The scientific name of the Whooping Crane is Grus americana but I always thought it should be Grus problematica. One would think it would be simple to switch from the aircraft-led migration method that required months of training to a parent-reared method where nature does much of the work, but that’s not the case. I will try to explain some of the complications but I warn you, it will take some time and the results will likely provide more questions than answers.
The Whooping Crane Recovery Team must balance the allocation of the available eggs between the Louisiana Non-Migratory Population (LNMP) and the Eastern Migratory Population (EMP). To do that they have proposed that the eggs produced in the captive breeding centers should go to Louisiana and the EMP should use eggs that can be collected from the nesting birds at Necedah NWR.
For the past three years, the biologist at Necedah has been experimenting with a forced re-nesting study. The early nests produced at Necedah every spring seem to coincide with peak of black fly season so he has been collecting all the eggs from half the nests and leaving the other half as his control group. Pairs that lose their eggs early in the incubation cycle will often re-nest, and that generally occurs after the short black fly season has run its course. Those later nests are generally more successful. In fact, twenty-three chicks were hatched last year at Necedah. There is a downside to this practice, as it requires intensive management. A full time team must monitor the cranes and the air temperatures to estimate when the black flies will emerge and when to collect the eggs. Long-term, intensive management is not one of the characteristics of a self-sustaining flock. Still, the Refuge is willing to continue for now as it provides eggs that will hatch into chicks that we can then release into the Wisconsin Rectangle. A few nests just outside of Necedah are also affected by the black fly issue. More eggs could be collected if they included those nests; however, they have to guesstimate when to limit collection lest they overwhelm the captive breeding centers with eggs.
Nest abandonment happens quickly when the black flies are thickest. The eggs are collected over a short time period and are transferred to ICF, and maybe eventually to Patuxent in Maryland. That means the captive centers are inundated with eggs around the same time that their captive birds are producing, resulting in a heavy workload.
That same principle of multiple clutches is also applied to the captive breeding cranes. Eggs collected from them are hatched in incubators, prompting them to produce more. Except, of course, if they have to stop the production and allow the adults to raise young chicks for the parent-reared (PR) project. That balancing act limits the breeding centers to a combined production to around fifteen parent-reared birds per breeding season.
There is also a Canadian Whooping Crane breeding center at the Calgary Zoo in Alberta. Last year, they produced three parent-reared chicks but could not get them into the U.S. in time for a release in Wisconsin. Shipping live animals across the Canada/U.S. border usually involves livestock transported in trucks or on trains. There are only a few ports of entry at airports that can deal with animals, including endangered birds. The only commercial aircraft flying out of Calgary to the nearest of those entry points does not have cargo doors large enough to handle the crates in which the cranes are transported. Instead, they were flown in a larger aircraft to Texas, which is much closer to Louisiana, so they were added to that release program.
All of this has to do with eggs collected from the wild or produced in captivity. And, just like every year, that’s a guessing game played by professionals with years of experience with captive breeding birds. But not all of the eggs hatch. The formula for calculating the number of eggs that will hatch into chicks is roughly 75 percent, and 75 percent of those that hatch will survive to be released. That calculation has been simplified and updated recently to 59 percent of fertile eggs will result in releasable chicks.
To all of this balancing, calculating, estimating and guessing, WCEP has added another variable. We also hope to produce a small group of costume-reared whooping cranes in 2017. If approved, and if there are enough eggs available, and if the captive centers can handle the workload, we may be moving six to eight costume-reared chicks to the White River Marsh pen facilities early in the season. Our first objective it to get more birds into the Wisconsin Rectangle but we also want to experiment with improvements to the PR release method.
One of the issues that concerned WCEP last year was the inability or reluctance of some of the PR birds to fly when they were first released. That is not surprising, considering that Whooping Cranes fledge at 80 to 100 days of age. For the parent-reared birds, that happens when they are in captivity where they can’t get airborne for more than a few yards. The costume-reared cranes we will raise at White River Marsh will spend the summer learning to fly at the appropriate time. This fall when both the costume-reared and parent-reared cranes are released, we will be able to compare the difference.
Philopatry, or their propensity to return to where they were introduced, is also a problem. Birds that are released late in the fall may not form an affiliation to the area as a wild crane would to its natal area. Costume-reared birds at White River Marsh will spend the entire summer there and, during that time, we expect they will have opportunities to interact with some of the adults that use the marsh. Although it will be a small sample size, by the spring of 2018 we should be able to compare the behavior of both groups.
Our job is to replicate the natural life cycle of these birds as best we can. Ideally, the cranes we reintroduce would spend as much time as possible in the wild, so the plan is to transport them to White River Marsh at the earliest shippable age, around 35 days. Our pen facilities include a dry pen that is fully enclosed and a visually open wet pen where the cranes can roost at night. If this all works out, we will enlarge that pen to include not only the water but also more uplands. We will seed the pen with natural foods like insects and crawfish so the chicks learn to forage as they would in the wild.
Ideally, chicks would spend the summer with their parents and maybe in the future we could arrange for some adult role models during that time. That would be about as close as we could come to providing a natural environment for reintroduced cranes but it wouldn’t be easy. We may be able to use captive adults that are too old to reproduce, yet still have nurturing skills – if they exist. And what do we do with them over the winter while the chicks they raised head south? And how many chicks could a pair raise? Two would be the maximum in the wild but that means we’d need lots of non-reproductive adults to act as alloparents, and many pens to get a reasonable sample size. Still, it would be an interesting learning opportunity with much to gain if it worked.
As I mentioned earlier, twenty-three chicks were hatched at Necedah last year and I am sure you all know that none of those birds survived. With intense nest management, the black fly problem has been circumvented, at least for now, but we don’t yet know what is causing the post-hatch mortality. This year, OM’s ecologist, Jeff Fox, will be working with Refuge Biologist, Brad Strobel, and Professor Misty McPhee from UW Oshkosh to find out what is happening to those chicks during that vulnerable stage before they can fly. The new study, <strong>Survival and Cause-Specific Mortality of Whooping Crane Chicks on the Necedah NWR</strong> has been approved for this year. According to Pete Fasbender, Field Supervisor for the US Fish and Wildlife Service, Twin Cities Ecological Services Field Office, <em>“There is not higher priority for our eastern U.S. reintroduction project to achieve success than determining the cause of Whooping Crane chick mortality in their first 90 days of life.”</em>
The Whooping Crane Recovery Team recently conducted a population viability analysis (PVA) that included all the Whooping Crane populations. For the EMP it was determined that only a moderate reduction of mortality from egg to fledge, from 92-96% to ~ 85% is needed to stabilize the population and eventually reach our self-sustaining goal.
We have two pairs that frequent the White River Marsh that have now reached breeding age. We hope to relocate our camera, getting it close enough to monitor at least one pair during their incubation and, with luck, be able to track them as they introduce their chick to the surrounding habitat. Remember that “the beast” was so named for a reason, it will not be easy relocating it deep in the marsh, or guessing where the birds will nest before that process begins. But, if we are successful, it will be the first time in history that nesting and nurturing Whooping Cranes will be captured on streaming video and broadcast live.
If all of this comes to fruition, it will be a busy season. We will be monitoring nesting birds in the spring and attempting to capture one pair on camera. Depending on egg availability/survival, we will be caring for costume-reared chicks at the White River Marsh pen and assisting with the releases and intensive monitoring in the fall, while trying to determine what is causing the loss of all those chicks at Necedah. Plus, we have our ongoing job of capturing the growing list of birds that must be captured to replace non-functioning transmitters.
This is just an outline of the plan and a lot of details have yet to be finalized within the various WCEP teams. Each project has pros, cons, and a hundred variables. If we can sort them out ourselves, we will keep you posted.