The growth and development of Whooper Swan cygnets Cygnus cygnus

Abstract

The growth and development o f ten captive Whooper Swan cygnets hatched at the Wildfowl & Wetlands Trust Centre at Llanelli on 10-13 May 1990, were documented fo r the first 23 weeks o f life. Weekly recording o f biometrics, together with a photographic record, revealed: rapid growth with the first contour feathers appearing at 4.3 weeks and a 30-fold increase in weight relative to hatching weight within nine weeks. Fledging occurred at around 11.4 weeks, when the birds had achieved 79% o f mean adult mass; and the tarsus reached 99.8% of its mean adult length by 18 weeks. Males were always heavier and usually larger on
average than females o f the same age. Data obtained were compared with other published studies. Development was more rapid than that for wild Whooper cygnets in Iceland indicating that captive rearing conditions were overcoming the presumed detrimental effect of shortened day length, with lower latitude, upon time available for feeding.