Stairway to survival
The loss of amphibians migrating to and from their breeding ponds and trapped in road gullies has been well documented and featured in Froggerblogger recently. Losses can be severe enough to cause local extinction of at risk populations, isolated from their ponds by new roads with kerbs and gullies. Now innovative work by Trevor Rose of Friends of Angus Herpetofauna, supported by Tayside Biodiversity Group and Angus Council, has created a practical escape ladder that could be simply inserted into road gullies, and easily removed for gully pot cleaning too (and replaced afterwards, with a bit of training).
The inserts are a plastic mesh on a steel shoe, resembling a short ski in shape.
Photo credit: Trevor Rose
The photograph above shows Trevor Rose with one of his amphibian-friendly gully ladders. Below, a ladder in situ, providing an escape route for animals to get out of the toxic pool in the gully.
Photo credit: Trevor Rose
87 ladders have been tested in and around Angus in NE Scotland, with the assistance and positive co-operation of Angus Council. Ladders were placed in two-thirds of the trial gullies (leaving one third un-laddered for comparative studies), at 3 such locations, on known mortality hotspot streets where amphibians regularly move to and from their breeding ponds each year. Numbers of trapped or dead amphibians in gullies with a ladder were compared with numbers in the conventional gully with no escape ladder. In total, after 36 visits, 115 out of 158 amphibians that fell into gullies fitted with the ladders had escaped (73%), and 89 were found in the other gullies with no chance of escape.
The detailed findings and project background are set out in a report launched on 22nd May 2015, by Friends of Angus Herpetofauna and hosted by the Tayside Biodiversity Group at William Wallace House, Forfar, with a presentation by author Trevor Rose (see the Tayside Biodiversity Partnership website www.taysidebiodiversity.co.uk, and The Courier article of 25th May 2015 http://www.thecourier.co.uk/news/local/angus-the-mearns/a-green-cross-code-for-frogs-and-toads-1.878109 and Angus Council’s Statutory Biodiversity Duty ‒ Report on Delivery at http://www.angus.gov.uk/downloads/file/1201/statutory_biodiversity_duty_%E2%80%92_report_on_delivery ).
Later on 22nd May a return visit to look at the test gully project found the same pattern, with continuing trapping of amphibians in the road gullies, except where ladders had been fitted. A road maintenance truck happened to pass along one of the test streets and it was pleasing to see the crew recognise Trevor and have a blether about the gullies and ladders. Trapped amphibians at another currently unprotected site also visited on 22nd May were lucky: we lifted them out and returned the living ones to the ponds which they had been trying to reach before falling to certain death otherwise.
The future for managing this problem is probably targeted deployment of the ladders in gullypots in the primary migration routes, together with use of no-gullypot drainge options such as roadside swales, or filter drains or permeable surfaces (components of the SUDS technology that has the potential to be such a positive infrastructure opportunity for nature conservation, especially amphibians (see subsequent blogs…!).
We are indebted to Trevor Rose for the above information (email email@example.com ). See McInroy C & Rose TA (2015) Trialling amphibian ladders within roadside gullypots in Angus, Scotland: 2014 impact study. The Herpetological Bulletin 132, 2015: 15-19
Froggerblogger, 2nd August 2015.
Please note that unless otherwise indicated, all photographs in Enviro Experience blogs are copyright of Brian J D’Arcy.