Thursday, August 28, 2008

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.

Tuesday, August 26, 2008

EIC newsletter available

The latest issue of "Natural Explorations," the newsletter of the Environmental Interpretive Center here at UM-D, is now available; click this link to download the PDF. In addition to the fall public natural history program announcements, there are two things that should be of interest to Net Results readers. First is a book review on Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens, a book also on RRBO's recommended books page. This important book explains that when native plant species disappear, or are replaced by alien exotics, the insects that depend on them disappear, thus impoverishing the food source for birds and other animals.

A related flyer I developed, Landscaping for Migratory Birds, is also included in the newsletter, or you can download a PDF of the flyer alone by clicking here. It includes a list of points to remember when landscaping for birds, plants that are important to birds for both spring and fall seasons, non-native species to avoid, and further resources. If you are contemplating doing some planting this fall, please check it out!

Friday, August 22, 2008

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!

Wednesday, August 20, 2008

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:

Tuesday, August 19, 2008

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!

Sunday, August 17, 2008

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!

Friday, August 15, 2008

Welcome to Net Results!

Communicating regularly with supporters is a challenge for a bird observatory on a budget. The RRBO web site contains over 100 pages and a wealth of information, but is not always the best venue for relaying more casual news or for conversational exchange.

The intention of Net Results is to bridge that gap. All of our latest bird sightings, banding results, publications, and other research will continue to be posted at RRBO's site. Net Results will be an outlet for more in-depth insight to the day-to-day goings-on at RRBO, a place to post and discuss other bird-related news, and offer readers a chance to comment on posts and interact. I generally have a pretty full plate, so you will have to excuse me if I don't post something daily, but I will try to make what I write here worth stopping by to read.

Feel free to offer suggestions on topics for further posts in the comments!