With the addition of today's new satellite readings, we're beginning to get a picture of the peregrine falcon's winter home range. Scientist Skip Ambrose suspected his Alaskan peregrines would go to the tropics because banding returns suggested this. But he wasn't sure, and before satellite tracking he had no way to learn about their behavior on the wintering grounds.
If you were a scientist studying the data from these falcons, what could you now say about their behavior during the winter? As you compare the falcons' locations from one month to the next, see if you can answer these questions:
* Do the falcons seem to stay in one place or travel around?
* Which falcon moved the most? Which one moved the least?
* What is the home range of each bird?
* What do you know about the habitat each falcon is using?
Are there oceans, rivers or wetlands nearby?
* What's the climate of the region? The average rainfall?
Today's temperature? Where could you find this information?
* Why are all these questions important?
Staying Alive
As Skip explained in last week's report, there are can be several reasons for a "No Data" reading. A cliff or ravine may interfere with satellite reception, for example. Even so, one can't help but be concerned about these falcons. What are their chances for survival?
"Survival of migratory birds is particularly low in their first year of life. For these peregrine falcons, we estimate 65% die in their first year! But tracking them is especially important because we have no idea where young falcons go after they leave the nest. They are seldom seen on the breeding grounds, but that does not mean they are not here. They may just sort of wander during that first year, looking for potential available breeding sites. They generally breed first at two years of age. We know we start seeing them again in about two years on the breeding grounds. But between the time they fledge and come back to breed two years later, we know nothing.
So what we learn about juveniles will be very interesting. We have tried to program the transmitters to last almost two years so we can track them during this peirod. Each time the date rolls around for the transmitter to send another signal we hold our breath--hoping to hear from all these birds--but especially the young ones. We have so much to learn from them."
In today's data chart below, the age of each bird is provided. "Hatchling year" (HY) birds hatched last summer, and were only 2 months old at the time they were captured. When they began their fall migration last August, they had learned to fly only weeks before. (Juvenile falcons can be told from adults by their plummage as you can see in any field guide.) "After Second Year" (ASY) birds are breeding adults and were captured while nesting.
Falcon # 651
Age=ASY
Date Latitude/Longitude
11/23/95 5.963 N, 56.632 W
12/13/95 No Data
01/22/95 No Data
02/11/95 No Data
# 652
Age=ASY
11/20/95 5.807 N, 68.921 W
12/10/95 7.909 N, 70.631 W
01/19/96 No Data
02/08/96 No Data
# 655
Age=HY
11/18/95 17.758 N, 92.145 W
12/08/95 17.816.N, 92.312 W
01/16/96 17.873 N, 92.616 W
02/05/96 No Data
# 658
Age=HY
11/17/95 20.684 N, 87.077 W
12/07/95 17.877 N, 89.331 W
01/05/96 No Data
02/02/96 No Data
# 867
Age=ASY
11/21/95 17.497 N, 91.241 W
12/11/95 17.488 N, 91.194 W
01/20/96 17.418 N, 91.126 W
02/09/96 17.485 N, 91.217 W
# 868
Age=ASY
11/19/95 18.428 N, 95.920 W
12/09/96 18.481 N, 95.949 W
01/18/96 18.471 N, 95.947 W
02/07/96 18.683 N, 95.503 W
# 871
Age=HY
11/21/95 61.411 N, 130.576 W
12/11/95 60.752 N, 133.576 W
01/20/96 No Data
02/08/96 No Data
# 895
Age=ASY
11/20/95 22.102 N, 105.216 W
12/09/95 22.145 N, 105.209 W
01/19/96 No Data
02/08/96 No Data
# 897
Age=ASY
11/21/95 22.058 N, 105.262 W
12/10/95 No Data
01/20/96 No Data
02/09/96 No Data
For Classroom Discussion
The Next Peregrine Falcon Update Will Be Posted on February 26, 1996
 |
|
|---|
