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2. Kleptoparasitism in wintering grey heron Ardea cinerea
- Creator:
- Lekuona, Jesús M.
- Type:
- article and TEXT
- Subject:
- age, feeding parameters, handling time, and robbery attemps
- Language:
- English
- Description:
- Eighty-six cases of kleptoparasitism in grey herons, most of which were intraspecific, were observed in northern Spain and southwest France during four winters (1992-1995). Herons more often attacked individually than in groups, but the success was similar in both cases. Robbing success was significantly higher when herons attacked a young bird (44.4%) compared to adults (17.6%). Adult herons were significantly more successful (37.5%) than young herons (10.0%). Handling time had a great effect on the size of the prey item robbed by the herons. Adult herons were more frequently attacked by both young and adult birds. Age- related differences in winter foraging parameters (total time foraging, feeding success and biomass intake) may favour discrimination between victim age classes by kleptoparasites. Adult heron ingested 0.82 g min-1 during the winter season and young heron 0.45 g min-1. For kleptoparasites adult herons seems to be a more profitable species than young. Kleptoparasitism increased the biomass intake of the pirate (62.8 g more than the normal intake of a young heron), probably to compensate for the inefficiency of young birds.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/