I arrived at a sighting of a buffalo bull that had been killed earlier that morning by a group of hyenas. It had been found by ranger Melvin Sambo and tracker Milton Khoza, who watched it being brought down inside a small, shallow waterhole. When tracker Judas Ngomane, the Fitkin Family from Oregon and I arrived, there were two hyenas feeding on the carcass. After a short while they abruptly stopped feeding and started to look around nervously.
They then left the carcass. Two more hyenas showed up whose hollow bellies indicated they had clearly not fed yet. At the opportunity of the smallest morsel, hyenas would normally come steaming in and feed as fast and ferociously as their powerful jaws would allow them.
However the new arrivals skulked around the edge of the waterhole, stopping for long periods while staring about and sniffing the air.
We sat for a while trying to work out why these hyenas were so hesitant of going in and feeding. With 27 years of tracking experience at Londolozi Judas is always a good brain to pick on matters like this. The theory he and I came up with was that perhaps there were most likely lions in the area and the hyenas had caught their scent and were afraid of being attacked if they went in to feed.
We initially thought this to be unlikely. Well, at least we thought no lions were close by. We had arrived at the sighting late in the morning and because it was quite an unusual sight, a few of the other Londolozi rangers and trackers had been there already, none of whom had reported any lion tracks in the area.
Billie from the back row of my vehicle’s brain was now working. She asked, “Well, from how far off could these hyenas smell a lion.. or smell anything for that matter?”
This got me thinking; How good is a hyena’s sense of smell? Or any of the larger mammals for that matter.
So, the probability of a kill being smelt out by a predator depends on a few main criteria: Wind direction, age of the carcass, distance to the carcass and whether the stomach of the carcass has been ruptured releasing their pungent contents. These are just a few of them, but are the main ones we ended up discussing that morning.
The exceptional eyesight of the hyena is backed up by a sharp nose and large rounded ears with excellent hearing; the perfect setup for detecting an animal being killed by another predator or a sniffing out a carcass.
Hyenas rely tremendously on their sense of smell. This I know not only from observing them out in the field but also because they smelt out my leather shoes I left outside my door a few night ago that they proceeded to tear apart and eat. I only found scraps the next morning.
However, in terms of measuring smelling capabilities, scientists can actually measure the brain’s olfactory lobe and count the smell receptor cells in the nasal cavity of animals. This has been one way of comparing different animals’ smelling capabilities. Elephants for example have 1,948 odorant receptors, the most recorded in any animal, while humans have 396 receptors. Elephants have been recorded to smell water from 12 miles away (19.2km)!
This way of measuring who has the best nose is not foolproof though as different animals have a keener sense for different scents. According to a study posted in the journal Science last year, human noses are about as sensitive as dogs at detecting amyl acetate, a chemical with a banana odor, and we’re better than mice at detecting a smelly compound in human blood. Abstract, I know, but the fact that specific animals detect specific smells better than others is important.
Unfortunately, I could not find any accurate studies that measure the hyenas’ sense of smell. In fact this is a largely understudied field in all animals. I did, however, once follow a hyena with its nose to the ground for about 2 km. It would follow the scent in one direction for a while then scout about for a short period as it tried to re-establish the direction of the scent trail; a bit like a tracker would when the tracks he is following temporarily disappear over hard ground. Hence the logo of the Tracker Academy is a hyena. Picking up on the scent again each time, the hyena led us up and over a crest. Then – Leopard! 100 meters ahead! The hyena had been following the Tamboti female’s scent. We bypassed the hyena and moved ahead to see the leopard, which the hyena had yet to see.
The Tamboti female inhabited the south-eastern sections of Londolozi, having a large part of her territory along the Maxabene Riverbed.
Ten minutes later the hyena came sauntering up having tracked down the scent owner. It sidled up to her, as if inquiring about a possible meal as she growled at it. It would have been hoping to find her with a kill it could steal. After all this hard work the hyena realised there was no food on offer, and simply moseyed on as if the track-and-find was as easy as a Sunday morning mud wallow. We had followed the hyena for approximately 2km, but I’m sure they can follow scent trails for significantly further than this. They have been recorded following scent trails that are over three days old!
On returning to camp I bumped into ranger Fin who had gone to check on the buffalo carcass an hour or two after we had left. He was excited as he told me that a Birmingham male lion and Ntsevu lioness had moved onto the carcass, chasing the hyena off! The hyenas’ strange behaviour was explained! I wondered where the lions had been while we were there and at what distance the hyena would have sensed them from.
One has to take your hat off to these animals. There we were sitting with the hyena at the same distance from the lions but with their superior senses they had detected them while we remained clueless.
Undoubtedly, future studies will probe into the olfactory world of animals and further our understanding in this field. It’s exiting to think what we still have to learn and what might be discovered about this important sense.