Individuele herkenning bij de gladde slang De ontwikkeling van een digitale zoekformule

Identifying individuals of the Smooth Snake (Coronella austriaca) A digital search formula For population studies of snakes, it is important to be able to recognize individuals in the field. Starting in the 1970s, various marking techniques were used in field studies,most of which were harmful to the animals, leading to unnatural behaviour or even death. Therefore, the use of the variation in particular natural characteristics was looked at as a preferable way of identification. The colour pattern of the Smooth Snake seemed to be unique for each individual (Sauer, 1994; 1997). Photography makes it possible to identify individuals in a small population. However,screening a population of thousands of snakes for similarities in colour and patterning needs the help of a computer program. I have developed a formula based on the location and colouration of the scales on the back of the snake’s head, focusing on the temporal, post-parietal and dorsal scales. The search formula consists of six numbers, the first three indicating the location of the temporal and postparietal scales, the last three relating to the colouration of the temporal, parietal and dorsal scales. A pilot study in the Meinweg National Park in the southern province of Limburg, which concerned 31 individuals, showed that the formula gives a unique outcome for each snake. Recaptured animals could easily be traced in the data bank. These results are so encouraging that I call upon others to use this formula in their studies of the Smooth Snake, both in the Netherlands and abroad. I would welcome their findings.