Straatkolken, valkuilen voor amfibieën

Death trap for amphibians Gully pots are essential for ridding the roads of rainwater but can be death traps for amphibians and other small vertebrates. Each year, when amphibians are active (from March till October), large numbers of both adults and juveniles fall “down the drain”. Here they die, either through starvation or by being washed away into the sewage system when there is a surge of rainwater. Also many other small vertebrates like mice and shrews fall into the gully pots, incidentally also reptiles and young birds. The results of a survey carried out in the Netherlands in 2012 show how serious the problem is. Three random counts were carried out from March to May. A total of 782 vertebrates, of which 683 amphibians, were retrieved in 526 gully pots spread over thirty-six locations. The Netherlands has 7 million gully pots, many situated along migration routes. A rough estimate of the number of amphibians falling victim to the drainage system each year lies between several hundred thousand to more than half a million adults, and many times this number of immature individuals. This loss is not confined to the Netherlands: surveys carried out in Switzerland, Germany and the UK show that the problem is widespread. Possible solutions to the problem were tested in 2011. They showed that this unnecessary loss of life can largely be prevented either by fitting devices to prevent animals from falling into the gully pots or to provide them with a means of climbing out of the pot. Suggestions for both approaches take into account that the flow of water should in no way be impeded. Both water management authorities and manufacturers have been invited to think about ways of implementing such changes with the existing models of gully pot, and also to look for further technical adaptations or innovations.