I expect that you know the answer to both parts of the question, and I would also expect you to say yes to both parts. But it’s not quite as straightforward as that. Actually a fifth of UK cat owners don’t know that cats are carnivores! Not great. Education is the passport to better cat welfare.

Carnivores
Millions of pages have been written about cats being ‘obligate carnivores’. This means they are obliged because of their physiology to eat the flesh of animals. This has happened because of evolution. Over millions of years the various species of cat in the family of cats i.e. felidae, evolved, through genetic mutations, to be dependent upon the flesh of animals for their food. It’s surprising, therefore, that commercial cat food manufacturers sell cat foods full of grain and plant-based protein. They also provide cat food which is incredibly dry; unnaturally dry. But the deficiencies in commercial cat food is another story.
The answer as to whether felines are carnivores should be a little more nuanced than simply saying that they are. For example, the snow leopard eats quite a lot of vegetation – click here for more info on that. They target a particular bush and in a couple of studies it was found that their faeces contain a high proportion of plant material, up to 50%. This would indicate that 50% of their diet might on occasions and under certain circumstances be plant material.

I have a theory about this which is that they eat plant material in the rarefied atmosphere of the Himalayas in order to improve the efficiency of haemoglobin in their blood which carries oxygen. This in turn allows them to better survive at high altitude. However, no scientist has written about this on those terms so this is exclusively my idea. I think a study is required by the way.
Also, we all know that domestic cats eat grass and if they eat mice (and a lot of them do, to the consternation of their owners) they eat the stomach contents of mice which contains vegetation because they are herbivores. Also, the big wild cat species such as mountain lions, lions and tigers eat herbivores and therefore they eat at least some plant material on a regular basis. It is probably necessary for the cat to eat some plant material in order for their diet to be balanced. Perhaps this vindicates the commercial cat food manufacturers including plant material in their foods?
It is said that domestic cats eat grass because it contains folic acid in the juice which is a vitamin which helps with the transportation of oxygen around the body. I have written before that “folic acid is essential to their health. It plays an important role in the production of haemoglobin. A cat deficient in folic acid may become anaemic and it affects their growth”. The reason is up for grabs to be honest but the one I have suggested is the most likely, in my view. Want to read more on this topic? Click here please.
So felines are carnivores because they evolved that way. They are specialist meat eaters. We have to respect that but there’s a drift towards veganism in humans in order to save the planet from climate change and to save the animals. Some domestic cat food manufacturers have produced a vegan food for cats. This sounds totally contrary to common sense and starkly against the health and welfare of domestic cats. However, if you make domestic cat food from plant-based materials and add in all the specialist nutrients domestic cats require in their food then I would argue that it is no different to a meat-based food. That might be a contentious viewpoint but it makes sense to me.
- Practical implications for the cat being a strict carnivore
- Is it true that cats can’t taste sweetness?

Nocturnal
As to being nocturnal, the nuanced answer is that the wild cat species (and domestic cat) are most active when their prey animals are active. In other words, common sense applies. If the animals that they attack and eat are active at night then the cat is active at night whatever the species of cat. This normally points to the fact that cats are nocturnal or active at dawn and dusk (crepuscular) when prey animals tend to be active. But sometimes some cat species are active during the daytime. The Canada lynx is active at night because the snowshoe hare, which is their primary prey animal, is active at night.

The domestic cat is active at dawn and dusk because mice are active at dawn and dusk. But then domestic cats catch birds and birds are active during the daytime. Tigers tend to be active at night and lions and leopards sometimes are active at night in order to avoid the activities of people during the daytime. It is said that some lions in some parts of Africa are particularly active at night in order to avoid trophy and sport hunters who want to kill them.
It’s about circumstances. The cats are active when they have to be active and they rest and sleep when they can. This normally leads to nocturnal activity or activity when it is dark or darker than daytime. But that is not an exclusive state of affairs. It just depends on the circumstances.
I have written about the same topics under two heading on another site which you can read by clicking here (carnivores) and here (nocturnal) if you wish. They made add a little more information.
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