Mixed species flock.

This is one of the strategies that woodland birds employ when their food supply becomes scarce. There are a number of benefit's for them doing this. Between them the birds have more eyes to look for the food. They will then use less energy finding the food. Any energy used will have to be replenished so its important that they all find a reliable food source. As they are in a mixed flock their are then more eyes to look out for predators. Some of the flock will act as guard to the other birds, They will give a call if a sparrow hawk flies over them. Blue tits need to find forty% of their body weight everyday to enable them to survive. Blue tits may loose up to sixty% of their population in a mild winter. If they loose these high numbers then the females will lay lots of eggs in the spring to regenerate the numbers that have been lost during the winter.