A recently published paper in Biodiversity and Conservation has demonstrated that the grass snake hatching success is significantly affected by the medium within which eggs are deposited.
In a novel relocation experiment, Kristin Löwenborg, Simon Kärvemo, Alma Tiwe and Mattias Hagman placed grass snake eggs in different materials and monitored hatching success. Hatching success was highest in manure heaps (71%). When placed in compost piles, hatching success declined to 43%. When eggs were placed in what the authors considered to be 'natural' nests, hatching success failed completely (0%).
The authors suggest that more stable thermal conditions within manure heaps facilitate the successful development of embryos. The decline in storage of large manure heaps on farms that adopt more modern management practices may therefore be highly detrimental to grass snakes.