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Whooping Crane Migration Update: April 23, 1998
Today's Update Includes:
- Latest Migration News
- Field Notes From Aransas--[Most] Flying Ahead Of Schedule!
- Challenge Question # 8
- Field Notes And Migration Data From The Great Plains
- News And Migration Data From The Nesting Grounds
- Discussion of Challenge Question # 7
- How To Respond To Today's Challenge Question
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Migration Route |
One family group of whooping cranes was still present at Aransas National Wildlife Refuge in Texas on April 20th! But Tom Stehn saw them taking "test flights" so they may already be on their long 2,500 mile migration to their nesting grounds in Canada.
Meanwhile, Wally Jobman in Nebraska reports that more migrating cranes have been sighted in North Dakota. And even further north, Brian Johns from Saskatoon, reports additional new sightings of the whoopers in Saskatchewan, near the nesting grounds in Wood Buffalo!
Field Notes From Aransas--[Most] Flying
Ahead Of Schedule!
To: Journey North
From: Tom Stehn
April 22, 1998
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USFWS |
The migration seems about one week ahead of schedule, especially for most of the non-breeding subadults to have departed. My aerial census flight on April 16 found only 6 cranes at Aransas. The two things that really surprised me were that so few birds were present, and that one family group was still here. All the adults have left except for the Rattlesnake Island family. Their chick has very little brown feathers left on it and it is very hard to tell apart from the adults.
All adult pairs have always left Aransas by April 21. They have a long way to go and need to be building nests by early May. But this year I'm not sure if this is going to be the case. On April 20, the Rattlesnake Island family group was still here. At noon, two of the three were observed spiraling high in the air with the third bird making numerous calls but staying put in the marsh. We think the two adults were flying with the chick staying behind since the calls were not like an adult whooping crane. In fact, the juvenile crane is coming into his adult voice just as he is starting to wear mostly adult feathers. After 20 minutes, the two adults returned to the marsh and landed next to their offspring. It really looked like the adults were ready to migrate but the juvenile was not. Was the chick saying "Where are you going" and "What are you doing" as his parents circled overhead?
Sometimes we observe cranes do a "test" flight before they start the migration, so perhaps the family group left later that afternoon. I'm going out in a boat in a little while to select additional areas of marsh that the Corps of Engineers is going to place cement mats on the edge of to stop erosion of the whooping crane habitat.
I'll look for that family group of cranes to see if they have started the migration. If they didn't leave the afternoon of the 20th, then I think they would still be here since winds on April 21 and 22 and conditions would have prevented them for going.
Take a look at the satellite weather maps and then see if you can answer
Challenge Question # 8:
"Why did Tom Stehn say that winds on April 21 and 22 might have prevented the Rattlesnake Island family of cranes from departing? How were those winds different from winds on April 20th?"
Remember: The white "tail" coming off of a circle indicates the direction
the wind is coming from (i.e. a tail coming straight off the very bottom of a circle
would indicate wind coming from the south)
(To respond to this Challenge Question please follow the instructions at the end
of this report.)
Until next time,
Tom Stehn
Tom Stehn
Whooping Crane Biologist
Aransas National Wildlife Refuge
Austwell, Texas
Field Notes And Migration Data From The Great Plains
To: Journey North
From: Wally Jobman
April 21, 1998
Generally favorable migration weather since April 17. Winds have been mostly from northwest, but not strong. No major storms. Most of the sightings are coming from North Dakota. Assume many birds are now in Saskatchewan
The following confirmed sightings have been received since my message of April 17:
Wally
Wally Jobman
USFWS Ecological Services
Grand Island, Nebraska
News And Migration Data From The Nesting Grounds
To: Journey North
From: Brian Johns
April 22, 1998
Dear Students
Whooping Cranes have just begun to trickle into Canada! There have been reports from the following locations below as of April 22, but I am sure that there are more birds here that I don't know about yet.
Except for the sighting near Harris all of the others are from the southeastern portion of Saskatchewan. This is the location where the cranes first enter the province on their northward migration to Wood Buffalo National Park.
Doug Bergeson, a warden from the park, reports that this past winter's snow conditions were similar to previous years and that spring has come early to the crane marshes. There is lots of open water in most areas and only the large lakes are still frozen.
I will be surveying the crane nesting area in a couple of weeks when the birds are nesting so I will send a report at that time. Stay tuned for further updates on the progress of migration!
In the meantime, here are the sightings as of today:
Date # Of Cranes City Province 04/12/98 1 WHCR near Harris Saskatchewan 04/15/98 3 WHCR near Caron Saskatchewan 04/17/98 2 WHCR near Lake Alma Saskatchewan 04/18/98 3 WHCR near Briercrest Saskatchewan 04/20/98 2 WHCR near Vibank Saskatchewan
Brian
Brian Johns
Canadian Wildlife Service
Saskatoon, Saskatchewan
Discussion Of Challenge Question # 7
Last week in Tom's report, using the chart below, we asked:
Challenge Question # 7
"How many additional whoopers left Aransas between April 2 and April 9?"
Census
Date#Cranes
Counted#Cranes
DepartedPeak 182
0
03/26/98 154
28
04/02/98 139
15
04/09/98 34
*105
04/16/98 06
28
Using this chart, it shows that 105 cranes left Aransas between 4/2 and 4/9 (139-34
= 105)
How to Respond to Today's Challenge Questions
1. Address an e-mail message to: jn-challenge-crane@learner.org
2. In the Subject Line of your message write: Challenge Question # 8
3 In the body of the message, answer the question above
The Next Whooping Crane Migration Update Will be Posted on April
30, 1998.
Copyright 1998 Journey North. All Rights Reserved.