[Sharing Lights]

Lion Prides



Lions form a very complex pride unit that Packer terms as a fission-fusion social unit (Packer 1990). The average pride consists of 1-4 males, as many as 15 lionesses, and various numbers of offspring. The actual size of the pride is highly variable and depends on factors such as food availability, environmental conditions, reproductive success, etc. Therefore, there is no specific pride size due to the variability caused by these factors.



Females within a pride stay together for life. These natal female prides are comprised of mothers, daughters, aunts, and nieces. Each generation of females will live in the exact same place that their mothers did and generations of females before them. The only lions that have a temporary status within a pride are males. Male lions by the age of 2-4 years will eventually leave the pride and form a coalition with the other males in their pride which typically tend to be their brothers. Male cubs can be driven out earlier by infanticidal males during a coalition takeover. The resident adult males defend their access to the females against any incoming males. Schaller sees pride membership actually as a form of life insurance. Resident males will eventually lose their pride in a coalition takeover (Schaller 1972).





Male Coalitions



The brother/pride-mate male coalitions form very quickly after leaving their pride. The coalition is nomadic until they find a pride they can overtake. Overtaking a pride is not an easy task, and the resident males will fight significantly to try to avoid being kicked out of their pride. These overthrows result in many injured and/or dead lions. Regardless of whether the resident males die in fighting the incoming males or not, they will die of starvation shortly after losing their pride. Male coalitions that are evicted rarely ever establish residence within a pride again, and if they don’t have a pride then they can’t reproduce nor gain access to food as easily and consequently die due to starvation. The typical residence for a coalition is only 2-3 years. Therefore, the life expectancy of a male lion is very short (Grinnell 1995).



The larger the coalition, the easier it is to take over a pride and the longer they will retain their residence. Large coalitions are also capable of holding onto two smaller prides as well. However, there is a certain degree of difficulty in having such a large coalition of males. Male lions only form coalitions with their brothers and their pridemates; therefore, their native pride must have been very large with multiple females in synchronous birth and lacking in predation or infanticidal males to produce this large of a coalition. Unfortunately, not that many male cubs actually make it to form such a large coalition. Therefore, the average size of a male coalition is around 1-4 males (Bygott 1979).





Grouping Patterns



There are plenty of different reasons mentioned that suggest why lions would group themselves the way they do, but Packer seems to think there are three main factors for this grouping behavior:



1) Cooperative Cub Defense

a. Females must protect their offspring against infanticide. This is a key reason as to why they group together and care for cubs in the egalitarian ways they do.

2) Group Territoriality

a. Females must be able to leave their territory to hunt the home range animals they commonly eat. They need the territory to return to after hunting. Similarly, it would be nearly impossible to have successful breeding without a territory. Lions fight more over their territory than they do over their kills.

3) Female Reproductive Patterns

a. Females will enter estrous moreso when prey is abundant, and the ability to exploit pride hunting to gain access to food benefits the reproductive success of the females (Packer 1990).





Sex Ratio



What is a sex ratio? A sex ratio is just determining the percentage of males vs. females within the offspring. Packer has found that lions actually do bias their sex ratio in favor of males. If pride females have more males, then they are more likely to increase their reproductive success by spreading their genes to multiple females, but they also increase the capability of the males have better reproductive success by increasing the coalition size. As a result, female lions increase their inclusive fitness and the reproductive success of their male offspring by biasing their sex ratio towards males (Packer 1987).