Oriole Migration Update: April 8, 1999
Today's Report Includes:
Here They Come!
On the Texas coast, teacher Harlan Aschen says the rule is "Start looking March 15th but don't expect much until the tax has been sent in (April 15th). The fruit on the mulberry trees is just turning from green to white ... when it is ripe there will be orioles and tanagers."
Just as the weather influences fruiting mulberry trees, it influences birds. So Dr. David Aborn, who works in Central Florida at the Archbold Biological Station, is back again this spring to help us figure out just how birds take advantage of weather systems to migrate.
Weather-Wise Letter from Dr. Aborn
April 7, 1999
A strong cold front moved across the Great Plains, bringing powerful storms to Texas and Louisiana. Birds that had just crossed the Gulf of Mexico were forced to land because of the bad weather and the north winds that follwed the front. Texas was the big winner in terms of the number and variety of birds that landed. Seven different species of warblers were seen along the Texas coast, along with Wood Thrushes, Red-eyed Vireos, and an Orchard Oriole. Mississippi and Lousiana also saw lots of warblers landing, particularly Prothonotary Warblers and Hooded Warblers.
As the front moved east it became weaker. There was not as much rain and the north winds were not as strong, so not as many birds were forced to land in Alabama and Florida. In northern Florida, a Black-throated-green Warbler was seen, along with the first Summer Tanager of the season. In central Florida, the north winds did not make it down here, so I did not see many migrants.
By Monday, the winds in Texas and Louisiana were coming from the south and the skies were clear; good flying weather for migrants, so many of them have left.
What Will the Weekend Bring?
Another cold front is set to move across the Gulf coast states Thursday night and Friday. Once again, the rain in front of it and north winds behind it will make for poor flying and there should lots of birds over the weekend. It will be good for bird watchers, researchers, and Journey North students! Take care!
David A. Aborn
How do Birds Forecast the Weather?
When they're about to leave on migration, birds don't have access to the WWW. So they can never be completely certain what the weather is like where they're going. But they can judge what the weather is like right where they are. You must be wondering:
Challenge Question # 4
"How do birds sense weather conditions, and know whether good or bad migration weather might be coming?"
Discussion of Challenge Question # 2
We asked: "What is the rate of recovery for banded orioles? That is, how many orioles must be banded for one oriole band to be found again?" We also provided the information that of 92,010 orioles banded, only 959 have been recovered. Alyssa, Jamie, and Erika of North Albany Elementary School correctly calculated that on average 100 orioles need to be banded before 1 will be found again. That is, 1% is the rate of recovery.
How to Respond to Today's Challenge Question
Please respond to only one challenge question in each e-mail message.
The next Oriole Migration Update will be posted on April 22, 1999.
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