Methods

TRAPS

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.

BLINDS

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.

DATA COLLECTED

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.

PTT PROGRAMMING

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.

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