Infanticide: Did lions escape to protect cubs?

TENDER CARE: A new lion asserts authority by killing small cubs
TENDER CARE: A new lion asserts authority by killing small cubs

The four lionesses who briefly escaped from the Nairobi National Park last week may have been running away from a violent, lovelorn male.

Kenya Wildlife Service lion expert Tuqa Jirmo, who is also a senior warden, says the lionesses might have feared for the safety of their cubs if their pride was taken over by a new male.

"If the pride is taken over, the new male will kill cubs, a phenomenon called infanticide. This incident happens a lot in a lion population," he said.

Jirmo says in such cases females normally look for safety outside their usual range.

The lionesses and their cubs escaped last Friday morning but some later returned on their own while others were captured.

Jirmo says lions live in stable kin groups of about one to 18 females.

Lions by nature form prides which act as a gang to defend their territory against other lions.

A study by Jon Grinnell and Karen McComb from the department of ecology, evolution and behaviour at the University of Minnesota, corroborates Jirmo's view.
The study, titled “Maternal Grouping as Defence Against Infanticide By Males, Evidence From Field Playback Experiments On African Lions”, says lionesses also roar to stay in contact with their pride mates and to defend their territory from other prides. Sometimes they roar to attract males for sex.

The roar is audible five to eight kilometres away. But this roar risks attracting the attention of non-resident, dangerous males.

The study was done on lion population in Serengeti and Ngorongoro ecosystems in Tanzania. It was published in 1996 in Behavioral Ecology, a bimonthly scientific journal by Oxford University Press.

“However, females with cubs stand to incur substantial fitness losses if their roars attract potentially infanticidal males,” says the study.

A defenceless female may just have to run away with her cubs. Some experts think this is what sometimes happens at NNP.

But nobody knows exactly why the lions have been trying to escape.
KWS spokesman Paul Gathitu says in the last three weeks, they have received various reports of lions being spotted within the adjoining army barracks.
“We locked the culvert last week for lions to be captured and brought back to the park,” he said.
Gathitu said one of the lionesses might have been looking for a place to give birth, or was probably worried over the safety of her cubs.
“The mother might have even been disturbed,” Gathitu suggests.
One of the largest studies on behavior of African lions is titled “Optimal Group Size, Dispersal Decisions and Post Dispersal Relationships In Female African Lions”.

It was done by Kimberly VanderWaal, Anna Mosser, and Craig Packer from the department of Ecology, Evolution, and Behaviour of the University of Minnesota.

The study used 40 years of long-term data to test whether dispersal decisions of female African lions, Panthera leo, are sensitive to variations in pride size, interpride competition and the quality of their natal territory.

This study has previously been cited to explain human-wildlife conflicts around the shrinking Nairobi park.

"A larger proportion of each cohort dispersed as the number of breeding females in each pride increased and this pattern clearly reflected the greater within-group competition in larger prides," the experts say in the study done at the Serengeti National Park. It was published in 2009.
They said female cohorts were sensitive to the different pride-size-specific reproductive rates on the plains and in the woodlands.

Per capita reproductive success reached a maximum at three to six females on the open grass plains of the Serengeti and at three to 11 females in the woodlands.

Approximately 50 per cent of female cohorts dispersed when potential pride size exceeded the habitat-specific optimum, whereas only nine percent of cohorts dispersed at smaller pride sizes.

Cohorts of one to two females rarely dispersed, especially in high-density habitats.

This is not the first time lions have escaped from the Nairobi park. Conservationists have mostly blamed developments that encroach on the park land, turning it from a legitimate reserve to a naturalistic zoo.

In June 2012, six lions were killed by villagers after they strayed into their farms near Kitengela and killed animals.

NNP is bounded on the north by the sprawling capital city and hemmed into the south near Kitengela by increasingly privatised, subdivided, and fenced-in plots.

It recently emerged that KWS has allowed the phase two of the Standard Gauge Railway to cut through the park.

There are fears more animals may be killed in future as they roam private lands that were once their territory, or as they look for prey outside the dying park, or while running away from jealous males.

About 2,000 lions remain in Kenya and in 2012 the KWS said the country was losing them at a rate of around 100 each year.

Some are dying due to destruction of habitat and others have been killed by disease.