BREEDING SUCCESS, NESTLING DIET AND PARENTAL CARE IN THE WHITE-BACKEDWOODPECKER DENDROCOPOS-LEUCOTOS

In western Norway, pairs of White-backed Woodpecker breeding in coasta l areas (<2 km from the sea) started egg laying earlier than pairs in inland areas (2-15 km from the sea). Laying was earlier in years when the ambient temperature was higher during the pre-laying period. About half of 69 pairs studied started laying within the period 25-30 April over the 10 study years. Clutch size ((x) over bar = 4.0 eggs) and br eeding success values (fledglings per egg; (x) over bar = 0.63) did no t differ between years. The mean number of fledglings per nest was 2.4 . The mean body mass of fledglings differed between years and were neg atively correlated with the laying date. Fledgling mass differed betwe en sexes (males (x) over bar = 87.8g, females (x) over bar = 84.2g), a nd both sexes were heavier in coastal than in inland areas. The mean h ourly feeding rate of nestlings increased with nestling age, but feedi ng rate per nestling did not vary with nestling number. The nestling f ood was mainly comprised by wood-living beetle larvae ((x) over bar = 72% by dry mass). It is suggested that breeding success is related to territorial quality, which, in turn, strongly influences female qualit y.