Hint:

1. Cattle egrets eat the insects stirred up by cattle when they are grazing is an example of commensalism.
2. A niche  is the role species play, and includes the type of food it eats, where it lives, where it reproduces, and its relationships with other species.
3. The three different species of Warbler birds live in the same tree and can feed at different level of tree.
4. Parasites like canine roundworm are found in puppy's intestine.