Over recent months, when travelling down the A470 towards Dolgellau, I've been parked at the traffic lights at Ganllwyd wondering what the plastic fences were for.

About two feet tall, they run parallel with the road and up the mountainside where excavators are clearing the site for a road widening scheme.

Are they preventing seepage of toxic chemicals? Maybe some form of rhododendron control? More recently the stone walls have been lined with fine green mesh.

None of my friends knew what it was for so I went on site to meet Chris Jones, environment officer for Gwynedd Council.

This part of the construction site is home to common lizards and slow worms which are protected under the Wildlife and Countryside Acts.

Ahead of work beginning the lizards were trapped, not by any high-tech gadget, but by pieces of roofing felt. Soaking up the rays of the sun these made tempting loungers for lizards that could then be picked up and taken to safety away from the tracks and buckets of diggers.

The plastic fencing encircles the site and is there to stop them returning. It's angled outwards so that any that were missed in the trapping can crawl out, but not get back in. As for the fine green mesh on the stone walls, that's to stop birds nesting where work will be going on during the summer.

I was amazed to discover how much wildlife consideration goes into a project like this. In addition to the reptiles and birds, measures were in hand to safeguard roosting habitat for colonies of bats and bales of straw were filtering sediment out of streams to prevent run off into the Afon Mawddach that could damage the breeding grounds for freshwater pearl mussels. Huw Jenkins

Listen to Huw and Chris Jones talking about the project on Country Focus.