What does this saying means one sparrow does not make a summer?

How do penguins check for enemies? What do quail eggs taste like? Why is it important to protect the pelican habitat? Do beagles shed? Who would be considered a hawk? Pigeon eggs keep going missing from our balcony- this has happened several times with different pigeons- Can pigeons fly with their eggs to another nest if they are stressed by a cat or children? Is there a fine for keeping eagle feather? Is hand fed the same thing as hand raised? Do sirens have to have wings? What is the importance Darwin finches? Do turkeys get egg bound? What happens if you shoot an albatross? What is the sweat duck? How do osprey hunt? How does a Whooping Crane effect its Ecosystem? Where do bats dwell? Who does the voice of pelican in finding nemo? Why poultry should have access to adequate amount of cool and clean water? Why does a Woodpecker peck a tree? Is a dodo bird from the dinosaur age?