Hyena hunting techniques - diversity and adaptability Part 1

Several weeks ago, I was lucky enough to see my first full hunt since I've come to the Mara. Seeing the event in person has made me really appreciate the extent to which the hunting tactics of these animals have been evolutionarily tailored and refined. Due to the influence of the migration, no one hunt in the Mara is the same, and making use of a variety of tools and techniques is crucial to ensuring the survival and well being of the individual year round. The prevalence of group hunting in spotted hyenas adds an additional dynamic to the tactics each individual can or should use, and depending on the rank of the hunter can be a help or a hindrance to the successful acquisition of prey. Whether one makes the choice to hunt alone or recruit the help of their group mates, each individual is a precise and deadly hunter in their own right. Here, I'll give a brief introduction to the diverse set of skills and traits which make them so.

PC Lily J-U

Making use of the environment
Especially in times of the year when prey is abundant, it seems like everyone in the clan should always be able to find a suitable meal at any time of the day. However, hyenas in hunting mode constantly assess their environment and, unless a better opportunity arises, will consistently hunt in conditions which render prey species most compromised. For example, spotted hyenas are primarily crepuscular, and will take advantage of their superior eyesight in low-light to no-light periods of the day to more easily overcome prey. In addition, the landscape type is chosen specifically to match the preferred hunting style of hyenas. Spotted hyenas often prefer to hunt in open plains to areas with denser vegetation because it affords them higher visibility and more room to either maneuver as a group or run down prey using their exceptional endurance. Some hyenas have even been known to take advantage of terrain and weather conditions and will actually preferentially hunt in wet and stormy conditions because prey can be rendered more vulnerable during these times.

PC Lily J-U

Prey choice
Like many other carnivores which make the Mara their home, prey choice is an important part of the hunt. Hyenas will engage in a behavior called "test chasing" as a means of assessing the availability of prey within any one herd of ungulates. The age and weakness of each individual in the herd is assessed based on their ability to run away from the pursuing hyenas. If no individual is determined to be a suitable candidate for the hunt, then the hyenas will simply give up the chase and look to another herd. However, if one is found which can be separated from the group, the hunters will quickly do so and take it down within minutes. Opportunism is a large part in what makes hyenas excellent hunters. Due to the large fluctuations in the composition of prey over the course of the year, one will also see similar changes reflected in the proportions of different prey species hunted. While our Mara hyenas certainly have their preferences in prey (zebra happen to be one of their favorites when they can get it), they will eat pretty much any herbivore found in the Mara in proportions which roughly reflect the ease at which they can acquire it at any one point in the year.

PC Lily J-U

Vocalizations
Among the most interesting and useful tools in a spotted hyena's repertoire is the variety of vocalizations they use in different phases of the hunt. Among the most famed, and incidentally the most versatile, is the classic whoop. While often used for long distance communication (e.g. in alerting other members of the clan kilometers away to one's presence), this call can be used in the short range as an indication of alarm. In these instances, individuals will use a shorter, higher frequency series of calls than the classic long and low variety. For lower ranking hyenas, whooping can also be a powerful deceptive device. It is not uncommon to see an immigrant males and other low ranking hyenas stand off to the side of a carcass and whoop for the attention of the rest of the clan (a favorite tactic of our very own immigrant male Roswell, I might add). This causes the higher ranked hyenas feeding to pause and scan the area for danger, allowing our whooper to sneak in and steal some food for a few seconds before he is caught!

The alarm rumble, a low staccato sound, can be used in the same manner, although this vocalization is more often used as an indication of a sighting of real danger. The first individual to see the imminent approach of a lion, human, or some other danger which could attempt to steal food or otherwise interrupt feeding will vocalize in an attempt to mobilize the entire group. In this way, every individual present at the carcass has an immediate cue to alert and cooperate in the defense of their prey.

PC Lily J-U

Giggles are also a highly useful tool in the hunting of prey. When directed at other hyenas, they often serve as a way of communicating distress or telling a clanmate to back off. They can also indicate excitement, and call other clan members in the immediate area to the scene. Simply due to the properties of the vocalization (the irregular pitch and length especially), giggles can serve other functions like conveying fear or confusion to the prey being targeted, especially when many hyenas are doing so at once. This likely lowers the effectiveness of a prey animal's ability to escape the hunt, and may have even selected for such qualities of the vocalization to become more pronounced. In any event, the numerous ways in which any one of these vocalizations can be used has allowed hyenas an equal versatility in their control of the pitch, speed, and frequency of each vocalization employed in the hunt.

To be continued...

Happy Thanksgiving from the Mara

I hope that everyone had a wonderful Thanksgiving weekend, with lots of family, food and fun!!!

Every year the Mara Hyena Project research assistants and graduate students also get together for our own little Thanksgiving in the field to stuff our faces with good food. Of course getting the food, and cooking here is an adventure all in its own!

Pre-planning and getting some last minute work done

The little oven that could!

As you can see our stove and range are not huge, so we had to strategize. We made the pumpkin (butternut squash) pies the day before. Then in the morning we prepped the stuffing, and started the chicken stock. Once the chickens (graciously donated by our neighbor Ali from Balloon Safaris) went in the oven, we peeled the green beans (which just happened to be found at the local Masai market!?) and made some cream of mushroom sauce. Stuffing went in next utilizing the broiler pan, while we started the mashed potatoes. Last, Joseph fried us some onions to go on top of the green been casserole, which switched places with the stuffing in the oven, all while the gravy was made with the chicken drippings and chicken stock. We even had time to grill some extra chicken legs that would not fit in the oven.

Time to feast!

Once around the table, and in between bites, we shared our stories about all of our great experiences out here in the Mara, as well as some of the things we are thankful for. As usual Ali, who has been here for decades with her husband John, was able to top all of our crazy stories. However, combined the RAs and camp staff were able to hold their own with Mara "tale tales", and we eventually got down to talking about what we are thankful for this year. I won't share the more personal thanks, but the most common were for health and happiness of friends and family, and science in general. We also like to think that others in the Mara have their own thanks.

Balloon pilots like Riz here are thankful for tourists.

Mothers are thankful for new life

Hyenas are happy for one of the largest wildebeest migrations in a decade

"Fay" is thankful that the rains have come

"Legend" is probably just happy for lazy and warm sunny mornings

We could go on and on about what we think the people and animals may be thankful for, but in the end we are all thankful for the chance to live and work in the Masai Mara with great friends.

Happy Holidays from the Mara.

Multi-Access Box Hall of Fame

Hall of Fame

Opening the multi-access box is proving to be a challenging task for wild hyenas. The MAB tests a hyena’s ability to innovate, i.e. learn something new. So far only a few hyenas have shown that they have what it takes. First for the hall of fame, here are my champion MAB solvers.

REMI

REMI

Remington is a mid-ranking subadult male hyena in North clan. He’s part of the “guns” lineage. While the three other hyenas hanging out at this session all fell asleep, Remi persisted and opened the box using the door knob side. You can see he figures out how to bite the knob to pull open the door opposite the camera.

SHTR

SHTR

Next up, “Shoot Her” is a very low ranking subadult male in North clan. I put out the box for some young, newly graduated cubs that were highly enthusiastic about the box. However, after playing with the box for an hour none of them had opened it. Shooter decided he would check it out and opened it within minutes using the door knob side, despite having never seen the box before!

SOUP

SOUP

Soup is a high ranking subadult female in North clan. Are you noticing a trend here? Subadults are rocking the box. Soup is one of only two hyenas to open the box using the “push” solution. Hyenas really like to bite and pull on things and to open the push flap a hyena has to push it inwards. Here, Soup quickly pushed open the push flap using her paws; she opened the box in record-setting time! In addition, Soup beat out Remington, who had already opened the box!

BANG with a mouthful of milk powder.

BANG

Bang is one of only two hyenas to open the box twice! He’s a subadult male in South clan. He’s opened it once with the door knob side and once with the drawer.

LADY

Lady is a subadult male from North clan. At the time he opened the box however he was deep inside of South Clan’s territory! It looks like he might be immigrating to South because we saw him hanging out at South Den with Toledo (TLDO), one of South’s highest ranking immigrant males. Lady was super enthusiastic about the box and spent a lot of time biting and pawing at it before he got the push flap to open. Toledo wasn’t so sure about the box, he watched warily from a distance during Lady’s trial. (I posted about LADY a month ago here.).

RANG is a tough young hyena.

RANG is easy to identify by her ear damage.

RANG

Rangsang is a distinctive looking hyena, she’s a young adult female in South clan and she just recently had her very first cub! However, a few months before I arrived in Serena she was involved in a nasty clan war and got some very distinctive ear damage! She’s a cognition trial fiend and has already completed all of inhibitory control cylinder trials and now she’s conquering the box!

RANG's first cub, JEMI.

RANG opens the box. 

Tervuren is still a little fluffer! 

TERV

Tervuren is the youngest hyena to ever open the box! He is still a little fluffy cub at South's communal den, yet he beat out all the older subadults and adults that were also investigating the box. I put out the box almost 100m from the den hoping to see if RANG or BANG could open it again. Also present was the infamous HONR, who was so enthusiastic about his inhibitory control cylinder trials that he wouldn’t let the RAs have the cylinder back! However, none of these hyenas opened the box today… nope… little Terv comes loping up and opens the door knob!

Yola is difficult to ID by his spots. 

YOLA

Yola is the only hyena in Talek to open the box so far and he’s also opened it twice. He opened the box first using the sliding door, and then again using the door knob side. Yola is a fluffy young subadult in KCM clan. He’s mostly ID-able by the fact that he’s too fluffy to have spots.

Coming up soon: Hall of Shame

Which hyenas have tried, but failed, to open the multi-access box?

Hyenas and Prehistory

Most of our blog readers know that hyenas are strange animals, but have you ever wondered how hyenas became hyenas?  How they evolved throughout time to be so unique today?  Which environmental pressures forged their variety of adaptations? Well today is your lucky day because you are about to find out. 

Today, there are only 4 extant species of hyenas in the family Hyaenidae: Spotted Hyena, Brown Hyena, Striped Hyena, and Aardwolf.  However, many more species have persisted throughout the ages.  The ancestors of modern hyenas were arboreal creatures similar to civets and mongoose, which lived in the jungles of western Eurasia during the Early Miocene, 22 million years ago.  One of the earliest described species of these arboreal hyenids is Protictitherium, grouped into this family by dentition and structure of the middle ear which it shares with modern hyenas. Protictitherium occupied omnivore and insectivore niches in these ecosystems rather than the megafauna predators and scavenging niches that hyenas occupy today.  Utilizing its retractile claws, Protictitherium prowled the branches of trees foraging on fruit and hunting small mammals, birds, and insects.

Protictitherium and other early arboreal hyenas likely resembled this Malay civet
(C: Nick Garbutt, naturepl.com and Arkive.org)

The descendents of Protictitherium developed longer legs and more pointed jaws, giving rise to a wide array of terrestrial, nimble, dog-like hyenas that radiated across greater Eurasia during the Middle Miocene.  One of the most common species during this time was Ictitherium viverrinum.  In fact, it was so prevalent that in some Miocene fossil sites, it and other dog-like hyenas outnumbered all other carnivores combined.  The early dog-like hyenas like filled the niches of extant foxes, jackals, and coyotes.   Between 11-7 MYA, in the Late Miocene, Hyaenidae achieved its peak diversity during a second radiation of dog-like hyenas, known commonly as “hunting hyenas” to paleontologists.  This group was generally larger than the previous radiation, their limbs had more cursorial ability, and extended dentition allowed for specialized cutting and slicing of meat.  This dentition in particular reduced any hypothetical bone-crushing capability in these hunting hyenas, thus these species were on a radically different evolutionary course than the species which exist today.  The Late Miocene was also the temporal period when hyenas colonized the African continent. 

Drawing of the coyote-sized I. viverrinum, by Mauricio Anton (Turner & Anton, 2004).

Between 7-5 MYA, Hyeanidae experienced a series of drastic extinctions that corresponded with strong climate change and Canidae species crossing the Bering land bridge from North America.  The hardest hit were the civet- and dog-like hyenas, in fact, the only species surviving from these groups today is the dog-like Aardwolf.  Scientists believe the Aardwolf escaped extinction by evolving to forage on termites – an underexploited niche in Carnivora.  Another hyena to escape extinction was Chasmaporthetes ossifragus, which was the only hyena to cross the Bering land bridge into North America.  C. ossifragus managed to persist for some time in North America by diverging from the cursorial and bone-crushing niches dominated by canids on this continent and evolving into a cheetah-like sprinter.  The evolution of bone-crushing hyena specialists directly preceded the second radiation of hyenas.  These bone-crushing genera survived the appearance of canids in Eurasia and flourished to become the dominant scavengers of Eurasia by around 5 MYA.  One behemoth that prospered during this time was Pachycrocuta brevirostris, a 220 kg, lion-sized hyena which scavenged on the large herbivore carcasses felled by sabre-toothed cats and was capable of cracking the bones of the largest pachyderms.  Pachycrocuta were robust hyenas with a stocky build and possessed none of the cursorial elements present in extant bone-cracking hyenas.  Interestingly, some paleontologists believe P. brevirostris prevented expansion of the early hominid species into Europe through significant niche overlap (Madurell-Malapeira et al., 2015).  Unfortunately, with the decline of large herbivores and sabre-tooth cats during the late Pleistocene, such a large body-size had a negative impact on these hyenas and they gave way to the smaller Hyena, Parahyena, and Crocuta genuses of modern day. 

Here's one of those typically unrealistic-yet-very-beautiful prehistoric animal panoramas (due to density of animals) displaying P. brevirostris competing with some species of large sabre-toothed cat for a Megaloceros.  This is a good illustration the shear size of Pachycrocuta 
(Credit: http://prehistoricanimal.blogspot.co.ke/2010/07/famous-is-force-that-have-jaws-of.html).

The four extant hyena genera originally evolved in Africa during the Pleistocene and took refuge here during glacial periods.  Impressively, spotted hyenas dispersed out of Africa around 3.7 MYA and colonized virtually all of Europe, Asia, and Africa – save the wettest jungles of sub-Saharan Africa. Astonishingly, spotted hyenas remained in Western Europe as recently as 12,000 years ago; only receding from the continent as forest habitats returned and canids out-competed them.  These ranges aren’t surprising, given a few key adaptations.  Ancestral spotted hyenas may have resorted to the sociality of clans due to increased pressure from competitors at carcasses, allowing them to overpower larger singular scavengers at kills.  Spotted hyenas also developed sharp carnassials (cutting and slicing meat) behind their bone-crushing premolars – an adaptation not possessed by their larger, bone-crushing ancestors.  Increased cursorial capabilities, along with bi-specialized dentition, allowed spotted hyenas to hunt living prey in packs as well as scavenge on dead animals when prey availability was limited.  

Well, there you have it, the story of the hyenas from beginning to present.

Sources:

Madurell-Malapiera J, Alba DM, Espicgares MP, Vinuesa V, Palmqvist P, Martinez-Navarro B, and Moya-Sola S.  Were large carnivorans and great climatic shifts limiting factors for hominin dispersal? Evidence of the activity of Pachycrocuta brevirostris during the Mid-Pleistocene Revolution in the Vallparadis Section (Valles-Penedes Basin, Iberian Penninsula). Quarternary International, August 8^th 2015.