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Gouldsboro, ME, United States

Negoita L.,Syracuse University | Dickinson M.,P.O. Box 571 | Mittelhauser G.H.,Maine Natural History Observatory | Rajakaruna N.,College of the Atlantic | Rajakaruna N.,North West University South Africa

Strong environmental gradients and varied land-use practices have generated a mosaic of habitats harboring distinct plant communities on islands on the coast of Maine. Botanical studies of Maine's islands, however, are generally limited in number and scope. Baseline studies of Maine's islands are necessary for assessing vegetation dynamics and changes in habitat conditions in relation to environmental impacts imposed by climate change, rising sea levels, invasive species, pests and pathogens, introduced herbivores, and human disturbance. We conducted a survey of the vascular plants and soils of forest, field, and ocean-side communities of Great Duck and Little Duck Islands, ME. These islands differ in environmental and land-use features, and in particular the presence of mammalian herbivores; Great Duck Island has had over a century of continuous mammalian herbivory while Little Duck Island has been largely free of mammalian herbivores over the last 100 years. We recorded 235 vascular plant species in 61 families on the Duck Islands, 106 of which were common to both islands. The composition, abundances, and diversity of plant species substantially differed within similar plant communities between the islands. These differences were particularly evident in the forest communities where Little Duck Island had significantly greater sapling regeneration and a more recent peak in tree recruitment. Soil properties also significantly differed between these islands, with a higher pH in all three communities and higher P, Ca, and K in field, forest, and ocean-side communities, respectively, on Little Duck Island, and higher soluble salts in forest and ocean-side communities of Great Duck Island. Together, our findings suggest that soil characteristics and the dominance and regeneration of vascular plant species can differ substantially even between adjacent islands with otherwise similar geologic characteristics and glacial history, and that mammalian herbivory along with other ecological factors may be important drivers of these differences. © 2016 by the New England Botanical Club. Source

Mittelhauser G.H.,Maine Natural History Observatory | Tudor L.,50 State Street | Connery B.,Acadia National Park
Northeastern Naturalist

We systematically surveyed the Maine coastline from Washington County to York County to provide baseline data concerning Calidris maritima (Purple Sandpiper) population status. Focusing on a particular region each winter, we conducted 66 winter surveys by boat along the entire coast of Maine between 2002 and 2007 plus three days surveying from the mainland between Kittery and Biddeford during the winter of 2005-2006. We tallied 13,318 Purple Sandpipers during these surveys. After accounting for birds present but not detected, we estimate that 14,000 to 17,000 Purple Sandpipers wintered annually in Maine between 2002 and 2007. Based on an assessment of historical records and data collected during this study, flocks of≥250 Purple Sandpipers have been reported from 48 sites along the Maine coast. The area from Isle au Haut to Swans Island along the midcoast supports the highest concentrations of wintering Purple Sandpipers in Maine and the largest wintering concentration of Histrionicus histrionicus (Harlequin Ducks) in eastern North America, highlighting the potential importance of this geographic region. Source

Mittelhauser G.H.,Maine Natural History Observatory | Allen R.B.,50 State Street | Chalfant J.,Maine Natural History Observatory | Schauffler R.P.,U.S. Fish and Wildlife Service | Welch L.J.,Maine Coastal Islands National Wildlife Refuge

The status and trends of Maine's island-nesting Herring Gull (Larus argentatus) and Great Blackbacked Gull (L. marinus) populations have changed dramatically over the last century. Aerial photographs were used to count nesting Herring and Great Black-backed gulls at all colonies along the coast of Maine, USA, in 2008 and 2013. Population trends were assessed by comparing current survey data to a previous coastwide survey in 1977. The breeding population of Herring Gulls in Maine was estimated at 24,302 pairs nesting on 180 islands during 2008 and 21,488 pairs nesting on 180 islands during 2013. This represents an annual decline of 2.3% in the number of nests in Maine from 2008 to 2013. The breeding population of Great Blackbacked Gulls in Maine was estimated at 10,094 pairs nesting on 197 islands during 2008 and 6,934 pairs nesting on 191 islands during 2013. This represents an annual decline of 6.3% in the number of nests in Maine from 2008 to 2013. Nesting populations for both species appeared to peak in the 1990s. Between 1977 and 2013, the number of Herring Gull nests in Maine declined by 17%, and the number of nesting islands declined by 19%. Great Black-backed Gull populations also declined between 1977 and 2013, with a 30% decline in the number of nests and a 14% decline in the number of islands supporting nesting. The reason for the decline is unknown, but we speculate that these declines may be related to changing food availability around colonies and increased predation rates by Bald Eagles (Haliaeetus leucocephalus) and mammals. Source

Mittelhauser G.H.,Maine Natural History Observatory | Tudor L.,50 State Street | Connery B.,Acadia National Park
Journal of Field Ornithology

Although within-year site fidelity to specific wintering sites allows shorebirds to use prior knowledge of resources and microhabitats, such fidelity may also make populations more vulnerable to extirpation in the event of increased predation pressure, habitat loss, or disturbance. In the eastern Atlantic, Purple Sandpipers (Calidris maritima) have been found to be highly faithful to specific sites in wintering areas. However, little is known about the use of wintering areas by these sandpipers along the coast of Maine. We quantified movements of 60 radio-marked Purple Sandpipers in a bay near the mainland and on an offshore cluster of islands along the mid-coast of Maine during two winters (2005-2006 and 2006-2007). Birds marked in early- and mid-December remained until spring migration, with no evidence of onward migration. Mean maximum distances moved did not differ significantly between either males (8.6 ± 1.0 [SE] km; N= 30) and females (7.4 ± 0.8 km; N= 30) or juveniles (9.9 ± 1.6 km; N= 9) and adults (7.8 ± 1.1 km; N= 26). We also detected no monthly (January-May) differences in maximum distances moved. Sixty percent of marked individuals moved ≤5 km between the two most distant relocations and no birds moved >25 km during the 2- to 4-month tracking period. We attribute the high site fidelity primarily to the plentiful prey base in the study area. During a 2-d period with severe cold, feeding areas at locations protected from wave action became encased in ice and birds at these locations moved up to 10 km offshore to sites with less ice. Species with strong site fidelity, like wintering Purple Sandpipers, may be at higher risk in the event of large-scale changes in their food base, increased predation pressure, habitat loss, or disturbance. However, the short-distance movements made when intertidal feeding areas became encased in ice suggest that Purple Sandpipers could potentially move greater distances in response to changing conditions in their wintering areas. © 2012 The Authors. Journal of Field Ornithology © 2012 Association of Field Ornithologists. Source

Mansfield M.R.,College of the Atlantic | Pope N.S.,University of Texas at Austin | Mittelhauser G.H.,Maine Natural History Observatory | Rajakaruna N.,College of the Atlantic | Rajakaruna N.,North West University South Africa

Metal-contaminated soils provide numerous stressors to plant life, resulting in unique plant communities worldwide. The current study focuses on the vascular plants of Callahan Mine in Brooksville, ME, USA, a Superfund site contaminated with Cu, Zn, Pb, and other pollutants. One hundred and fifty-five taxa belonging to 50 families were identified, with the Asteraceae (21%), Poaceae (11%), and Rosaceae (9%) as the most species-rich families. Ninety-six species encountered at the Mine were native to North America (62%), including 11 taxa (7%) with rarity status in at least one New England state. Fifty-one species were non-native (33%), including nine taxa (6%) considered invasive in at least one New England state. We characterized how the plant community changed across different habitats at the Mine, from disturbed and exposed (waste rock piles, tailings pond) to inundated and relatively undisturbed (wetland, shore), and documented concurrent shifts in the ionic content of the soils across the habitats. We found substantial differences in both the plant community and soil chemical features among habitats. Habitats separated out along a single axis of an ordination of the plant community, with wetland and shore habitats at one extreme and tailings pond and waste rock-pile habitats at the other. The first principal component axis of the 21 soil variables was significantly predicted by the ordination of the plant community, indicating a gradient of increasing organic matter, Fe, Mg, Mn, total N, Na, and K roughly parallel to the gradient of increasing wetland vegetation. None of the plant species tested accumulated substantial concentrations of metals in their leaf tissue except Salix bebbiana and Populus balsamifera, which accumulated 1070 ppm and 969 ppm Zn in dry leaf tissue, respectively-approximately one-third of the concentration considered as hyperaccumulation for Zn. © New England Botanical Club. © 2014 by the New England Botanical Club. Source

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