start laying live young, where will the nation get its breakfast eggs from? It could devastate an already exasperated industry."
Almost all mammals give birth to live young and live birth is common among fish, reptiles and amphibians. However, this is the first observation of live birth among the world’s 10,000 bird species.
