TY - JOUR
T1 - Reduced Density and Nest Survival of Ground-Nesting Songbirds Relative to Earthworm Invasions in Northern Hardwood Forests
AU - Loss, Scott R.
AU - Blair, Robert B.
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2011/10
Y1 - 2011/10
N2 - European earthworms (Lumbricus spp.) are spreading into previously earthworm-free forests in the United States and Canada and causing substantial changes, including homogenization of soil structure, removal of the litter layer, and reduction in arthropod abundance and species richness of understory plants. Whether these changes affect songbirds that nest and forage on the forest floor is unknown. In stands with and without earthworms in the Chequamegon-Nicolet National Forest, Wisconsin (U.S.A.), we surveyed for, monitored nests of, and measured attributes of habitat of Ovenbirds (Seiurus aurocapillus) and Hermit Thrushes (Catharus guttatus), both ground-dwelling songbirds, and we sampled earthworms at survey points and nests. Bird surveys indicated significantly lower densities of Ovenbirds and Hermit Thrushes in relation to Lumbricus invasions at survey point and stand extents (3.1 and 15-20 ha, respectively). Modeling of Ovenbird nest survival (i.e., the probability that nestlings successfully fledge) indicated that lower survival probabilities were associated with increased sedge cover and decreased litter depth, factors that are related to Lumbricus invasions, possibly due to reduced nest concealment or arthropod abundance. Our findings provide compelling evidence that earthworm invasions may be associated with local declines of forest songbird populations.
AB - European earthworms (Lumbricus spp.) are spreading into previously earthworm-free forests in the United States and Canada and causing substantial changes, including homogenization of soil structure, removal of the litter layer, and reduction in arthropod abundance and species richness of understory plants. Whether these changes affect songbirds that nest and forage on the forest floor is unknown. In stands with and without earthworms in the Chequamegon-Nicolet National Forest, Wisconsin (U.S.A.), we surveyed for, monitored nests of, and measured attributes of habitat of Ovenbirds (Seiurus aurocapillus) and Hermit Thrushes (Catharus guttatus), both ground-dwelling songbirds, and we sampled earthworms at survey points and nests. Bird surveys indicated significantly lower densities of Ovenbirds and Hermit Thrushes in relation to Lumbricus invasions at survey point and stand extents (3.1 and 15-20 ha, respectively). Modeling of Ovenbird nest survival (i.e., the probability that nestlings successfully fledge) indicated that lower survival probabilities were associated with increased sedge cover and decreased litter depth, factors that are related to Lumbricus invasions, possibly due to reduced nest concealment or arthropod abundance. Our findings provide compelling evidence that earthworm invasions may be associated with local declines of forest songbird populations.
KW - Aves canoras neotropicales migratorias
KW - Cascading effects
KW - Catharus guttatus
KW - Depredación de nidos
KW - Efectos cascada
KW - Hermit Thrush
KW - Invasive earthworms
KW - Lombrices de tierra invasoras
KW - Neotropical migratory songbirds
KW - Nest concealment
KW - Nest predation
KW - Ocultamiento de nidos
KW - Ovenbird
KW - Seiurus aurocapillus
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U2 - 10.1111/j.1523-1739.2011.01719.x
DO - 10.1111/j.1523-1739.2011.01719.x
M3 - Article
C2 - 21797927
AN - SCOPUS:80052574165
SN - 0888-8892
VL - 25
SP - 983
EP - 992
JO - Conservation Biology
JF - Conservation Biology
IS - 5
ER -