WHY DOES A FEMALE ANTELOPE HAVE HORNS?
turn down an opportunity to read a journal called Gnusletter, a
publication of the Antelope Specialist Group of the International Union
for Conservation of Nature? Gnu is the African name for wildebeest, from
the rather unimaginative Dutch name meaning "wild beast." Gnus
are one of the 140 species in the true antelope family, the Bovidae.
Estes' account covers wide-ranging behavioral literature about animals with horns and considers extensive biological and evolutionary nuances. But his basic premise is that when females of species in the antelope family have horns, they did not evolve for purposes of defense for themselves or their offspring. Most antelopes use their speed to escape predators rather than staying to fight them. Even males of most horned species of antelope and deer use their horns for male-male combat rather than predator defense. Estes maintains that when both sexes have horns, it reduces "male despotic competition toward developing males." The behavioral concepts involved are complex, but the essence is that adult males tend to attack young males and drive them away. But dominant males are less likely to be provoked into attacking a young male if it looks and acts similar to young females, including both having horns. If juvenile males are not driven away, they can stay for a longer period with their mothers and have the benefits of herd protection. Once young males leave a herd, their horns continue growing and they assume distinctively male behavior patterns; the same is not true of females.
Estes explained how his hypothesis could be tested in the wild by studies among species to determine when young males leave female herds and what the survival rate is of offspring of horned and hornless females. His rationale for not conducting the field studies himself was sensible"both on account of my advanced age (83) and on the labor of writing a book on the behavioral ecology of the Serengeti wildebeest population." He invites "any antelope specialist or other biologist" who wants to pursue such a study to contact him via email.
I am looking
forward to reading a book on the Serengeti wildebeest, aka gnu, for which
Richard Estes has provided insights and suggestions. He clearly knows
more about antelopes than anyone else in the world.
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