When you're on your own it's hare to keep an eye out all around you. When you are in a group, your friends can watch out in different directions. Some bird specides play safe by staying together in groups which can number thousands of individual birds. The alarm call of one bird can alert the entire flock to danger.
It's much harder for predators to catch birds in the air when they stick together. When a mass of birds takes to the air at once, like the starlings in the picture, this confuses hunting birds such as peregrines or sparrowhawks, that would just love a nice little starling for tea. Birds of prey find it very difficult to pick out and chase just one bird when they flock together especially when they perform aerobatic displays. All of a sudden, the birds swerve or dip together at exactly the same time and this helps them to get away.
Birds also stick together on land. Inland you might find a rookery near to where you live. This is a place where lots and lots of rooks all live together. If you are near the sea you might be lucky enough to see a seabird colony, with hundreds and hundreds of seabirds all nesting together. The picture above is of a gannet colony in Scotland. These are busy, noisy and smelly places, so why do birds choose to live this way? One reason so many pairs of birds are attracted to the same site is because there is a good supply of food nearby. There is also strength in numbers when raising chicks. An invading predator is more likely to be scared off by the mobbing attack of a whole colony - rather than just one bird acting to protect its own territory and young. The biggest advantage of being in a group like this is that the birds are encouraged to breed at the same time. This is probably because there are so many other birds displaying and mating around them. Because all the eggs are laid and hatched around the same time you might think the birds are making life easy for predators by serving them up lots of ready meals. But because predators are swamped by more eggs and chicks than they can possibly eat, the chances of any one nest being robbed are actually smaller.