Poulin B. & Lefebvre G. (2003) Variation in booming among Great Bitterns Botaurus stellaris in the Camargue, France. ARDEA 91 (2): 177-181

We address the potential of booming in Great Bitterns as an indicator of male condition through a seasonal analysis of 5299 boom trains recorded from early March through mid July 2000 in ten reedbed sites in the Camargue, France. Boom train length peaked in May, averaging 3.6 and 4.7 booms at sites with single and multiple Great Bitterns, respectively. Overall, 21.6% of the 24 371 booms recorded were classified as incomplete, failed booms. These 'poor' booms occurred predominantly at the beginning of the season (Mar). Proportion of poor booms was similar at sites with single and multiple Great Bitterns, but their position in the boom train differed. Isolated bitterns most often produced poor booms at the start of boom trains, whereas Great Bitterns from large reedbeds did so more commonly at the end of a long boom train. These results suggest that male Great Bitterns try to produce the longest possible boom train without emitting poor booms. Given the cost of booming, boom train length is likely to reflect body condition of males. This finding has interesting conservation implications for the Great Bittern, which is a vulnerable species in Europe