Scientific Name:
Vermivora ruficapilla
Nest Type: Cup
Nest Location: Ground
Clutch Size: 4-5
Food: Insects
Foraging Guild:
Foliage and ground gleaner, hover and glean
The Nashville Warbler is
a common to abundant breeding bird throughout most of the forested zones
of Minnesota, but is relatively rare or absent from the southern portions
of Minnesota (Janssen 1987). It has a disjunct breeding distribution
with one population in the east centered around the Great Lakes transitional
forests and the other in the northwestern U.S., extending from northern
California to southern British Columbia (Bent 1953, DeGraaf et al. 1991).
The Nashville Warbler is
a long distance migrant with its primary wintering grounds in Mexico
and Guatemala (Finch 1991). It generally arrives in Minnesota during
late April to early May with the bulk of migrants arriving in mid-May.
It begins its return flight to the tropics in late July and most individuals
are gone by early October (Janssen 1987).
Nashville Warblers nest
on the ground and are highly insectivorous, primarily gleaning insects
from foliage found both in trees, shrubs, and on the ground (Roberts
1932). The Nashville Warbler is found in a variety of forested habitats
from black spruce/tamarack bogs and mature deciduous forests to recently
cut areas (Green and Niemi 1979, Niemi and Pfannmuller 1979, Niemi and
Hanowski 1992). Data gathered from a variety of sources indicate that
the Nashville Warbler is found in a wide variety of habitat types, but
the presence of a well-developed shrub layer and ground vegetation suitable
for nesting are important. It is most abundant in conifer-dominated
vegetation with suitable shrub cover such as in moderately-aged (15-40
yr old) spruce, fir, or pine. In these habitats, densities can approach
more than 4 pairs per 15 ha throughout northern, northeastern, and central
Minnesota. It also is relatively common in many deciduous habitats,
but population densities are generally lower, ranging from 1 to 2 pairs
per 15 ha.
Based on Breeding Bird
Survey roadside counts, no trend in the relative abundance of the Nashville
Warbler was evident in Minnesota since the 1960's (Janssen 1990). Similarly,
no trend was detected by Sauer and Droege (1992) within its continental
range or within the eastern United States.
The Nashville Warbler is
a species that has presumably increased over the past 150 years due
to the increase of young, second growth forests (Morse 1989). Hence,
the species will likely be positively affected by increased forest harvesting
if this results in increased edge habitats with shrubs. However, it
may be susceptible to increased predation along edge habitats, if this
is associated with an increased number of nest predators.
