Are low infidelity rates in feral horses due to infanticide?
Gray, ME and Cameron, EZ and Peacock, MM and Thain, DS and Kirchoff, VS, Are low infidelity rates in feral horses due to infanticide?, Behavioral Ecology and Sociobiology, 66, (4) pp. 529-537. ISSN 0340-5443 (2012) [Refereed Article]
A growing number of studies conducted on di-
verse taxa have shown that extra-pair/group paternity is
higher than what would be predicted from behavioral obser-
vations alone. While it may be beneficial for females to mate
with multiple males, this often results in offspring not sired
by the behavioral father, which could influence offspring
survival, especially in social mammals. Feral horses (Equus
caballus) maintain stable social relationships over several
years, usually with one stallion defending a harem band of
unrelated mares against other males. Sneak copulations by
subordinate males have been observed and mares some-
times change bands, both of which can result in foals
sired by males other than the dominant band stallion.
We measured female fidelity in free-ranging feral horses
in 23 bands, with 51 foals over four foaling seasons and
tested offspring paternity against parental behaviors. We
used 12 polymorphic microsatellite loci and the program
CERVUS 2.0 to determine and exclude potential sires.
The majority of mares remained in the band with the sire
of their foal resulting in most foals being sired by the
band stallion. Most foals that were not sired by the band
stallion were born in the year after a round-up and we
could not determine if they were the result of band chang-
ing or sneak copulations. Foals born into a band without
their sire had lower survival rates and mothers were
significantly more protective of foals not sired by the band
s t a l l i on. The s e f i ndi ngs s ugge s t t ha t b a nd s t a bi l i t y
increases the reproductive success of mares and support
the importance of infanticide risk in equid social structure.