Biologists welcome any encounter with the animals they
study, but consider themselves particularly lucky when the same individual is
encountered multiple times. The odds of
a re-encounter can be improved by marking animals that reliably return to the
same breeding, stop-over or wintering sites year after year.
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Breeding cliffs in Arctic spring (J. Kennedy) |
A great deal has been learned about
peregrines because of their tendency to behave this way. But it takes many years, a lot of birds, huge
resighting effort and persistent people to build individual encounter histories
representative of the peregrines in our study.
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Hilde Marie Johansen with marked adult female (A. Anctil) |
For example, at Rankin Inlet this spring we captured a
female (banded A|X) that is at minimum 15 or 16 years old. First encountered in adult plumage (likely 3
or 4 at that time) in 1999, A|X has been encountered on five other occasions
during her tenure at Rankin Inlet.
We
know quite a bit about A|X. Over the
years she’s been paired with several different males at three different
sites. Despite her longevity and ability
to hold a territory, she’s a reproductive dead-end! We have not banded a single nestling at the
sites she has occupied – she failed even to lay a single egg this year and
last.
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A|X, ~15 years old, but zero young (V. l'herault) |
Like A|X, few of our breeding birds are encountered
elsewhere. We have no idea where they
winter or which migratory routes they use.
More than ¾ of the annual cycle of the vast majority of the birds we
study is veiled from us…this is not so with “Joe’s Hag”.
In 2 short years, the Hag has shown us that migratory routes
between years are not necessarily fixed (first through Texas in 2009 and then through Florida in 2010), and it’s clear birds that breed at high
latitudes (69°N) do not necessarily winter at low latitudes (6°).
This year she identified for us what may be
the outer limits for a peregrines breeding at the northern limits of mainland Canada. It seems the narrow margins experienced by
breeders far north of the Arctic Circle have
at least some slack.
Her inward migration
started normally. She departed from her wintering territory in Colombia in synchrony
with other peregrines wearing GPS PTTs. Her rate of travel matched those
documented previously in our study and others. She typically stopped for 2 or 3 days after a few
days of back to back passage, including a 2-day stopover on South Padre Island
where she had been trapped 19 months earlier.
Everything, it seemed, was going according to plan.
Then, in early June, soon after she crossed
into southern Manitoba,
the Hag’s rate of travel slowed dramatically, then stopped. And to make matters worse, her
transmitter entered “Hibernation Mode”, then stopped functioning altogether.
As usual, most birds arrived on territory in late May, but the last signal we received from the Hag was
on June 10th at a location almost 1000 miles south of her breeding
location. She was at least 2 weeks late,
her 2010 eyrie was occupied by Rough Legged Hawks, and the male with which she
had been paired was also absent. We were in the
dark – everything about her was veiled from us once again, perhaps for good!
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Spring survey in late May as peregrines arrive to breed (V. l'herault) |
The possibility of a re-encounter seemed slight, but we needed to make sure and
wanted (even more) one last shot at trapping her. Mark Prostor had put the PTT on her and he was
determined to get it off if at all possible. He and Barry Robinson set out on August 5th,
when most pairs are feeding young between 10 and 14 days old.
Here’s how Mark tells the story...
Getting to the Hag’s site is no easy task. From our field cabin, it first requires a 18
mile ride in freighter canoe followed by 10 very rough “tundra” miles on Honda
ATVs just to reach the band of cliff on which she may be perched.
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The Coxe Islands from the Freighter canoe (M. Fredlund |
We drove the cliff base surveying for any signs of raptors. Two
sites that turned out to be Rough-leg sites initially raised our hopes, but 4hrs into
the search our initial expectation that she’d not made it back seemed most likely.
As we approached the end of the long
band of cliff, I decided to deploy our trap in an attempt to bring any not yet
seen falcons to us instead…it was a long shot, and resulted in nothing.
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Rough-legged Hawk (G. Court) |
With cliff and options running out fast, it seemed like a
good time to do nothing at all but wait, watch and eat lunch. The
trap got no attention other than that from Barry and me. Then, over the sound of the wind, I heard what
could have been the kak-kak-kak of a peregrine.
“Barry, did you hear that?”
We both turned and saw a male peregrine land atop a large boulder, and
perched below him was a female. We had a pair of birds, and the female was wearing a
PTT. Joe’s Hag had made it back, and she was
defensive! Barry searched to the east. I
had not searched far west when I found the nest ledge with three “very” young
chicks…the eyes of one had not yet opened. The Hag’s brood was 10 to 14 day younger than
most of the other broods we knew of.
The day was warm, but the age of the chicks left little time
to trap the Hag. She returned to the
ledge 15 minutes after Barry and I had hidden ourselves, and it took only 5 minutes
more to trap her. She was in beautiful
condition with no abrasions whatsoever from wearing the harness for over a
year. But, on the patagium of her left
wing was a well-healed, but still apparent injury. Could this have slowed her down in the spring?
On the way out we drove past the cliff. She
was back at the ledge with her young.
The PTT felt damn good in my pocket.