JACKSONVILLE, Fla. – A tiny bird that once ranged across much of Florida is now only found around the St. Johns River in Duval and in Nassau counties due to increasing human development. The marsh wren’s range in Florida has contracted by 80 percent from its historical extent. The marsh wren’s range contraction, small population size and restricted distribution led to the species being listed as threatened in the state. Researchers looked for Marsh Wren nests at five sites on the Nassau River and Clapboard Creek in Duval and Nassau counties in 2016 and 2017 and found troubling issues. Survey points sampled for Worthington’s Marsh Wrens and MacGillivray’s Seaside Sparrows during 2014 and 2015 breeding seasons.