CONTRIBUTION TO THE BREEDING BIOLOGY OF WlSKERED TERN CHLIDONIAS HYBRIDA IN CAMPOTTO (NORTHERN ITALY)

Spina F.



Abstract:

In the 1argest Ita1ian co1ony of the Wiskered Tern, 200-240 pairs nested in 1980 and 150-170 in 1981. Oata on c1utch size, egg measurements, in - terspecific and intraspecific aggressive behaviour are reported. Sexua1 dimorphism in the co1our of the cheek was noted in 5 pairs intensive1y observed. From behavioura1 observations, a reasonab1e assumption is made that white-cheeked individua1s are fema1e, dark-cheeked ones ma1es. "Fema1es" took the heavier share in brooding activity.