Monday, September 9, 2013

Late Summer Hummingbirds

Hummingbird banding has continued throughout the summer, at a number of private homes across the southern Lower Peninsula of Michigan. 

In addition, three public banding programs were conducted during August, the first at the Shawnee Prairie Nature Center in Darke County, Ohio (none banded, too many bees!). The next weekend it was at the nature center of the Indiana Dunes State Park, Indiana (25 banded), and the weekend after that it was at the Birds and Blooms festival at The Dahlem Center in Jackson, Michigan (5 banded including one rescued from inside one of the buildings!). So far, preliminary results from the summer seem to show that there have not been record high numbers banded so far, but neither has it been a record low year.

August is the month to study molt in hummingbirds at Michigan's latitude (42-48 degrees north). After the adult females are finished with nesting duties, they molt their body feathers, but not wing or tail feathers. Adult males play no role in raising the young, but they also molt at this time of year. Some of them are quite obviously molting, as they have many visible pinfeathers, while many are molting feathers under the surface and appear not to be molting to the naked eye. Only in-hand examination can accurately assess the molt status of a Ruby-throated Hummingbird.
After hatch-year female Ruby-throated Hummingbird

Adult male Ruby-throats migrate early, often beginning to depart the Upper Peninsula at the beginning of August, with most of them gone from the state by September 10. It is not clear whether they complete their body molt  before they leave, or if they molt and migrate simultaneously. My impression is that they do the latter. But finding an adult male in early September with no molt, and pristine-looking feathers, is an indication that it has completed its molt. There is a little controversy about whether or not this species has a separate "alternate" plumage, with the spring throat feathers being ruby red while the fall and winter throat feathers sometimes being claimed to be "orange". The bird below, wearing what is almost certainly fall/winter throat feathers, does not appear to me to have a different coloration than I'd expect in May or June.
Adult male Ruby-throated Hummingbird, September 3, 2013

An odd situation occurred this summer, with the capture of two different adult female Ruby-throats with bright orange bellies; something we've never seen before. The first was captured by Brenda Keith in late July in Barry County, southwestern Michigan, and the second was captured by yours truly in early August in Jackson County. This second bird was photographed, and some of these orange feathers were collected (my USFWS permit allows for collecting feather samples) for later analysis. The two photos below show this orange coloration of the Jackson County bird, which was also on the bird's feet and the skin of its belly. In the larger cropped image, it is interesting that there are some tiny seed-like objects, suggesting the possibility of a plant as the source of this "staining".
Orange-stained belly of female Ruby-throated Hummingbird

Close-up of orange-stained belly showing tiny seeds?

 One thought is that this might be nothing more than an exhuberant expression of the normal, occasional buffy coloration found on the flanks of some individuals. But the presence of orange on the breast skin of both individuals suggests this is not the case. Another possibility is that this could be staining from some orange liquid, possibly such as that often used on oriole feeders, as the coloration is very similar. It was also suggested that this was a color-marked bird, by some nearby researcher, but the fact is that these birds were unlikely to be migrating yet, and there are no other hummingbird banders in Michigan. A hummingbird host, who is an experienced gardener, suggested that this might be pollen from Stargazer Lilies, which apparently will stain bright orange if touched, and which have only recently found their way into gardens. This latter suggestion to me sounds the most plausible. Below are two photos of the Barry County individual showing the coloration beneath the feathers on the skin of the breast.
Barry County, Michigan orange-bellied Ruby-throat

Barry County, Michigan orange-bellied Ruby-throat

Samples of these orange "stained" feathers as well as a sample of normal buff-colored flank feathers from another individual were sent to a friend who has access to a scanning electron microscope as part of his job (lucky guy!). He has not finished his examination of these feathers, so there will be a future post on that topic later this fall.

On September 1, an article was published about our hummingbird banding in the Lansing State Journal. Immediately following publication of this article, I got an email and photos from a homeowner north of Lansing, stating that they had a Rufous Hummingbird coming to their feeder! So, the next day (Labor Day), I drove up there to confirm (back coloration was not clear from the homeowner's photos), and banded the bird. Unfortunately, it appears that it continued on its travels and did not stay around. This is par for the course for these early migrating Rufous Hummingbirds, based on many individuals I've tracked as well as many more just passing through early in more southern regions. More Rufous Hummingbirds will turn up as the fall progresses, and hopefully I get prompt reports of all of these.
Adult male Rufous Hummingbird, Clinton Co., Michigan

And finally, other strange things do happen during these summer banding sessions. At one home, I noticed a Northern Walkingstick (Diapheromera femorata) walking on the inside of a screened porch where I was banding. While I was holding it for the homeowner, and some visitors, to take photos it decided to walk up my arm heading for the highest point....which was the top of my had via my face!
Allen Chartier having "face time" with a stick insect

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