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.

Week #4 in review, and longevity records

Another week shortened by rain at the beginning (Sunday) and end (today). In between, numbers were disappointing. Over last weekend one wave of migrants representing good diversity arrived, but it continued to dissipate over the course of the week. Not helping matters was an adult Broad-winged Hawk (Buteo platypterus) that was hanging around the area the entire time. This is the first time in 16 years we have ever had an individual of this species even perch in the banding area, much less stick around for a few days! It hasn't approached the nets (Broad-winged Hawks eat primarily small mammals and amphibians, and rarely adult birds), but has a chilling presence. It may be attracted to by what seems an unusually high number of chipmunks and Red Squirrels in this immediate area. Happily, this issue should be self-limiting, as Broad-winged Hawks migrate almost en masse, with peak passage in this area tightly focused around 15 September. I think these are beautiful birds, but won't be sad to see the last of this one!

I've updated the fall totals in the right sidebar. They are quite dismal for this time of year, and our capture rate actually declined this week. We have only had 5 years out of the last 16 in which our rate was less than 50 birds per 100 net-hours, and only two where it was below 40 (our high was in 1996, when it was 63).

Only a few new species were banded this week, including Yellow-bellied Flycatcher (Empidonax flaviventris), pictured at the top of the post. This is probably the easiest eastern Empid to identify, although I have never been entirely successful at capturing their beautiful yellow-olive color with a point-and-shoot camera.

We did have a few interesting recaptures from previous years. Two were catbirds -- one was first banded as an adult in September 2007, the other as an adult in September 2006. It isn't too unusual for us to get a lot of between-year recaptures of catbirds. The third bird was a female American Goldfinch. She was first banded as an adult in August 2004. Almost four years between captures is not a record for us (that stands at 6 years, 7 months for goldfinches here), but still impressive for a small songbird. I have a compilation of some of the birds that have had at least two years between recaptures at the RRBO web site. You can also examine longevity records based on banded birds at the USGS's Bird Banding Lab web site.

Bill deformities and tumors

The other day I banded this HY (hatching-year) cardinal with a bill tumor. It looks sort of like a scab or blob of gunk stuck on the bill, but it's actually growing out of the tissue near the base of the bill. The dark coloration of the rest of the bill is normal: young cardinals have dusky-colored bills well into fall. It's one of the easiest ways to tell a juvenile from an adult.

Bill tumors and other deformities are not terribly uncommon. They often are seen on young birds, probably because many of the deformities ultimately impact survival. Most tumors I have seen have been due to a virus called avian pox. As I wrote on the RRBO bill tumor page, avian pox most frequently causes lesions on the feet and legs of birds, but also affects other soft parts. Pox lesions are scabby, crusty, or warty growths. If near the nostril they can obstruct breathing, or can obstruct vision if near the eyes. The lesions fall off after about a month when the virus runs its course, but it appears they can sometimes compromise the bill structure -- some post-pox birds have chunks of bill missing. This may not be due to the pox itself, but might be due to secondary infections of the pox lesions. Pox can be spread by mosquitoes, or contact between birds (thus it can be spread at feeding stations).

The tumor on the cardinal does not appear to be due to pox, as it actually seems to be growing out of the horny structure of the bill versus "on top," which is how pox often presents. I don't think this tumor is life-threatening in any way, if it doesn't continue to grow. The inside of the bill and mouth are okay, it doesn't look like it will interfere with feeding or grooming, and the nostril is open.

Bill deformities such as crossed bills are a whole other matter. Many years ago, upon capturing a catbird with a crossed bill, I did some research, and ended up publishing a paper on the incidence of bill deformities in passerine birds (songbirds) in North American Bird Bander. Since then, I have kept a compilation of these kinds of deformities in songbirds on the RRBO web site. Many have been contributions from banders and people who have seen the information on the site (I moderate a group on the photo sharing site Flickr on bill deformities which includes all types of birds, not just songbirds).

It is hard to say whether these types of deformities are increasing, or if awareness is just elevated. However, there is one geographic region where something is definitely going on: the Pacific Northwest and in particular Alaska. The USGS's Alaska Science Center has devoted a section of their web site to these abnormalities, many showing up in chickadees.

The USGS Alaskan researcher, Colleen Handel, cited my paper and the RRBO web site several times in her presentation on "The mystery of the long-beak syndrome" at a recent ornithological conference. Colleen and I have discussed these deformities several times over the years, and are planning on collaborating on a paper next year.