The Courtship of a Whooping Crane………in Captivity
For those of us blessed to work with the whooping cranes at Patuxent there are a number of ways, on any given day or in any given year, we are rewarded for our dedication to their recovery.
During a recent morning walk through of the Blue Series pens, where many whooping crane pairs reside, I could hear the birds begin their familiar symphony of unison calls. When I listened to the cranes, I could hear one new, still unfamiliar unison call. The sound of this call has given the crane crew much reason to smile, because it is that from a newly formed pair.
In the late fall and winter of each year, long before eggs are laid and chicks start hatching, we focus on future generations of whooping cranes. It is during this time that we begin the process of forming new whooping crane pairs. This is a carefully planned process, sometimes lasting months or even years.
Many of our whooping cranes are closely related, so we must arrange appropriate genetic matches, rather than let the birds choose their own mates. The crane flock manager and the genetics advisor for the Whooping Crane Recovery Team direct the planning of potential pairs. First, they examine the genetics of both captive and release flocks. Ideally, they will match single male and female cranes living in a specific captive breeding facility. On occasion however, birds may need to be shipped between facilities for the most ideal new pair formation since the goal is to unite the rarest genetics. The pairing process can take a great deal of work on the part of the people involved, but in the end whether the pair is formed or not is all up to the birds.
When potential mates are chosen, we place the birds in separate pens, side by side. The birds then have the opportunity to live next door to each other for weeks or months, depending on each pair and the way they behave toward each other. Once the crane flock manager and crew are comfortable with the amount of time the birds have had to get to know each other, the dating process begins.
On a first “date”, the male is walked into the female’s pen so that she has the home field, or “home territory” advantage. In the wild, it is the female who would follow the male back to his territory. In captivity, we try to reduce any intimidation the female may feel by being in a new area, and try to provide her with the comfort of her own surroundings. Unlike in the wild, if birds have a fight or if one of the birds is intimidated by the other bird, they do not have the freedom to fly away. Therefore, the crane crew is very watchful of the of the birds’ behavior when they are first together: it is extremely important to identify potential problems as soon as they occur.
In pairs that function well, both the male and female will forage together, probe the ground close to one another, preen their own feathers while standing near each other, move throughout the pen together, dance and unison call. Although it is rare for all of these positive behaviors to happen in new pairs right away, sometimes they do. More times than not however, the process takes time.
Initial dates last an hour or two under a technician’s constant watchful eye. Only after many dates, will the crew leave the birds together for the day with frequent checks. Over time, checks become less frequent when the birds continue to look well together. After a lengthy period of daytime dates, the pair will be ready to spend their first night in the same pen together. As we joke about lighting the candles and playing romantic music, we never forget that the decision to leave birds together overnight is a serious one. The birds must look so at ease together that we can trust them to get along without our watchful eye. No matter how confident we are that the birds are compatible, we are always relieved when we find the birds still looking great during our early morning check.
One of our greatest rewards is the joy of seeing a new pair comfortable together, dancing and unison calling. A bird that lived singly seems to suddenly exhibit a new found confidence when it has a new mate. The crew is also familiar, however, with the disappointment when new pairings do not work out.
Sometimes a genetically matched pair is not behaviorally matched. Even though their genetics would be ideal together, their personalities are not. If fighting develops the cranes must be separated immediately. There are also times when birds tolerate the presence of the other bird, but just do not have that important special bond. Several pairings have been tried this year, but only two have progressed to the status of a “new pair”. As in any marriage, the first year together may prove to be the most difficult and only time will show the strength of the pair bond. The new crane pairs continue to be carefully monitored after they are moved into the whooping crane breeding colony.
The pairing of birds, whether a genetic or behavioral match, is an important process in the recovery of the whooping crane. Some pairs have provided many chicks for release and their genetics are well represented in captivity and in the wild. Although they are no longer the best genetically matched pair, they remain together because they have been successful together as good incubators or parents and the strength of their pair bond is invaluable. Their particular genetics may be suitable for new research projects in the future.
The crane crew has learned to be patient when pairing whooping cranes. The process can be a long one, sometimes it takes years to find suitable mates. Just a few years ago a 16 year old female, finally paired with her perfect match, laid eggs for the first time, an event well worth the wait.
When we listen to the sound of our new pair as they unison call, we can only hope that together they will prove to be a successful pair, and in years to come provide us with chicks that will safeguard the genetic diversity of future generations of whooping cranes. We hope that these chicks in their own time survive to become adults, find mates, and together sound their own triumphant unison call, giving us all just one more reason to smile.