SEASONAL AND ONTOGENIC CHANGES IN THE DIET OF THE AUSTRALIAN SKINK EGERNIA-STOKESII

Seats were collected from outside crevice refuges of the skink Egernia stokesii from sis populations in the Warruwarldunha Range, South Aust ralia. There were small seats present in late summer soon after the bi rth of juveniles. Over two years, these small seats had significantly less plant material than large seats, and a higher percentage of them contained the remains of insects than did large seats. Also over two y ears the large seats showed more plant material and fewer had insect r emains in late summer, when juveniles were present, than in mid summer , before juveniles were born. In laboratory, trials, adults and juveni les were fed either an all plant diet or an all insect diet. Juveniles consumed more insects per gram of body mass than adults. juveniles sc atted more than adults on both diets. In the laboratory, adults had co nsistently larger seats than juveniles, independent of the diet. This implies that large and small seats from the field were deposited by ad ult and juvenile lizards, respectively. The field data suggest that ju veniles have more insects in their diet than adults, and that adults c hange their diet away from insects when juveniles appear in the popula tion. This could result from altered foraging behavior or from a respo nse to the presence of feeding juveniles.