Whooping Crane Migration Update: May 9, 2000
Today's Report Includes:
Good News From the Nesting Grounds
"The Whooping Crane migration into Canada has been stretched out this spring. The first sightings were reported at the beginning of April and continue into May. The majority of the migrating birds arrived in Canada (southern Saskatchewan) during the two weeks surrounding Easter. This is the usual arrival time for the cranes. During spring migration, about two thirds of the sightings and most of the breeding pairs arrive in Canada between April 10 and April 30. A second smaller peak of sightings occurs between May 10 and 15 when the non-breeding birds or subadults (those that are too young to breed) arrive. The breeding birds are usually in a hurry to complete the migration, set up their territories, and begin nesting. The non-breeding birds are in less of a hurry to migrate north, and these are the birds that tend to arrive later into May. These subadults usually arrive on the breeding grounds after the territorial pairs have already established their territories and have begun nesting. The non-breeding birds then usually move around to find a place that they can call their own for the summer. If the area they choose is suitable, the birds may return to nest in a later year."
What's the Route?
Brian reports this exciting news: "The first breeding pairs arrived on their territories in Wood Buffalo National Park the last week in April. Approximately 75% of the small ponds were ice-free while most of the large ones were still covered in ice. On April 30 one of the wardens from Wood Buffalo National Park flew over the nesting area and observed about 15 pairs of cranes and a few single birds. Two pairs were already nesting. It appears that the nesting season is on or slightly ahead of schedule."
The chicks aren't here yet, but it won't be long! After the head-bobbing, bowing, leaping, flapping, grass tossing, and trumpeting of courtship, a female crane aged 4 years or older will usually lay two eggs. Each is cream or olive in color, and marked with brown. The eggs are large (about 3.9 inches or 98 mm long) and valuable--as cranes have just one brood each season. The male and female will incubate the eggs for 29-31 days. Then what?
The inner membrane (the air cell) of a crane egg breaks about 10 to 39 hours before the baby cranes start pipping. As soon as the air cell breaks, the chicks start to make little sounds from inside their eggs! They make three different calls: contact, pipping, and stress. The chicks' parents purr, possibly responding to or stimulating, maybe even encouraging, the babies to pip. The babies weigh an average of 114.2 grams when they hatch. It's a safe assumption that their rusty color helps them hide more easily.
How many cranes will hatch and survive the summer breeding season? That's the news everyone is waiting for. Will the world's wild whooping crane population reach 200 in the year 2000?
An Unusual Migration
Wally Jobman in Grand Island Nebraska told us that only one sighting has been reported since his last update. On April 21, 2000, 4 birds were sighted from Ward Co., ND, 8 miles south of Kenmare. Wally said, "The past week was warm and uneventful weather-wise. I expect most of the birds are now in Canada."
Because not many whoopers came Wally's way, we asked him to comment. He said, "This was a very unusual migration. I don't recall a past spring migration with so few confirmed sightings throughout the flyway. The two birds that arrived early with sandhill cranes were the only birds confirmed in Nebraska this spring. I guess we can blame it on the weather patterns."
Wally may have received his last whooper sighting for the year. Read on for Tom Stehn's final letter and you'll see why he's happy to report no more whoopers.
Outta Here! No Whoopers at Aransas
Aransas National Wildlife Refuge
May 8, 2000
Dear Journey North,
Whooping Crane Coordinator
Now you can complete your sighting log for this year's migration of the world's 187 wild whooping cranes!
Who Is That Bird?
"April 13: 2 birds seen over Ward Co., ND, 3 mi. south of Makoti. Color-banded silver on the left and blue on the right leg." Wouldn't it be amazing to know "who" was seen in Makoti, ND? After all, each individual whooper has its own incredible life story.
Thanks to Wally Jobman, who sent us all the sighting records for one of his favorite banded cranes, you CAN "meet" a migrating whooper! Such raw data sightings are a careful collection of observations and records from which scientists can piece together the stories of cranes' lives. It takes a bit of detective work and a lot of curiosity to figure it out, and often results in more questions than answers. But that's what scientists must do each time they get a "helping" of raw datañand we're eager to give you the same challenge and adventure! What kind of story will you piece together from Crane RwR-B's raw data? Before you rush to read the banding data, see what else Wally told us about the banding program and RwR-B:
Cracking the Code
Wally explains, "The whooping crane color-banding program was conducted between 1977 and 1988. No birds have been banded since 1988. Therefore, most of the banded birds have bands that are difficult to identify because they're faded, broken, or missing. A lot of valuable information has been collected from banded birds, such as whether the same birds use the same sites each migration, the stability of the pair bonds, and the establishment of territories on the nesting and wintering areas.
Try This! Digging Into Data
Here are the original sightings data, collected during the lifetime of "RwR-B." You can analyze the data just as scientists do. See:
Response to Challenge Question #23
Last time we asked, "Why would chicks be more likely to survive in years with high water levels than in drought years?"
The answer to this question lies in the food necessary for cranes to grow and thrive. (Remember that chicks need about 80 days to get big enough to fly.) As Brian Johns told us last time, "Food items that they use are insects (the dragonfly nymphs are usually available in from late May to July); small fish (stickleback and dace); snails; tadpoles; frogs; and seeds. " Did you notice that most of these foods require a water habitat? That's why Brian said chicks do poorer in years with low water or drought conditions. Let's hope for the right amount of rain in Wood Buffalo National Park this summer!
It's a Wrap!
This is the FINAL Crane Migration Update for Spring 2000. Thank you for joining in the excitement of tracking this magnificent bird's journey north! We'll be back next year to report on the summer breeding season, the journey south, and new research. Tune in so you won't miss the answer to the Big Question on everybody's mind: Will the population of the world's only wild whooping crane flock reach 200 in 2000?
This is the FINAL Whooping Crane Migration Update.