The Dusky Seaside Sparrow (Ammodramus maritimus nigrescens) was non-migratory and lived only in the marshes of the St. John’s River and Merritt Island on Florida’s mid-Atlantic coast. A 70 percent decline in population was recorded following the use from 1942 to 1953 of DDT to control mosquitos on Merritt Island. In further efforts to eliminate mosquitos in 1956 in the Kennedy Space Centre region, Merritt Island nesting grounds were flooded to make mosquito control impoundments, causing another drop in numbers. Then marshes along the St. John’s River were drained to aid highway construction, putting yet more pressure on the population.
By 1980, six remaining individuals, all males, had been captured to establish a captive breeding program that was eventually unsuccessful because no females were ever found. They lived out their lives in a Walt Disney World nature reserve called Discovery Island. The last male died in June 1987.
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