[MARMAM] new article: porpoise mate guarding

pmwillis at mail.utexas.edu pmwillis at mail.utexas.edu
Mon Jun 11 10:21:27 PDT 2007

Dear All,

The following paper is available online:

Willis, P.M., and Dill, L.M. 2007. Mate guarding in male Dall's porpoises
(Phocoenoides dalli). Ethology 113:587-597.


Mate guarding, whereby a male closely attends and defends a fertile female from
extra-pair matings, is one mating tactic males of many species use to protect
their paternity. Although female defense occurs in many species of terrestrial
mammal, comparable examples among cetaceans are largely absent, potentially as
a result of the wide dispersion and mobility of females and their prey. Here,
we investigate whether the close association of individual male Dall's
porpoises with individual females during the breeding season is consistent with
mate guarding. As mate guarding is predicted to be costly, and in other taxa is
often associated with a reduction in foraging efficiency, we also examine
whether males trade-off this activity with time at depth. Males maintained
longer associations and closer distances with female partners than with male
ones. They also surfaced in greater synchrony with, and more often approached,
their female partners than male ones. In contrast to males with male partners,
males paired with females engaged in agonistic interactions with other adult
males, and infrequently affiliated with extra-pair individuals. These data
suggest males are actively attempting to maintain their associations with
females, while also acting to reduce female extra-pair copulations and increase
their own paternity. Guarding males also undertook shorter dives than
non-guarding males, suggesting that they trade-off time at depth with guarding.
Such a trade-off is likely to involve a reduction in foraging opportunities, due
to a decrease in time spent at foraging depth. Mate guarding in this species may
be facilitated by the relatively smaller size and decreased mobility of newly
calved, estrous females, particularly if females also benefit from guarding.

Please contact me (pmwillis at mail.utexas.edu) for PDFs.


Pamela Willis
Section of Integrative Biology
University of Texas at Austin
1 University Station, C0930
Austin, TX, USA 78705
Phone: 612-475-6164  Fax: 512-471-3878
pmwillis at mail.utexas.edu

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