Good morning and Happy Valentines Day from matching mole, guest host of the Dawn Chorus this week. You won't see any photos of lineatus' caliber today but hopefully the story the cranes will make up for that. I'd also like to remind you that this weekend is the Great Backyard Bird Count so look out your window and start making a list. BirderWitch will be posting a community diary Monday (changed from Tuesday) at 7 PM eastern/4 PM pacific for everyone to post their results. tgypsy will be helping with the hosting later in the evening. So don't forget to check it out.
This story has nothing to do with plane crashes but rather with a more beneficial interaction between bird and aircraft.
Four weeks ago, my wife and I rose at 5 AM and headed down to the town of St. Marks, on the coast some 20 miles south of Tallahassee. It was the coldest morning of the winter with the temperature hovering at 20 F. About a thousand people patiently stood on the frozen ground of the city park near to the confluence of the St. Marks and Wakulla rivers. Many of them had been there the day before as well.
About 9 AM this came into view, flying directly towards the park.
As it got closer what we were seeing became more obvious
Three ultralight planes with a group of birds flying behind one of them. The birds were Whooping Cranes and they were being taken to St. Marks National Wildlife Refuge by Operation Migration.
So why all the effort to move birds around is this rather elaborate and cumbersome way? It is part of a massive effort to conserve one of the rarest birds in North America.
The Whooping Crane is one of two species of crane native to the new world, the other being the more abundant Sandhill Crane. All discussion of the whooping crane seem to mention that it is the tallest North American bird so I will follow tradition – they are significantly taller than other large white wading birds such as the Great Egret, the ‘Great White Heron’ (a geographic race of the Great Blue Heron), and the Wood Stork . Both Sandhills and Whoopers are omnivorous wading birds most commonly seen in or near wetlands. Although they resemble storks, egrets and herons, cranes are actually more closely related to rails.
Whooping cranes bred in numerous locations in North America in the past. By the late 19th Century, hunting, habitat destruction, and egg collecting had reduced the birds to a couple of populations. A non-migratory population in Louisiana stopped breeding in 1939 and was gone by 1950. The remaining migratory population breeds in Wood Buffalo National Park in the Northwest Territories of Canada and winters on the gulf coast of Texas at Aransas National Wildlife Refuge. In the early 1940s this population dropped to only 16 individuals and remained at very low levels for many years thereafter. In 1967 the cranes were declared an endangered species and the Wood Buffalo breeding population has gradually increased to over 250 birds today. This is approximately half of the total current world whooping crane population.
Since 1975 a number of additional conservation attempts have been made including captive breeding and attempting to establish other populations in the wild. This has been a costly and not always successful endeavor. If the Wood Buffalo/Aransas population is doing well why go to all this work?
The last remaining original population has protected breeding and wintering habitat ad the birds are protected from hunting. However they can’t be protected from the vagaries of chance. A population of only few dozen pairs, each pair only producing at most a single chick a year is terribly vulnerable. The birds are likely all very genetically similar, given that they are all descended from no more than 16 individuals a few generations back, raising possible problems with inbreeding. More serious is the possibility of a major storm, an epidemic, or a couple of years of bad luck suddenly bringing the population back to 1940s numbers. And this time they might not be so lucky. Instead of a slow climb back up they could just as easily spiral down into extinction.
Establishing other populations is insurance – spreading the risk around. It is also a daunting prospect. Animals that are highly social are difficult to reintroduce into the wild. If they have been raised in captivity they not likely to have learned how to be wild cranes – how to feed, how to court and mate, how to raise a chick. And the most difficult thing to learn (or at least for humans to teach) - how to migrate.
There are five captive breeding populations. These birds produce eggs and chicks that can be used to found wild populations but the adults cannot be returned to the wild. They lack the skills needed to survive.
Since 1975 there have been three attempts to establish new populations, two of which are still ongoing.
- The first attempt was to produce a second migratory flock that bred in Idaho. The birds came from eggs taken from the Wood Buffalo Birds and foster reared by Sandhill Cranes in Idaho. The Whoopers would then learn to migrate to Bosque del Apache NWR from the Sandhills. This project was not successful for two reasons. First the birds suffered very high mortality, too high for the population to sustain itself. Secondly although the Whooping Cranes were often reared successfully and did learn to migrate they never bred. As chicks they had imprinted on their Sandhill foster parents and did not recognize the other Whooping Cranes as members of their species. This project was abandoned and the Whooping Cranes in the Idaho population slowly died out.
- Eastern non-migratory population. This population was started in 1993 at Kissimmee prairie in central Florida with the idea of establishing a southern non-migratory population similar to the Louisiana one that died out 60 years ago. Birds have been added to the Kissimmee population several times over the years. Unfortunately mortality in this population is high and reproduction is low and the population remains very small.
- Eastern migratory population – This is the most recent and most ambitious reintroduction project. It is run by a consortium of government and non-profit conservation groups. One of these groups, the aforementioned Operation Migration, is responsible for the ultralight led migrations. The birds are raised in Wisconsin where they are cared for by people dressed in crane costumes. Once fledged the birds are led to wintering grounds in Florida by ultralight aircraft (flown by pilots in crane costumes). This project has suffered setbacks from high storm-related mortality and low levels of reproduction but birds are now migrating on their own and some breeding is occurring in Wisconsin.
On that cold morning 4 weeks ago we were watching 7 birds reared last summer in Wisconsin making their first migration. This group is the first to use St. Marks as a wintering ground. I’m not sure but I imagine that this additional insurance against catastrophic mortality.
So good luck to newest ‘Snowbirds’ to visit Florida. Here's a shot of six of the seven, taken blind as they flew directly overhead and close to the sun. This is by far the best shot I got when they were close - the next best has one crane, the one after that the wing of the ultralight!
Most of the information in this diary was taken from the International Crane Foundation, the Whooping Crane Conservation Association, the Operation Migration web site referenced above, and the Whooping Crane page in Wikipedia.