Breeding success of the Great Bustard Otis tarda in Zamora Province, Spain, in 1984 |
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| Authors: | VICENTE ENA ANA MARTINEZ DAVID H. THOMAS |
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| Affiliation: | Departamento de Ecologia, Facultad de Biologia, Universidad de León, 24071 León, Spain;*Department of Zoology, University College (University of Wales), Cardiff CF1 I XL |
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| Abstract: | Great Bustards are still fairly abundant (5-2 nests/1000 ha) in Zamora. Overall fecundity was high (92% of adult females attempt to nest; 2–47 eggs/clutch; 89% egg fertility), but pre- and post-hatching mortality were also high (50% of eggs laid; 57% of nestlings hatched), due mainly to agricultural machinery but also to natural predators. Calculated annual yields per 100 adult females were: 227 eggs, 102 hatchlings, 44 fledglings. Production of 44 fledglings/y could sustain a stable adult population (mortality approx. 8%/y) if mortality of immatures is not more than 18–22%/y. |
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