In 1851, Brooklyn released 100 house sparrows from England; 175 years later, the birds are found across nearly all of North America

A bird that now seems almost impossible to escape once began as a deliberate introduction in Brooklyn. In 1851, about 100 House Sparrows were reportedly released after being brought from England, with the hope that they would help control caterpillars and protect trees.

The plan worked in a way no one could have fully anticipated.

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House Sparrows did not stay in Brooklyn. More releases followed, cities across the United States took an interest in the small Old World birds, and their range expanded rapidly. By 1900, they had reached the Rocky Mountains. The reports is sourced from All About Birds and Today in Ottawa's History.

Today, House Sparrows are among the most familiar birds in North America, especially wherever people live and buildings provide places to nest. Their story, however, is not simply one of an introduced species taking over. The birds that once numbered around 150 million in the United States in the 1940s have declined dramatically.