Sandhill cranes were captured using noose lines, an ancient
bird-catching technique from India, demonstrated to us by Tracy Grazia of
Mississippi Sandhill Crane NWR, Gautier, Mississippi. A capture site was baited
with field corn, and after birds began using the bait, noose lines were set
during the pre-dawn period. A noose line is a series of one hundred 100-lb test
monofilament snares, each attached to a 5-inch wooden stake, and tied together
with a nylon cord. The stakes were pushed into the earth about 10 inches apart
to form a wall of upright nooses. One or two lines were set out at each site.
Birds feeding on the bait stepped into the nooses and their leg became ensnared.
Strain on their legs was reduced by the elastic nylon line and the few sticks
which were pulled from the soil by the struggling cranes. There never appeared
to be any injuries to the bird's legs from the lines, and when we caught smaller
non-target species such as a Canada goose or mallard, they appeared unharmed as
well and flew off upon release. As soon as birds became
trapped, we rushed out to secure them and process them for banding and marking.
We watched the trap site from a blind nearby, and when cranes
became entangled in the line, we rushed out and removed them for processing. At
first, we tried hiding in a blind made out of corn stalks in standing corn, but
decided to give this up after a few days because of cold temperatures, rain, and
wary cranes. Subsequently, we used a parked vehicle for a blind and monitored
trap lines with spotting scopes. At
Sauvie Island, we were able to park the vehicle inside
an old barn which provided an ideal situation for being
hidden, yet close to the trap lines.
BANDING AND MARKING
To limit stress to the cranes, they were hooded while they
were being handled. PTTs were fitted to one leg using rivets and
glue; federal and colored plastic bands of a
unique color combination were placed on the
other leg. The two cranes without PTTs were
similarly marked with colored bands.
Measurements were taken from each bird including length of wing chord, tarsus, middle toe, exposed culmen, and nares to tip; each
bird was also weighed. In addition, a blood sample was collected from each bird for genetic analyses.
The PTTs were programmed to activate for 8 hours after 60 hours of deactivation, resulting in locations being recorded from satellites
about every 3 days.
Click the following items to see detailed results for this study: