Update from the Whooping Cranes' Winter Headquarters
A pair may go, and sometimes a neighboring pair will actually take off right behind them and all migrate together. But I've also observed one pair leaving and 30 minutes later some other cranes from the same area depart. Usually several small groups of cranes may all leave the same day, but not be flying together. I've always felt that one pair's departure may actually influence other birds to start the migration. Kind of "peer pressure" behavior.
Today is the first day in about two weeks where the cranes have excellent migration conditions. Instead of headwinds from the north, the winds are blowing from the southeast at about 20 miles per hour. These tail winds, plus thermal currents resulting from temperatures in the 70s and partial sunshine, will make it easy for the cranes to make progress northwards, and could persuade some of the whooping cranes to leave today. Similar weather conditions are predicted all week, so I'll make a prediction that a majority of the whooping cranes will depart right on schedule the first two weeks in April.
Our researcher doing studies of the blue crab population just completed three days of sampling at the end of March. Blue crabs are the favorite food of the whooping cranes. Unfortunately, blue crabs are still NOT plentiful in the marshes. The researcher spent three days walking transects through the marsh and only counted 20 crabs. When crabs are plentiful, one can usually find about one crab per minute of walking. So the cranes have definitely not been able to build up energy reserves needed for the migration, and especially for nesting. I really expect this to be a poor nesting year up in Canada because of the marginal food resources at Aransas this past winter. But hopefully the species will be able to bounce back from these hard conditions and surprise me.
Tom Stehn, Whooping Crane Coordinator
U.S. Fish and Wildlife Service
P.O. Box 100
Austwell, TX 77950
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