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THE WILSON JOURNAL OF ORNITHOLOGY • Voi 123. No. 4. December 2011 
passerines is scarce. We used micro-computed 
tomography (microCT) (Ruegsegger et al. 1996). 
to look for medullary bone in wing and leg bones 
of Wood Thrush (Hylocichla mustelina) and 
Veery (Catharus fuscescens), two species of 
passerines. 
METHODS 
Field Collections.—We collected Wood Thrush 
and Veery during the spring migratory period 
(24-28 Apr 2005 and 16-30 Apr 2006). near 
Johnson Bayou in southwest Louisiana. USA (29 
45' N. 93 37' W) on the northern coast of the 
Gulf of Mexico, during the fall migratory period 
(18 Sep-15 Oct 2005) at Bon Secour National 
Wildlife Refuge. Fort Morgan Peninsula. Ala¬ 
bama (30 13’ N. 88" 10' W). and during the 
breeding season (24-27 May 2006) at a study site 
in Lackawanna County, northeastern Pennsylva¬ 
nia (41 33' N. 75° 43' W). Detailed study site 
descriptions have been published by Woodrey and 
Moore (1997) (Fort Morgan Peninsula). Barrow et 
al. (2000) (Johnson Bayou), and Smith and Hatch 
(2008) (northeastern Pennsylvania). 
We collected the majority of the birds passively 
using mist nets (12 x 2.6 m with 30-mm mesh). 
We used a combination of passive and target mist 
netting techniques at northeastern Pennsylvania to 
maximize captures and classified males and 
females in the field by presence of a brood patch 
or engorged cloaca! protuberance. We euthanized 
birds using C0 2 upon capture and, at necropsy we 
classified males and females and also recorded 
any egg formation in the oviduct. All procedures 
AnSi«ir eWe<1 approved b >' lhe Institutional 
Arnma care a"J Use Commiltee at the University 
of Southern Mjsstssipp 1 (protocol 217-003) and at 
the University of Scranton (protocol 3-03) Birds 
were collected under U.S. Fish and Wildlife 
Service permit MB 758364. 
Micro-computed Tomography.— The wing (hu¬ 
merus and radius-ulna) and leg (tibiotarsus-fibula) 
bones were dissected free of soft tissue in 
preparation for scanning. The femora were 
unavailable for dissection due to another ongoing 
study on body composition (JCO. unpubl. data? 
a W S:^ individual usin 
MedkS r a 7 ng System (pCT 8() - Scanco 
sitv or Sd ° rf ’ Switzerland) at The Univer- 
vivo spedmer* Wh,Ch is . Capuble Scanning ,.v 
‘o examine seasonajTffl^e^^ 0 " 801 ^ SU,dy 
ogy (MES ' *■*>. w= ™ 
ulna and tibiotarsus-fibula when we found med¬ 
ullary bone in the humerus. We also scanned 
tibiae from an actively laying Domestic Chicken 
and a broiler chicken as positive and negative 
controls. We scanned all Wood Thrush and Veen 
specimens vertically in a cylindrical sample 
holder (20 mm diam X 65 mm height) at a 
voltage of 55 kV. intensity of 45 nA. and 
resolution of 10 pm (isotropic voxel size). The 
scanning time ranged from 12 to 18 hr. for the 
humerus, and up to 20-28 hrs for the tibiotarsus- 
fibula complex. We scanned the chicken hones, 
because of their larger size, in larger sample 
holders (35 mm diam X 65 mm height) at a 
resolution of 18 pm (isotropic voxel size), which 
took —30 hrs of scanning time. 
We used Scanco Software (Scanco Medical. 
Basscsdorf, Switzerland) to examine two-dimen- 
sional (2D) cross sections for presence of 
medullary hone. We evaluated 2D slices of each 
bone to create a three-dimensional (3D) image. 
We drew contour lines around each bone in its 
entirety prior to evaluation. We applied a 
Gaussian filter to remove noise from each image 
followed by segmentation using a single threshold 
to separate bone from non-bone (marrow and soli 
tissue). The resultant images were opened in the 
3D-viewer and the bones wee virtually sliced, 
making the interior available for examination. 
RESULTS 
Eight Wood Thrush (4 females and 4 males) 
and eight Veery (2 females. 5 males, and 1 
undetermined) were collected during spring mi¬ 
gration (Johnson Bayou), nine Wood Thrush 
females and 6 males) and nine Veery (I female 
and 8 males) were collected during the breeding 
season (northeastern Pennsylvania), and five 
Wood Thrush (2 females, 2 males, and 1 
undetermined) and two Veery (both males) were 
collected during fall migration (Fort Morgan 
Peninsula). We examined these birds as well - 1 - 
an actively laying Domestic Chicken and a broiler 
chicken (positive and negative control, tespe^- 
tively) lor presence of medullary bone. We found 
no evidence of medullary' bone in any 
collected during spring or fall migration, in an) 
female 
the males collected during any season, nor in 
—vum.ntu uuiuig any scasuu. w 
broiler chicken (Fig. 1). Medullary' bone was 
present in the laying Domestic Chicken as - 
as in one (# 16) of three female Wood Thrushes 
and in the female Veery (# 10) collected m 
breeding areas (Fig. 1). Medullary bone was 
well 
