Salt marshes and the organisms that depend on them are subject to a variety of anthropogenic threats. In Florida, Worthington’s Marsh Wrens (Cistothorus palustris griseus) and MacGillivray’s Seaside Sparrows (Ammospiza maritima macgillivraii) are species of concern that inhabit a small, narrow range of salt marsh in the northeastern corner of the state, an area of increasing human development. The historic ranges of these subspecies encompassed salt marshes in five counties, but their ranges had contracted to just two counties by the early 2000s and their populations declined. We surveyed the historic ranges of the two subspecies during the breeding seasons of 2014 and 2015 to document their distributions, identify habitat features that influenced occupancy and density, and assess whether any recolonization had occurred in areas previously abandoned. We found that the ranges of both subspecies remained relatively stable compared to the early 2000s, with no signs of either further contraction or recolonization. Both Marsh Wrens and Seaside Sparrows were more likely to occupy areas farther from uplands. Marsh Wren occupancy was positively associated with marshes dominated by smooth cordgrass (Spartina alterniflora) and negatively associated with marshes dominated by black needlerush (Juncus roemerianus). Seaside Sparrows were more likely to occur at sites of moderate elevation. We found greater densities of both subspecies in areas farther from uplands, with moderate elevations, and dense vegetation. Marsh Wren density also increased in smooth cordgrass marshes, whereas sparrow numbers increased in areas of moderate vegetation height. Despite these differences between subspecies, the need for dense vegetation away from uplands highlights the importance of smooth cordgrass marshes in the region.

中文翻译：

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影响佛罗里达州东北部盐沼鸣鸟的居住和密度的因素

盐沼及其赖以生存的生物受到各种人为威胁。在佛罗里达州，沃辛顿的沼泽W（Cistothorus palustris griseus）和麦吉利夫雷的海边麻雀（Ammospiza maritima macgillivraii））是在该州东北角（人类发展不断增加的地区）的一小片盐沼中栖息的令人关注的物种。这些亚种的历史范围包括五个县的盐沼，但到2000年代初，它们的范围已缩小到仅两个县，并且其人口减少了。我们调查了2014年和2015年繁殖季节这两个亚种的历史范围，以记录它们的分布，确定影响居住和密度的栖息地特征，并评估在先前被废弃的地区是否发生了任何再殖民化。我们发现，与2000年代初相比，这两个亚种的范围都保持相对稳定，没有进一步收缩或重新定殖的迹象。沼泽W和海滨麻雀都更可能占据远离高地的地区。沼泽W的占用与以光滑草皮草为主的沼泽地呈正相关（互花米草（Spartina alterniflora），与以黑色针刺（Juncus roemerianus）为主的沼泽地负相关。海边麻雀更有可能发生在中等海拔的地方。我们发现，在远离高地，海拔中等，植被茂密的地区，这两个亚种的密度都较高。在光滑的草丛沼泽中，沼泽ren密度也增加，而在中等植被高度的地区，麻雀数量增加。尽管亚种之间存在这些差异，但远离山地的茂密植被的需求凸显了该地区光滑禾本科沼泽地的重要性。