Comparative Biochemistry and Physiology Part A 125 (2000) 25 – 32 The physiological state of captive and migrating Great White Pelicans (Pelecanus onocrotalus ) revealed by their blood chemistry Marva Shmueli a , Ido Izhaki b , Oren Zinder c , Zeev Arad a, * a Department of Biology, Technion, Haifa 32000, Israel b Department of Biology, Uniersity of Haifa at Oranim, Tion 36006, Israel c Department of Medicine, Technion, Haifa 32000, Israel Received 25 February 1999; received in revised form 15 September 1999; accepted 22 September 1999 Abstract The Great White Pelican Pelecanus onocrotalus is an endangered migratory bird, threatened by diminishing natural feeding sites and by persecution by fishermen. The majority of the migrating White Pelican (71 000) stop-over in Israel during their autumn migration to Africa. As part of a larger study, aimed to assess the necessity of feeding during the stop-over in Israel, we examined the blood chemistry of captive and migrating White Pelicans. Blood was sampled from captive birds maintained on a fish diet, after food deprivation for 48 h and from wild birds brought from the field during migration. Food deprivation resulted in increased plasma levels of triglycerides and in lower levels of urea, potassium and calcium. In migrating birds, increased plasma levels of urea and CPK and lower levels of creatinine were revealed. In general, the coefficient of variation in the blood chemistry of migrating pelicans was higher than in the captive birds, that is to say, that these birds were in a variable physiological condition. The blood profile of migrating and wintering pelicans did not indicate a state of dehydration but did indicate energy deficiency. The less extreme changes in blood chemistry of the 48 h food-deprived compared to migrating pelicans suggest that the former did not reach a state of starvation. We conclude that for White Pelicans the stop-over in Israel is a must in order to rest and replenish their fuel reserves for completion of their autumn migration to Africa. © 2000 Elsevier Science Inc. All rights reserved. Keywords: Pelecanus onocrotalus ; Blood chemistry; Migration; Stop-over; Diet; Food deprivation; Energy; Dehydration www.elsevier.com/locate/cbpa 1. Introduction The Great White Pelican Pelecanus onocrotalus is widely distributed in eastern Europe, Asia and Africa. Declining numbers of White Pelicans in Europe resulted in its listing as an endangered migratory species (CMS, 1983). The majority of the Palaearctic White Pelicans (71 400) (Leshem and Yom-Tov, 1996) stop-over in Israel for a few days during their autumn migration from Europe to Africa. There is almost no information about their physiological needs during migration over this area, on route to their wintering grounds in east Africa. From satellite records of two trans- mittered pelicans we found that in the autumn migrating birds cover about 2400 km during 2.5 weeks from Europe to Israel (Shmueli, Arad, Izhaki and Crivelli, submitted) and continue for additional 2500 km to southern Sudan (in prepa- ration). On their long migration route from Israel * Corresponding author. Tel.: +972-4-8293416; fax: +972- 4-8225153. E-mail address: zarad@techunix.technion.ac.il (Z. Arad) 1095-6433/00/$ - see front matter © 2000 Elsevier Science Inc. All rights reserved. PII:S1095-6433(99)00162-2