Fall 2009: Week #8 in review

The brown birds of fall have arrived. Here's our first Winter Wren of the season. This species has a very broad range across the Northern Hemisphere. In England, it known simply as the "Wren." In Germany, it is called "Zaunkoenig," which translates to "King of the Fence." An evocative and accurate description for these little balls of fiesty attitude! We often seem to catch them early in the morning. Extracting from a mist net what amounts to an energetic and slippery ping-pong ball in dawn's dim light is one of banding's challenges.

Another brown bird of fall is the last of the Catharus thrushes to migrate through, the Hermit Thrush. This is my favorite of the thrushes in my study, although I like them all. They can be very common this time of year, although so far they have not reached a peak here by any means.

Our #1 species right now is the American Robin. Early October is the peak of migration for them, and the time when large numbers in wandering flocks are descending on campus. Because migration has been relatively slow this fall, I've been coming in on my days off whenever the weather is okay. The first net run or two in the morning can be loaded with robins. I had to drag my good friend Jim "The Big Bwana" Fowler out of banding retirement earlier this week to help out in case I got swamped with robins.


Dana Wloch is the UM-D student in charge of identifying and compiling all the seeds found in the droppings of robins and species other than Catharus thrushes, so she's pretty happy with all the robins right now.

The other group of brown birds that are abundant this time of year are the sparrows, especially White-throated Sparrows. They have certainly arrived, but not yet in the numbers I expect. The non-brown sparrow that is conspiciously scarce so far is the Dark-eyed Junco. We've only seen a few so far this fall. That should change in the coming week.

Fall 2009: Week #7 in review

Things picked up this week, although overall the weather was quite uncooperative, with rain or wind cutting down our hours substantially. We began the week with a Detroit Audubon Society field trip, which occurs around this time every year. It's an informal morning of talking about RRBO's research, answering questions, discussing the species that we bring out to show the group after they've been banded and just before they are released. This year there was a nice variety of birds. The photos below were taken by Bill Rapai, of Grosse Pointe Audubon.

Orange-crowned Warbler

Gray-cheeked Thrush. Speaking of which, one was
recaptured twice this week that ended up gaining
a whopping 12.8 grams over 11 days -- that's a
gain of 40% of it's original mass! I have had other
over-achieving Gray-cheeked Thrushes over the years,
including one that gained 16 grams. I don't have an
answer why this particular species would pile on so
much fat at this relatively early stage in their
migration (they winter in northern South America). In
these situations, I usually recapture them more than
once over 10 days or so in which weather doesn't seem
to be a factor in delaying their departure. They are
often recaptured the first time quite fat, and just get
fatter every time I catch them.

I've been training a new bander this season, Guadalupe Cummins. She is an environmental science graduate student here at UM-D, and I'm trying to convince her to work on a project having to do with birds. She began extracting birds and banding them on her own this week.

"Probie" and a goldfinch.

Speaking of student projects, we have now collected over 100 samples of bird droppings from robins and catbirds to examine for seeds (and far fewer from thrushes). Robins are especially productive, although sometimes they don't wait until they are in a bag to provide a donation. I carry little glassine envelopes to collect any errant seedy blobs, so long as I can attribute them to an individual bird. This activity has been the source of a lot of amusement and a variety of suggested names and titles. I'll leave you with the winner.

Julie Craves, the Number One of Number Two.

Where's the jet stream?

In my last post, I blamed the poor fall migration on the position of the jet stream. Fall migration is best following the passage of a low pressure system/cold front, with winds from the north or northwest. Weather systems in North America generally travel from west to east across the continent, with their route guided by winds aloft -- the jet stream. Thus, a nice dip in the jet stream somewhere in the western Great Lakes is most likely to bring the right kind of conditions for birds to move into our area.

My friend Mike McDowell posted some graphics and a nice explanation on his blog last week. Go take a look! His four-panel image comes from WeatherImages.org, and is updated at least daily. The direct link to the current jet stream position image is here, and as I write this on Friday afternoon, it looks like this:

At long last, the jet stream is beginning to sag south. Although it isn't in the ideal position (such as the example Mike posted), it should help move birds along.

The California Regional Weather Service has a great web site that has all sorts of jet stream images and forecasts, including loops. Use the North America "latest available" link here for a detailed current map. This link goes to an animated loop of a five-day forecast.

These maps and forecasts should be used in conjunction with radar images. The Wisconsin Society for Ornithology has a tutorial on how to understand radar images and so does New Jersey Audubon.

Here are those handy links again:

• Current jet stream position and three-day forecast, all in one panel.
• Current jet stream, detailed image with isobars.
• Animated loop, five day forecast.
• Menu of many jet stream image options.
• Radar image tutorial (WSO) and NJA.
  

Fall 2009: Week # 6 in review

Another slow week has gone by. We finally broke 400 new birds banded this week, after 28 days of banding. This time of year, we can expect to band 400 birds in a week. Other folks in the western Great Lakes have also complained about this being a really lousy migration so far. The culprit: the jet stream has for the most part been stubbornly parked at a high latitude, through the middle of central Canada. It's been in this general position since mid-August, a highly unusual situation. Migration is strongly influenced by weather systems, and weather systems are influenced by the jet stream. Rather than going into this here, I'll put some links together in my next post.

We did have a few mildly interesting days. The predominant warbler has been the Blackpoll, followed by Magnolia (below) and Nashville.

This is the time of year when we get very large flocks of blackbirds, mostly Common Grackles and lesser numbers of Red-winged Blackbirds, along with some Brown-headed Cowbirds and (if we're lucky) Rusty Blackbirds. So far, it has only been grackles, and they seem to have arrived/gathered a little early this fall. They mass on the oak trees, ripping off acorns, and carpet the forest floor flipping through the leaf litter. Because of their weight, grackles don't "stick" in the banding nets very well, but it isn't unusual to catch a whole batch of them if they are moving through the net lanes. This is never very fun. They can (do!) pinch quite hard with their sharp bills. They also have very strong feet and it can be uncomfortable if they grab on and get a toenail stuck in your cuticle.

I happen to think that grackles are pretty handsome, but right now they are molting. The one below is a young bird, molting from its dull juvenile plumage into the more typical glossy garb. Judging from the color, this is probably a male. The wing feathers are also molting, or I'd be able to tell which gender by the length of the wing -- males are larger than females.

Speaking of toe nails, here's a robin with pale nails; they are usually dark-colored. We see a number of birds lacking pigment in their nails every season. Often it is Gray Catbirds and robins for some reason.As you'll see in my next post, the jet stream and weather systems are finally on the move. So long as we can avoid rain and wind, things should pick up next week.

Fall 2009: Week #5 in review

It was another quiet week. There was an influx of migrants on Sep 15, and some obvious large movements of American Robins and Blue Jays beginning on Sep 17. Some new species were recorded this week. Philadelphia Vireos have a very tight fall migration window right around September 15. We saw our first on Sep 12, and banded two on the 15th.

The 16th saw our first White-throated Sparrow of the season, and more were around on Sep 20. Sep 19 we had our first Gray-cheeked Thrush. Cape May Warblers seem to have had a good year. We banded two nice-looking hatching-year males, one of which is shown at the top of the post.
Two older birds were also recaptured this week. The first was a female Northern Cardinal first banded as an adult on April 13, 2003, making her at least 7 years old. We had recaptured her a number of times in 2003 and 2004, but this was the first recapture since then.

Next was a Gray Catbird that had been banded as an adult, in its second year, on May 17, 2005, making this bird at least five years old. We have captured it several times each year, often in breeding condition -- this was a male.
And here's my ID tip of the week (don't get your hopes up that I'll have one weekly!). The bird above is a Chestnut-sided Warbler. Like many (most that I see) individuals of this species in the fall, there isn't any chestnut on the sides. However, the color of the back and top of the head are very distinctive. To me, it's just like the color you get when you use a fluorescent yellow highlighter on newsprint. What do you think?