365 Urban Species. #190: Common Tern
Photo by cottonmanifesto. Location: Pleasure Bay, South Boston.
Urban species #190: Common tern Sterna hirundo
Generally speaking, terns are not animals that have benefitted from man-made changes to the land. The individual pictured above, however, was catching fish in the artificially stilled piece of ocean called Pleasure Bay, in South Boston. The Bay was created when a looping walkway was built that connected Castle Island to the mainland. This lone tern, taking advantage of a human created food source, is a remnant of a population of terns that once numbered in the hundreds of thousands around Boston.
The changes that humans cause to the landscape almost always benefit certain species while creating a negative impact for others. Terns in North America have suffered in numerous ways throughout modern history. In the nineteenth century, many thousands of terns were killed to be used to decorate hats--the first Audubon Society, founded in Boston to protect birds from this usage, still uses the silhouette of a tern in its logo. Off-shore islands, important nesting areas, were disturbed and put to various human uses, preventing these sensitive birds from nesting successfully. Pollution impacts the supply of prey fish for terns, and can affect tern egg quality. And most importantly, human activity such as intensive fishing and related industries, and the creation of garbage dumps, greatly increased the numbers of gulls. The fact that gulls do well around humans has been the greatest detriment to terns, as gulls compete with terns for food and nesting sites, and will prey on tern eggs and nestlings.
Terns are still considered fairly common birds worldwide, but are declining. While the animals that succeed around civilization are the most fascinating to me, those that suffer are important to the ecosystem and to biodiversity. Knowing what causes certain species to do poorly around cities can hopefully help us to create more livable urban spaces, for all species. A healthy Boston seashore will have both gulls and terns, for centuries to come.