THE WHOOPING CRANE REPORT: 16
A pair of whoopers takes turns incubating eggs in their pen at Patuxent. While the female incubates the egg, the male stands nearby, keeping watch and waiting his turn. Both parents care for the eggs and rear the chick.
Photo by USFWS
We use a portable suitcase incubator when we collect crane eggs. The suitcase is small enough to be easily carried by a single person. We keep the suitcase in a horizontal position to keep the eggs from jostling. Hot water bottles in the bottom of the suitcase keep the eggs warm. The eggs are enclosed by a Styrofoam holder which cradles the eggs securely and keeps them warm. The entire suitcase is lined with shock-absorbing insulating foam. A long thermometer is inserted through the top of the incubator to make sure the eggs are not too hot or too cold.
Photo by USGS
Eggs that are
ready to go into the mechanical incubator in the propagation building are
placed in this rack, cushioned with paper towels, after they've been
weighed and candled. The position of the egg is always small end down,
large end up.
A sandhill crane patiently incubates whooper eggs on her nest at the Patuxent.
Photo by USFWS
Whooper eggs that are close to hatching may be placed in a mechanical
incubator in the last 10 ten days. These eggs may be scheduled for
costume-rearing, either for the WCEP migration study, or the Florida
Life of a Patuxent Whooper Egg
In nature, whooping cranes usually mate, establish territory, build a nest, then lay two eggs. If everything goes right, they will raise one chick. But life for the Patuxent cranes, and the people who care for them, is more complicated.
At Patuxent, whoopers usually mate, establish territory in their pen, build a nest, then lay two eggs, which is called a clutch. However, the birds don't get to keep these eggs. After they lay the second egg, we remove the clutch. Why? Because removing the clutch after it's laid causes the cranes to lay again in about 10 days. By taking the eggs away, we can increase production 3 or 4 times. So instead of only laying 2 eggs and raising at the most one chick, as they would in the wild, Patuxent's whoopers may lay 6 or 8 eggs each year. Depending on the year's production goals, Jane, the flock manager decides when to end egg production for each pair. The whoopers are usually allowed to incubate their last egg, and raise the chick themselves.
But what happens to all the other eggs? Whooper eggs do best if incubated by cranes instead of mechanical incubators, at least in the early stages. Every time we remove an egg, we take it to the propagation building, carrying it in a rigid suitcase redesigned to be a portable incubator. The eggs are handled carefully, since jostling them can kill a fragile embryo, as can temperature extremes. At the propagation building, the eggs are weighed, measured, and examined to be sure they are not cracked or have weak shells. (Eggs with cracks or thin shells will have to receive special care if we hope to hatch a chick from them.)
We give each egg an identification number based on the parent's pen location and the order in which the egg was laid. (For example, the 4th egg from the whooper pair who lives in the 12th pen in the Blue series will have as its ID number, B12 #4.) This number is written directly on the egg's shell with a lab marker. After this is done, we bring the egg back to crane pens and place it under an incubating sandhill crane for the next 10 days.
Patuxent maintains a flock of Florida and greater sandhill cranes, both for incubating whooper eggs, and for providing non-endangered birds to use in studies. The Whooping Crane Eastern Partnership (WCEP) ultra light migration, for example, used sandhill cranes first, to work out the best techniques. Pairs of sandhill cranes are rated, based on previous years' breeding experience, on their incubation and parenting skills. Only the highest rated pairs are trusted with whooper eggs. Detailed charts are kept on each pair's breeding schedule -- when they laid their own eggs, and how long they've been incubating -- so the birds will be ready when we give them a whooper egg.
The surrogate sandhills will incubate the whooper egg for 10 days. Both the male and the female will take turns caring for it. After 10 days, we'll remove it, take it back to the propagation building, and weigh and examine it again to see if it's fertile. Weighing it also tells us if the egg has lost too much weight. A fertile egg is a living thing. All fertile eggs lose weight as the chick inside grows and uses up the egg's material. However, excessive weight loss indicates the egg is dehydrating too quickly. We can often remedy problems like this, so the egg weight is critical.
If the egg is fertile and healthy, Jane, the flock manager will check the charts to decide which pair of sandhills would be best to incubate the egg for the next ten days. After those twenty days, the whooper egg will be brought in again to make sure it is developing normally. At 20 days, it is safe to place the egg in a mechanical incubator for the last 10 days of incubation.
Managing the care of whooper eggs means knowing what stage of incubation they're at, what condition they're in, and most importantly, where they are. At the height of the breeding season, there might be over 50 whooper eggs to keep track of, and over 100 sandhill eggs. Since all crane eggs look similar, proper identification of each individual egg and careful record keeping is critical. Even if we're in a hurry -- and in the breeding season, we're always in a hurry -- paper work must be done precisely and on time.
WCEP news: All 5 whoopers are doing very well at the Chassahowitzka National Wildlife Refuge in Citrus County Florida. Read regular reports and see pictures of the birds at:
Recent videos can be downloaded here:
Patuxent Crane Videos --To see these videos, you will need to install the free Real Player application. Go to the Real Player link, above, and make sure you select Download Free Real Player. The .rm extension on the files indicates a RealVideo file. The rate with which you connect with our system can affect the quality of the video transmission. Low connectivity rates caused by noisy phone lines or heavy internet traffic may make the video hard to view. If that happens, try during a less busy time and the video may transmit better. Some systems may not have the appropriate hardware or internet connection to handle videos so we provide the still-photos on the left, that were taken directly from the videos. These photos show some of the scenes from the video, so users who cannot access the video can still experience the story.
Whooping Crane Videos:
See Report 10 for more info on pre-flight
Click here to ask questions about Patuxent's whooping crane program.Whooping Crane Reports
Hatch Day (Click on numbered links to view all other egg (negative numbers) and chick days).