The Wilson Journal of Ornithology 123(3):536-547, 2011 
DISTRIBUTION OF MIGRATORY LANDBIRDS ALONG THE 
NORTHERN LAKE HURON SHORELINE 
DAVID N. EWERT,' 7 MICHAEL j. HAMAS, 23 ROBERT J. SMITH. 2 - 4 
MATT E. DALLMAN, 2 - 5 AND SCOTT W. JORGENSEN 6 
kn^n ST ^Scri^ntS b ,J ti ^h 0 !-in forested landscapes of eastern North America is pood, 
function of distance from northerr t "i" u ^ northern whilc cedar (Thuja occidental^ ) dominated forests as • 
hat Z affectTe dZhuf M,Ch ' gan **"'* ^ a " d «*«umn migration, and (2) discuss factor, 
T S u m,gra ' ,ts - Bo,h and short-distance migrant, in spnng and fa., 
aquarictaledts^s s^h a mZ" <T Thh paltern * as P^^ariy pronounced during spring 
near heshore! ne L hh S" Preda,0fS < e *" spidcr » “« "»t common and occur in large t number- 
comrdmng Zdate ZnJ snLZio " bundan ** elated with midge abundance after 
because of the barrier effect of L ike Huron and "T , ' ni ' Cr: " lun - Migrant# may concentrate near the shoreline 
Terrestrial habitTa^^ ,bod —■ especially during spnng urig.au, 
important stopover sites for landbird miermis o ** , tlUC depcndcnI mvcr tcbratcs are relatively abundant may pr.--v.de 
cri,ica, ““ T "* ^ **” *** 
Migration is a high-risk, energetically cost! 
event (Alerstam and Lindstrom 1990, Blem 1990 
that is associated with relatively high mortalit’ 
(Moore et al. 1995, Sillett and Holmes 2002) 
especially among young birds of the yea 
(DeSante 1983, Ketterson and Nolan 1983) 
Landbirds use stopover sites during migration 
which are areas where migrants rest, refuel, anc 
seek shelter from predators and adverse weather 
conditions (Berthold 1975. Blem 1980, Alerstam 
and Lindstrom 1990. Moore et al. 1995). How 
migrants respond to stresses encountered is key to 
a successful migration. Thus, a network of 
stopover sites ranging from refugia with little 
rood, such as islands or coastlines, to food rich 
sites may be needed by landbirds when migrating 
and vvinterin 8 areas (Mehlman 
et al. -005). Coastal stopover sites, including 
those adjacent to the Great Lakes, may be 
especially important to migrants because they 
i The w/T Conscrvanc y- 101 East Grand River 
Lansing, MI 48906. USA. 
2 Department of' Biology. Central Michigan University 
Mt. Pleasant. MI 48859. USA * 
U05 WCSt Pafk DriVe ’ Midland ’ MI 
4 Current address: Department of Biology, University of 
Scranton. Scranton, PA 18510. USA. ‘ V 
54548 e usT eC “" SerVa " C> ’’ P ' °' B ° X 421 *««“?"■. WI 
om C SH y fT Ub ° nu **- 
48090. USA. ' 3 ° 5(X M ° Und Road ’ War rcn, MI 
7 Corresponding author; e-mail: dewert@tnc.org 
536 
may provide refugia and food resources to 
accumulate energy stores, both before and after 
crossing expanses of water (Moore et al. 1995; 
Dunn 2002; Smith et al. 2004, 2007; Bonier etal. 
2007, 2009). 
Recent work suggests shoreline areas adjacent 
to northern Lake Huron provide important stop¬ 
over habitat to spring migrant landbirds (Seefell 
1997; Smith et al. 1998, 2004, 2007), possibly due 
to the presence of emergent aquatic midges 
(Diptera: Chironomidae). For example, at least 
two species of landbird migrants, Black-throated 
Green Warbler (Dendroica virens) and American 
Redstart (Setophaga ruticilla) foraged and used 
habitats differently, depending upon whether 
individuals were observed in shoreline habitats 
containing abundant midges or inland where few 
midges were observed (Smith et al. 1998. 2004) 
Smith et al. (2007) provided evidence that 
shoreline habitats within Michigan's eastern 
Upper Peninsula are resource rich during spring 
migration. Arthropod biomass estimates suggesi- 
ed more midges and spiders (Araneae; Arachni- 
dae) were present within shoreline habitats than 
inland and American Redstart foraging behavior 
reflected shoreline/inland differences in resource 
abundance (Smith el al. 2007). Furthermore, a 
suite ot migrant species appeared to gain mass 
quickly in shoreline habitats during early spnng 
when midges and spiders were the predominant 
resource (Smith et al. 2007). 
The Great Lakes strongly influence nearshore 
terrestrial habitats (Eichenlaub 1979, Albert et al. 
