Endangered Mississippi Sandhill Cranes get a boost

11/09/2009

Three endangered Mississippi sandhill cranes Credit US Fish & Wildlife Service

Starting at the crack of dawn Friday, November 6th, some 25 to 30 volunteers hid in blinds throughout the Mississippi Sandhill Crane National Wildlife Refuge's wetland pine savanna to count and identify individuals by looking for colored bands around each crane’s long legs. The crane count not only provides refuge staff with critical information about the endangered birds' habitat use, but also allows volunteers who have a passion for birds to get a close-up view. They observes the birds for five hours, between 5am and 10am. "It is a snapshot survey of the population that allows us to track population trends over the years," says Refuge Ranger Emily Neidigh.

This was the first refuge established specifically to help an endangered species; Mississippi sandhill cranes (Grus canadensis pulla) are a critically endangered subspecies of the wide-ranging sandhill crane that have distinct coloration, behavior, and genetics. The refuge, initially established in 1975, is on the Mississippi Gulf Coast, near Gautier, and currently consists of over 19,000 acres in four separate units.

In addition to the crane count, last week biologists released ten captive-reared Mississippi sandhill cranes onto the refuge.  Only 100 individuals of this subspecies remain in the wild, and a mere five percent of the original acreage of pine savanna habitat remains along the Gulf Coastal Plain. The flock lives only on the refuge and on private lands surrounding it, but the good news is the flock has increased from an all-time low of 30 to 35 in the mid-1970s - albeit ever so slowly.

Ten young cranes, between five and six months old, were released using two different methods so biologists could determine which works best. "We're still refining our release techniques to give the cranes the best chance at survival and incorporation into the wild population," said Scott Hereford, Refuge Supervisory Wildlife Biologist. 

The first group of six, reared at the Audubon Center for Research of Endangered Species in New Orleans, Louisiana, got introduced into an enclosure where they’ll stay for 30 days with wing restraints as part of a gradual or "acclimated" release. This allows other wild birds to interact with them, since others can fly into the pen but the young cranes can't fly out. until the wing restraints are removed. It also lets the young cranes get used to the area and develop site fidelity. "They were socialized prior to transfer to the refuge to develop group cohesion, thereby increasing survival, mimicking the tendency for wild subadults to form groups of three to seven," says Hereford. Five of these six crane chicks were “costume reared” by humans using crane suits and puppets on their hands.

"Caretakers are costumed the entire time we are raising the chicks, from hatching to the point that they get transferred to the refuge," explains Megan Savoie, Crane Program Coordinator for the Audubon Center.  Like all birds, cranes imprint on the first thing they see, so in order to avoid the crane chicks imprinting on a human, biologists use crane puppets to feed them when the chick is young. One of the six cranes in the enclosure was reared by crane parents but then socialized with the other crane chicks.

The second group of four cranes got released directly onto the refuge, without any enclosure or wing restraints. All four of these birds were reared at the White Oak Conservation Center in Yulee, Florida. Two got released together, near other individuals from the wild flock. The other two of the four got released individually in different parts of the refuge, but each near other wild birds.

"Nearly all the releases thus far have been via the acclimated release. It was developed here, and has been used in crane releases elsewhere," says Hereford. "We've rarely used direct releases, but I thought I'd try a few since it would have the advantage of allowing cranes to more quickly colonize new areas - no big expensive pen needed. We hope direct releases will be another tool in our toolkit of techniques in recovery efforts for the endangered Mississippi sandhill crane." It will be intriguing to see how the released cranes fare in the future!