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.

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.

Week #3 in review

Although spring warblers are bright and colorful, I have always enjoyed fall banding the most. The pace is steadier and a little less weather-dependent, and I like seeing all the young birds and gauging the success of the breeding season. The nice variety of bird species which inevitably begins in September makes up for the inescapable reality that winter is on the way.

The Nashville Warbler (Vermivora ruficapilla) above was, as are over 80% of the fall birds we band, a hatching-year (HY) bird. Nashville's have a very protracted fall migration, with the earliest records from late August, and some lingering into early November.

Blackpoll Warblers (Dendroica striata) are one of my favorite species. In the field, they can be hard to distinguish from Bay-breasted and Pine Warblers in the fall, and these three species are the classic "confusing fall warbler" complex. In the photo above, you can't see the yellow feet, which help distinguish this species. McGill Bird Observatory has a nice guide to the fall warblers.

Magnolia Warbler (Dendroica magnolia) is one of our top-ten most frequently banded species. In all seasons, they show a pretty wide variation in plumage, from dull young females to bright old males. Because of this variation, banders are not "allowed" to sex HY Magnolia Warblers (if we submit records to the federal Bird Banding Lab that say a HY Magonlia is a male or female, we are told to change the sex to "unknown"). However, very dull birds with short wings are likely female, so for this bird, I noted "female" -- but only in the comments of our data form.

At the other end of the spectrum are most small Empidonax flycatchers, in which not only do the ages and sexes look alike, but so do many species. Wing and bill measurements, and examination of the shape of some of the feathers helps tell apart many of the species in the hand. For the most part, however, Willow and Alder Flycatchers (E. trailli and alnorum) cannot be told apart in the hand. We submit them as "Traill's" Flycatchers.

Stats for the season so far have been updated in the right sidebar.

The first migrant thrushes

Many new species of migrants are coming through this week. Today I banded the first Swainson's Thrush of the fall season. I am really looking forward to thrush migration this year. The three most common species of migrant thrushes here -- Hermit, Gray-cheeked, and Swainson's -- are the subjects of a major paper I recently had accepted to the peer-reviewed Wilson Journal of Ornithology:

Craves, J. A. 2009. A fifteen-year study of fall stopover patterns of Catharus thrushes at an inland, urban site. Wilson Journal of Ornithology 121:112-118.

I analyzed weight and fat data for over 2,000 individual thrushes banded here at RRBO during the fall seasons 1992 to 2006. I used both a regression analysis for all initial captures, and recapture data to examine weight and fat changes in these birds as they used our site as a migratory stopover.

In the paper, I present and discuss a number of different findings. Among them, the majority of individuals of all three species gained significant fat and weight during their stopover on campus. This is especially important because in an urban site such as this one, migrant birds are faced with unique challenges, including a high level of human disturbance which may decrease foraging opportunities, and a preponderance of non-native fruits.

These thrushes rely heavily on fruit during fall migration. Much of the native fruit, to which they are evolutionarily adapted, has been depleted by other species by the time the bulk of the thrushes move through, in particular Hermit Thrushes, which are late migrants. The remaining fruits are predominantly introduced, invasive species such as buckthorn and honeysuckle.

My findings have conservation and management implications. It suggests that thrushes are in fact able to find sufficient resources in urban natural areas similar to our site. Since thrushes gain mass on a diet high in non-native fruits, it demonstrates that some introduced plants do perform ecological functions.

The next question are which fruiting plants and shrubs commonly found in urban areas -- both native and introduced -- are most important to migratory birds? What is their relative availability? If highly invaded urban natural areas are to undergo restoration efforts, which introduced plants should be left to provide resources for migrant birds while native plants become established? In a future post, I'll talk about exactly how we intend to shed some light on those questions with ongoing research!

The vast majority of published papers on stopover ecology have focused on coastal or rural sites, and frequently cover a study period of only 2 or 3 years -- the length of time a graduate student takes to complete a degree. RRBO's work is unique with its focus on an urban, inland site, and especially its long-term nature. It's not enough to catch some birds and see that they've gained some weight between captures. There are many pitfalls in designing studies and gathering data that can be used to draw statistically and biologically significant conclusions. Large data sets are needed to account for many extrinsic variables (such as weather) and weed out ambiguous or problematic data points. I have raw data for a suite of other species besides the thrushes. At some point, they will also be run through the analytical mill, but first I'll be concentrating on the thrush and fruit connection. Stay tuned!

Week #2 in review

Well, this week was nothing to write home about. Only 39 new birds were banded in 3.5 mornings of banding. It has been dry, dry, dry in the banding area. While it's nice not to get wet feet or be bothered by mosquitoes, foraging opportunities are reduced in a drought. Fruit development is a bit delayed as well. With rain forecast this morning, I walked the standard survey route rather than open the nets. There was more insect activity near the Rouge River and by Fairlane Lake, although overall it was still quiet. I'll be periodically updating the running totals for the banding season in the right sidebar.

I recaptured both of the molting Tennessee Warblers from last week, and their feathers are coming along nicely. My only new migrant was an Ovenbird (Seiurus aurocapilla), a personal favorite.

There are several species that we capture that we release unbanded. One is Ruby-throated Hummingbird (Archilochus colubris). A special permit is required to band hummingbirds, and a project involving them is outside my focus of research. This time of year, most of the ones we catch are immature/female-plumaged birds.


The one above was in fresh plumage; I think most of the adults will still be molting, like the adult male below. He was a bit bedraggled looking.

Once again, Gray Catbirds made up most of the catch, and represent half of all the birds handled so far this fall. The pace has been a little slower than most of our fall season starts, but should pick up soon. I'll be back at the nets after the holiday weekend.

The week in review

Our short week of banding wrapped up with 55 birds being captured, 44 of them new birds. Most were catbirds. I did recapture an adult first banded in 2006 (as well as a Song Sparrow also banded that year). But the majority were young birds. The baby catbirds are still sort of cute, but will soon look really scruffy as they molt into their adult feathers.

The first Wilson's Warbler of the season was in the nets today. Their typical fall arrival date here on campus is 29 August, but the earliest date we've recorded them is 18 August. It's not too unlikely that they may arrive a little earlier, but we ordinarily don't do much field work on campus in July, so they could be overlooked. If you are interested in extreme and typical arrival dates for the common species in southeast Michigan, pick up a copy of my book, The Birds of Dearborn, An Annotated Checklist. You can have a PDF copy on our desktop in a few minutes for only $5!

The Wilson's was a young female. In a future post, I'll talk about how we age birds. As for determining gender, the nearly complete lack of a dark glossy cap is indicative of a female, as was the length of the wing. In many songbirds, males have longer wings than females. Although there is overlap in most species, extremes can indicate gender.

Another thing to notice in the photo above are her "whiskers" which are actually modified feathers known as "rictal bristles." Many birds have them, but they are most well-developed in species that forage for insects on the wing. The flattish bill shape and prominent (for a warbler) rictal bristles prompted Audubon to refer to this species as "Wilson's Flycatching Warbler."

Today I also caught another molting Tennessee Warbler. It was just as sorry-looking as the first one, although it was further along with its molt. The photo below shows the obvious contrast between the fresh new and incoming wing feathers and the three older, worn feathers.

At least, this bird had a tail. One thing we note for all Tennessee Warblers is the extent of the white spot on the outer tail feather. Not all of them have a spot; this one was quite large. It's not certain why there is such variation, but perhaps once we get a large enough sample size, we can see if there is any correlation with age, sex, or some aspect of geographic range.

I'll be back at the nets on Monday!

Molt migrants

Today RRBO banded its first fall migrant, a Tennessee Warbler (Vermivora peregrina). While the majority of migrant songbirds undergo their autumn (prebasic) molt on the breeding grounds before proceeding south, Tennessee Warblers have a different strategy. Adults travel south from nesting areas in northern boreal forests, then stop part-way, and undergo or finish their prebasic molt. About 4% of the Tennessee Warblers banded in fall at RRBO are molt migrants.

This molt is a complete prebasic molt, and includes not just body feathers but also all the flight feathers. As you can see, this bird is pretty pathetic looking.


It was molting 4 of its 9 primaries (outer wing feathers), a few secondaries (the inner wing feathers), and all of its rectrices (tail feathers). Yes, it could still fly quite well!

At RRBO, we record the extent of molt on every bird. The number of body feathers being molted are scored on a 3-point scale, and we note the number of each molting flight feather. Over time, this gives us a great idea of the local annual timing of molt for the bird species we band.

Molt migration is common in waterfowl, and more common in songbirds in the western U.S. The other common molt migrant here is Swainson's Thrush (Catharus ustulatus); about 2% of RRBO's fall birds are molt migrants.

A little more information:

• An overview of bird molt -- Cornell's All About Birds
  
• Tennessee Warbler, featured bird -- Smithsonian Migratory Bird Center
  
• Tennessee Warblers are a classic example of a North American migrant that winters on shade coffee plantations -- Coffee & Conservation

Opening day

Today was the first day of RRBO's 16th fall banding season. Unfortunately, it was pretty breezy this morning, so I was only able to open a handful of our most protected nets. We have a strict weather policy that guides us as to when it's safe to open the nets. Young birds are especially vulnerable to getting wing sprains if they are caught in a net that is moving around a lot in a breeze.

And young birds are always the first order of business the opening days of a fall season. Today was no exception. Of the 18 birds that were captured this morning, only one, a robin, was an adult. The rest were youngsters, including 15 Gray Catbirds. This is our #1 species, with over 3200 banded since 1992 (nearly 40% are recaptured, many multiple times).

This is how it will go the rest of the week. I'll open different nets in various sections, and catch many of the resident birds. Then things will quiet down until migration begins in earnest.

Meanwhile, it's time to enjoy the catbirds!

Getting ready for fall banding

Many people don't realize how much work goes into just getting ready to start a banding season. I've been using one main site for banding for 16 years, but every season requires a lot of preparation of the net lanes. Weeds under and near the nets have to be eliminated and vines and shrubs that have started to reach closer to nets have to be removed. In order to keep the site as static as possible, woody growth is cut back in our old field portion of the site so that succession doesn't turn it into secondary forest. If the habitat changes too much, it would be difficult or invalid to compare current banding results with those of past years.

We do have a grounds department at the campus, of course, but apart from being busy keeping the more visible parts of campus looking nice and respectable, they do require payment for special work that they might do for other departments. Because RRBO is funded via grants and donations, I do this type of work by myself and with the help of volunteers.

All the rain here earlier this summer made growth particularly lush. I'll admit to being pretty depressed when I saw how much work had to be done before I could open the nets. It's not as if much of it can be done too far ahead of time! Starting early this week, it took me about 25 hours of my time, plus another 12 hours of help to get things shaped up. Many thanks to Rick Simek, Darrin O'Brien, and Mike O'Leary for their labor!

I wish I'd taken some "before" photos, but here are a couple of shots from the final efforts over the weekend. Here is some of our gear...you'll notice that we rarely use any power tools.

Here is a stretch that is in pretty good shape. You can see the furled up nets.

Another regular task is to make sure that the deer fencing which now surrounds the entire banding area is checked for holes and downed trees and repaired. The deer herd has grown so much in recent years that we've had to exclude them from the area. Each net costs over $100, and the deer were running through them or getting caught on the nets on a routine basis, destroying them. The deer on campus are quite fearless. Here are two on the other side of our fence (draped with grape vines). In the lower right corner, you can see the fine mesh of one of our open nets.
We hit one final snag as we were finishing the pruning. Darrin and I were cutting back a lot of overhanging grape vines, when he exposed a chest-high Bald-faced Hornet nets. He got stung on the chin, and we both fled as unhappy hornets chased us down the trail.

Much as I loathe it, I'll have to get rid of the nest before I can finish up and start banding. We'll be ready to open this week!

Small Canada Geese

In 2004, the 45th Supplement to the American Ornithologists’ Union Check-list of North American Birds split Canada Goose into two separate species: the larger forms remain Canada Goose (Branta canadensis) while most of the smaller forms are now Cackling Goose (Branta hutchinsii).  The Cackling Goose form most likely to be seen in Michigan is the former Canada Goose race B. c. hutchinsii, or Richardson’s Goose. The other small former Canada Geese are western birds that would be considered very rare in the east.  An excellent report on this is on the Ontario Field Ornithologists’ web site.  David Sibley’s website also provides great information.  In particular, read the information on neck size and voice, which from his discussion appear not to be as conclusive as some have been implying. There’s also a nice map indicating which races breed where.  The Ocean Wanderers web page, by Angus Wilson, includes photos, links to specific individuals being debated, and extensive literature citations.

What follows is some information on the identification of Canada Geese found in Dearborn, focusing on an interesting case of a “runt” Canada Goose from Canada.

The most common subspecies of Canada Goose in Dearborn is the Giant Canada Goose, or B.c. maxima.  This largest of the races was extinct in much of eastern North America, and in Michigan, at the turn of the 20th century, wiped out by hunting and habitat destruction.  Aggressive reintroduction campaigns resulted in the surplus of these big, non-migratory geese we see today.  This is the subspecies that nests in Dearborn.

During spring and (especially) fall migration, Giants are joined by the slightly smaller, somewhat darker-breasted migrant race B.c. interior.  Around the UM-Dearborn campus, many geese wearing orange neck collars can be found in the fall.  These birds have been banded on Akimiski Island, Nunavut, in James Bay (while closest to Ontario, all islands in James Bay belong to Nunavut, formerly Northwest Territories).  One neck-collared goose was seen by us in the fall of 1995 and again in the fall of 1998.  It was originally banded in 1990 on Akimiski.

There are other even smaller races of Canada Goose than  B.c. interior. An example is this goose, photographed by Jim Fowler, Jr. at Greenfield Village on 25 Oct 93.  Notice the pale breast, and small size compared to the nearby Giants.  This was probably B.c. hutchinsii (a.k.a. “Richardson’s Goose”), the smallest of the pale-breasted races.  They nest in the northern portion of Hudson Bay.

Next, look at this little dingy-breasted goose below, shown in these two pictures with one of  her two B.c. interior buddies that she hung around with from late September until early October 1998 on the UM-Dearborn campus.  This goose had a regular leg band and a colored leg band.  As it turns out, she was banded as a young female not yet able to fly on 15 Jul 98 on…Akimiski Island!  Since none of the small, dark-breasted races are known to nest in this part of Canada, I contacted the person who bands on Akimiski, Jim Leafloor of the Ontario Ministry of Natural Resources, for more information.

Dr. Leafloor explained to me that all the geese breeding on the island are considered B.c. interior.  This goose was banded on the north shore of the island, where the geese are smaller than other interiors due to low food availability.  The habitat has been degraded over the last two decades by high densities of nesting Canadas (seven times higher than on the nearby mainland and up to 300 times higher on the north coast of the island), use by migrant Brants (another type of goose), and especially increasing numbers of migrant and nesting Snow Geese.  Eggs of these birds when raised in captivity grow to “normal” size like their mainland counterparts.  Therefore, one should use caution assigning subspecies to varying sizes of Canada Goose seen in this region.

For more information on this very interesting phenomena, please see a paper Leafloor and his colleagues  published in the  journal The Auk:

Leafloor, J.O., C.D. Ankey, and D.H. Rusch.  1998. Environmental effects on body size of Canada Geese. Auk 115:26-33.

UPDATE: David Sibley has a post and photos on his site regarding recent research and evidence of hybridization between small (Cackling) Geese and larger Canada Geese. Please see Cackling-ish Geese; here is the paper he refers to:

Leafloor, J.O., J.A. Moore and K.T. Scribner. 2013. A hybrid zone between Canada Geese (Branta canadensis) and Cackling Geese (B. hutchinsii). Auk 130: 487-500.

Ruby-crowned Kinglet from Toronto

A (but not the) Ruby-crowned Kinglet
banded by RRBO

On 22 April 2005, I captured a banded Ruby-crowned Kinglet.  I was amazed to see that it was not a bird that I had previously banded.  The rule of thumb is that fewer than 1% of small songbirds are ever encountered away from the place they are banded.  And kinglets are one of the smallest songbirds, weighing in at around 6 or 7 grams, or the same weight as an American nickel and a dime.  They are so tiny, in fact, that properly-sized bands have only been made since 1993.  Prior to that time, the smallest band size had to be modified to fit them, and many banders released kinglets without banding them at all.

On 2 May, I received acknowledgment from the U.S. Bird Banding Lab that this kinglet was originally banded as a hatching-year bird (born the same year it was banded) on 10 Oct 2003 outside of Toronto, about 216 miles east-northeast of Dearborn.

In The Canadian Atlas of Bird Banding, I looked up the number of encounters of Ruby-crowned Kinglets, an encounter being a subsequent observation of a banded bird, dead or alive.  Between 1921 and 1995, with over 48,000 banded in Canada between 1955-1995 alone, the number of Ruby-crowned Kinglets encountered was only ten.  The Atlas noted this is one of the lowest encounter rates of any species.  While the U.S. has no similar publication, they do provide  simple tallies of numbers banded and encountered.  Although 127 Ruby-crowned Kinglets sounded more substantial, the encounter rate was actually only 0.03%.  What a special event this was!

The only other foreign encounters I’ve had here at RRBO were an American Goldfinch and a Sharp-shinned Hawk. Both were originally banded within 25 miles of here, and were caught by me within four months of the banding date.  Figuring this kinglet, too, was from nearby, I contacted other regional banders, but nobody could claim this diminutive traveler. Finally, I tracked down the original bander.

The location was Tommy Thompson Park (a.k.a. Leslie Street Spit),  man-made peninsula constructed from dredge and fill which juts out 3 miles into Lake Ontario from the Toronto shoreline. The kinglet was banded by the Tommy Thompson Park Bird Research Station (TTPBRS), a partnership between Toronto and Region Conservation and the Toronto Bird Observatory. The station began operation in 2003. Here is a great map showing the location of the station.

Kinglets, especially Ruby-crowned, are a  bread-and-butter bird for TTPBRS, making up 30% of all birds banded over fall 2003-2004.  This is not surprising. Other lower Great Lakes banding sites located along the shores of Lakes Erie and Ontario also band hundreds or thousands of kinglets: Long Point Bird Observatory, Prince Edward Point Bird Observatory, Braddock Bay Bird Observatory, and Haldimand Bird Observatory, for example.  At our inland site, we don’t even SEE as many kinglets as these stations band in a typical fall season. This seems to provide evidence that these little mites prefer to travel along shorelines rather than over water during their journeys between their nesting areas in northern spruce-fir forests and their wintering areas in the southern U.S., Mexico, and Central America.

The capture of this one bird provides only a single data point, and while it is a notably rare event, in itself it doesn’t deliver a big scientific wallop.  But this encounter is valuable in other ways.  Ruby-crowned Kinglet number 2310-75634  has provided a special connection between two bird research stations studying urban bird ecology — an underappreciated focus that often struggles for acknowledgment and recognition.  And it provides an opportunity for us all to marvel at the resilience of such a small creature, and how much we still don’t know about this common bird that flits among us, just passing by.

Gyrfalcon in Dearborn, 2005

The Gyrfalcon (Falco rusticolus) is the world’s largest falcon, nearly the size of a Red-tailed Hawk.  This Arctic-nesting bird is rarely seen in the United States.  When populations of ptarmigan, chicken-like tundra birds that are a main prey item of Gyrfalcons, fall below certain levels, some Gyrfalcons move into southern Canada and the United States in the winter.  When one is found, many birders will rush to see it.

According to The Birds of Michigan, 40% of the state’s records are from Sault Ste. Marie, 20% from Whitefish Point in the U.P., and 10% from the Muskegon area. As of 2005, there were only eight published records from southeast Michigan:

• A questionable record from Washtenaw Co., 1974.
• A questionable record from Jackson Co., 1997.
• Three records for Wayne Co.: Nov 9, 1995 at Lake Erie Metropark (not Oct 9, as has been published elsewhere); Nov 9, 1997 at Point Mouille headquarters (perhaps another bird at Lake Erie Metropark); and Nov 19, 1999 at Lake Erie Metropark.
• Three records from Pointe Mouille SGA in Monroe Co.  One from the 1970s; one from 12 to 27 March 1994 (this bird also crossed into Wayne Co. on occasion); and one from 6 to 15 March 2003, also at Pointe Mouillee.

Thus it was sensational when Kim Hall, Julie Craves, and Darrin O’Brien located a subadult (first year) Gyrfalcon at a Dearborn office complex while participating in the annual Detroit River Christmas Bird Count on 1 Jan 2005. The Rouge River Bird Observatory coordinates the Dearborn portion of the count.

Initially, the bird puzzled the observers. The possibility of Gyrfalcon seemed so outrageous that they watched the bird move from a small woodlot to various trees, light posts, and buildings in the Parklane Towers office complex for some time while they convinced themselves they were actually looking at this species, a first for Dearborn.  The Parklane Towers are large concrete structures that are among the tallest in the immediate area. Their cliff-like appearance may have made the falcon feel at home.

They quickly got the word out via cell phone and the Internet, and by the end of the afternoon over 20 birders had ignored their hangovers, abandoned the Rose Bowl, or otherwise dropped their New Year’s Day plans to see this rare visitor. Gyrfalcons come in three color types, or morphs: white, gray, or dark.  This bird is a dark morph. In the Arctic, Gyrfalcons feed on large birds and small mammals.  Here, this bird likely fed on rabbits, squirrels, pigeons, and ducks. It was last seen on 4 Jan 2005.

Michigan’s first Virginia’s Warbler

On the morning of 13 May 1993, an unusual bird was removed from the mist nets of the Rouge River Bird Observatory on the UM-Dearborn campus.  Initially, the bird appeared to be a strangely-plumaged Nashville Warbler (Oreothlypis [Vermivora] ruficapilla).

The bird was primarily grayish, with little or no contrast between the color of the head and that of the back and wings; the back and wings were not olive-colored like a Nashville Warbler. There was a restricted amount of yellow on the upper breast and undertail coverts with much of the breast and belly grayish, rather than the uniform yellow of a Nashville. Like a Nashville, the bird had a complete, pale gray eye ring, and a small concealed rufous crown patch. We had an unbelievable hunch about what it was, and after going through a series of photographic references and technical references, we confirmed that this bird was not a Nashville Warbler, but rather the closely related Virginia’s Warbler (Oreothlypis [Vermivora] virginiae).

This capture represented the first record of Virginia’s Warbler for Michigan. In summer, this species is normally found in the Rocky Mountain southwest. It winters mostly in mountainous regions of Mexico, and also California.

Virginia's Warbler and Julie Craves

 
The typical breeding habitat for Virginia’s Warbler is dense shrubs, Ponderosa pine and pinion-juniper forests at 7500 to 8000 feet elevation.
This Virginia’s Warbler had a great deal of body fat, and weighed 9.1 gr. After it was banded and photos and other measurements taken, it was released. It was not resighted.
Prior to this 1993 record, there were very few records of Virginia’s Warbler east of the Mississippi. They were:

• 16 May 1958, Point Pelee National Park, Ontario. Male, collected.
• 6 October 1962, banded at Island Beach State Park, Ocean Co., New Jersey.
• 9 to 11 May 1974, photographed at Point Pelee National Park, Ontario.
• 5 May 1975, Point Pelee National Park, Ontario.
• 6 May 1979, Evanston, Illinois.

Since the RRBO record, there have been two others in Michigan. One 20 to 21 May 1997 in Chippewa County, and the other a bird banded 25 June 2006 in Kalamazoo County.