Components of fitness in Lapwings Vanellus vanellus and Black-tailed Godwits Limosa limosa during the breeding season: Do female body mass and egg size matter?

Body mass of incubating females, their egg sizes, hatching success, hatchling masses and brood survival were recorded for individually colour-marked Lapwings Vanellus vanellus and Black-tailed Godwits Limosa limosa breeding on meadows in Kiskunsag National Park, 50 km south of Budapest, Hungary. We found no relationships between egg size and body mass of females, but there were positive correlations between female body mass and hatching success in both species. Laying date did not effect hatching success. Females replaced a clutch only if the first clutch 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 interval, and the greatest nest distance, between first and replacement clutches were respectively 17 days and 94 m in Lapwings, and 20 days and 120 m in Black-tailed Godwits. Egg sizes were smaller in replacement clutches than in first clutches. Egg size was positively correlated with hatchling mass and with brood survival in both species, but brood survival decreased with hatching date. Females tending the chicks together with their mates suffered fewer chick losses before fledging than lone females

Hegyi Z. & Sasvari L, ARDEA 86 (1): 43-50.