Digestive efficiency in captive white storks Ciconia ciconia Zbigniew Kwieciński 1 *, Honorata Kwiecińska 1 , Radosław Ratajszczak 1 , Piotr Ćwiertnia 1 & Piotr Tryjanowski 2 1 Zoological Garden Poznań, Browarna 25, 61-063 Poznań, Poland 2 Department of Behavioural Ecology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland *corresponding author; e-mail: zookwiatek@interia.pl ABSTRACT: Digestive efficiency in the white stork was studied in the Poznań Zoo in 2004–2005. Altogether 29 individuals of this species were investigated (9 males, 20 fe- males). During 10-day-long experimental cycles, the birds were presented with food accord- ing to the ‘Cafeteria’ test. The diet consisted of mammals, birds, fishes, amphibians, insects and earthworms. The mean daily food intake per bird was 284.88 g (SD 113.99 g). The mean digestive efficiency was 72.06% (SD 6.19%)? The research showed that the digestive effi- ciency is positively correlated with the quantity of food intake and body weight increase. The daily dietary requirement of captive birds proved to be very significantly lower than in wild birds. Introduction The composition of the diet of the white stork was a subject of several investiga- tions in different regions of Europe (Pinowski et al. 1991, Muzinić & Rasajski 1992, Tsachalidis & Goutner 2002, Antczak et al. 2002). It was usually performed on the basis of pellet analysis or direct observations under field conditions. The above-mentioned papers describe food preferences depending on the life cycle stage and habitat type. However, we still lack the basic understanding of the nutri- tive value necessary for covering the energy requirements for hunting, egg produc- tion, rearing of chicks, or migration. Detailed research on the digestive efficiency and digestibility of different kinds of food in the white stork (and other bird species) is very difficult to achieve under Tryjanowski, P., Sparks, T.H. & Jerzak, L. (eds.) White Stork study in Poland: biology, ecology and conservation. Bogucki Wydawnictwo Naukowe, Poznań 2006