Pictorial_Highlights_08260901

POWDERMILL NATURE RESERVE
PICTORIAL HIGHLIGHTS
August 26-September 1, 2002

August 19-25:

With 81 banded, Ruby-throated Hummingbird was far and away the most numerous species this week (just 62 were banded in the preceding three weeks of the season). During the fall at Powdermill, we catch comparatively very few adult male RTHUs (one is pictured below next to a photo of one of its favorite early autumn nectar sources at Powdermill, Lobelia cardinalis, or cardinal flower [cardinal flower photo by Darlene Madarish]). In fact, although we catch immature males and females in approximately equal numbers at this season, adult females can outnumber adult males by up to 4:1. For example, during the current week alone, our totals were 3 AHY-M, 7 AHY-F, 37 HY-M, and 34 HY-F.

About ten years ago we published a study in The Condor entitled, "A possible relationship between reversed sexual size dimorphism and reduced male survivorship in the Ruby-throated Hummingbird." Briefly, we concluded based on consistent patterns of seasonal variation in sex ratio, sex differences in body mass and body mass dynamics, and sex differences in return rates of proven site-faithful adults, that male RTHU experience much higher rates of mortality than females between the time they return to their breeding grounds and the end of the nesting season. We hypothesized that male RTHUs are more energetically stressed than females during the summer due to their smaller body mass and higher energy demand (stemming, in part, from their aggressively promiscuous mating strategy) at this season.

Just recently, the Cooper Ornithological Society has made all articles published in its journal, The Condor, available on-line. Anyone interested in reading our hummingbird study can now easily view it in .pdf format at www.cooper.org (follow links for 102 year archive >> years 1990-2000 >> 1992 (Vol. 94) >> Vol. 94 No. 2, and then scroll down to our article, the third major article from the bottom).

Among seven new species for the fall this week was a Northern Mockingbird, a very uncommon bird here in the mountains of southwestern Pennsylvania, where, presumably, winter conditions are ordinarily too severe for this semi-hardy southern species. This is only the tenth NOMO ever banded at Powdermill (and the first since 1996). For whatever reason, its population in this area does not build up, even over the course of successive mild winters, like that of another southern species, the Carolina Wren. The NOMO banded here on 9/1 was a hatching year (HY) bird still in full juvenal plumage. We know of no nesting NOMOs closer than about 12 km away from Powdermill--apparently, this species retains its juvenal plumage for a comparatively long period of time and/or disperses well away from its natal area comparatively soon after fledging.

Two weeks ago we noted that we were still catching very recently fledged (i.e., local) young of another mimic thrush, the Gray Catbird. The comparatively long (and likely double-brooded) nesting season for this species at Powdermill is illustrated by two HY GRCAs banded in the same net round on 8/29--one (top bird) was a stub-tailed juvenile, and the other (bottom) had already completed its first prebasic molt.

Seventeen species of wood warblers accounted for 164 (42%) of the 390 birds banded this week. Most numerous was Hooded Warbler (30 banded), followed by Magnolia Warbler (28), Common Yellowthroat (25), Ovenbird (15), and Canada Warbler and American Redstart (10 each). The first heavy movement of migrant (i.e., northern nesting) warblers was noted on 8/31, when we banded, for example, 13 Magnolia Warblers.

Some miscellaneous wood warbler photo highlights from this week (top to bottom) include: an HY male Cerulean Warbler (our third CERW this fall); an AHY male Black-and-white Warbler; an AHY male Wilson's Warbler; an HY Blue-winged Warbler (best fit) with very broad yellowish wing bars that suggested some Golden-winged Warbler in its ancestry but, in our opinion, the bird was too uniformly bright yellow beneath to classify as a "Brewster's" type hybrid; an HY Worm-eating Warbler (a new species for fall 2002 that we missed banding in fall 2001); lastly, an HY Ovenbird.

FALL 2002 BANDING TOTALS, AUGUST SUMMARY

SPECIES	Week 1 8/1-8/11	Week 2 8/12-8/18	Week 3 8/19-8/25	Week 4 8/26-9/1	8/1-9/1 TOTAL
Sharp-shinned Hawk	0	1	1	0	2
Solitary Sandpiper	0	1	1	0	2
Eastern Screech-Owl	0	1	1	0	2
Chimney Swift	0	3	0	0	3
Ruby-throated Hummingbird	16	25	21	81	143
Belted Kingfisher	0	0	1	1	2
Downy Woodpecker	3	2	0	1	6
Hairy Woodpecker	1	0	0	1	2
Northern Flicker	0	0	0	1	1
Eastern Wood-Pewee	0	0	0	5	5
Yellow-bellied Flycatcher	1	1	10	15	27
Acadian Flycatcher	1	4	0	2	7
Traill's (Willow and Alder) Flycatcher	10	3	8	12	33
Least Flycatcher	6	1	6	9	22
Eastern Phoebe	10	9	2	5	26
White-eyed Vireo	0	0	0	1	1
Yellow-throated Vireo	1	0	0	1	2
Blue-headed Vireo	0	1	0	0	1
Red-eyed Vireo	7	27	11	16	61
Blue Jay	1	1	2	2	6
Black-capped Chickadee	0	0	0	4	4
Tufted Titmouse	5	1	3	4	13
Carolina Wren	7	5	3	3	18
House Wren	1	0	5	1	7
Blue-gray Gnatcatcher	1	2	3	1	7
Veery	1	0	0	4	5
Swainson's Thrush	1	1	0	0	2
Wood Thrush	5	1	2	5	13
American Robin	1	0	0	0	1
Gray Catbird	33	15	9	19	76
Northern Mockingbird	0	0	0	1	1
Cedar Waxwing	12	18	8	3	41
Blue-winged Warbler	2	4	1	2	9
Golden-winged Warbler	0	1	1	0	2
Northern Parula	0	2	2	0	4
Yellow Warbler	3	0	0	0	3
Chestnut-sided Warbler	7	3	4	12	26
Magnolia Warbler	4	1	3	28	36
Black-throated Blue Warbler	0	1	0	5	6
Black-throated Green Warbler	0	0	0	5	5
Blackburnian Warbler	0	1	1	0	2
Cerulean Warbler	2	0	0	1	3
Black-and-white Warbler	2	1	2	3	8
American Redstart	17	16	9	10	52
Worm-eating Warbler	0	0	0	1	1
Ovenbird	6	3	1	15	25
Northern Waterthrush	3	1	6	5	15
Louisiana Waterthrush	1	1	0	0	2
Kentucky Warbler	3	6	1	3	13
Mourning Warbler	0	0	2	2	4
Common Yellowthroat	8	4	5	25	42
Hooded Warbler	10	14	10	30	64
Wilson's Warbler	0	0	2	7	9
Canada Warbler	7	1	2	10	20
Yellow-breasted Chat	0	1	0	0	1
Scarlet Tanager	0	2	1	0	3
Eastern Towhee	2	1	0	3	6
Chipping Sparrow	0	2	1	2	5
Field Sparrow	1	0	0	0	1
Song Sparrow	17	8	6	5	36
Swamp Sparrow	5	3	0	0	8
Northern Cardinal	4	3	0	4	11
Rose-breasted Grosbeak	1	3	4	3	11
Indigo Bunting	5	7	2	4	18
Orchard Oriole	0	1	0	0	1
Purple Finch	2	0	2	3	7
House Finch	0	2	2	0	4
American Goldfinch	3	3	3	4	13
Weekly Banding Total	239	219	170	390	1018
Number of Species	44	49	42	50	68
Number Net-Trap Hours	1250	995	955	1815	5015
No. Birds/100 Net-Trap Hours	19.1	22.0	17.8	21.5	20.3
No. Recaptures	37	31	23	47	138

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