Lizards Saved at a Sewage Works: A Case Study
Spending Christmas in a log cabin sounds more like the sort of thing to appeal to people, rather than 100 sleepy lizards – but that’s exactly what happened to one group of reptiles when they found themselves caught up in a major construction project at a Dartford sewage works.
The colony was discovered in the summer of 2010, as Thames Water began to prepare the ground at their Long Reach wastewater treatment plant ahead of its planned £40 million upgrade – part of a huge project aimed at improving the general water quality of the River Thames. As fate would have it, the reptiles were living precisely where the work was going to take place and with some 35,000 tonnes of soil excavation scheduled to happen, it was immediately obvious that they would need to be relocated for their own safety.
Catch and Re-homeDespite the name, and like other native British reptiles, the common lizard (Zootoca vivipara – formerly known as Lacerta vivipara) is nowhere near as common as it once was, now being a priority species in the UK’s Biodiversity Action Plan, and protected by law. Thames Water turned to a specialist to help them re-home their new-found population.
The first step, obviously, was to capture them safely and as Thames Water’s own ecologist, Claudia Innes, explains, the relocation team used the lizards’ natural thermoregulation behaviour to help, laying lengths of roofing felt on the ground around their home. The lizards weren’t slow to notice how quickly the felt warmed up in the summer sun, compared with the rest of the site, and started using it to get a head start on the day – allowing Thames Water’s hired expert to collect them with minimum disturbance in the early hours of the morning.
A Real Success StoryThe lizards’ new winter ‘log-cabin’ hibernaculum was created out of logs and soil left over from the work and has been contained within a lizard-proof reptile fence to keep them out of harm’s way until well after the construction traffic has left in 2012. Perhaps most importantly, they seem to have settled into their new home very successfully and are “doing well” according to ecologist Claudia.
“In some ways it’s an ironic tale,” says consultant herpetologist, Mike Steading. “You’ve got one project underway to bring environmental improvement – and it causes an environmental problem for a locally significant population of lizards at a time when numbers are dwindling nationally, and good habitats are disappearing fast. Thames Water need to be congratulated on turning this into a real success story.”
Looking to the FutureHe thinks that this kind of thing may become more common as changes to legislation force many industries to re-vamp their facilities. “For things like sewage plants that have been around for years, once they’ve been built, they tend to be surprisingly quiet in day to day use. Add to that the fact that you tend to build them away from people and houses, and they occupy a fair chunk of ground, and you’ve sort of accidentally created a mini wildlife habitat that few people ever visit.”
If it becomes necessary to modify or expand the facility some years later, he explains, there may well be things living there that nobody knew about, and some of those animals may be very vulnerable to that kind of disturbance.
“Someone at that Thames Water plant was pretty eagle-eyed,” he says, “to spot those lizards in the first place. It would have been so easy for them to have been missed and buried under all that soil.”
Steading believes that raising awareness of just how important supposedly ‘industrial’ sites can be for a variety of native animals and plants could be a key factor in maintaining British biodiversity for future generations – especially when it comes to the UK’s reptiles. “Surveys show that numbers are down generally and it seems to be all bad news, and then you come across sites like these and their forgotten colonies.”
If wider awareness does ultimately prove to be as important as he believes, then Thames Water and the ‘log-cabin lizards’ will have done a lot to help.