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Mass transfer during lactation of an ice‐breeding pinniped, the grey seal ( Halichoerus grypus ), in Nova Scotia, Canada
Author(s) -
Baker S. R.,
Barrette C.,
Hammill M. O.
Publication year - 1995
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1995.tb02730.x
Subject(s) - lactation , biology , zoology , weaning , population , nova scotia , fur seal , demography , pregnancy , history , genetics , archaeology , sociology
Mass transfer during lactation was examined by serial weighing of mother‐pup pairs in an ice‐breeding population of grey seals, in the southern Gulf of St. Lawrence (c. 46° N‐ c . 63° W), Canada. Male pups (171 ± 1–3kg, n = 4) were significantly heavier at birth ( P = 001) than females (14.6 ± 1.4 kg, n = 9), and grew significantly faster until weaning (males: 2.7 ± 0.6kg/d, n = 45; females: 2.4 ± 0–5kg/d, n = 63, P = 004). At weaning, males (56.2 ± 6.7 kg, n = 24) were significantly heavier ( P = 0‐01) than females (51.6 ± 53kg, n = 25). Lactation for both sexes lasted 14.9 ± 1.4 days ( n = 13). At parturition, adult females weighed 227 ± 26 kg ( n = 26). During lactation they lost 5.6 ± 1.lkg/d ( n = 35). An analysis of carcass composition of six females collected during different stages of lactation showed that they utilized 61% of their fat reserves during lactation. Efficiency of mass transfer varied from 25–3% to 70–4% (49.3 ± 10.8%, n = 35). Examination of stomach contents indicated that some ice‐breeding females consumed food during lactation. Our results in this ice‐breeding population show that females invest more in sons than in daughters.