Authors: ALONSO, J. C., ALONSO, J. A., MARTÍN, E. and MORALES, M.
Published: Volume 42(1), June 1995. Pages 69-76.
Language: English
Keywords: dispersal, Great Bustard and movements.
Summary:
We studied the range of juvenile dispersal and adult seasonal movements in the Great Bustard (Otis tarda) population of Villafáfila Reserve, NW Spain, using data from censuses and individual marking between 1983 and 1994. Thirty birds (22 males, 8 females) of those marked as young were seen during their juvenile dispersal outside the Reserve, at distances of up to 63 km, preferentially northeastwards, over an area of 2800 km2. All males and 40% of females abandoned the Reserve during their juvenile dispersal. About half the males born in the Reserve never returned to it as breeding adults, while all females returned. With respect to seasonal movements of adults, about 40% of females wintering in the Reserve abandoned it during the spring-summer to nest, most of them returning in October. A 20-30% of the males present at the display arenas in early spring only entered the Reserve during the exhibition and copulatory phase. About half the males present at that time abandoned the Reserve once the peak copulation period was over, remaining at up to 20 km of the display arenas during the summer. The observed dispersal patterns are discussed in relation to current conservation policy of the species in the region of study.
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