Before I begin, let me clear up a few definitions:
Nocturnal – a species primarily active at night.
Diurnal – a species primarily active during the day.
Crepuscular – a species active in the twilight, normally around sunrise and sunset.
Go and read any field guide and it will tell you that both lions and leopards are nocturnal animals. The classic line is that lions will sleep for 20-22 hours a day. I’m not sure where this figure comes from but it seems to be quite a popular one across the board. I personally believe this is a bit of an over-exaggeration. Let’s discuss this by looking at a few examples of lion and leopard activity on Londolozi.
Lions
I learnt a harsh lesson a few months ago when I set out to go find the Tsalala pride one afternoon. It was a hot day so I decided to loop around, killing time talking about the many other wonders of the bush. About 20 minutes before sunset I headed to the last place the pride had been seen, expecting to find them lying in the shade of some trees. All that we found was a herd of impala calmly grazing in the exact spot the lions had been. No lions in sight. They were soon found by someone else several kilometres away. We did not see them that evening…
Since that day, I have watched lions moving long distances – and hunting – at midday. A male lion was seen killing an impala at 12:00 pm just the other day. After speaking to some of the experienced guides and trackers, it turns out the Tsalala and Tsalala Breakaway prides are well known to be active throughout the day. Not the 20 hours of sleeping that they are supposed to be doing.

The Tsalala Breakaway pride walk down a road at 11h30 in the day. This particular day I followed these lionesses for over two hours in the heat of the day while they hunted and walked across open landscapes.
Leopards
Textbooks will also tell you that leopards are the silent creatures of the night. I will agree with this statement for the most part. However, they are by all means also the silent creatures of the day.

The Flat Rock male takes a short break and glances in our direction. Shortly after this photo was taken, we followed this leopard as he walked along an open road at 11:00 am.
Born 2013 Kruger, seized prime territory at young age. Strategic dominance led to successful lineage before current eastward shift.
On numerous occasions I have been alerted to the presence of leopard moving around during the day by monkey alarm calls, shortly to see a leopard walk past in full sun. I believe that due to their superb camouflage, they are almost as comfortable to walk around and hunt during the day as they are at night.

The Nhlanguleni female pictured during the day, showing how the rosette pattern aids in a leopard’s camouflage.
Initially skittish female who transformed into a regular presence. Made history by raising first intact litter since her own generation.
“Kleptoparasitism: the stealing of food or prey from one individudal by another”
One reason for leopards hunting during the day may be to avoid kleptoparasitism from hyenas. It is well known that hyenas will trail behind leopards with the hopes that they will be able to overpower them and steal a freshly made kill. Studies have shown that almost weekly, hyenas will steal a kill from a leopard. One leopard in the Sabi Sand Game Reserve was even documented being seen handing over kills to hyenas to distract them before immediately hunting again in peace.

A spotted hyena lurks around the periphery of where a leopard had stashed a kill in a tree. Hyena will wait patiently for pieces of meat to drop to the ground, if they were unable to steal the entire kill in the first place.
Another theory could be that both lions and leopards with cubs hunt during the day to allow the youngsters to feed without the risk of: i) nocturnal hyena stealing the kill; and ii) hyena potentially finding and killing the lion or leopard cubs.

A leopard cub feeds on a hoisted impala kill in the middle of the day. This is one of the Nkoveni female’s cubs. The Nkoveni female has been seen hunting throughout the day on numerous occasions in the last few weeks.
Londolozi's most viewed leopard and prolific mother. This gorgeous female has raised multiple cubs to independence.

The Tsalala Breakaway cubs play in a dry river bed. These cubs are still very young and extremely vulnerable to attack from other predators. They have been viewed feeding on kills in the daylight hours several times lately, possibly to avoid the risk of being attacked by hyena at night.
Although I have merely touched the surface of this argument, I think it is quite clear that lions and leopards are not completely nocturnal. It may be that certain individual leopards or prides of lions are an exception to the rule and have adopted diurnal activity more so than most others. It may be that we still don’t quite understand why animals behave the way that they do. In any case, these predators continue to provide exciting game viewing at all times of the day and night here at Londolozi.
Definetely a very interest post and argument. I guess it depends which area the cats live in. I think lions in Savuti are predominately nocturnal (at least according to past studies) but are more dinurnal in the Masai Mara (the same is true here with leopards). I guess it can also vary with the seasons too in some cases.