Friday, October 21, 2016

What do north clan hyenas, south clan hyenas, and a lioness have in common?


Yesterday was a pretty exciting morning. It started off quiet; we went to the South clan’s den where we saw Java, south clan’s matriarch nursing one of her cubs. Toledo, south’s alpha male was also resting close to the den. There was one other subby looking hyena wandering around that it took us a little bit to ID, but I soon recognized him as Lunch Lady, a young male hyena from North clan. We’ve never seen him in South clan before, but the way he was chilling with Java and Toledo made it look like he was already well accepted. Lunch Lady is part of the "professions" lineage; his mother is Sherman. 

Lunch Lady, a beautiful young male hyena.
Male hyenas almost always disperse from their natal clan between the ages of 3 and 5 and join a new clan in search of mating opportunities. It usually takes some period of time before they’re fully accepted by the hyenas in their new clan and they’ll join as the lowest ranking hyena. I’ve known Lunch Lady since he was a little cub in North clan chewing on the car, so it was really exciting to see that he’s most likely joined South clan.
Lunch Lady when he was a little cub chewing on my back pack strap that was accidentally sticking out of the car door.

As it started to get light out, Lunch Lady started to wander away from the den. We followed him and gave him some inhibitory control cylinder trials and some multi-access box trials on which he did great! Lunch lady is now the fourth hyena in Serena to open up the box. Interestingly, he used the push flap by pawing at the box with his front paws. He’s the first wild hyena to use this solution!
Lunch Lady solving the multi-access box while Toledo looks on. Toledo was too afraid to come close!  
After doing trials with Lunch Lady we did a prey transect and then drove through North territory to get back to camp… that’s when we saw a mob of hyenas that we quickly recognized as South hyenas just inside of the North territory boundary! This group included Lunch Lady as well as natal South animals Palazzo, Nali, Star, and Seabiscuit. We followed these guys to a zebra carcass that North hyenas were chowing down on. Two other south immigrant males, Strummer and Slim were also born in North clan and were seen feeding with North clan despite being well accepted into South clan. 
Slim, a South immigrant male who was born in North, excitedly approaches the zebra carcass with a few other South hyenas.

Slim (left cub) when he was a cub nursing form his mom Ink with his brother Dalt (right).

Nali, a natal south hyena, eagerly looks at the zebra carcass. 
Strummer, a South hyena who was born in North, feeds on the carcass with other North hyenas.

Oakridge, an immigrant male in North clan, is covered in blood as he feeds on the zebra carcass.
This was a clan war over the zebra carcass!! Two South hyenas, Taylorsville and Onekama were extremely drenched in blood which made Mike and I think that they killed it and North clan had run them off it. Clearly, Taylorsville and Onekama had called in reinforcements because more and more South hyenas were showing up by the minute! South clan charged the carcass causing the North hyenas (Oakridge, Ypsi, MrsB, and Kath) to scatter.

Taylorsville's face was black with blood. Maybe he killed the zebra?
Taylorsville, a South immigrant male, faces off against Ypsi, a North immigrant male.
This South hyena was literally foaming at the mouth.

When South clan charged the carcass to take it back from the North hyenas, Slim, with the help of Onekama, ran off with a zebra leg. A few minutes later, Strummer ran off with a second zebra leg. All three of these South immigrant males retreated into South territory while the rest of South clan beings to feed from the carcass.

Strummer running off with a chunk of zebra leg.

Strummer when he was a cub chewing on a tourist vehicle.

Interestingly, Lunch Lady was not allowed to feed at the carcass despite his good relations with Java and Toledo at the den. Lunch Lady actually seemed quite confused about which hyenas were supposed to be his friends and which his enemies and attempted to socialize with both South and North hyenas. Immigrating to a new clan can be confusing! A male hyena has to learn the identities and ranks of a brand new clan of hyenas which can number from 30 to over 100 individuals!

Lady (left) making a goofy face while he feeds on the carcass with North hyenas.
Anyway, South hyenas started devouring the carcass when… a lioness explodes out of the thicket growling and sends South hyenas scampering for their lives. She takes one look around, decides there are WAY too many hyenas for her to deal with and promptly walks back into the thicket. Now this is not only a clan war, but a lion-hyena interaction!

Video of lioness charging (my apologies for cutting the audio, there was some inappropriate language due to surprise from myself and Mike).

Some rangers that we talked to after the session said that she might be the lioness who has some babies in the area. We didn’t get a good look at this one, but we did see a heavily lactating female a few days ago.

Lactating lioness. 
South hyenas retained the carcass after the lioness retreated, but five minutes later North rallies and chases them off the carcass again. At this point there were about 4 North hyenas and 7 South hyenas (including Lunch Lady as a South hyena). By this point the South hyenas seemed pretty full and they did not try to take the carcass again. Interestingly, Lunch Lady continued to feed with the North hyenas and when they finished eating he followed Ypsi back into North territory. It seems like he’s not completely part of South clan yet and is still associating with members of his natal clan!

North hyenas feeding on the carcass.

Wednesday, October 12, 2016

Urbanization, neophobia, and problem solving

So, if you’ve been keeping up with the blog you’ve probably read a few posts about my cognition apparatuses and seen plenty of photos. Link here and here. If you haven’t read them, I’ll summarize briefly. I’m a graduate student on the Hyena Project and I’m testing the cognitive abilities of hyenas with a general problem solving task. I’m interested in the individual, social, and ecological factors that affect how good they are at learning to solve novel problems.

Studying cognition in the wild poses unique challenges…
I’ve been out here for four months now- so what’s happening with the hyenas? So far, I’ve mostly been conducting familiarization trials with the hyenas to help the hyenas learn to associate food with the puzzle box. In familiarization trials I leave the puzzle box wide open with food easily accessible (no problem solving required to open). This is to overcome any neophobia (fear of novelty or new things) a hyena might have and to increase their motivation to participate in cognition trials. There is a lot of increasing interest in testing the cognition of wild animals, since animals in captivity grow up in an unnatural environment. However, in the wild the results of a cognition study can be skewed based on which individuals decide to participate in trials. I put out the puzzle box within eyesight of a hyena and then the hyena decides whether or not to investigate the puzzle box or walk away. This can definitely skew results if hyenas with specific characteristics are more likely than others to participate. But, studying wild hyenas gives me the chance to assess how urbanization might affect learning in the wild.

A hyena watches a herd of cattle (credit
How does urbanization affect animal cognition?
I’m collecting data in two different parts of the Maasai Mara National Reserve: Serena and Talek. In Talek, hyenas live on the border of the reserve and regularly encounter Maasai villagers, heavy and poorly regulated tourism, cattle grazing, and snares from poachers. In other words, they experience a high degree of “urbanization”. In Serena, hyenas are well protected from poaching and cattle grazing and tourism is strictly regulated. There’s a lot of interest in the scientific community on how the dramatically changed urbanized environments affects animals, and in particular, animal cognition. A large body of research suggests that rapidly changing environments, like urbanized ones, select for bigger brains and greater smarts (Marino 2005). Some studies have shown that urban animals have larger brains than rural animals (Maklakov et al. 2011; Snell-Rood & Wick 2013) and that large brained animals are better at invading new habitats (Amiel et al. 2011; Sol et al. 2008; Sol et al. 2005). However, in the short run changing environments can be highly stressful for animals and many species are unable to cope with change, resulting in extinction. In addition, large brained animals are also more like to be endangered (Abelson 2016).  

Some hyenas investigate the box, but even more of them hang out at a distance without ever touching it. 
Talek hyenas are more neophobic?
So far, it looks like Talek hyenas might be more neophobic than Serena hyenas because they’re less likely to eat the bait from inside the box. I’ve collected 149 trials with 63 different hyenas in Talek and 176 trials with 69 different hyenas in Serena. Out of these trials in just 28% trials a hyena fed from the puzzle box in Talek while in 38% of trials in Serena a hyena fed from the puzzle box. These were all familiarization trials (no problem solving required) where the box was left wide open with the food easily accessible. All the hyena has to do is walk up to the box, stick their head inside and eat the food. Whether or not a hyena is willing to eat food from a novel source could indicate their level of neophobia (though it could also indicate their food motivation level). Since a greater percentage of Serena hyenas were willing to feed from the puzzle box this could suggest that hyenas in Talek are more neophobic (more nervous about the puzzle box). However, it’s important to note that these are raw percentages and I have not controlled for the fact that some hyenas have gotten more than one trial with the box.

Neophobia and urbanization
Other studies have also found that urban animals are more neophobic than rural animals in addition to being better problem solvers (Griffin et al. 2015; Miranda et al. 2013; Audet et al. 2016).  However, other studies show that animals in novel or urban environments are less neophobic (Martin & Fitzgerald 2005; Møller 2009). While neophobia may help individuals to avoid dangers in a novel environment, it may also make them less likely to find novel sources of food to exploit.

VENI, an immigrant male hyena in Serena was fairly nervous about approaching the box.
Neophobia and problem solving
The relationship between neophobia and problem solving in animals is mostly inconclusive (Griffin & Guez 2014) but previous research with hyenas by hyena lab alumni Sarah Benson-Amram suggests that neophobic hyenas are less likely to successfully problem solve (Benson-Amram et al. 2013; Benson-Amram & Holekamp 2012).  If Talek hyenas really are more neophobic then they might be less likely to solve my puzzle box - if neophobia is a causal factor in performance and not just correlative. My hypothesis is that Talek hyenas will be better problem solvers, but neophobia could superficially make them worse. I.e. Talek hyenas could  be better problem solvers than Serena hyenas in reality, but neophobia could prevent them from interacting with the box making them look worse on paper. Therefore, I have to make sure to get as many familiarization trials to both Talek and Serena hyenas as possible to try and overcome any effect of neophobia so that I can test the effect of urbanization independently. Hopefully Talek and Serena hyenas will start getting test trials soon where they have to learn how to open the box to retrieve the bait inside. Who knows what I’ll find out!

References cited
Abelson, E.S., 2016. Brain size is correlated with endangerment status in mammals. Proceedings. Biological sciences / The Royal Society, 283(1825), p.20152772-.
Amiel, J.J., Tingley, R. & Shine, R., 2011. Smart moves: effects of relative brain size on establishment success of invasive amphibians and reptiles. PloS one, 6(4), p.e18277.
Audet, J.-N., Ducatez, S. & Lefebvre, L., 2016. The town bird and the country bird: problem solving and immunocompetence vary with urbanization. Behavioral Ecology, 27(2), pp.637–644.
Benson-Amram, S. & Holekamp, K.E., 2012. Innovative problem solving by wild spotted hyenas. Proceedings. Biological sciences / The Royal Society, 279(1744), pp.4087–95.
Benson-Amram, S., Weldele, M.L. & Holekamp, K.E., 2013. A comparison of innovative problem-solving abilities between wild and captive spotted hyaenas, Crocuta crocuta. Animal Behaviour, 85(2), pp.349–356.
Griffin, A.S. & Guez, D., 2014. Innovation and problem solving: a review of common mechanisms. Behav Processes, 109(Pt B), pp.121–134.
Griffin, A.S., Guillette, L.M. & Healy, S.D., 2015. Cognition and personality: an analysis of an emerging field. Trends in ecology & evolution, 30(4), pp.207–14.
Maklakov, A.A. et al., 2011. Brains and the city: big-brained passerine birds succeed in urban environments. Biology letters, 7(5), pp.730–2.
Marino, L., 2005. Big brains do matter in new environments. Proceedings of the National Academy of Sciences of the United States of America, 102(15), pp.5306–7.
Martin, L.B. & Fitzgerald, L., 2005. A taste for novelty in invading house sparrows, Passer domesticus. Behavioral Ecology, 16(4), pp.702–707.
Miranda, A.C. et al., 2013. Urbanization and its effects on personality traits: a result of microevolution or phenotypic plasticity? Global change biology, 19(9), pp.2634–44.
Møller, A.P., 2009. Successful city dwellers: a comparative study of the ecological characteristics of urban birds in the Western Palearctic. Oecologia, 159(4), pp.849–858.
Snell-Rood, E.C. & Wick, N., 2013. Anthropogenic environments exert variable selection on cranial capacity in mammals. Proceedings. Biological sciences / The Royal Society, 280(1769), p.20131384.
Sol, D. et al., 2005. Big brains, enhanced cognition, and response of birds to novel environments. Proceedings of the National Academy of Sciences of the United States of America, 102(15), pp.5460–5.

Sol, D. et al., 2008. Brain size predicts the success of mammal species introduced into novel environments. The American naturalist, 172 Suppl, pp.S63-71.

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