Pup growth of the guadalupe fur seal, Arctocephalus townsendi
Keywords:
Guadalupe fur seal, Arctocephalus townsendi, Isla Guadalupe, pup growthAbstract
Pups of the Guadalupe fur seal were captured, marked with hair bleach, measured and weighed between two and four times during their first year of life, during three consecutive years (1991, 1992 and 1993) conforming a sample of 132 pups of both sexes. The following paramÂeters were measured: standard length, body mass, and axilar girth, these were measured in the first hours to days of birth when the pup still had attached a soft umbilical cord, and at 40, 145 and 220 days after birth. Mean birth body mass was 4.9 ± 0.5 kg, n = 17 (males: 4.9 ± 0.4 kg, n = 7; females: 4.9 ± 0.5 kg, n = 10), mean length was 64.4 ± 4.3 cm, n = 17 (males: 67.2 ± 3.5 cm, n = 7; females: 62.5 ± 3.7 cm, n = 10). Growth was exponential to 145 days and stabilized to 220 days at weaning age (weanÂing takes place between February and March at 9-10 months of age), mean weaner’s body mass was 14 ± 2.8 kg, n = 13 (males: 13.7 ± 3.6 kg, n = 5; females: 14.3 ± 2.0 kg, n = 8) with a mean length of 89.4 ± 8 cm, n = 13 (males: 91.3 ± 8.5 cm, n = 5; females: 86.4 ± 6 cm, n = 8). Body mass was not significantly different between the sexes for the fur seal pups, although lengths were significantly different at birth and at several other stages. The curves of body mass-length relationship showed high variability, but nevertheless showed a high correlation, the body mass and length regression was significant (r2 = 0.7024, P < 0.001). Much of this variability is caused by the long foraging trips of the females. This leads to drastic changes in pup body mass due to rapid milk intake during a mean of 5.03 days of female attendance and major body mass loss during female absence of a mean of 11.5 days.Key words: Guadalupe fur seal, Arctocephalus townsendi, Isla Guadalupe, pup growth.References
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