ADAPTATIONS OF FEMALE LIONS TO INFANTICIDE BY INCOMING MALES.

By: Craig Packer, Anne Pusey, Karen McComb, Jon Grinnell

Lion Social Habitat

Some Facts… Prides of 2-18 adult females with cubs

Coalition of 1-7 adult males Males come and go

Communication involves roaring Infanticide is common

Location of Field Studies

Numerous river courses

Lions are able to conceal themselves

Experiments

#1 Female response to infanticide

Increased cub mortality during male takeovers#2

Females can distinguish between the roars of familiar and unfamiliar males and unfamiliar females

Questions???

Why and how does infanticide occur in a given population of lions?

How do female lions adapt to it?

Effect of infanticide on lion population and overall fitness?

Methods (#1)

15 prides of lions were studied (1978-1981) in Serengeti National Park,

Tanzania Infanticide occurrence, female

behavior, incidence of wounds, and mating activity were recorded during

male takeovers

Methods (#2)

Playbacks of roars from fathers of cubs, from unfamiliar males and from unfamiliar females were given to female

lions with cubs

Behavior of female lions with cubs was documented based on the responses to these playbacks

Retreating Approaching speakers

Moving towards their cubs Snarling

Results (#1)

Infanticide was observed 6 times Cub mortality higher during male takeover None of the cubs survived up to 6 months

during takeover Cubs aged 13-20 months were evicted

Overall male takeover had a detrimental effect on the fitness of females

Results (#1 cont.)

Responses of mothers to incoming males at takeovers

Defense of cubs

Avoidance of new males

Heightened female sexual activity

Low fertility period

Mating Levels

Results (#2)

Females and cubs agitated in response to playbacks of roars of unfamiliar males

Retreating-common response to roars of unfamiliar males

Females also moved towards the cubs in response to roars of unfamiliar males

Results (#2 cont.)

Females with cubs approached speaker in response to playbacks of unfamiliar females

No movement towards the cubs in response to playbacks of unfamiliar females

Cubs participated in all activities together with mothers

Data (#2)

Discussion

Heightened female sexual activity and low fertility during takeovers elicits competition between male coalitions for

control of the pride --> results in larger coalition

It is adaptive, females need protection from male harassment

Only large male coalitions remain in a pride for more than 2 years

Periods of infertility improve females reproductive success

Discussion cont.

Females can discriminate between roars of unfamiliar and familiar males, and unfamiliar females

Encounters between alien males and females with cubs are very costly for the females

Vocal recognition has been demonstrated in lions

Grouping by females appears to be an important adaptation to infanticide by males

Future Research

Other prides in different areas should be studied

Other mechanism of female defense are interesting

Infanticide in larger coalitions

Further playbacks would be necessary to see if cubs are able to distinguish between vocalizations

Evolution of the skills of social cognition

Critiques

Small groups studied

Data for Part I inconclusive

Difficult to observe (lions conceal themselves)

Difficult to determine cub age (cubs are hidden after birth)

More methods of protection should have been studied