SEXUAL DIMORPHISM IN NEWBORN SOUTHERN SEA LIONS

  1. H. Luis Cappozzo1,
  2. Claudio Campagna2,
  3. Jose Monserrat3

Article first published online: 26 AUG 2006

DOI: 10.1111/j.1748-7692.1991.tb00113.x

Issue

Marine Mammal Science

Marine Mammal Science

Volume 7, Issue 4, pages 385–394, October 1991

Additional Information

How to Cite

Cappozzo, H. L., Campagna, C. and Monserrat, J. (1991), SEXUAL DIMORPHISM IN NEWBORN SOUTHERN SEA LIONS. Marine Mammal Science, 7: 385–394. doi: 10.1111/j.1748-7692.1991.tb00113.x

Author Information

  1. 1

    Museo Argentino de Ciencias Naturales “B. Rivadavia,” Av. Angel Gallardo 470, 1450 Buenos Aires, Argentina

  2. 2

    Centro National Patagónica, 9120 Puerto Madryn, Argentina and Wildlife Conservation International, New York Zoological Society, New York, New York 10460

  3. 3

    Museo Argentino de Ciencias Nan&es “B. Rivadavia,” Av. Angel Gallardo 470, 1405 Buenos Aires, Argentina

  • The order of the first two authors was determined randomly.

Publication History

  1. Issue published online: 26 AUG 2006
  2. Article first published online: 26 AUG 2006
  3. Received: August 2, 1989 Accepted: January 21, 1991

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Keywords:

  • southern sea lion;
  • Otaria byronia;
  • sexual dimorphism;
  • Peninsula Valdes;
  • body mass;
  • growth rate;
  • maternal behavior

Abstract

Male southern sea lion, Otaria byronia, pups born at Peninsula Valdés, Argentina, were significantly heavier (13.7 ± 1.6 kg, n = 37 vs 12.3 ± 1.4 kg, n= 38) and longer (0.82 ± 0.04 m, n= 29 vs. 0.79 ± 0.03 m, n= 29) than females. The rate of mass and length gain during the first month of life did not differ between the sexes (males: 0.21 kg/d, 0.003 m/d; females: 0.20 kg/d, 0.004 m/d). Sex differences in pup body size were not reflected in female nursing behavior, attendance patterns, and duration of feeding trips. These results suggest that southern sea lion mothers invest more energy in sons than in daughters during gestation, a difference consistent with the importance of large body size to the reproductive success of males in a polygynous species.

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