What are three reason's bird's are useful to man?

One of the key ways to see if a Pond is healthy is by the presents of a water bird such as herons ,loons or other sharp beak water birds . Birds also time the breeding and the number of chicks with the with the amount of food present such as owl numbers in the south relates to the number of skunks. Another main point was the decline in raptors with the use of DDT. The osprey numbers have really came up from the 70's to today. Birds are a good way to see how we are doing with the stewardship of the land more grain and flood timberland in the Midwest means the duck and geese count will go up .