The observations below were made during the
project (until 1992). A more detailed description of the species of prey of the grass
snake can be found in Kabisch , about the sources of food and food intake
in Hemmer .
Regurgitated animals during catch or mapping:
Alpine Newt (Triturus alpestris), Palmate Newts (T. helveticus) und Warty Newt (T. cristatus)
Common Toad (Bufo bufo)
Grass frog (Rana
Green frog (Rana lessonae or R. kl. esculenta)
Field-mouse (Microtus agrestis) with an abdominal injury
A grass snake caught in Remscheid regurgitated a spotted salamander, Salamandra s. terrestris (Müller oral comm. 1990).
Some grass snakes did not eat Warty newts during the land phase.
Furthermore, it was possible to observe that juvenile grass snakes hunted and ate Palmate Newt larves (Triturus helveticus) in 2- 3 cm deep water puddles. Tree frog (Hyla arborea) and grass frog tadpoles (Rana temporaria) also formed part of the quarry.
Weight distribution of nutrition
A Common toad (Bufo bufo) regurgitated by a female grass snake weighing 205 g and measuring 76,5 cm had 65 g of weight; thus, it formed 32,5 % minimum of the total weight.
A grass frog (Rana temporaria) with 22,7 g which was also regurgitated by a female grass snake (82,2 g/71 cm), equally adds up to at least 27,7% of the total body weight.
A male snake measuring 30 cm and weighing 9 g regurgitated a female Alpine Newt (Triturus alpestris) which had a weight of 3 g that was partly digested. When caught, it added up to at least 22,2 % of the total weight.
Small mammals as nutrition
As indicated above, an adult femal snake regurgitated a field-mouse (Microtus agrestis), which had already been hurt badly with an open abdominal injury or which was eaten already dead.
On the 26 February 1990, an animal from a clutch in Wuppertal-Morsbach ate a hairy but still blind mouse in a terrarium. The grass snake only reacted when the mouse started to bleed.
Later, the same animal caught an adult and alive laboratory mouse from behind and swallowed it within 45 minutes. The snake was bitten several times by the mouse around its head.
Steward  writes that a grass snake in custody prefers dead mice to amphibians.