The energetic demand of the Great White Pelican during migration in Israel and its implication to the conflict between fish industry and pelicans

Abstract

Shmueli, M., Arad, Z., Izhaki, I. & Crivelli, A. 2000. The energetic demand of the Great White Pelican during migration in Israel and its implication to the conflict between fish industry and pelicans. Ostrich 71 (1 & 2): 1.

The Great White Pelican Pelecanus onocrotalus is a migrating bird, which is an endangered species. The majority of the western Palaearctic populations stopover in Israel during their autumn migration (71 421 ± 127 individuals per year). Although most of these birds are transient over Israel, an increasing number of individuals (1 142 ± 882, between 1990–1994) stay and winter in the northern part of Israel. The natural feeding sites for pelicans diminished during recent decades due to human activities, and the aquaculture sites of intensive fishery became their favourite feeding places either during migration or during winter. The fish industry reports huge damages to fish yield. This study tried to assess ecophysiological needs of the White pelicans during migration and wintering in Israel, and to evaluate the necessity for pelicans to feed in Israel on their route to east-central Africa. The study combines laboratory measurements of energy consumption of captive pelicans, and field observations of migrant and wintering pelicans, and satellite tracking of migrating pelicans. The mean mass-specific metabolic rate (BMR) of the pelican was 236 kJ/(kg*day), without significant differences between sexes or diets (fish or chicks) and seasons: digestible energy intake (DEI) was 490–730 kJ/(kg*day) also without significant differences between sexes and diets. Wet food consumption (WFC) was greater on the fish diet (1.120 kg/day per bird) than on the chick diet (0.970 kg/day). Digestive efficiency was higher on the fish than on the chick diet (86% and 77%, respectively). Fat deposition in dead migrant pelicans during autumn, was 290 g (3.4% + 2.6% of body mass, n = 81). Fat deposition in wintering pelicans was significantly higher (5.4% ± 3.4% of body mass, n = 21). From these data, the average flight range of transient pelicans was estimated as 1 120 km without refueling. Although satellite records gave us information on the northward migration routes of pelicans from Israel, we need further information about the precise area of the pelicans in Africa. Nevertheless it is concluded that pelicans need to feed during their stopover in Israel, or at some unknown feeding sites along their southward migratory route, to complete their journey to their wintering grounds in east-central Africa. The results of this research should contribute to the establishment of new management policies, to the solution of conflict with the fish industry and to the conservation of pelicans in Israel.