2002 - Midwest Peregrine Falcon Restoration Project

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the nesting population. In fact, it now appears that most of the unbanded adults have
actually come from known nests in which the young were not banded for a variety of
reasons and that there is no substantial undiscovered population. This is an important
insight for any analysis of the population dynamics of Midwestern peregrines and for
their future management. Here is the evidence for this conclusion.
From 1987 through 2002, 2029 young have fledged from known nests; 1720 of
these have been banded. The 309 young known to have fledged unbanded are 15.2% of
the total fledged (Table 1).
TABLE 1
Banding Status of Peregrine Young Fledged Wild from Known Nests in the Midwest
Year
No. of
Pairs
Fledging
Young
Total Young
Fledged
Young
Fledged
Banded
Young
Fledged
Unbanded
% Young
Fledged
Unbanded
1987-1993 102 265 203 62 23.4%
1994-1996 132 361 319 42 11.6%
1997-1999 208 586 512 74 12.6%
2000-2001 185 533 445 88 16.5%
Subtotal
through
2001
627 1745 1479 266 15.2%
2002 106 288 242 46 15.9%
Grand Total 733 2033 1721 312 15.3%
In 2002, 144 pairs were known to be on territories, 288 adults. Of the 199 adults
whose banding status was determined (banded vs. unbanded), 32 (16.1%) were
unbanded. This translates to an estimated 46 unbanded adults in the total of 288. The
source population for the 2002 territorial population is made up of birds fledged in year
2001 or earlier (Table 1, subtotal). A comparison of the frequencies of unbanded birds in
the source population (15.2%) and in the 2002 territorial population (16.1%) shows that
enough unbanded young have fledged from known nests to account for many, if not most,
of the unbanded nesting adults, without having to postulate a substantial “undiscovered
population.”
The banding status of the 2002 population can be summarized as follows:
288 territorial adults (144 pairs)
199 banding status known
167 banded (83.9%)
144 individually identified
7 immigrants (4.9%)
137 local (Midwestern in origin)