(^72) Vol. 6 Issue 12
cubs die she comes into oestrus almost straightaway.
Is the situation the same elsewhere? Possibly – though,
given the difficulties in observing wild tigers, we can’t be
certain. Dale Miquelle, director of the Wildlife Conservation
Society’s Russia Program, reports that in Sikhote-Alin
Reserve, the largest reserve in the Amur tiger’s range, just one
case of infanticide has been documented in the past 20 years.
“This one was quite dramatic: the male ate the cubs, which
were about six months old, then died – apparently from
wounds incurred while fighting with the cubs’ mother, or
possibly another male in the area.”
We currently interpret this behaviour according to
the selfish gene theory, which elevates the interests of an
individual’s gene package over those of the wider species. It
does not necessarily seek to ensure the survival of the fittest
- only the survival of those particular genes carried by that
particular male.
The kids aren’t alright
To the female, infanticide represents a massive loss of genetic
and nutritional investment. So how, from an evolutionary
point of view, can this be ‘fair’? The answer lies in what
David Smith calls the ‘land-tenure’ system. He was one of the
lead scientists of the long-term Smithsonian Tiger Ecology
Project in Chitwan National Park, Nepal.
It’s no exaggeration to claim that modern tiger research
dates from December 1974, when the Smithsonian team
radio-collared its first tiger. The researchers went on to collar
dozens more, and discovered a fascinating phenomenon.
Clockwise from left: Anup Shah/naturepl.com; Andy Rouse; Suzi Eszterhas/naturepl.com; Patrick Kientz/BIOS/FLPA Tigresses living ‘next door’ to each other, just 10km apart,Carnivores
Infanticide has been recorded in leopards, jaguars and
bears, but lions provide the best-studied example. Each
pride is a community of related females and cubs. Male
coalitions or two or three related lions compete for access
to the pride; if successful, they defend all cubs born during
their tenancy, regardless of paternity. But when a new
coalition wins a takeover battle, infanticide often results.
Mothers defend their cubs but if the cubs are killed they
may eat the carcasses, minimising the nutritional loss.Primates
Infanticide by males hoping to accelerate access to
females has been observed in more than 40 species
of primate. Some female primates employ ‘paternity
confusion’ – mating with several males, all of whom are
likely to protect ensuing offspring as their own. This is
particularly effective among species such as baboons in
which numerous males may be attached to each troop.Small mammals
Male meerkats are not known to kill babies. Why would
they? Females are ready to mate again as soon as they
give birth. But female meerkats, living communally, kill the
young even of close relatives to focus the group’s efforts
on raising their own babies. Young gerbils also kill babies
but apparently stop once they have mated themselves.
Some male mice are murderous when they have just mated,
knowing that extant babies cannot yet be theirs. Female rats
kill alien young, for food and to take over nests.INFANTICIDE IN MAMMALS
Above: a mother
tussles with her
18-month-old
cub – a sign that
she is ready for
her offspring to
disperse and
establish their
own territoriesThis lion and lioness in the
Maasai Mara are less than
happy to see this cubCheetahs
DNA analysis in the Serengeti revealed that, of litters
containing more than one cub, nearly half were sired by
multiple males. It seems female cheetahs can ovulate ‘to
order’, so different eggs can be fertilised by different males
during a single oestrus. Males form long-lasting, fiercely
territorial coalitions, only socialising
with females during mating.
Females have larger ranges,
travelling through the territories
of several males, so by ‘habitual
promiscuity’ they may cut the
risk of infanticide. Most cubs die
anyway, killed by lions, hyenas,
leopards or starvation.COMMON IN...
NOT SEEN IN...
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oestrus. Males form long-lasting, fiercelcely y
ons, ,only sy sociocialising
rinng mating.ng.ng.
argrger ranganges,eses,
ghgh ththe te terrerritoitoorieries s
s, so bby y ‘ha‘haabitbituall
ey mamayyy cu cucut tt the
e. MMososssttct cububs diee
y y liolions,ns, hyhyenanas, s,
vvation.TIGERS
A cheetah cub
nurses for four
months, but
doesn’t become
independent till it
is 18 months old