COMPONENTS OF FITNESS IN LAPWINGS VANELLUS-VANELLUS AND BLACK-TAILED GODWITS LIMOSA-LIMOSA DURING THE BREEDING-SEASON - DO FEMALE BODY-MASSAND EGG SIZE MATTER

Body mass of incubating females, their egg sizes, hatching success, ha tchling masses and brood survival were recorded for individually colou r-marked Lapwings Vanellus vanellus and Black-tailed Godwits Limosa li mosa breeding on meadows in Kiskunsag National Park, 50 km south of Bu dapest, Hungary. We found no relationships between egg size and body m ass of females, but there were positive correlations between female bo dy mass and hatching success in both species. Laying date did not effe ct hatching success. Females replaced a clutch only if the first clutc h was destroyed during the first half of incubation. Females that laid replacement clutches were heavier at the start of incubation of their first clutches than females that did not relay. The longest time inte rval, and the greatest nest distance, between first and replacement cl utches were respectively 17 days and 94 m in Lapwings, and 20 days and 120 m in Black-railed Godwits. Egg sizes were smaller in replacement clutches than in first clutches. Egg size was positively correlated wi th hatchling mass and with brood survival in both species, but brood s urvival decreased with hatching date. Females tending the chicks toget her with their mates suffered fewer chick losses before fledging than lone females.