Increasing/decreasing animal groups?

Question

Out of the following groups of animals, which ones are increasing in number(of species and individuals) and which are decreasing?

1. Mammals
2. Fish
3. Birds
4. insects
5. Nocturnal animals
6. reptiles

Answer 1

your categories are too broad. some mammals are increasing (humans, probably rats, cats, dogs) others are decreasing (tigers, orangutans, elephants). same with birds (starlings and sparrows are increasing) lots of others are decreasing.
for a basic answer: animals that are generalists and can adapt well to multiple habitats and food sources are increasing. animals that are specialists are decreasing. plus there are constantly new species being discovered. so "we" really don't know everything and it is impossible to know how many animals are really out there.

Answer 2

If you're talking about number of *species*, everything is decreasing, because of habitat destruction by humans. If you're talking about number of *individuals*... well, urban pigeons seem to be doing pretty well.