Mission: Endangered Crane Protection

Surveys are conducted throughout the year - often daily - to monitor the cranes. Official estimates of crane numbers are figured in January based on information gathered at several official crane counts, including the Fall Crane Count.

Current estimate is 99 cranes. This includes 25 nesting pairs.

Cranes are often 3-4 years old or older before they form a pair bond. After that, pairs can nest for 2-3 years before they lay viable eggs. They generally lay 1-2 eggs, but rarely is more than one young raised to fledging.

Tracking and Monitoring

At the refuge, a lot of habitat work goes on to restore the natural ecosystems used by the cranes and other wildlife. In addition to restoring the savanna and creating a home for the cranes, biologists spend the year tracking and monitoring the cranes.

The information obtained is put in a refuge data base and provides clues to habitat use, nesting, survival rates, cause of mortality, and many other aspects of local crane life.

Yearround monitoring is conducted with biologists spending the early mornings in blinds hoping to catch a glimpse of the birds and tracking the birds using radio telemetry.

Many birds on the refuge are outfitted with a radio transmitter. Using antenna equipment like seen to the right, biologists go out onto the refuge and in the community to track the signal produced by the transmitter. Each radio has signal on a different frequency.

Using telemetry - taking several points where the signal is picked up - biologists are able to find, identify and monitor the cranes.

To the right, you see a close up of a crane's legs where the right leg has a long white band with a radio transmitter. The crane's left leg has three bands. These band combinations are unique to this bird and allow us to identify the birds from a distance.

Radio transmitters have small batteries in them with an estimated life of 2 years. Not all cranes with color bands get radio transmitters. Each of these methods helps the refuge to identify the birds, document their bonds and behaviors and conduct research on them that will be useful for their recovery and for recovery of other endangered cranes.

During the winter, biologists attempt to trap the cranes to outfit them with new transmitters, band young birds and replace bands where they have fallen off of older birds. 2008 is the first year that the MS sandhills have been fit into backpack transmitters. The battery life on the backpacks far exceeds the leg transmitters.

In the spring, biologists search for cranes and monitor their nests. In the photo to the left, biologists have located a nest and are checking the egg viability using a floating egg test.

Other tests identify how far along the nest is into the incubation period. Biologists can watch for chicks and record how many cranes are hatched.

It's important to locate nests each year for crane recovery data, but also to plan the fire management around units and areas where the cranes are nesting.

From high in a helicopter, the nest to the left is found. Can you find it?

Many times nest will be in wet areas like this, other times they will be in the more dry savanna. If this nest was hidden in the grass of a dry savanna, it could be even more difficult to find while flying over.

Nests are often located using helicopters and radio transmitters, but biologists also have methods of locating nests on the ground using known pair data.

Natural recruitment is one of the limiting factors to crane population growth each year. Very few eggs are hatched, the young survive to subadulthood and join the MS Sandhill Crane population.

Predators such as bobcats, armadillos, raccoons and other egg lovers find the nests. Pairs will often attempt to nest again. Once colts have hatched, they are still susceptible to predation. Crane parents will raise the young crane until it is about 10 months old and nearly full grown.

To supplement the crane population, the refuge uses a system of captive rearing. Each year, 10-15 young birds are released on the refuge (crane release crate seen to the right).

Beginning in 1965, "extra" eggs, the second viable egg from a two-egg nest, were occasionally removed from the local nests and taken to the U.S.G.S. Patuxent Wildlife Research Center to become part of a captive flock. This flock was useful as a genetic reservoir and for physiological and behavioral research that would be difficult with wild birds.

By 1980, there were enough captive breeding pairs to produce juveniles for release.

It is very important that the colts do not imprint on humans and so, in captivity, they are raised by humans wearing the crane costume pictured to the left.

Using a crane head puppet, young cranes learn life skills. They imprint to the puppet and the remainder of the costume is a simple "grey blob" to them.

After the cranes are fully grown, they are captured, banded and brought to the refuge. They are released into pens with a brail on their wings to keep them from flying out while they acclimate to their new home and surroundings.

Continuing with the captive rearing system, anytime biologists take food to the cranes, they wear the crane costume. After a month, the cranes are re-captured, the brails are taken off their wings and they are able to leave the pens and join the rest of the population in the wild.

Since 1981, captive reared cranes have been released annually on the refuge. This program is the largest crane release program in the world and has been so successful that 90 percent of the free-flying cranes seen today are captive-reared.

All but a few of the 22 breeding pairs are captive-reared cranes that are surviving and finally breeding. The captive flock established at the U.S.G.S. Patuxent Wildlife Research Center has been split and now about half of the cranes reside at the Audubon Institute's Species Survival Center outside New Orleans and about half at the White Oak Conservation Center near Jacksonville, Florida.