Exploring the future of birds and urban nesting

TWO centuries ago, just 3% of the world’s population lived in cities, says Richard Collins.

By 2008, urban dwellers accounted for 50% and their numbers continue to rise. Wild creatures too are being seduced by the bright city lights. Magpies first bred in Dublin around 1850. Dr Brendan Kavanagh, studying them in the early 1980’s, found that the city had the highest density of breeding magpies to be found anywhere. More recently, foxes have moved to the suburbs where they are now more numerous than their country cousins. Peregrines are nesting on sky-scrapers and church steeples on both sides of the Atlantic. Even wolves are flirting with life in the fast lane; they are visiting town dumps in Eastern Europe. Leopards have taken to prowling the back lanes of some Indian cities at night.

The most conspicuous new urban dwellers are gulls. These scavengers nested traditionally on islands and rocky headlands but, 50 years ago, they needed more breeding space. Roofs and chimneys in towns and cities offer ideal nest locations. Waste food, discarded by slovenly humans, is a ready food source in the metropolis while built-up areas, lit at night, allow more time to forage and feed. Temperatures are higher in cities than on the windswept coastal outcrops the gulls frequented traditionally. Over 400 towns in Ireland and Britain now have nesting gulls. Urban ones escaped the outbreaks of botulism which decimated those at traditional sites.

The new avian citizens have not been welcomed with open arms, however. Untidy nesters, whose white droppings deface buildings, gulls are messy creatures. Noisy calls disturb the beauty-sleep of their hosts in the early morning. Parent birds defend eggs and young aggressively, swooping at anyone venturing too close to the nest. Actual contact is rare but, occasionally, an intruder is struck. Gulls are becoming more brazen; office workers have been mugged while lunching in city parks, their sandwiches snatched by the ravenous pirates.

So, how are urban gulls faring? Do more youngsters fledge from city nests than from traditional ones? How many chicks survive to adulthood? Might they, like their parents, nest on roofs when they come of age, or opt for the more traditional coastal haunts? Will city-fledged gulls remain in the built-up environment for life? Could urban nesting even become the norm for large gulls?

The Irish Midlands Ringing Group is trying to answer some of these questions. Young gulls have been fitted with coloured leg-rings in Dublin. About 220 herring and lesser black-backed chicks have been marked to date, 90 of them in the city centre; one, nick-named ‘Leo’, was caught on the roof of Leinster House. Ireland’s Eye, off Howth, is a traditional breeding haunt; 85 herring gull chicks and 45 great black-backed chicks have been ringed there.

Each ring has letters and numbers inscribed on it. These can be read through binoculars, identifying the wearer. A metal ring, asking the finder to ‘inform BTO British Museum London’, is carried on the bird’s other leg. Where they go and how far young gulls travel after leaving home should become apparent fairly quickly. Determining the ages at which they start breeding and comparing the survival rates of youngsters from the two locations will be much more challenging. Gulls don’t breed until they are at least three years old and some don’t do so for several years after that. Many more chicks will have to be marked, and tracked for years, before meaningful patterns begin to emerge.

The project organisers need your help in finding the ringed chicks. If you should happen upon a gull wearing a ring, whether you can read the code on it or not, please report the find to Sean Kingston at medgullring@gmail.com.


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