The Whooping Cranes of Aransas National Wildlife Refuge
Suddenly, across one of those glimpses of eternity, there flocked the forms of two majestic birds; and from them came a far croaking trumpet sound. By their long wings, long necks, long legs and snowy plumes, I later knew they were two white cranes, the noblest thing that flies, sailing on to their northern home, and the ring triumphant of that stirring trumpet call still echoes in my heart.
Ernest Thompson Seton, on the Whooping Crane, from “Trail of the Artist-Naturalist, 1940.
Last post, I wrote about the parrots of the Rio Grande Valley in Texas. My main reason for visiting Texas was to attend the Rio Grande Birdwatching Festival. I chose this festival in particular because I would get to see wild parrots, and because one of the post-festival trips featured one of North America’s rarest birds: the Whooping Crane.
The Whooping Crane (Grus americana) came perilously close to extinction during the first half of the twentieth century. Populations had been declining due to hunting and habitat destruction, and by 1941, there were only 23 Whooping Cranes left in the world. Today, there are about 600 of them, with about 400 of those being wild birds.
Increasing the number of Whooping Cranes in the wild was a very difficult task for conservationists. The breeding range of last population was not discovered until 1954, well after it had become apparent that the species was in mortal danger. The species also has a low growth rate, as Whooping Cranes do not breed until age four (at the youngest) and pairs typically raise only one chick to fledgling each year. It helps that Whooping Cranes can be bred in captivity, but ensuring the survival of large numbers of released birds is difficult because they must learn their migration routes. To get around this problem, some cranes have been conditioned to follow ultra-light aircraft, which can then escort the birds on the appropriate migration route.
Today, there is only one self-sustaining wild Whooping Crane population, which is the one that overwinters on the Gulf Coast of Texas and breeds in Wood Buffalo National Park in northern Canada. There are also ongoing efforts to establish a non-migratory population in Louisiana, and a migratory population that overwinters in Florida and breeds in Wisconsin. The latter population has almost 100 birds in it.
Efforts to establish a “Rocky Mountain” population that would breed in the northern Rocky Mountains and winter in New Mexico was not successful. This is because the population was started by placing Whooping Crane eggs in Sandhill Crane nests. The Sandhill Cranes raised some Whooping Crane chicks, but as adults, the Whooping Cranes did not try to mate with each other but courted Sandhill Cranes instead.
There is also a small population of non-migratory Whooping Cranes in Florida (about 20 birds) and these are the descendants of captive-bred individuals that were released into the wild. No more captive-bred birds will be released into this flock as it has suffered from a high mortality rate.
Despite the difficulties inherent with conserving them, Whooping Cranes are no longer in imminent danger of disappearing and can thus be seen as a conservation success story (albeit one that is still ongoing, as they are still endangered).
I live in Alberta, and part of Wood Buffalo National Park, where Whooping Cranes breed, is in Alberta. However, the Whooping Cranes there are (apparently) very difficult to see and tend to nest in some very inaccessible muskeg areas. So, to have a chance at seeing these rare cranes, I headed to Texas.
The Whooping Crane tour group I was with stayed in the Rockport Area, and took a boat ride into the Aransas National Wildlife Refuge to see the cranes. It was a grey and chilly day, but that didn’t matter, as I managed to see 19 Whooping Cranes, including some juveniles. This year had been a particularly good one for the population, as at least thirty-two chicks were raised to fledgling.
The above photo shows an adult pair with their offspring, which is the one with some rust-coloured feathers. The young stay with their parents during their first winter.
That adult Whooping Cranes are territorial was apparent from seeing them in the wild. Each pair or trio (pair with young) had its own feeding area located at least a few hundred meters from other cranes. Birds would sometimes get too close to each other, which would result in some vocalizations and a threat display.
Cranes would sometimes erect their ‘bustle’ feathers (as seen above) and call out to each other. These calls presumably help the cranes maintain their territory boundaries. Cranes have unusual and distinctive-sounding calls because they have very long tracheae. In most birds, the trachea goes straight from the pharynx (back of throat), down to the syrinx (which is just above the lungs), and then it branches to form two bronchi that connect to the lungs. In a crane, the trachea is not straight, but forms a long, looping coil along the sternum (breastbone). Their long, coiled tracheae allow Whooping Cranes to produce resonating calls.
Occasionally, a pair of Whooping Cranes would engage in a courtship display, where they would open their wings and leap up and down, facing each other. It was a wonderful thing to get to see, and I managed to get a picture:
Sometimes, a bird would start a courtship display while its partner just foraged or gazed into the distance.
Although I did get to see their courtship displays, the cranes spend most of their time foraging. They are omnivorous, but eat more animal than plant matter. Blue crabs are one of the most important sources of food for them at the Aransas refuge, but they will also eat other crustaceans, molluscs, plant matter such as berries, and small vertebrates.
As can be seen in the above pictures, many Whooping Cranes have leg bands so that biologists can track the activities of individual birds. However, not all cranes I saw were banded, and biologists often avoid banding them now, as being captured and handled can be stressful for a wild bird. This does not mean that biologists cannot identify individual birds, as cranes can be identified by their voices. Cranes can be difficult to differentiate by just listening to them, but by recording their calls and making a digital ‘voiceprint’ for each crane, individual birds can now be recognized and studied.
That these graceful and stately birds can still be seen living in the wild is due to the hard work of multiple generations of conservationists, both amateur and professional. I am very grateful that I had the opportunity to view them in the wild, and I hope that future generations will be able to as well.