Amazing gravity-defying ballets make swallows some of the most entertaining birds in Montana. Darting above rivers and under the eaves of lonely old barns, these little birds are known not only for their acrobatics but also for their nest building abilities. They make their nests from hundreds of tiny pellets of mud stuck together in a half cup shape. One quick look under a river bridge and you'll spot lots of examples, but beware of low-flying mothers who fearlessly defend their nests. Swallows eat a diet consisting entirely of insects they catch in flight (much like smiling motorcyclists who refuse to wear helmets). They even drink on the wing by skimming along the surface of the water. The swallow's most identifying feature is its deeply forked tail.