Galimberti, F., A. Gallastroni and S. Sanvito (2002)
Behavioural and morphometric measurements of parental investment in southern
elephant seals at the Falkland Islands.
Polar Biology 25: 399-403.
Parental investment is a key variable in the study of breeding strategies and
life-histories evolution. In Pinnipedia, parental investment is usually
calculated from direct measurements of pup weight gain or energy transfer
between the mother and the pup. These direct methods always involve handling and
restraining procedures that pose practical, logistical and ethical problems. To
evaluate if weighing can be substituted by indirect observational estimates of
parental investment, we analysed the relationship among various behavioural
measures of suckling and post-natal growth in the southern elephant seal
population of Sea Lion Island (Falkland Islands). Behavioural measures were in
all cases a poor predictor of true investment as estimated by weighing. We
concluded that there are currently no e.ective alternatives to direct handling,
and that the best way to reduce the potential adverse impact of investment
studies is the improvement of the handling protocol, which should include an
estimation of the long-term e.ects on the health of handled animals. Further
research is needed to test the validity of non-behavioural indirect methods
(e.g. 3D photogrammetry).