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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 1, March 2011 
TABLE 2. Mean density (birds/10 ha ± SD) of grassland and 
unmowed buffers on the Eastern Shore of Maryland, winter 2007. 
scrub-shrub 
bird species detected in mowed and 
Management type 
Common name 
Scientific name 
Mowed 
Unmowed 
American Kestrel 
Falco sparverius 
0.0 ± 0.0 
0.1 ± 0.5 
Eastern Bluebird 
Sialia sialis 
0.0 ± 0.0 
0.1 ± 0.4 
Field Sparrow 
Spizella pusilla 
0.0 ± 0.0 
11.3 ± 34.7 
Savannah Sparrow 
Passerculus sandwichensis 
0.6 ± 2.1 
7.2 ± 16.2 
Song Sparrow 
Melospiza melodia 
2.1 ± 5.3 
70.1 ± 60.1 
Swamp Sparrow 
M. georgiana 
0.0 ± 0.0 
5.5 ± 13.3 
White-throated Sparrow 
Zonotrichia albicollis 
1.6 ± 5.7 
15.9 ± 51.0 
Dark-eyed Junco 
Junco hyemalis 
0.7 ± 2.4 
3.4 ± 12.2 
metrics and species’ abundances tested were 
significantly greater in unmowed than in mowed 
buffers, and 98% of all bird detections were in 
unmowed buffers. Wintering birds use herbaceous 
habitats for foraging, roosting, and escape cover 
(Watts 1990, Marcus et al. 2000, Smith et al. 
2005, Conover et al. 2007) and fall mowing 
removes valuable habitat that wintering birds 
could otherwise exploit (Harper 2007). 
These results are especially important because 
most birds detected in unmowed buffers were 
grassland or scrub-shrub species, two guilds 
experiencing substantial population declines 
(Hunter et al. 2001, Askins et al. 2007, Sauer et 
al. 2008). Three species detected in buffers (Field 
Sparrow, Savannah Sparrow, and Dark-eyed 
Junco [Junco hyemails]) are listed as species of 
greatest conservation need in Maryland (Maryland 
Department of Natural Resources 2004). Thus, 
reducing the practice of fall mowing could 
provide additional habitat for several birds of 
conservation concern. 
Our findings agree with other studies of 
wintering bird use in mowed and unmowed 
herbaceous habitats. Saab and Petit (1992) 
reported relative bird abundance and species 
richness were lower on grazed pastures main¬ 
tained by mowing compared to abandoned 
pastures in Belize. Marcus et al. (2000) found 
greater sparrow abundance in herbaceous field 
borders than in mowed field edges in North 
Carolina. However, compared to studies of 
breeding birds, there have been few studies on 
the response of wintering birds to mowing of 
herbaceous habitats. 
This study focused on the response of wintering 
birds to fall mowing but did not examine bird 
response to mowing at other times of year. Late 
winter or early spring mowing instead of fall 
mowing could provide additional habitat for 
wintering birds (Harper 2007). For example, 
mowing a buffer on 15 March instead of 15 
August could provide 7 months of additional 
unmowed habitat. There are practical reasons why 
fall mowing may be preferred, including wet 
weather or lack of time to mow in late winter or 
early spring, that should be considered prior to 
altering mowing schedules. Late winter or early 
spring mowing may also remove habitat for 
wintering birds that may have become dependent 
on unmowed buffers for food or cover. When 
mowing is necessary, leaving nearby herbaceous 
areas unmowed will provide habitat that may be a 
refuge for some bird species (Bryan and Best 
1991). Following the recommended guideline of 
mowing one-third of the area per year will provide 
more habitat for wintering birds than completely 
mowing buffers. 
interim? 3 ' ^ COmmunity raetrics (mean * SE) in mowed and unmowed buffers on the Eastern Shore of Maryland. 
Management type 
— 
Bird community metric 
Mowed 
Unmowed 
F 
p 
Total abundance 
Species richness 
Total avian conservation value 
0.3 ± 0.2 
0.5 ± 0.3 
0.4 ± 0.2 
11.0 ± 3.1 
3.3 ± 0.8 
19.9 ± 5.8 
48.8 
11.0 
94.4 
<0.001 
0.006 
<0.001 
