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THE WILSON JOURNAL OF ORNITHOLOGY • Vol 123. No. 3. September 2011 
TABLE 3. Arthropods quantified during timed prey availability counts within a 1-m radius. Arthropods were quantified 
for a 90-sec observation period and then for an additional 90 sec while flipping over leaves to simulate the most common 
Louisiana Waterthrush foraging strategy. Data (x ± SE) are shown for the two most highly used substrates (stream and 
mud) as well as use and non-use locations. 
Otdcr 
Stream 
Mud 
Use 
Non-use 
Diptera 
3.48 ± 0.46 
3.97 ±1.19 
2.93 ± 0.41 
2.83 ± 0.62 
Hymenoptera 
0.82 ±0.17 
1.45 ± 0.39 
1.24 ± 0.18 
1.85 ± 0.6 
Aranea 
0.59 ± 0.1 
0.87 ± 0.34 
0.52 ± 0.1 
0.44 ± 0.21 
Platydesmida 
0 ± 0 
0.19 ± 0.17 
0.1 ± 0.05 
0.08 ± 0.05 
Orthoptera 
1.06 ± 0.28 
0.22 ± 0.1 
0.6 ± 0.17 
0.9 ± 0.49 
Lepidoptera 
0.06 ± 0.02 
0.13 ± 0.05 
0.07 ± 0.02 
0.08 ± 0.04 
Odonata 
0.01 ± 0.01 
0 ± 0 
0.01 ± 0.01 
0 ± 0 
Hemiptera 
2.59 ± 0.82 
0 ± 0 
1.33 ± 0.48 
0.03 ± 0.03 
Pulmonata 
0.07 ± 0.02 
0.09 ± 0.05 
0.06 ± 0.02 
0.01 ± 0.01 
Unidentified larva 
0.22 ± 0.06 
0.24 ±0.12 
0.23 ± 0.06 
0.03 ± 0.02 
Prairie Warbler (Dendroica discolor) (50%) 
(Latta and Faaborg 2001), American Redstart 
(Setophaga ruticilla) (40-70%) (Marra and 
Holmes 2001), and Northern Walerlhrush (14- 
52%) (Reitsma et al. 2002) during the non¬ 
breeding season. It was not possible to discern 
mortality from emigration. Use of radio transmit¬ 
ters may be a cause for the low return rates (see 
Mattson et al. 2006). but 59% of the birds with 
transmitters were recaptured and harnesses re¬ 
moved prior to spring departure. Use of cotton 
string as a harness increases the probability that 
transmitters are lost within 4-6 weeks of applica¬ 
tion, prior to migration (Hallworth et al. 2009). 
Previous work on Louisiana W'aterthrush dur¬ 
ing the non-breeding season suggests this species 
is a riparian specialist with similar habitat 
requirements to those used during the breeding 
season (Master et al. 2002). Our study suggests 
Louisiana Waterthrushes are not strictly associat¬ 
ed with headwater streams and use a variety of 
habitat types including muddy substrates and 
housing developments. Food availability influ¬ 
enced habitat use of individuals although it did not 
appear to impact home range size or core area. 
Water quality parameters were not measured 
although Master et al. (2002) found the highest 
waterthrush densities (10 individuals/km) in Costa 
Rica occurred along streams with moderate to 
high abundance of macroinvertebrates. 
Waterthrush use areas as far as 150 m from 
streams despite being closely associated with 
riparian habitats. Our study illustrates the impor¬ 
tance of food availability for Louisiana Water¬ 
thrush and indicates this species uses a wider 
array of habitat types than previously thought. The 
frequent use of saturated soils adjacent to rivers 
and streams as foraging sites is an important 
component to understanding their non-breeding 
distribution and, potentially, for considering this 
species’ conservation throughout their wintering 
distribution. 
ACKNOWLEDGMENTS 
We thunk J. M. Wunderle and J. E. Mercado for support 
and assistance as well as the staff at Sabana Reid Station, 
Sabana, Puerto Rico. The authors also thank P. M. Benham. 
A. J. Lcppold, R. S. Mulvihill, F. L. Newell, and Carly 
Reitsma for help in the Held. This study was supported by 
the New England Institute for Landscape Ecology. We 
thank C. E. Braun and two anonymous reviewers who made 
comments that improved this paper. 
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