• Sunday, November 11, 2001:

 
• We banded another male Northern Flicker today--today's bird showed the characteristic wing molt limits (photo below) of a third year (TY) bird (i.e., hatched in 1999):  it had freshly molted outer primary coverts (black with bright yellow shafts) contrasting with retained juvenal inner primary coverts (now >two years old and very brown and worn with pale whitish yellow shafts).  In their first fall, HY flickers molt their primary flight feathers (these molted feathers have bright yellow shafts), but not their juvenal secondaries (which have pale whitish yellow shafts), giving a molt limit between the primaries and secondaries.  The bird banded today had bright yellow shafts on both its primaries and secondaries, only its inner primary coverts were still retained from the juvenal plumage that it molted in two years ago.

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• Saturday, November 10, 2001:

 
• Banding effort was minimal again due to the windy conditions, and once again, American Goldfinches (23 banded) comprised more than half of the day's banding total (40).  Banding highlights were two hatching year (HY) male Northern (Yellow-shafted) Flickers (bringing our fall total to eight).  Male NOFLs have a black "moustache" mark that the females lack.

• Friday, November 9, 2001:

 
• If the recent drop in banding totals and capture rate wasn't evidence enough, another sign that we may have turned a corner with our banding--shifting from the capture of large numbers of passage migrants to smaller numbers of birds destined to make up our local wintering populations--was our recapture of an American Tree Sparrow (photo of that individual below) originally banded here last fall.  When we checked our records for ATSP #1741-69544's banding history, it was clear that it belonged in the category of "trap-happy" birds, having been processed no less than 17 times since its original banding a little less than a year ago!  The data from all of those handlings is presented in the table below its photo.

ATSP #1741-69544, This is Your Life...

DATE	TIME	AGE/SEX	WING LENGTH	FAT SCORE	WEIGHT
11/17/00	0930	HY/U	72.5	1	17.9
11/18/00	0955	HY/U	73.0	1	17.4
11/25/00	1015	HY/U	73.5	1	16.9
11/28/00	1030	HY/U	73.0	1	18.3
11/28/00	1500	HY/U	73.0	2	18.6
12/7/00	0930	HY/U	72.0	1	18.0
12/30/00	1220	HY/U	72.0	3	19.6
12/30/00	1445	HY/U	72.5	3	20.0
01/03/01	1205	SY/U	72.0	2	19.3
01/06/01	0955	SY/U	72.5	2	18.7
01/06/01	1200	SY/U	72.5	3	19.4
01/13/01	1355	SY/U	72.0	3	19.5
01/20/01	1040	SY/U	73.5	2	19.9
02/03/01	0925	SY/U	72.0	2	18.8
02/03/01	1310	SY/U	73.5	2	18.9
03/25/01	0840	SY/U	72.0	0	16.7
04/03/01	0850	SY/U	73.0	2	17.8
11/09/01	0945	AHY/U	74.0	1	17.2

• A great deal can be learned through recaptures of previously banded birds, including length of stay (for stopover migrants and seasonal residents), seasonal and daily variation in fat stores and body mass, and survivorship.  The record above for #69544 is unusually complete and provides a good example of what we can learn from recapturing banded birds.  We know that #69544 spent a minimum of 138 days at Powdermill during the winter of 2000-2001.  We know by catching it today that it survived its first year, something which many juveniles do not succeed at doing, and that it exhibits winter site fidlety (i.e., it returned to the same wintering area that it used last year).


Other information provided by the recaptures includes variation in #69544's wing length (72.0-73.5mm) from November 2000 through April 2001--because the same wing feathers were measured throughout this this period, this variation reflects so-called measurement error (which influences statistical analyses) and not any real change in wing length.  The 74.0mm recorded today, however, may reflect a real increase in wing length since last spring, because the bird, following its first breeding season as an adult, has now molted in its first set of non-juvenal flight feathers (all previous measurements involved retained juvenal flight feathers).  Future measurements will, of course, also have an associated measurement error, but they likely will average longer than the set of measurements describing the bird's wing length when it had juvenal primaries.  In general, a bird's wing length increases between juvenal and subsequent "adult" plumages, with little or no change thereafter (see Francis and Wood, 1989, Journal of Field Ornithology 60:495-503 [a study of wing length changes in wood warblers measured at Powdermill]).

Another pattern to notice is the seasonal increase in fat score and body mass (from original banding 11/17/01 through mid-winter), and, on days when #69544 was handled more than once (11/28, 12/30, 1/6, and 2/3), a diel, or daily pattern of weight gain from morning to afternoon.  Both the daily and seasonal patterns of mass and fat gain reflect the importance of stored energy reserves to many wintering birds--first, for fueling a bird's metabolism through the unavoidable nocturnal fast; second, to serve both as insulation and buffering against increasingly inclement winter weather.  The low fat and mass recorded on #69544's 3/25 recapture likely reflects milder weather conditions in the preceding days/weeks and/or hormonal changes (i.e., a physiological shift from wintering to pre-breeding condition) triggered by increasing photoperiod (i.e., longer days).  Finally, the increased fat score and body mass observed on its last rehandling before today (on 04/03/01) probably represents pre-migratory fattening, as it is very unusual for this species to remain at Powdermill after early to mid-April  (ATSP breeding grounds are far from Powdermill, at the edge of the tundra in northern Canada and Alaska).

Considering that it "checked in" with us so early in the season (it is only our second encounter with an ATSP so far this fall), it would appear that experience gained during its first year of life has not affected #69544's "trap-happy" ways!  Who knows, by next April we may be writing the second chapter in #69544's"This is Your Life...!"