A study of selected factors influencing the reproductive performance of the common tern (Sterna hirundo) at Port Colborne, Ontario in 1973 and 1974

摘要

Several study areas were investigated at two Port Colborneterneries during the summers of 1973 and 1974 in an attempt todetermine the influence of clutch size, time of clutch initiation,position in the colony, proximity to Ring-billed Gulls, vegetationand nesting substrate on the reproductive performance of the CommonTern. Hatching success and reproductive success (the number ofchicks fledged per egg laid) were generally higher for 3-egg than2-egg clutches but fledging (the number of chicks fledged per egghatched) success was usually independant of clutch size. Hatching,fledging and reproductive success declined as a function of time ofclutch initiation. Mean clutch sizes also generally declined as afunction of time. Nests located in the center of the colonyexhibited higher fledging success than those on the periphery.Rock-based clutches had a lower hatching success than clutchesinitiated on sand or dried vegetation. Reproductive performancedid not appear to be related to proximity to Ring-billed Gullsor vegetation within the study area.