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This Week’s Creature Feature: Billions of Small Birds Passing Thru

How to see a Butter Butt among them

The yellow-rumped or myrtle warbler, stops in Maryland to spend the winter. The little bird is also fondly referred to as the Butter Butt.
      Early October is the height of the fall bird migrations. Each day, thousands of hawks fly south along the Appalachian mountain ridges, and many more smaller birds are swept to the coastal side of the mountains as they move south. The small birds — including vireos, warblers, fly catchers and sparrows — travel at night and rest during the day.
      So many small birds travel together nightly that they can be seen by radar as a low cloud and have been called ground clutter. Cornell Ornithology Lab has used the radar density to estimate that some 4.7 billion birds fly across the U.S. headed south for the winter. Early bird counts in 1960 estimated nine billion birds made the trip.
     One particular small bird, the yellow-rumped or myrtle warbler, frequently stops in Maryland to spend the winter. The little bird is also fondly referred to as the Butter Butt. A western variety with an added bright yellow chin patch is called Audubon’s warbler.
     Our warbler is called myrtle because it is one of the few animals and the only bird that can digest wax myrtle berries. As wax myrtle bushes are common in Maryland, thousands and thousands of the warblers fly in from Canada to spend the winter here. Some myrtle warblers summer here, but the winter population is much larger.
      Warblers are colorful birds that prefer insects to berries. They are known for their spring singing. In the fall, however, they stop singing as they try to elude predators and have no nesting territory to defend. Several different species fly and hunt for food in groups that are kept together by short high-pitched peep or chip sounds. 
      To find the migrating small birds, watch for movement and listen for the peep along the edge of woods and especially around bushes. When feeding, the birds hardly ever hold still, and the hyperactivity is easy to see. When you find one migrating warbler, there are usually many more. Wintering myrtle warblers are attracted to suet feeders and bird baths.