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At E&M we are passionate about nature, so set out to explore our particular biodiversity in a different way. In Europe's Green Gems you will learn about the hidden gems of Europe's biodiversity - or not so delightful uniquenesses. In this issue, you decide whether it's a gem, or a dark stone: pigeons. Erik Gerritsen goes over their bad, bad reputation and gives you reasons why you should start looking at those "flying rats" differently.

The flying rat

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Photo by Alexander Garnauf, Creative Commons 3.0
The typical horror picture: thousands of pigeons invading parks and squares.

For most a symbol of love and peace. For some a disgusting flying rat. Pigeons have become an inseparable part of most urban dwellers – and are to some inner-city folks the only wild bird encountered on a daily basis.

The pigeons roaming our cities are descendants of the Rock Dove (Columba livia), a species originally found in the Mediterranean, Middle-East, Central Asia and India. Their name Rock Dove was not pulled out of thin air: this pigeon likes it raw - Rock Doves find both shelter and breeding places in caves, and spend the time in between with peacefully eating seeds. While most pigeons are found in more wooded areas, like for example the Wood Pigeon, the Rock Dove took an interesting evolutionary road to avoid nesting competition and became a cave-dweller. Pigeons are remarkable flyers, and their harsh living environment means flying longer distances for food. Despite their commuting behaviour, Rock Doves quickly suffer from homesickness and return to their own cave every night.

Humans appreciate pigeons for many different reasons. Pigeons taste good, as do their eggs, pigeons are gracious and peaceful, they can deliver mail. Pigeons were even kept in large numbers for their dung, a potent natural fertiliser, until chemical fertiliser made this practice unnecessary (in Cappadocia, central Turkey, where dovecotes are cut from natural rock, this tradition is kept alive, at least for tourists). Domestication of pigeons started in the late Stone Age in the ancient Middle East. The Greeks introduced pigeon keeping to Europe (isn't that worth a bail-out?) and the Romans marketed it all over the continent. In Medieval times, pigeon keeping had become an exclusive business for the rich, who both sold pigeon-dung fertiliser and served pigeon breast to unexpected guests. This increasingly lead to conflict with farmers, as flocks of pigeons frequently ate their freshly sown seeds. A French law granting the possession of a dovecote, a right reserved exclusively for nobility, was only abolished as late as 1789.

 When there is food around, pigeons can breed up to eight times per year.

Rock Pigeons are very fertile too. The constant temperature in caves allows them to breed all year round. When there is food around, pigeons can breed up to eight times per year. A blackbird, for comparison, can breed up to 4 times a year. Most albatrosses start breeding after at least 5 years and only lay one egg every other year. Pigeons are one of the only birds that are able to reproduce in the year that they are born: so while we waste our time holding hands and exploring playground love, pigeons just grow up and start womanising. And what better place to womanise than in cities? One big rock, with plenty of perfect edges to drop a couple of eggs. Few enemies, except for some fat cats. Fastfood available 24/7. Hey, it almost gets me enthusiastic! British research showed that of all birds adapted to urban life, only city pigeon density keeps increasing with increasing human density. With inner cities we have created the ultimate pigeon habitat!

The siege of our cities

The conquest of our cities by pigeons is not to everyone's satisfaction: anyone who had breeding pigeons above their shop or balcony can understand why. Pigeons don't shy away from shitting on their own doorstep. In the city of Prague, pigeons have been estimated to be responsible for around 500 tonnes of droppings every year. Pigeons and their shit have been accused of bringing the most horrible diseases to European cities. This has been well studied, and except for a Bird Fanciers Lung, caused by daily direct contact with pigeon dung and dust, it has never been proven! Nonetheless, starting your day by slipping on bird shit, or even worse catching it on your head, is not why you moved to the city. 

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Photo by Jasper Yue, Creative Commons 2.0
In France, breast of squab (young pigeon) is a delicacy.

Many methods have been tried to control pigeon numbers. Most strategies were built on killing grown up pigeons. Gas, poisoning, nets, shooting, and many other creative ways have been explored. However, none of these strategies has proven to be effective: as you now know, pigeons breed fast and taking large parts of the population out means lower competition for food and higher reproduction rates. Numbers restore themselves rapidly. Very rapidly. To illustrate: in Barcelona, it wasn't possible to reduce the 71 000 pigeon population by killing 108 000 pigeons over a period of only four years. In the Netherlands, public outrage broke out when the secret came out that one of its cities had caught thousands of city pigeons in cages and sold them as exclusive pâté.

If killing is not an option, scaring could be. A simple method is to make favourite spots on buildings inaccessible, for example with spikes. An effective strategy, but not very neighbour-friendly. But there is more to choose from: electronic ultra sound raptor noise. Re-designing new buildings. Even kites have been strategically attached to buildings to scare away pigeons. Natural solutions exist as well: raptors like hawks have increasingly occupied cities because of tasty pigeon abundance. The most well-known is probably the Peregrine falcon, the fastest member of the animal kingdom, which is nowadays a common sight in most European capitals. Peregrine falcons are normally found breeding on cliffs. High-rise buildings like churches, sky-scrapers and factories don't seem like a big difference to them. Still, a hungry falcon only eats a couple of pigeons a week. The city of New York decided to speed up this process by training hawks to catch pigeons continuously. This program nearly ended when a trained hawk named Galan caught a stray Chihuahua for breakfast.  

their bright side  

Apparently, scaring pigeons out of their urban paradise is not an easy task either. And why would we? Pigeons bring a lot of life to public places. Continuous reproduction also means continuous courtship: it is worth having a closer look at pigeon mating behaviour - especially with your date or lover. Besides that, who would clean up all those French fries voluntarily? The best thing we can do is welcome our pigeons as friends and, like friends, helping them by showing our boundaries. The most effective solution for harmonious human-pigeon co-habitation seems to be the good-old dovecote. In 1994, the German city of Aachen started to strategically place small dovecotes on rooftops, specifically designed to seduce pigeons away from places where they were causing inconvenience. In the dovecotes, some of the eggs are replaced by plastic decoys, keeping pigeon numbers down. Other countries soon followed.

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Photo by Dora, Creative Commons 3.0
So what do you think? Some pigeons look gorgeous.

In difficult times, people tend to rely on ancient wisdom. Recently, inhabitants of the besieged Syrian city of Homs used pigeons to send information asking emergency services for assistance. Pigeons have saved human lives in many ways and will continue to do so. So if one of them chooses your balcony as a home, think twice before serving it to your cat for lunch. Perhaps your balcony looks too much like an empty rock. Maybe your neighbours waste too many French fries. Maybe your house is badly insulated, making temperature on your balcony constant year-round. Maybe all three? In any case, the pigeon can't help feeling at home. Drop an e-mail to your local government to request a dovecote. If they don't know what you are talking about, ask them to look beyond borders. Pigeon lofting is still open source. 

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