"Kettle" of hawks and vultures
Counting raptors (including both vultures and hawks) involved estimating the numbers of each species as they moved northward past an imaginary east-west line centered on the hawk tower. Typically, raptors gain elevation by soaring up a column of rising air (called a thermal) and when sufficiently high, slowly gliding downwind without the need to flap and expend energy. This allows them to travel several hundred miles in one day. Counting is easiest as the birds descend in a wide swath from the top of one thermal to the base of the next. Migrating hawks move in mixed flocks that may contain several different species. Kettle size varies from 20 to over 500 birds. The small kettle shown in the picture contained about 36 individuals of three species (19 Turkey Vultures, 15 Broad-winged Hawks, and 2 Swainson’s Hawks).
Britain's American colonies broke with the mother country in 1776 and were recognized as the new nation of the United States of America following the Treaty of Paris in 1783. During the 19th and 20th centuries, 37 new states were added to the origina... ... read more 
