The population of Bittern Botaurus stellaris  in the Diaccia Botrona marsh, Central ltaly: four years of census (1991-94)

PUGLISI L., FONTANELLI A., PERFETTI A. and TAVERNI M.



Abstract:

The Bittern population of a marshland in Centralltaly was censused using a network of listening stations. This technique appears to be sufficient to quantify the population being examined, but does not allow an accurate analysis ofthe positions ofthe boorning males. The data in the literature, dating from 1974, indicate that the population studied had a progressive increase up to the early 1990s (from O-l to 14-18 males) and then a phase of decline (with 7-9 in 1994). These variations seem mainly due to the changes in the marsh vegetation. This was positive at first, thinning out the reedbeds, then negative with their progressive reduction. However, the role ofprimary irnportance ofthe studi ed population in ltaly has been confirmed.