FIDÉLITÉ DES MÂLES DE BÉCASSE DES BOIS Scolopax: rusticola À LEUR SITE DE REPRODUCTION

Carrying out a census of the woodcock population during the breeding season is a recurrent problem. Indeed, how can you count birds during their displaying flight when the birdwatcher stays in a fixed point? The key to solving this problem is the individualisation of woodcock males by the characteristics of their songs. From 2002 to 2008, thousands of sonograms were recorded in one roding area in the Jura Mountains in order to determine the best way of individualisation. To test it, a second roding area was investigated from 2006 to 2008 and a radio-tagging study of three birds carried out in 2005. One of these ringed males -nicknamed "Crocus" - was recorded and photographed from 2005 to 2008 in the same roding area. Thanks to the stability of its song, we identified this woodcock in 2004, one year before its capture. Tests of vocal stability over time have been based on eleven woodcocks well-known to us, one of whom is "Crocus". This stability is excellent for the variable E (length of the sound "tsip" at 4,5 kHz: coefficient of variation (cv) < 5%) and good for two others (cv < 7%). A standardized method for individualisation can be applied, enabling us to monitor the fidelity of males to a roding area over many years.