March 4, 2014
African Lions have always been a fascination of mine, in all honesty it is most likely due to my love of the Lion King growing up. So to me lions were the perfect choice to discuss territoriality. African lions, Panthera leo, live in prides and exhibit group territoriality allowing them to occupy and maintain control over a large area while acting as a group. Territories are defending through roaring, patrolling, and scent marking, and if the other lions do not get the hint with those methods, they employ more drastic methods using direct aggressive encounters (here is an example from the Lion King– http://www.youtube.com/watch?v=y6INp3k-vFc ). As you can expect, the more lions are present, the better they will be able to maintain and occupy more territory.
I will be using Mosser and Packer’s study on group territoriality and benefits from sociality (link to paper: http://proxy.library.unbc.ca:2138/S000334720900219X/1-s2.0-S000334720900219X-main.pdf?_tid=38c66c26-a264-11e3-b278-00000aab0f6c&acdnat=1393803888_5c92fa29b1718dc5ec7fab2ed5abde16). This paper hypothesized that group-territorial behavior has fitness costs associated with territorial competition therefore, it must be subject to selective pressure; potential risks from neighboring prides may account for the grouping patterns of prides; larger groups usually ‘win’ isolated interpride encounters; grouping patterns are not associated with foraging efficiency; and finally that group size determines access to potential resources.
Some may wonder why lions form groups instead of performing individual territoriality like many other organisms do (I know I did). This study found lion in prides have better success than solitary lions and furthermore, larger prides have higher success compared to smaller prides. Larger prides in group territoriality form larger territories, and are able to expand that territory as the pride size increases. The leading explanation for group formation in lions was that cooperative hunting increased success. Hunting success is observed to increase slightly with size of hunting groups. Interestingly, lions can opt out of hunts and hunt individually. It has been observed that individual hunts or hunting groups larger than five are ideal during prey scarcity, larger prides provide this option. When prey is abundant, the group size has very little effect on food intake. Larger groups are more adept to protect their carcasses from scavenging animals such as the spotted hyena.
Unrelated female lions in opposing prides present a higher aggression compared to female lions that have shared genes. However, this lowered aggression only lasts for about 2 years after the daughter lions split from the pride until the mothers begins to treat them like any other unrelated pride (out of sight out of mind?). Male lions practice infanticide when taking over a pride, and more established prides will not be taken over as easily, therefore, they will have a reduced rate of infanticide. Male lions will also kill female lions in opposing prides to change the territorial competition by altering the balance of power using lethal methods, especially with females that they would not be able to mate with in the future. It is also suggested that it may be to remove individuals that would compete for the limited resources. The pride protects the females in risky areas by never allowing them to venture alone, whereas females in safer areas are able to venture away from the group at times.
Benefits of Territoriality
As schooling fish have learned, there is safety in numbers; the more lionesses present, the lower probability an adult female has of dying. This study found that prides containing more adult females have higher rates of reproductive success and lower rates of mortality and wounding, this is likely due to the ability to form larger subgroups when potentially risky situations emerge. Female mortality and wounding is also reduced because as previously mentioned, the rate of male takeover and infanticide will be reduced so the rate of mothers and mothers-to-be injury or death will be lower because they will not be needing to protect their young from other males. In conclusion, lions are far more successful in large prides compared to small prides.
P.S. All lions want is a little love– man hugging ‘wild’ lions video (http://www.youtube.com/watch?v=krFQ4FbHaKQ)
Kissui BM, and Packer C. 2004. Top-down population regulation of a top predator: lions in the Ngorongoro Crater. Biological Sciences. 271:1867-1874
Mosser A, Packer C. 2009. Group territoriality and the benefits of sociality in the African lion, Panthera leo. Animal Behavior. 78:359-370