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Pictorial Highlights, Fall 2008

October 2008

Yellow Palm Warbler Generally, more birds are banded in October than any other month, and this year was no different.  In total 3,139 birds were banded at Powdermill during October. In addition to those, we recorded 1,090 recaptured of previously banded birds. 

On October 2 we had an extraordinary day for Palm Warblers banding 30 individuals.  For a single day, this represented the most Palm Warblers captured at Powdermill in 40 years and the third best day ever (on September 22, 1967 forty-seven PAWAs were banded and fifty-two were banded on October 2, 1965). 

These all belonged to the western population and it wasn’t until October 17 that we captured a single individual from the eastern population (only one this fall).  This subspecies can readily be identified by the extensive yellow through the underparts and is called the Yellow Palm Warbler.  The subspecies of Palm Warbler is always an uncommon visitor to Powdermill. 
Golden-winged Warbler By the end of the first week in October the majority of warblers had moved south of Powdermill and were being replaced by waves of kinglets and sparrows.  On October 7 we captured a lingering Golden-winged Warbler. 

In fact, this hatch-year female was the only Golden-winged Warbler captured during the entire fall migration.  On this bird outstretched wing notice the contrast (molt limit) between the darker (replaced) first alula feather compared to alula 2 and 3 (retained juvenile). 

In addition, notice the lack of yellow edging on the retained primary coverts compared to the replaced carpal covert and greater coverts.
David and Annie at the wedding reception Once again, Dr. David Norman (Powdermill research associate) visited Powdermill and helped out with the bird banding operation. They arrived in early October this year so that he could attend the Annie Lindsay's wedding. 

Annie became involved with Powdermill when she was an undergraduate at Grove City College and has dedicated countless hours to bird banding at Powdermill over the last several years.  She has just completed her M.S. in Environment and Natural Resources at The Ohio State University where she studied Yellow Warblers in the marshes of Lake Erie.
Dr. Claudia Mettke-Hofmann Organized by Robert Mulvihill, Powdermill held a Rusty Blackbird Conference between October 8-11.  Many of the participants spent their early mornings at the banding lab in hopes of capturing Rusty Blackbirds. 

Although we did not have any luck with the blackbirds during this period, everyone enjoyed checking out the bird banding lab. 

The three next pictures are of some of the conference participants.

Pictured to your left is Dr. Claudia Mettke-Hofmann who studies cognitive ecology at the National Zoological Park in Washington D.C. and at the School of Biological and Earth Sciences at Liverpool John Moores University in England.  Here she is shown holding a Common Snipe.  In fact, this was the only Snipe captured at Powdermill in all of 2008.  
Julie Hart an ornithologist Julie Hart, an ornithologist for the Vermont Center for Ecostudies, is pictured holding a Blue-headed Vireo
Rusty Blackbird conference Several participants involved in the Rusty Blackbird conference are looking for the presence of a molt limit in the wing of this songbird.
open wing of a yellow-rumped warblers  Molt limits are very useful in ageing many species of birds. Molt limits have been a major topic of discussion on this webpage, and you will probably recall that, in the fall, a molt limit generally indicate a hatching-year bird, and the absense of a molt limit signifies an adult bird (with few exceptions).

The typical pattern for many hatching-year warblers, vireos, and sparrows is to have a molt limit within the alula feathers and between the carpal covert and the primary coverts. In this photograph of the open wing of a yellow-rumped warblers a clear molt limit is present. Notice the very dark and freshly replaced carpal covert next to the much duller alula feathers and primary coverts (this bird did not molt the first alula feather as many individuals do).

In addition, the outer most greater covert was not replaced and notice how much darker all of the other greater coverts (replaced in first prebasic molt) is compared to the outermost one. In contrast to a hatching-year bird an after-hatching-year individual will undergo a complete pre-basic molt. 
Hermit Thrush wing On this Hermit Thrush wing there is a molt limit among the greater coverts with the innermost GCs replaced in the first prebasic molt and the rest of the GCs are retained from the juvenile plummage.

Notice the chocolate brown edging on the replaced inner coverts and the noticeable buffy tipping on the retained outer coverts. Also, note how the replaced coverts are a little longer than the retained coverts. 
Pine Siskin The wing of this Pine Siskin also shows a molt limit among the greater coverts. The outermost GCs have been retained from the juvenile plummage and the rest of the GCs are more glossy black in color and have been replaced in the first prebasic molt.

From this molt limit we can identify this bird as a hatch-year individual. 
Siskins foraging in the exposed flats of Crisp Pond Shortly after hearing reports of high numbers of Pine Siskins moving south we began capturing siskins at Powedermill. In October we banded 77 Pine Siskins as they moved through our region. Just before these birds arrived Crisp Pond was drained in order to install a fire hydrant on the property.

This left great shorebird habitat very close to our nets. Although no late migrating shorebirds were ever seen using this habitat, flocks of siskins began foraging on the exposed flats. On one lucky day we found 22 siskins in a single net.

A month after the siskins moved through we are getting news that White-winged Crossbills are moving south in large numbers and have been spotted on Powdermill property. 

To the left are Siskins foraging in the exposed flats of Crisp Pond. 
Pine Siskins

Pine Siskins
Pine Siskins
Cold Morning Cold Morning 
Frost Leaf Frost Leaf
Marja Bakermans Marja Bakermans checking empty nets on a cold morning. 
Gerardo with snow After a very slow week of banding we got one last push of migrating birds on October 28. In fact, this was the busiest day of the season as we banded 322 individuals in snowstorm conditions.

Yellow-rumped Warblers were everywhere on this day as they foraged on the abundant poison ivy berries found within the netting area. By the end of the day we had banded over 150 Yellow-rumped Warblers!

Gerardo returning to the banding lab with bags full of Yellow-rumped Warblers.

Yellow-rumped Warbler
One of the Yellow-rumped Warblers captured on that day showed a very unique tail condition presumably caused by fault bars. The presence of fault bars on retrix feathers has been previously discussed on this page, but a refresher on this topic can’t hurt. A fault bar occurs when actively growing feathers cease to grow for a period of time due to nutritional stress.

This results in a dark line across the feather. Fault bars are often found on hatching year birds. Young birds begin to grow their retrix feathers as nestlings, and growth continues after fledgling when they are dependant on their parents for food. Typically, at this time, adults are not only feeding themselves but also several fledglings. This is very energetically taxing and can result in undernourished young resulting in fault bars.

The first picture shows a hatching-year Ovenbird with a typical fault bar across the tail. The bottom photograph is of the Yellow-rumped Warbler with a tail that appears to be “sawed” off. The condition of the tail is likely the result of a very strong fault bar on the tail that weakened the feathers to the point that it literally snapped off at the fault bar.

Nutritional stress during the fledgling period will continue to have an effect on this individual at least until it molts its retrix feathers the next summer. 

Holding Owl
As a member of Project Owlnet we capture migrating Northern Saw-whet Owls during late fall. These owls primarily migrate through western Pennsylvania from the middle of October through November.

On several nights we used playback to try and lure these birds into mist-nets. In total, this fall we captured 31 Northern Saw-whet Owls. These numbers are lower than the previous Fall when record numbers of these owls were captured across the eastern United States (106 at Powdermill).

Interestingly, the great majority of owls captured this year were those in their second year as it appears that this species was a prolific breeder during the summer of 2007 but not 2008.

These owls primarily feed on deer mice (Peromyscus), and breeding productivity is probably linked to prey abundance. 
Owl Print In late October we were surprised to see a strange looking dust print on the window of the banding lab. Upon closer examination it was evident that this impression was left by an Eastern Screech Owl that had hit the window during the night.

Although this proved difficult to photograph, you can see the impression of the face (look for the eyes and the beak) in the right side of the photo about half way down from the top. One wing extends straight up from the head and the other towards the bottom left of the photograph.

Fortunately for the owl, it appears it was banking to one side when the collision occurred, and it most likely flew away without any major injuries. Despite wind, rain, and snow this print remains on the window nearly 2 months after the collision. 

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