The bird banding
lab was renovated in 2009 which included new displays, a pulley system to
hold bird bags, a computer to allow for direct entry of the banding data,
and, later in the year, we will be installing video equipment to upload
banding demonstrations to the internet. Pictured below are banded birds
hanging from caribiners attached to the pulley setup.
In August we captured
2 Great-crested Flycatchers, a species seldom captured at Powdermill despite
being a breeding bird on the reserve. The GCFL is a member of the group
of Myarchus flycatchers that all look very similar and reach their greatest
diversity in Latin America. However, they represent the only species of
this genus in eastern North America. The bird pictured below was identified
as a HY bird by the molt limit among its median and greater coverts.
On September
26th, a flock of about 25 birds (mainly warblers, and a few vireos) were caught
in a single net.
One of the most
exciting birds banded at Powdermill this fall was a Prairie Warbler (left)
with a vibrant orange face and breast. Prairie Warblers usually show an
entirely yellow and black face pattern (right). This plumage variation occurs
infrequently among bird species and is due to consuming large amounts of
berries from Morrow's and Tartarian honeysuckle during feather growth. This
is more commonly seen in juvenile Cedar Waxwings, but also has been found
in Yellow-breasted Chats, and Kentucky Warblers.
In the fall, a
few species of warblers can be easily confused. One of the best known cases
of this is differentiating between the Blackpoll and Bay-breasted Warblers.
As shown in the photographs below, the face patterns of these two species
can be incredibly similar. In fall plumage, the Blackpoll (left) and Bay-breasted
(right) Warblers can look very similar. However, once in the hand,
they are relatively easy to distinguish the two species. Bay-breasted Warblers
often have some bay color on their flanks, are slightly larger, and gray
feet (rather than yellow for Blackpoll).
Below
shows the plumage variation between sexes of Black-throated
Blue Warblers and Hooded Warblers. The female Black-throated
blue Warbler's (bottom left) plumage is more drab overall
and helps the bird better camouflage itself throughout the
nesting period. The male's (top left) plumage is much more
striking which aids mate attraction. However, in a number
of species, older females become more colorful and begin to
resemble males. This occurs with Hooded Warblers where old
females occasionally display a full black hood. The Hooded
Warblers shown below are of an AHY male (top right) and an
AHY female (bottom right). The HY female Hooded Warbler typically
has no (or very little) black on the crown or throat.
The
Cape May Warbler is another species that shows a lot of plumage variation
during fall migration. Pictured below is a drab HY female (left) and
a more colorful HY male (right). Although birders sometimes find this
species hard to identify during fall migration, all plumages include
streaking on the breast, and its latin name (Dendroica tigrina)
is derived from this characteristic.
Plumage
variation between age classes in male Rose-breasted
Grosbeaks can be seen below. The photo in
the middle shows a HY male (left) and an AHY
male (right). Notice the difference in coloration
(especially as it pertains to the amount of
black in the wing) and the size of the white
patch on the wing of the two age classes.
The photo on the left is of a HY male (notice
the molt limit among its greater coverts)
and the photo on the right is a closer look
at the AHY bird.
The
Golden-winged Warbler is an exciting bird to
capture at Powdermill. The brightly colored
male (pictured left) and the grayish female
(right) are beautiful to see up close, but are
also of conservation concern because of, among
other factors, the expansion of the Blue-winged
Warbler (bottom) into its breeding range (and
subsequent hybridization).
A
Philadelphia Vireo (left) and a Warbling Vireo (right) are shown together
below. These two species have extremely similar plumages and are best
identified using a number of criteria, including plumage aspect (extent
of yellow-wash on the underside which is often, but not always, more
extensive in the Philadelphia Vireo), bill size (generally larger in
the Warbling Vireo), and, perhaps most definitively, the length of the
vestigial tenth primary (bottom center), which is markedly longer in
the Warbling Vireo (longer than primary coverts) than in the Philadelphia
Vireo (shorter than primary coverts). Much of the literature also describes
a darker loral area in the Philadelphia Vireo versus the Warbling Vireo,
but as can be seen in the photos below, overlap exists and this criterion
should therefore be used with caution.
Each
fall we capture a handful of the 'skulking' Oporornis
warblers - birds that generally forage on or close
to the ground, making them a difficult target for
birders. A Connecticut Warbler (L) and a Mourning
Warbler are shown below. Both photos are of adult
males.
A
unique feature (among many!) of birds
is the ability to move the upper bill
relative to the skull, which is called
cranial kinesis. In species such as
the American Woodcock, this allows the
bird to easily grasp subterranean prey
items while the bill is plunged into
the ground.
This
fall an advanced banding workshop was offered at Powdermill for banders
to gain a better understanding the use of molt limits to determine age
in birds. For most species, the age of a bird can be identified by determining
whether a molt limit exists between retained juvenile feathers and those
replaced during the first pre-basic molt.
The
Eastern Phoebe wing pictured below shows a molt limit in the greater coverts
(two outer retained feathers) as well as a replaced CC (carpal covert)and
A1 adjacent to the retained A2 and A3 feathers. Note the difference in shaft
and overall color between the two generation of feathers - the older, retained
juvenal feathers are of poorer quality and are thus browner and less lustrous
than the formative, replaced feathers. This pattern indicates that this
is a hatch-year bird.
These
Black-throated Green Warblers
also illustrate the different
molt strategies found in after-hatch-year
versus hatch-year birds. An
A1 molt limit (somewhat difficult
to see in the photo) is seen
in the hatch year bird (top)
- this incomplete molt strategy
(replaced A1 but retained
A2, A3, and primary coverts)
allows banders to age many
species throughout the year.
An absence of any molt limit
can be seen in the adult wing
(below), reflecting the complete
feather replacement strategy
found in most adults.
Fall
2009 banding staff: Andrew Vitz, Mary Shidel, Jeff Moker, Tara
McAllister, Alice Van Zoeren, Bob Leberman
Visiting
banders and volunteers: David Hodkinson, Ian Ausprey, Marja
Bakermans (and Boden Vitz), Bob Vitz, Marcia Arland, Janet
Van Zoeren. Not pictured: Ellen McCallie, Cokie Lindsay,
Jeff Territo, Molly McDermott, Annie Lindsay, Julie Zeyzus,
and Mack Frantz.
