Owls and woodpeckers in montane forests: mapping nocturnal hooting and diurnal drumming in German SPAs

Purschke C.

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Natura 2000 requires the nations of Europe to monitor bird populations, thereby enabling scientists to detect changes in biodiversity levels. Since conflicting methods and evaluations have been used throughout Germany, the results of the various studies are diffcult to compare. The research presented here involved the short-term monitoring of woodpeckers and owls in the Black Forest in southwestern Germany, combining different census techniques. The species monitored were the primary excavators of nesting cavities in these montane forests, i.e., the great spotted woodpecker Dendrocopos major, the black woodpecker Dryocopus martius and the three-toed woodpecker Picoides tridactylus, as well as potential secondary cavity nesters such the pygmy owl Glaucidium passerinum, Tengmalm’s owl Aegolius funereus and the tawny owl Strix aluco. Woodpeckers and owls are among the species most diffcult to monitor in the SPAs of the Black Forest mountain range. The monitoring method employed was territory mapping. In addition to documenting territoriality and the species’ behaviour prior to and during breeding season, potential breeding sites were also examined. The playback of voice recordings was found to increase the number of contacts and sightings at the beginning of the breeding season, but was almost useless later in the season. For the owl species, evidence of breeding was detected by means of selective and systematic controls. The accurate monitoring of the populations of these species requires expertise with forest species and knowledge of their habitat requirements. One major task involves the designation of appropriate census periods that incorporate the periods of highest acoustic activity for each study species, to ensure optimal detectability during territory mapping. A standardisation of procedures, taking into account the species’ activity patterns, is urgently required on both the national and international levels.