Research Document - 2006/069
Timing of whelping among Northwest Hooded seals
By Hammill, M.O. and G.B. Stenson
Abstract
The temporal distribution of births was determined by assuming that the distribution of briths followed a Normal distribution and that this could be modelled by following the changing proportion of pups in three age-dependent morphometric and pelage specific stages. Stage data from surveys completed in the Gulf and at the Front were examined. At the Front, the mean date by which pupping had finished was 28 March (SE=2.21, N=8, Range=18 March-4 April). In the Gulf, pupping in most years had finished by the start of April, with the exception of 1994, when the model predicted that pupping continued until May. This late date, and high standard error indicate a very poor model fit to the data. Excluding the 1994 data and Patches 1 and 2 from 2005, births would have finished by 28 March (SE=1.73, N=4, Range=25-31 March). Nursing hooded seals are first observed early in March. This indicates that hooded seal births are spread over a longer time period than seen among harp seals that pup in the same area. From this limited data set, pupping on average should be complete by 2 April. Taking into consideration possible late births, particularly in heavy ice years, nursing should be complete by about the 8-10 April.
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