Changes in clutch size, brood size and numbers of nesting Squacco Herons Ardeola ralloides over a 32-year period in the Camargue, southern France

Changes in numbers of nesting pairs, clutch size, and brood size of Squacco Herons Ardeola ralloides in the Camargue, southern France were analysed over a 32‐year period. The annual numbers of breeding pairs [average 84 pairs pL 30 sd, n = 32 years) exhibited a possible increasing trend, but with co...

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Bibliographic Details
Published in:Ibis (London, England) England), 2001-01, Vol.143 (1), p.11-16
Main Authors: HAFNER, HEINZ, BENNETTS, ROBERT E., KAYSER, YVES
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Ardeola ralloides
Aves
Biological and medical sciences
Demecology
France
Fundamental and applied biological sciences. Psychology
Vertebrata
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Summary:Changes in numbers of nesting pairs, clutch size, and brood size of Squacco Herons Ardeola ralloides in the Camargue, southern France were analysed over a 32‐year period. The annual numbers of breeding pairs [average 84 pairs pL 30 sd, n = 32 years) exhibited a possible increasing trend, but with considerable variability. This variability is associated with local spring rainfall, which may influence the available surface area of their preferred freshwater habitats. In contrast to population size, clutch size decreased substantially in recent years. Our data do not provide a causal explanation for this change in clutch size, although the reduction temporally corresponds with increasing rice cultivation and with a dramatic increase in the number of Cattle Egrets Bubulcus ibis in the Camargue.
ISSN:0019-1019
1474-919X
DOI:10.1111/j.1474-919X.2001.tb04164.x