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A lion and his cub. It must be his, because it’s still alive. [1]
The lions in the study lived in Serengeti National Park, where the wet and dry seasons are affected strongly from year to year by the Southern Oscillation Index. After a wetter year, coalitions were more likely to immigrate to the study area and try to take over the local prides. It’s possible that the extra rain helped attract prey like wildebeests and gazelles, which in turn attracted the lions.
Persistence was also key for the invading coalitions to have a successful overthrow. The more times a coalition entered the study area, the more likely they were to defeat the tenured lions. Also, older (and wiser?) coalitions were more successful throne-snatchers. Practice makes perfect!
A male lion tries (unsuccessfully) to join a coalition. [2]
Of course, persistence and experience were not the only factors in the lions’ victories. They also needed to be able to fight. This was best achieved by simply ganging up on the pride leaders they were trying to take down -- the bigger the invading coalition, the more likely they were to triumph. Intimidation can be a tactic all on its own.
The final factor affecting how well lion coalitions did at upending the pride leaders was simply how many coalitions there were in the study area. Even if not all of the coalitions’ attempts to gain control of the pride were successful, defending their territory again and again had to have exhausted the pride leaders, making them less able to defend themselves against invasion the next time.
As climate change progresses and humans take up more and more of the lions’ habitat, there will be more competition between prides for resources like food and territory. This research shows that increased competition makes nomad coalitions more likely to strike out on their own and invade another pride, wiping out a generation of baby lions that otherwise would have contributed to the population. Currently, the way that we protect lions is by reserving small patches of protected area for them that are surrounded by human-controlled areas. However, this strategy may backfire, because it means that there are fewer immigrant males entering the prides in that area. This may seem to make the population more stable, but unfortunately could end up leading to inbreeding.
This research is really important because it points us to possible opportunities to improve our conservation strategies. Lions are on the decline in Africa, and wildlife reserves are already stretched to their limits trying to accommodate more lions as they are pushed out of their natural territories. We should keep focusing on protecting the areas that lions inhabit, and giving them more space when we can -- and the authors even had another suggestion, which was to “swap” the nomadic males between reserves. This might sound extreme (more cubs killed!) but could allow for more genetic diversity within each protected area. This would ultimately keep lion populations healthy so that we can continue to admire these beautiful child-killers from a distance.
Think of the kids! [3]
Media Credits
[1]: Photo by Tambako The Jaguar. https://flic.kr/p/nAPkSq
References
Australian Gov. Bureau of Meteorology, “Southern Oscillation Index,” Australian Gov. Bureau
Borrego, Natalia, Arpat Ozgul, Rob Slotow, and Craig Packer. “Lion Population Dynamics: Do
Wikipedia contributors, "Serengeti National Park," Wikipedia, The Free Encyclopedia,
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In the Bee Lab at Harvey Mudd College, we study more than just bees. We're interested in how groups of animals evolve to coordinate behavior. Honey bees, for example, search out flowers and use their famous dance to tell nestmates where to go. By recruiting more bees to the best flowers, dancing helps the group collect food more efficiently. Using mathematical models, computer simulation, and lab and field experiments with bees and ants, we explore how communication shapes collective behavior.
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Super interesting post! Does kinship ever play a role in the dynamics between nomads and prides? For example, would two siblings ever work together to gain control of a pride led by a non-related male? Thanks!
ReplyDeleteGreat question! The article didn't mention that specifically, but since brothers are usually "ousted" from their pride at the same time, I would imagine that coalitions usually contain siblings. But I don't think they have to be sibling coalitions exclusively. Thanks for asking!
DeleteGreat blog post! I'm curious as to how collaboration (in addition to competition) plays a role in the male pride takeovers. Do you think it will become advantageous over time for male lions to work together and collaboratively rule prides, or will more dominant and aggressive male always have a higher fitness?
ReplyDeleteThanks for your question Hannah! Each coalition works together to take over prides and then defend them from outside attack, so there is collaboration in that sense. I don't think it is likely that coalitions will ever allow tenured males to remain in a pride that they overtake, because it doesn't seem to be a favorable strategy for the males to spend time raising other coalitions' cubs.
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