How to make birds water feeder

Which one is filter feeder ?

How does a bird sing?

Out of 60 birds flying in the sky, (3)/(4) are moving in a flock and the rest in other flock.How many birds are there in each flock?

Read the following statements . I. In Porifera excretion mainly occurs by diffusion II. Sponges are ammonotelic animals. III. Sponges are filter feeders also known as suspension feeders. Which of the statements given above are correct ?

A fish is vertically below a flying bird moving vertically down toward water surface. The bird will appear to the fish to be

In the given figure , how many yellow birds are there ?

Describe how is the body of birds well adapted for flight?