SHORT COMMUNICATIONS 
621 
(Streby and Andersen 2011). Fledgling songbird 
survival is usually lowest during the First few days 
after fledging ( Anders et al. 1997. Berkeley el al. 
2007, Rush and Stutehbury 2008, Moore et al. 
2010) and variation in fledgling survival can 
influence population growth as much or more than 
nest productivity (Streby and Andersen 2011). 
However, telemetry and banding studies demon¬ 
strate use of non-nesting cover types by fledgling 
mature-forest birds occurs primarily utter birds 
reach independence from adult care (Anders et al. 
1998. Vitz and Rodewald 2010. Streby et al. 
2011b). a period of relatively high fledgling 
survival (King et al. 2006. Streby and Andersen 
2011 ) . 
Most studies describing non-nesting cover type 
use by mature-forest songbirds have used mist 
nets to capture birds in regenerating clearcuts and/ 
or forested wetlands (Pagen et al. 2000; Marshall 
et al. 2003; Vitz and Rodewald 2007; McDermott 
and Wood 2010; Streby et al. 2011a, b), and 
relatively few have used radiotelemetry to track 
movements of individual birds (Anders et al. 
1998. Mitchell et al. 2010, Vitz and Rodewald 
2010), However, capture data are limited in their 
utility for estimating the proportion of fledglings 
that move from mature forest to other cover types, 
how far birds move to access those stands, how 
long birds spend in those stands, and whether 
birds are selecting other cover types over mature 
forest (i.e., use them disproportionately relative to 
availability). We used radiotelemetry to monitor 
movements and cover-type selection by fledgling 
Ovenhirds after independence from adult care in 
managed forests of northern Minnesota. Our 
objectives were to: (1) assess how many fledg¬ 
lings used forested wetlands and regenerating 
clearcuts of different serai stages (shrub-dominat¬ 
ed and sapling-dominated). (2) leant how far birds 
moved to access those stands, and (3) whether use 
was in accordance w ith availability ot cover types 
on the landscape. We conducted this study at two 
sites similar in landscape cover-type composition, 
but differing considerably in mature-forest under¬ 
story density, and assessed whether availability o! 
dense understory vegetation alfected use ol 
clearcuts and forested wetlands. 
METHODS 
Study Am/.—We studied Ovenbirds in 2007 
and 2008 at two sites in the Chippewa National 
Forest in north-central Minnesota. Both sites 
consisted of forested wetlands, lakes, and legen- 
erating clearcuts of different ages interspersed 
within a matrix of mature forest >50 years of age. 
The two sites were separated by 25 km. and 
mature forest stands differed considerably in 
structure and species composition between the 
sites: one site was deciduous and the other was 
mixed-deciduous-eonifcr forest. Mature forest at 
our deciduous site was primarily open-understory 
deciduous forest dominated by sugar maple (Acer 
sacchartnn ). American basswood (Tilia america- 
nti), paper birch (Betula papyrifera), quaking 
aspen (Populus tremuloules). big-tooth aspen (P. 
grcindidentata), and red maple (A. rubrum). 
Mature forest at our mixed-deciduous-conifer site 
ranged from stands dominated by red pine (Pious 
resinoxa) to stands of mixed red pine and 
deciduous trees. The mature-forest understory at 
the mixed-deciduous-conifer site was: (1) domi¬ 
nated by dense sugar maple and hazel (Corylus 
spp.). (2) denser than the open understory of the 
deciduous site, and (3) similar in density to 
forested wetlands and sapling-dominated clearcuts 
at both sites (Fig. 1). 
Field Procedures.—We attached radio trans¬ 
mitters to nestling Ovenbirds in mature-forest 
stands at each site and tracked fledglings through¬ 
out the post-fledging period. We monitored nests 
in randomly selected 10-ha nest-search plots, and 
attached transmitters to 1-2 nestlings in each 
brood that survived to within 2 days of its 
expected fledge date. Wc attached transmitters 
using a figure-eight harness design for songbirds 
modified front Rappole and Tipton (1991). 
Transmitters were 4.3—4.9% ol nestling mass at 
time of attachment, and as low as 3.0% of 
fledgling mass before fledglings reached indepen¬ 
dence from adult care. Detailed nest-monitoring, 
transmitter-attachment, and ground-based teleme¬ 
try methods are provided in Streby and Andersen 
(2011). We continued to monitor all fledglings 
that survived beyond independence from adult 
care until either the birds were depredated or their 
transmitters failed. We assumed all birds were 
independent from adult core 25 days after fledging 
(Streby and Andersen 2011). A few birds (n = 3) 
were accompanied by adults 26-28 days after 
fledging but we did not observe them being fed by 
those adults. The 23 fledglings we monitored were 
from 23 separate broods, and we assumed their 
movements were independent ot each other. We 
monitored each fledgling daily (i.e.. one location 
per day) using ground-based telemetry methods. 
We located birds that moved beyond the range of 
