Whooping Crane Migration Update: April 17, 1997

They're on their way! Tom Stehn bid farewell to one hundred whooping cranes last week, as they soared a mile high on thermals and headed north. Here is his report, along with crane sightings recently reported from along the migratory pathway:

• Link to Today's Migration Data

To:	Journey North
From:	Tom Stehn, Aransas NWR
Date:	April 16, 1997

Claudia Fonkert, Macalester College

"The whooping crane migration started late this spring, but then caught up in a hurry. Every year, the bulk of the cranes leaves between the 7th and 12th of April. This year, I estimated that about 100 cranes started migration April 9th and 10th. This is a very large number of cranes all to have left within such a short time frame.

"Although migration conditions were only fair both days, the cranes had decided it was time to go. On both days, clear skies or high overcast provided thermal currents to allow the cranes to soar up to a mile high and then glide to the north. Winds were mostly from the east so the cranes used them to fly an angled course to the northwest just as a sailboat can travel perpendicular to the wind with great efficiency.

"The cranes usually travel in pairs and family groups. Sometimes two pairs will travel together. It is most unusual to have more than about 7 cranes migrating together.

"Unfortunately, the cranes did not have clear sailing for long. They flew into a low pressure system in central and north Texas that pinned them down. However, this kept them south of the severe blizzard conditions that hammered Kansas and Nebraska on April 11.

"On April 10th, an aerial survey of the Aransas NWR and surrounding areas was conducted. Tides were very high with the marshes flooded. Cranes are still believed to be feeding primarily on blue crab. Located were 49 adult and 6 young whooping cranes (17 adults, 32 subadults, 6 juveniles).

"To recap, the peak population this winter was 159 cranes (142 adults + 17 young), and the total population estimated still here on April 10th was 55. Thus, this means the following cranes were no longer here, and had apparently started the migration. By age group:

• 41 out of the 50 territorial pairs/families,
• 16 out of 48 subadults, and
• 9 out of 15 juveniles had started the migration

"The 'North Sundown Bay' juvenile was seen all by itself, its parents (r-nil male) having left it behind. We believe one family group (Lobstick) departed April 6.

"Since my flight on April 10, we have had only two days (April 11 and April 16) with favorable migration conditions. Low pressure has dominated with cloudy skies and north winds. I expect that I'll still see around 40 cranes when I next try to find them all."

Tom Stehn
Refuge Biologist

To:	Journey North
From:	Wally Jobman, USFWS
Date:	April 16, 1997

CNN

"The following confirmed sightings have been reported to the Grand Island Field Office during the past week:

• Link to Today's Migration Data

"In addition, the adult with sandhill cranes, located 3 mi. west of Doniphan, Hall County, Nebraska, is still present. I may have reported that this bird had left, but it is still here. This bird has been in this same area since March 10."

Wally Jobman
USFWS Ecological Services
Grand Island, Nebraska

The Next Whooping Crane Migration Update Will be Posted on April 24, 1997