Searching for the invisible

This is a grasshopper population monitoring action set up by our team.

It uses the method known as “Capture – marking – recapture”, which makes it possible to estimate the size of a population in relation to the number of individuals recaptured, i.e. individuals observed several times.

This year, this action concerns two sites where the grasshopper is present in the commune of Istres.

In the field, this translates into 16 observation and capture sessions, where three observers, for three hours, make random movements within a defined perimeter.

This is a tedious operation, as this grasshopper is a specialist in camouflage!

Each individual captured – very carefully – is dried, numbered with an indelible marker on the thorax, and carefully observed for possible parasites on its body. If it is a female, the observers also try to determine whether it is “full” of eggs (in which case its abdomen is well swollen), or whether it has already laid eggs (its abdomen is then retracted).

For this work, the LIFE project team is reinforced by two trainees from the University of Trier within the framework of our cooperation with Axel HOCHKIRCH, professor of the university and president of the IUCN SSC Grasshopper Specialist Group: Larissa BRANDL and Chiara HILLE, students in Biological Environmental Sciences. Thanks to them, who are working hard, despite the scorching temperatures of the Coussoul in this month of June!