Week #7 in review

Last week I mentioned we had banded our second Connecticut Warbler of the season, but I hadn't downloaded the photos yet. Here we go:

Connecticut Warbler #2

And we banded another last Sunday. Unfortunately, nearly everybody from the Detroit Audubon field trip had already departed for the day and missed it! Of course, it got a mug shot, too.

Connecticut Warbler #3

White-throated Sparrows arrived in good numbers this week. This species can be quite variable in plumage. There are two color morphs, one with brown and pale tan head stripes, and the other with black and white stripes. Some young birds can be really dull and dirty looking, and even have some breast streaking, like this one.

The adult below was a lot nicer looking. There is a subtle difference in the eye color of young and adult White-throated Sparrows. Young ones have gray-brown eyes, adults are a richer reddish brown color. This is best seen in bright light.

And to round off the sparrow gallery are these White-crowned Sparrows. Unlike White-throats, the difference in the head stripe color is strictly age-related, with the young birds having tan stripes, and the adults black and white.

Young (hatching year) White-crowned Sparrow

Adult (after hatching year) White-crowned Sparrow

So far, I've had a modest number of recaptures of passage migrants (those species that only use this area during migration, but don't breed or winter here). The species recaptures so far have been Gray-cheeked Thrush, Swainson's Thrush, Black-throated Blue Warbler, Blackpoll Warbler, American Redstart, Ovenbird, and Common Yellowthroat. Of the 12 individuals, all but 3 gained weight, the average being 7% of their original body mass. As a general rule of thumb, birds need to gain 3 to 5% to make another night's flight. Our analyses have indicated that the majority of individual birds do gain weight on stopver here at UM-Dearborn, but this varies widely between species. Most thrushes, for instance, gain a lot of weight. White-throated Sparrows overall tend to lose weight. This focus of our research will be discussed in upcoming posts.

Sampling for avian flu

RRBO is in its second full year of sampling birds for avian influenza. There are many different subtypes of "bird flu," most of which are mild "low pathogenic" avian flu viruses which are not dangerous to humans. The type of bird flu often in the news is the highly pathogenic subtype H5N1, which causes high mortality in domestic poultry. It has not been found in migratory songbirds in North America.

The Landbird Monitoring Network of the Americas (LaMNA; RRBO is a charter member) and UCLA's Center for Tropical Research initiated a program in 2006 to learn more about the identity, frequency, and geographic distribution of virus sub-types and strains carried by landbirds. Sampling for avian flu is done at migration monitoring stations such as RRBO, breeding bird stations (Monitoring Avian Production and Survivorship, or MAPS), and wintering bird stations in Latin America (Monitoreo de Sobrevivencia Invernal, or MoSI).

Sampling only takes an extra minute during our banding process. It consists of taking a very tiny sterile swab and sampling cells shed from the intestines at the entrance to the cloaca. The tip of the swab is cut off and placed in a vial of preservative. Two tail feathers are also taken. These can be used in stable isotope analysis, which can give us an idea of where a bird nested. Identifying the breeding areas of birds will help researchers map out where certain strains of virus originate.

Since beginning this project, RRBO has contributed over 300 samples of nearly 50 species. Some are migrants, and some are residents. For many years, we didn't band House Sparrows, beginning during a period when the band size they take (shared by abundant migrants such as thrushes, White-throated, White-crowned, and Song Sparrows) was in short supply. Now they are a valuable species to sample for viruses due to their communal nature and urban haunts. Here's a young male House Sparrow who donated a few cells and two feathers to science.

Sampling will continue through fall here on campus. Then I'll sample at my nearby home to use up any remaining vials -- I'm one of the only banders in the state that provides winter samples to the project.

This is just another way RRBO is making a contribution to a wider understanding of birds in North America. To learn more, check out these links:

• LaMNA avian influenza research project page
• UCLA's Center for Tropical Research Avian Influenza Virus in North American Migratory Birds page
• RRBO's frequently asked questions about avian influenza and migratory birds
  
• NPR's The Environment Report, April 2006, on this project, in which I was interviewed.
  

Week # 6 in review

While the numbers in the nets continued to be low, there was no decrease in our capture rate although it is still far below average. On the bright side, diversity increased this week, with some of my favorite species being banded. Let's just jump right to a photo salon of the week's highlights.

This is likely the brightest young male Blackburnian Warbler I've ever banded in the fall. Usually they stay pretty high in the trees so I don't catch many of them. They are always a treat.

Last week I was catching female Black-throated Blue Warblers, but this week I had a few males. Beautiful!

I expect to see Philadelphia Vireos between 15 and 25 September...they are pretty prompt and have a tight migration window. I just couldn't capture how fresh and bright the yellow on this bird was, but it was a beauty.

I like the fiesty personality of vireos, and my favorite species is Blue-headed Vireo. I don't catch many of them either, so I was happy to see this one. Isn't it gorgeous?

Another infrequently banded species is Eastern Phoebe. This photo doesn't show the nice, subtle yellowish color of the breast. The picture also makes it look a little more rotund than usual. They say the camera always adds a few pounds...

I banded our second Connecticut Warbler of the fall, today, too, but the photos are still in the camera.

On Sunday, September 28, the Detroit Audubon Society is having a field trip here, and it's open to the public. It will include short walks on the trails, and a look at birds in the hand, should we have some to show. I'll be available to answer all your burning questions. This program is weather permitting: we'll not be banding if it is windy or raining, or threatening rain. Meet on the south patio of the Environmental Interpretive Center (EIC) at 8 AM. Directions to campus and a campus map are linked about halfway down this page on the RRBO web site.

Week # 5 in review

We are officially off to the slowest start of any fall season in the past 16 years! While we focus on banding and not surveys in the fall, the few times someone has been out to walk the standard route not much has been found, so the shortage is not just limited to the banding area.

Connecticut Warbler (Oporornis agilis), hatching-year female

Connecticut Warblers are very sought-after birds, as they are not very common and notoriously hard to see. We band a fair number of them at RRBO, especially in fall. They are usually young birds, and the dull young females make you wonder what all the fuss is about. This bird was banded on 19 September; another individual bird was seen on a survey the previous day.

Indigo Buntings appeared in our nets this week. The bird above is probably the bluest female Indigo Bunting I have ever banded. This was an adult bird, and male-like coloration in old females is not too unusual -- I see it pretty often in Baltimore Orioles.

Female Black-throated Blue Warblers also don't compare to their gorgeous male counterparts. I don't band a ton of this species, but I did catch four this week -- and they were all females.

Sparrows begin moving through a little later than warblers. Our first Lincoln's Sparrows were banded this week. These are a commonly banded, but rarely seen, species at RRBO.

Savannah Sparrows are another handsome streaky-breasted species, but the streaks are wide and on a clean white breast, rather than fine streaks on a beige "vest."

Rose-breasted Grosbeak (Pheucticus ludovicianus)

One thing you learn early on as a bander: if you catch a grosbeak, give it something besides your fingers to bite! And there's a new face at RRBO who will learn this lesson soon...

I'd like to introduce the newest member of our banding crew, Dana Wloch (and her friend, a Nashville Warbler). Dana is a UMD student with a strong, lifelong interest in birds and wildlife. She tells us that the historical figure she'd most like to have dinner with is Charles Darwin, and the obsolete object she can't seem to part with is a dried up fish given to her as a gift. Dana is refreshingly enthusiastic and a fast learner...I hope she can put up with me us for years to come. Welcome to team RRBO, Dana!

Bald birds

Joe's comment on my last post reminded me that it's that time of year to address the perennial bald bird issue. It is one of the most frequently asked questions about birds. Northern Cardinals (Cardinalis cardinalis), Blue Jays (Cyanocitta cristata), and Common Grackles (Quiscalus quiscula) are the most common victims of this disturbing-looking feather loss. There's nothing wrong with most of these birds, despite how bad they look. All birds replace all of their feathers at least once a year, and fall is often the time that North American birds undergo this complete molt. Typically, this molt takes place over a few weeks. But some individuals, unfortunately, lose all the feathers on their head at the same time. I've often read that ectoparasites such as feather mites are responsible for this condition. I have never found mites on bald birds that I've banded. All birds have some of these mites -- they feed on oils, fungi, and bits of skin, and don't cause feather loss. It would also be unlikely, if not impossible, that they would cause all the feathers in one area to fall out simultaneously. In fact, they typically move to tail and wing feathers -- cooler locations on the bird's body -- in warm weather such as is typical in fall. There are a couple of other types of mites found on birds, but they have not been found on bald birds. My search for information on quill mites, for instance, didn't even turn up any evidence that they've been found on cardinals or jays. Nor does it make sense that these other mites would cause feather loss on the head but not elsewhere, since birds are not able to remove them easily from anywhere on their bodies via normal preening. Although the role of mites in bird baldness has not been thoroughly studied, the seasonal and localized nature of the baldness and the fact that it is most common in a relatively limited number of bird species leads me to believe that their presence is coincidental and not causative. That this catastrophic molt is "normal" in at least some individual birds comes from Cornell staffer and former wildlife rehabber Laura Erickson. She was in charge of a Blue Jay in captivity that always lost all the feathers on its head simultaneously once a year -- for the 8 years she had it! Sometimes bald birds are seen at other times of the year when they would not be expected to be molting. The reason for their feather loss may be different (running into a window, for instance, could cause at least a temporary loss).

Being bald is not harmful to birds, except perhaps in cold or wet weather. Within a few weeks, the feathers will grow back.

For more photos and information, see the Cornell web site. Top photo of a bald cardinal by Jimmy Smith.

Janet Hug from Commerce Twp., MI sends us this photo of an adult male cardinal at her feeder, on the road to refeathering, but still looking pretty shabby.