The diet of white-chinned petrels Procellaria aequinoctialis, Linnaeus 1758, in years of contrasting prey availability at South Georgia

The diet of breeding white-chinned petrels was studied during the summers o f 1996 and 1998 at South Georgia. Krill abundance/availability was high thr oughout 1996 but apparently low at the beginning of the 1998 breeding seaso n. The diet of white-chinned petrels was similar between years and consiste nt with previous studies. Krill Euphausia superba (41-42% by weight) was th e single most important prey item followed by fish (39-29%) and squid(19-25 %). Meal mass was consistent(110 g in 1996, 119 g in 1998) between years bu t a significant decrease (46%) in feeding frequency in 1998 (0.54 meals day (-1) compared to 0.75 meals day(-1) in 1996) resulted in 19% less food deli vered to chicks in 1998 than in 1996. Breeding success, however, was consis tent between years at 44% and similar to that recorded previously at Bird I sland. This is in contrast to black-browed and grey-headed albatrosses, bot h of which experienced almost total breeding failure in 1998. It is suggest ed that their varied and versatile feeding methods, together with their gre ater diving ability, capacity to feed at night and extensive foraging range , help white-chinned petrels minimise the effects of krill shortage.