Reed die-back and conservation of small reed birds at Lake Neusiedl, Austria

The reed belt around Lake Neusiedl is one of the largest connected reed areas in Europe, and thus bears crucial importance for the conservation of species depending on this habitat. In the last decades, a decline of reed harvesting has led to the formation of very old reed areas. Here we investigate how age and structure of degraded reed affect breeding bird species. We related extensive bird counts of eight species at 111 points to habitat measurements and reed age. Species differed in their preferred age class; for example, Great Reed Warblers Acrocephalus arundinaceus are found mainly in up to 4-year-old reed stands, while Little Crakes Zapornia parva prefer to settle in more than 14-year-old vegetation. We expected some species to be more common in older age classes, but our results demonstrate that large parts of the reed stands become too degraded even for these "old reed" specialists. Several bird species showed an inverse u-shaped relationship to habitat characteristics associated with reed die-back, e.g. accumulation of broken reed stems, occurrence of matted reed, low vegetation height or open water areas. At present, harvested areas are small and burning of reed is prohibited, and in the future, we expect more reed die-back with declining bird numbers. Missing ice cover in wintertime because of climate warming prevents sustainable cutting of these very old reed stands. We thus recommend a cautious introduction of fire management as a measure to secure this unique bird habitat.