Amphibians and Gullypots Mini Toad Summit 26th January 2019
What is the problem? • Gullypots installed on the roads can act as pitfall traps, once animals fall in they usually suffer one of three fates: either they get washed into the sewerage system, they get sucked out by vacuum cleaning or they simply remain in the gully pot until they die, usually from drowning or starvation. • Kerbs act to funnel the animals into the gullypots.
What is the scale of the problem? • Survey in Perth and Kinross, Scotland 20102012 checked 1,565 gullypots and found 2,735 amphibians including common toads (2,389), common frogs (255), and both palmate and smooth newts (91), plus a further 272 small mammals. • Extrapolated across Perth and Kinross this would equate to 47,421 animals trapped across the county each year.
And in the Netherlands…. • In 2012 RAVON carried out a study in the Netherlands: 15 gullypots in each of 36 locations across the country were checked on three occasions between April and June. A total of 683 amphibians were found including common toads (370), common frogs (211), smooth newt (76), natterjack toad (11), alpine newt (9), edible frog (4), crested newt (2). • Extrapolated across the Netherlands, with 7 million gullypots, RAVON estimate that half a million adult amphibians die in gullypots each year in the country. Numbers of juveniles is assumed to be much higher.
Solution No 1. • Modifications along the kerbs can prevent amphibians being funnelled into the gullypots. • Stephen Lowe working in S. Wales in 2005 found that moving the gullypots 10cm away from the kerb resulted in an 80% reduction in numbers of crested newts trapped in them. • However moving gullypots is prohibitively expensive for most local authorities. • But……..
• A cheaper effective solution is to recess kerbstones to funnel the animals around the gullypot. • Experiments with these kerbstones in Perth and Kinross in 2013 showed their installation reduced amphibian entrapment by an average of 83%.
Solution No 2 • Amphibians are good climbers. Gullypots fitted with a suitable structure allowing them to escape will work. • Both RAVON in the Netherlands and Trevor Rose in Scotland experimented with various designs of ladders. • Trevor Rose found that when appropriate ladders, constructed using Enkamat, were installed 73% of trapped amphibians used them successfully.