S ince the ancient times people have been fascinated by and kept cranes in captivity (Derrickson and Carpenter 1987). Destruction of their habitat throughout most of Africa and Southern Asia has been brought about by ever increasing human populations in these particular areas (Archibald and Mirande 1985). Humans can, however, through proper husbandry of captive populations, improve the chances of survival for many species of cranes.
By continually improving techniques in management, zoological institutions will play a major role in the survival of these majestic creatures (Archibald and Lewis 1996). Usage of a variety of enclosures in conjunction with different techniques of flight restraint has made it possible for zoos to exhibit cranes while also minimizing stress. Stress reducing exhibit options include domed outdoor walk-through free-flight aviaries, indoor free flight aviaries, and open exhibits with no over head structure.
With most closed free flight aviaries, birds of various sizes are left the ability of full flight. In open exhibits, the ability to have free flight is not an option. There are several flight restraint techniques, but only a few are used in zoological institutions. Some of these methods include pinioning, tenectomy, tenotomy, functional ankylosis, and palagiectomy. Methods such as these require some form of surgery and will permanently keep the bird from flying.
Feather clipping and vane clipping is another form of flight restraint. This technique involves cutting the primary and secondary flight feathers on one wing or removing a portion of the vanes of the primaries and secondary feathers. This does not harm the bird, but inhibits flight (Ellis and Dein 1996). After several weeks the feathers will
molt and new feathers will grow, therefore, regular monitoring is necessary. Clipped wings and vanes can also become irregular in appearance due to the growth of new blood feathers.
Another technique that is not well known is brailing. This type of flight restraint is accomplished by binding one of the bird's wings with the use of a plastic strip. It is a technique occasionally used in the shipment of large birds, to manipulate birds into pair bonding, or to prevent flight.
How does brailing work? The brail is a narrow piece of flexible plastic like clear strips of material you see holding the cold air in your grocer's freezer when the door is open. It is about 2 inches by 16 inches (depending on the size of the bird).
The strip has three holes - one at each end of the strip and the other in the center. Brailing a bird will require two people; one to hold the bird while the other will inspect the wing and situate the brail. The brail is placed
between the 3rd and 4th outer-most primary feathers. The strap is then looped over the patagium. The wing is folded thus aligning the center and top holes. A clear plastic electrical tie is then placed through the holes. The tie is fitted between the feathers and pushed through the bottom hole of the strap. When the strap is pulled tight it will resemble a figure eight. It is then secured and the tie cut.
Check the fit before releasing the bird. It can he easily checked with three fingers. If three fingers slide easily and snugly in the upper loop, the brail has been properly fitted. If not, cut the tie and re-brail the bird. Several problems can occur if the brail is fitted improperly. A loose brail can allow the primary feathers to slide out and the bird can gain flight. A brail that is fitted too tightly can constrict into the wing thus stopping circulation.
When the procedure is completed and the bird is released, it may stumble and fall. This is normal. It is just because birds use their wings for balance. Most birds compensate for the brailed wing within minutes and regain a normal stride. Usually within an hour birds will preen the brail in between the feathers and it will become almost hidden (Ellis and Dein 1996).
A brailed wing is less conspicuous to the public's eye and is less stressful to the bird, making it one of the most contemporary and aesthetically pleasing flight restraint techniques.
This kind of technique is widely used on crane species. How about using it on other large bird species? What about using it as a permanent technique? Sure - why not?
Over the last two years, the Jacksonville Zoo has implemented this technique on two large African bird species: the Marabou Stork Leptoptilos crumeniferus and the Goliath Heron Ardea goliatb.
Our rationale was that, should these pairs be chosen for a breeding program, they would be moved to a closed exhibit. With full flight capability and no modified breeding displays, successful copulation would be more likely.
Archibald, G. W., and C. M. Mirande. 1985. Population status and management efforts for endangered cranes. Pages 586-602 in Proceedings 50th North American Wildlife Natural Resources Conference.
Archibald, G. W., and James C. Lewis. 1996. Crane Biology. Pages 1-27 In David H. Ellis, George F. Gee, Claire M. Mirande (eds.), Cranes: Their Biology, Husbandry, and Conservation, Hancock House Publishers, Blaine, Washington.
Derrickson, S. R., and j. W. Carpenter. 1987. Behavioral management of captive cranes - factors influencing propagation and reintroducing. Pages 493-511 In G. W. Archibald and R. F. Pasquier (eds.), Proceedings of the 1983 International Crane workshop. International Crane Foundation, Baraboo, Wisconsin
Ellis, David H. and F.Joshua Dein. 1996. Special Techniques, Part E: Flight Restraint. Pages 241-244 In David H. Ellis, George F. Gee, Claire M. Mirande (eds.), Cranes: Their Biology, Husbandry, and Conservation, Hancock House Publishers, Blaine, Washington.