December 2012 - March 2013
Visitors to the banding lab frequently ask us how we deal with inclement weather over the winter. This year in particular, there was no shortage of snowy banding days. If the snow is light and the temperature is not too low, we can still use mist nets throughout the winter, although we do increase the frequency of our net checks as the temperature drops, sometimes checking as often as every 20 minutes. We also open fewer nets over in the winter, typically about seven nets, far less than 60-65 we run during migration.
If we cannot use mist nets, we use Potter Traps baited with seed like the one seen here. Potter traps, designed in the 1920's by a woman named Jessica A. Potter, have four individual cells to catch birds. In the photograph, you can see the doors are suspended by a lever attached to a raised lever on the floor. When a bird steps on the "floor," the wire sitting under the bottom of the door pulls out and the door falls down.
We usually have 2 traps on tables in three locations close to the lab. Additionally, we have one Potter Trap set on the ground which is a favorite or Fox Sparrows, Juncos and other ground foragers. Since most birds wintering here are seed eaters, Potter Traps area a reasonably effective way of monitoring wintering populations.
Some cold snowy days we might even find an animal of another taxonomic class in search of seeds. While it's a nice surprise for us, this Red Squirrel seemed quite keen to be on its merry way.
Between Thanksgiving and the end of March we banded for a total of 34 days; 15 of which we were able to open our nets and 15 days we used traps. On the other four days, we used a combination of nets and traps as the weather changed throughout the morning.
If you follow our daily or cumulative totals on our website , keep in mind that these numbers represent only the new, unbanded birds that we encounter. In the winter, recaptures (birds that are caught and have already been banded) are a high percentage of all the birds we catch. From December through March, we added 693 records to our database; only 189 (27%) of these were records for new, unbanded birds.
We processed 329 unique individuals of 25 species. Of those 329 birds, 189 were the new, unbanded birds and 140 (43%) were birds that had already been banded at this station. The remainder of the 693 records (364, more than half of our total), represent data gathered as we recaught some of these 329 individuals over the span of the four months.
Occasionally, we see a bird so often that we actually start to recognize its band number, such as Black-capped Chickadee #2590-50580. This chickadee, banded as a young bird in June of 2011, was recaught 12 times this winter and has been in our lab a total of fifty times in the fifteen months since that original banding.
The second runner-up for our most frequent winter visitor was Tufted Titmouse #2551-76661—recaught 11 times this winter, for a total of 32 times since its banding this past August as a Hatch-year bird.
Throughout the winter, the most-frequently banded bird was the Dark-eyed Junco (54). The second most-banded bird was the Song Sparrow (34, all of which were caught during the month of March), and the third runner-up was the Fox Sparrow (17).
Note the unusual white wing-bars on this junco-- according to the Sibley Guide to Birds, only about 1 in 200 Slate-colored variants have white wing-bars.
Black-capped Chickadees were present in our winter banding totals in small numbers (having processed only nine unbanded of these birds). But they were, hands-down, the most “frequent flyers” at our station with 139 recaptures this winter. The sum total of 148 records (new and recaptures) were gathered from 76 individual Black-capped Chickadees.
The Red-breasted Nuthatch pictured here is one of two that visited our station this winter− both were banded here in October. One was recaptured four times over the winter and the other was caught twice.
The first new bird banded in 2013 was, ironically, this Mourning Dove caught on January 9, the first banding day of the year (ironic because we don’t catch all that many of them even though they are year-round residents).
Up close one can see just how pretty these birds are with an iridescent patch on the lower side of the neck and a blue eye ring made of skin rather than feathers.
Common at feeders, these birds can be quite long-lived. The oldest known individual was a male first caught June 1968 in Georgia and shot October of 1998 in Florida. That means he lived to be at least 31 years, 4 months old!
Another common bird that turned out to be an extra-special capture for us was this Blue Jay caught on March 27th. As we were admiring the striking color and patterns of this species, Luke DeGroote, our bander-in-charge, decided to take a picture, something we sometimes don’t always think to do with more common species.
It wasn’t until later that day that we realized this bird was originally banded as an After-Hatch-Year (adult) on December 27 of 2000, making this bird more than 14 1/2 years old! The current longevity record for Blue Jays is 17 1/2 years, so hopefully we'll keep catching him/her for a few more years.
There was no doubt, however that we would want a photo when we found this Common Redpoll in our net on March 15th. We haven't banded one here since March 20th 1996 − 17 years ago!
These hearty finches breed in the northern arctic tundra and boreal forests around the arctic ocean. They often overwinter further north and can survive temperatures down to -65 F. To stay warm at night, these birds sometimes dig tunnels in the snow. In years when the seed production is low (wildflowers, birch, willow, grass) redpolls move further south in search of food. These years are called "irruption" years and this year has been a good year to see Common Redpolls, Hoary Redpolls, White-winged Crossbills, Red Crossbills, and Evening Grosbeaks in our area.
From banding data we know that Common Redpolls range widely in irruption years. One individual caught in Michigan was recaptured in Siberia, another banded in Belgium and was found 2 years later in China. Western PA could be this bird's version of wintering in a tropical paradise!
Other pictorial highlights for the winter included these two Hairy Woodpeckers from February 26 (the only two Hairy Woodpeckers caught this winter, incidentally). We have to admit it's pretty refreshing to catch two individuals of the same species but different ages at the same time. It makes for a great comparison.
One of the birds pictured is a young bird (Second Year, indicating hatched in 2012) and the other is an adult (After-Third Year). You might be thinking, "After-Third Year?" Woodpeckers, unlike songbirds, typically retain some of their juvenile feathers into their 3rd year of life. If an individual has molted all of its juvenile feathers and has only adult feathers we can say that it is more than 3 years old (After-Third Year). The possible age classes for most species of woodpeckers from Jan-July therefore include Second Year, Third Year, and After-Third Year.
Can you see the difference between the two? Which one is which?
Speaking of woodpeckers here's a nice picture a female Red-bellied Woodpecker's barbed tongue.
Woodpeckers have a number of remarkable adaptations to help them forage for insects living in wood or anthills, including a really long tongue. In vertebrates the tongue is supported by a bone called the hyoid. In woodpeckers the "Y" shaped hyoid apparatus extends around skull, over the top, and sometimes as far as the right nasal cavity. With long muscles and tendons which attach the hyoid to the jaw, the hyoid apparatus allows woodpeckers to extend their tongue like a spear down tunnels of wood boring insects or into anthills. The barbs at the tip of the tongue let woodpeckers hook onto their prey so that they can draw them back into their mouth.
One piece of data that we routinely collect when we process birds is a “fat score.” Since fat is the most caloric tissue animals can store, fat scores are an important measurement of energetic condition. Fat can help birds migrate long distances or survive freezing temperatures in the winter.
Because bird skin is translucent, we can actually see the fat deposited underneath the skin. One of the first places birds deposit fat is in the hollow area of the furcula (the wishbone). When we blow on the feathers near this hollow (as seen in the photo at left), we can score the amount of fat on a scale from 0 to 3, where 0 indicates no fat and 3 indicates that the furcula is overflowing with fat.
In the photo, you can see a small amount of fat just starting to fill in the bottom of this junco's furcular hollow, earning it a fat score of "1."
One must be careful when checking fat in the winter- since the skin is translucent and we're looking at the neck area, sometimes we see something else…
This American tree sparrow was enjoying some millet from our feeders and has stored the seeds in its crop to digest later. The photo clearly shows that this bird has no fat in the furcular hollow, so its fat score would be "0."
Although the winter affords us the opportunity for some spectacular
close-up pictures of ice on vegetation, and scenic views like this one of Alder Pond and the Price Hide, we are always excited to see the crocus next to the lab bloom (even if it gets covered in snow the next day!)-- we know then that Spring is just around the corner and that many birds will be heading north to use Powdermill as a migration stopover or perhaps to spend the summer here on our beautiful reserve.