CRYSTAL-BALLING THE NUMBERS

There are five breeding centers for Whooping cranes around North America. The largest is the USGS Patuxent Wildlife Research Center in Maryland, followed by the International Crane Foundation in Wisconsin. There is also the Calgary Zoo in Alberta, Canada, the San Antonio Zoo in Texas, and the Audubon Center for Research of Endangered Species in New Orleans, known to us as ACRES.

Each year around this time the Flock Managers of these facilities get very busy as the breeding season begins. They use natural pair bonding as well as artificial insemination to ensure proper genetic coupling.

There were only three breeding females in the flock back in the 1940’s when only 15 Whooping cranes were left in the world. That bottleneck limited the amount of genetic material available. In order to keep track of that tenuous lineage, each pairing and hatch is recorded in the Whooping Crane Stud Book.

Within the captive flock there are birds that breed well and produce many eggs each season. There is a great advantage to prolific parents, but it does not take long before their offspring begin to dominate the population. The more birds produced by one pair and released into the wild, the greater chance of sibling pairing.

This time of year the Flock Managers and the Co-Chair of the Whooping Crane Recovery Team conference on a call each Monday afternoon. That is when the crystal ball comes out and Flock Managers try to predict how many eggs their charges will produce.

This year, based on those predictions, the Recovery Team expects the five breeding centers to produce approximately 56 fertile eggs. There is also a possibility of collecting another ten eggs from nests at Necedah for a total of 66 eggs.

On average, about 75 percent of the eggs produced in captivity are fertile, and 75 percent of those actually result in chicks ready to be sent out for release. So, if all the guesswork is accurate, and nothing untoward happens, there should be 37 birds available this season.

37 may seem like a lot of chicks, but there are a number of uses for them. The non-migratory population in Louisiana is beginning its third season and the Recovery Team has assigned that reintroduction a minimum of eighteen chicks for 2012. A minimum of twelve have been allocated to the ultralight-led program, and a minimum of six allocated to the Direct Autumn Release (DAR) method.

For several years a Parent Reared study has been proposed by WCEP. By this method chicks would be raised at Patuxent, but rather than collecting the eggs for incubation, they would be raised by their parents. They would be moved to Wisconsin in the fall and released like DAR birds with older Whooping cranes. That project has been allocated four birds this year.

In addition to all of this, there are genetic hold backs. If any birds with more uncommon lineage are produced from parents that are not as prolific as others, they will be held back to ensure those blood lines are protected in the captive population.

If you have been doing the math along the way, you will realize those numbers add up to 40 chicks, not including potential holdbacks. That is three more than the expected total production, so you can see that the egg allocation calls are critical to everyone.

Cross your fingers for a good breeding season.

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