ORIGINAL ARTICLE Ursula Munro Æ Michael McFadden Food consumption, body mass and fat deposition in captive regent honeyeaters, Xanthomyza phrygia (Meliphagidae), during the non-breeding season Received: 19 April 2004 / Revised: 14 July 2004 / Accepted: 14 July 2004 / Published online: 7 October 2004 Ó Dt. Ornithologen-Gesellschaft e.V. 2004 Abstract The regent honeyeater (Xanthomyza phrygia) is a large endangered honeyeater from eastern and south-eastern Australia. Little is known about the ecology of this bird during the autumn-winter period, when it is absent from its breeding areas. In this study, food consumption and body condition of captive regent honeyeaters were studied during this period. Nectar was the dominant component of the regent honeyeaters’ diet and varied significantly throughout the study, peaking in early July. Fruit and mealworm consumption also showed significant seasonal shifts with maxima in late June and early March, respectively. In general, imma- ture birds consumed significantly more protein-rich food than adults. The average body mass of the male birds varied significantly with season. Female birds did not show a significant seasonal change in body mass but, similarly to males, attained their highest mass in late April. Fat deposition changed significantly over months, with highest levels of fat recorded from late April until late June. These seasonal trends, independent of food abundance, may suggest that body condition within this species is controlled endogenously. Keywords Australia Æ Body condition Æ Food consumption Æ Meliphagidae Æ Regent honeyeater Introduction The regent honeyeater (Xanthomyza phrygia) has suf- fered large declines in abundance in recent years, war- ranting it endangered species status throughout its range (Menkhorst et al. 1999). The main cause for these de- clines is thought to be the clearing and fragmenting of suitable habitat (Garnett and Crowley 2000). Much of the woodland that this species inhabits has been cleared for agricultural purposes, hence considerably reducing available food resources. To protect this species against further declines, it is of major importance that its feeding ecology be established such that existing resources and habitat can be better protected. A number of studies have investigated the foraging and food preference of the regent honeyeater (Frank- lin et al. 1989; Ford et al. 1993; Oliver 1998, 2000; Munro et al. 2003). These studies have almost exclu- sively been conducted between August and February when birds are congregated into recognised breeding grounds (Ford et al. 1993; Oliver 1998, 2000). After the reproductive period, the birds disappear from their breeding areas. Since we know little about the birds’ movements (Cooke and Munro 2000) and their whereabouts during the non-breeding period (Franklin et al. 1989), it is impossible to study diets and asso- ciated changes in body condition in wild birds. The most efficient way to gain information on these parameters is through studies on captive-held birds, as has been done on yellow-faced honeyeaters (Licheno- stomus chrysops) (Munro 1992, 2003; Munro et al. 2003) and a large number of northern hemisphere species (Berthold 2001; Bairlein 2002; Long and Stouffer 2003). It is of significance that seasonal trends in such parameters be established in regent honeyeat- ers, not only to increase our knowledge of this species, but also to increase the success of any future releases of captive birds by determining a release date when birds are in optimal condition and with high food availability. In a preliminary study, Munro et al. (2003) attempted to shed some light on the feeding behaviour and asso- ciated changes in body mass of captive regent honey- eaters during the non-breeding period. While this study provided some important information on these param- eters, it had considerable limitations: (1) it was Communicated by F. Bairlein U. Munro (&) Æ M. McFadden Department of Environmental Sciences, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia E-mail: Ursula.Munro@uts.edu.au Tel.: +61-2-95144150 Fax: +61-2-95144079 J Ornithol (2005) 146: 65–71 DOI 10.1007/s10336-004-0057-2