Saturday, August 28, 2010

Fall banding 2010: Week #2 in review

Warblers welcome!

Week #2 was abbreviated due to my participation on a state advisory panel. The modest totals for the week were 59 birds of 21 species, plus recaps and another batch of hummingbirds released unbanded. Returns of birds banded in previous years included a female American Robin from 2007, and a Gray Catbird from last fall.

The best part of early fall is the nice variety of warblers that start to come through. Later, we'll have higher numbers of some species, or more diversity of birds overall. But this early in the season there is a nice parade of often-subtle, but always pretty, warblers. Here are a few from this week:

Blackburnian Warbler.

Chestnut-sided Warbler. Am I the only person who thinks the green looks like the color you get when you use a yellow highlighter on newsprint?

Black-and-white Warbler.

Wilson's Warbler. Audubon called this species "Wilson's Flycatching Warbler" and you can tell they do some aerial flycatching by the "whiskers" around the bill, known as rictal bristles. They help trap small flying insects.

Tennessee Warbler. More of a gleaner, it lacks the long rictal bristles of the Wilson's Warbler and uses its sharp bill to probe leaves for insects.

One thing we note when we band Tennessee Warblers is the presence (and size) of a white spot on the outer tail feather. About 30% of adult and 20% of hatching-year birds have this spot at our site, and usually if it is present in hatching-year birds it is smaller than this.

Other highlights this week included our first Swainson's Thrush, one of my focal species in my study of use of resources during migratory stopover.

The biggest thing I got in the nets was a female Cooper's Hawk. This is only the third Coop we've caught at RRBO, since they are generally too large and heavy to stay in the nets; and the first female, which are larger than males.

I've been grabbed by little male Sharp-shinned Hawks, which are only about the size of a flicker, and they have needle-sharp talons than can hardly be felt going in...but can be a real problem when the bird starts tugging to get them out! This big female Coop had talons to be respected and very long legs. It's times like these I'm glad I always carry too many bird bags. I handed her a wad to grab onto until I could secure her legs. Really, you can never let go of the legs when handling a hawk, so banding one is much easier as a two-person job. As luck would have it I was working alone and nobody was even in the building to snap some photos. Everything went without mishap as she was quite calm and cooperative, but I wished I could have photographed her eyes -- she had the very green-gray eyes of a young bird (soon to turn yellow and eventually red). That and the fact that her back feathers had extensive rufous tips may indicate she was hatched locally and not a migrant from farther away.

With hawks you worry about the feet, with Rose-breasted Grosbeaks you worry about getting bitten. That bill is very strong and while I've never had one draw blood, they pinch so hard you get left with a divot on your finger that lasts for hours. Plus, they just have nasty dispositions. This adult female didn't nip me, since I've handled enough of them to know not to be careless and always put them in a distinctive colorful bird bag so I don't get surprised when I reach in.

The weather forecast for at least the beginning of next week sounds like a return to summer; not very conducive to migratory movement. We'll see what ends up in the nets.

A reminder that we are moving the RRBO web site in the next few days. Please use this URL to access the current/soon-to-be-replaced site, it will continue working: and use my long University address (jcraves AT umd DOT umich DOT edu) or gmail address (jac DOT rrbo AT gmail DOT com) to contact me. Don't use the jac AT rrbo DOT org until further notice.

I'll be posting frequent updates here -- I'm very excited about the new site and can't wait to hear what you think!

Saturday, August 21, 2010

Fall banding 2010: Week #1 in review

A week of scruffy birds

RRBO's 19th fall banding season got underway this week. First, a big thanks to local birder and RRBO volunteer Jim Fowler, who decided his songbird banding days are behind him, for donating his net poles to us. And to Robert Schubert, EIC student staffer, for cutting a whole batch more. We have a full set of straight poles to work with this season. Robert and Dana Wloch, one of my undergraduate research assistants, also helped out with getting the net lanes ready for banding. Many thanks!

The first week of banding usually starts slowly, as I tend to be putzing around pruning net lanes and putting up the final nets. This week there were 78 new birds banded, 4 recaptures, and 18 birds released unbanded (14 Ruby-throated Hummingbirds, the rest House Sparrows). This represented 25 species. Most were local breeders, but migrants included Least and Yellow-bellied Flycatchers; and Black-and-White, Nashville, Magnolia, and Chestnut-sided Warblers.

Most of the locally nesting species have one thing in common this time of year: they are in the midst of their fall molt. Once finished with nesting, adult birds replace all of their feathers. It occurs systematically, so they can still fly, but not quite as well. Thus a lot of adults tend to be a bit secretive.

Gray Catbirds are our #1 species. This adult female was originally banded in May 2008, and recaptured this week. What a mess.

Young birds (born this year and called "hatching year", HY for short) are also beginning to molt heavily now, replacing their juvenal* plumage with their first set of adult feathers. This HY catbird is actually one of the better looking individuals.

Most HY songbirds only molt body feathers, but some species also replace some flight feathers (wing or tail). Upon examination, it looked like this disheveled HY Song Sparrow lost its tail and was replacing it, versus a normal molt. The rest of the messy look was typical, though.

Indigo Buntings nest on campus, but I've never had a nest in the banding area until this season. This recently fledged bird was being tended by a male parent, or I might have had a hard time figuring out what species it was! When I catch a bird this young, I immediately run back to the banding lab, process the bird, and run back and return it where I found it. Once reunited with his offspring, the dad quit scolding me!

Up to about 5 or 6 years ago, Blue-gray Gnatcatchers didn't nest on campus. In fact, 20 years ago, I don't remember them nesting very frequently in the county. During the first Michigan Breeding Bird Atlas (1983-1988), breeding evidence was noted in only four quarter-townships in Wayne Co. Things have changed rather dramatically. During Michigan Breeding Bird Atlas II (2001-2007), 39 quarter-townships had breeding evidence, and for the last few years, three to five pairs have nested on campus. This HY bird, likely from a family that has been present this summer near the banding area, is only the 12th RRBO has banded since 1992, and only the second in fall.

Two interesting "abnormal" birds were banded this week.

This HY Eastern Kingbird, probably from a nest on campus, had fleshy tumors on the "shoulders" of both wings. The tumor on the left wing was small, but this one on the right wing was 14.2 mm. I see tumors of this sort from time to time. I suspect this was a feather cyst; a contributing factor for this condition may be malnutrition. This bird also had a prominent "fault bar" on the tail. This occurs when actively growing feathers stop growing for a period of time due to nutritional stress (lengthy discussion here). The bird flew well, but it's hard to say how much this will hamper it on its long fall migration.

American Goldfinches are abundant in one section of the banding area. They are just starting to fledge their young. This bird, however, was an adult male. Note that the first secondary feather on one wing was completely black on the underside, rather than having a white base. Usually when one sees birds with odd-colored feathers, the aberrant feather is white. Excessive dark plumage, or melanism, is less common, and I don't recall ever seeing single melanistic feathers or patches of melanistic feathers any birds, much less the many thousands of goldfinches I've handled.

This will be the fourth year of collecting fecal samples from Catharus thrushes to examine what kinds of fruit they are eating. It's the second year that Dana Wloch will be assisting by collecting and compiling samples from other bird species. This week resulted in 19 samples being "donated" by catbirds, American Robins, and a couple of Cedar Waxwings.

Welcome rain and the passage of a front this weekend should perk things up next week.


*"Juvenal" is the term for a bird's first plumage; "juvenile" is a generic term for a youngster. For more on plumages and molts, extremely useful in aiding in ageing and identification of birds, Plumage and Molt at Audubon Guides, and Molt and Plumage Lab at Biological Ramblings. An excellent new book on the topic for birders, Peterson Reference Guide to Molt in North American Birds was published this year. I recommend it.