Actually, animal rights activists are concerned with all animals, from the great ape to the bee. In practice, their involvement is restricted to farm animals or animals which are kept by humans, ie to a very small percentage of the total of more than 1.3 million known animal species worldwide.
Like all vegans, they can not eat meat or other animal products such as eggs, milk and honey, and also no butter, milk chocolate, milk ice cream and egg noodles for example. However, there are many other rules.
The founder of modern animal ethics is the Australian philosopher Peter Singer, who developed the conceptual, philosophical and political foundations of the animal rights movement with his books “Animal Liberation” (1975) and “Practical Ethics” (1984).