Thursday, 5 April 2007

Power lines and bird deaths

We are all aware of the carnage on the roads, but overhead cables are also amazingly hazardous to birds. In the past week I have found three rooks dead or injured beneath less than 100m of electricity cables that cross a small field we own. The rookery in the adjacent trees only has a dozen nests, and the casualties were all adults, not inexperienced young birds. Multiply that up and there must be a staggering number of birds killed. Of course not all power cables are as hazardous as these -- some kill very few, but others, sited on migration routes probably kill even more. The difficulty is that most of the birds are not killed outright, they are badly injured, and flutter to ground some distance from the cables. And then if large numbers of birds are being killed regularly, predators such as feral cats and foxes soon learn, and the injured birds are disposed of within a few hours.

Most people are surprised when they hear of these casualties, believing birds capable of avoiding cables. Which they are of course in many cases, but in high winds, at night and poor visibility this is not the case. And large birds such as swans are not very maneuverable, so that when a cable looms out of a mist, it is almost impossible for them to avoid a collision.. And it also depends on the species; corncrakes, for instance, are known to be particularly vulnerable -- they migrate at the right height, and are not very agile in flight.

Cars, cables, light pollution at night, pesticides, loss of habitat, desertification on their wintering grounds, hunting by Maltese -- it's a small miracle any birds are left.

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