Swallows in flight
Along the same lines as my ‘Trillogy’ post, I would like to cover the topic of Swallows in flight. The primary gray area lies among juvy Tree Swallow, Northern Rough-winged Swallow, and Bank Swallow but why not cover all swallows.
Chad and I have had, what I would consider, some pivotal experiences in our birding education in the area of swallow ID. The most unforgetable being the 6 seconds we spent with a Cave Swallow in Fair Haven Beach SP on the shore of Lake Ontario in mid-November. There are a handful of field marks that make or break swallow ID and color is not always one of them. Most often, a swallow in flight is sillouetted making it hard to lock in on the colors so lets try to cover every aspect that could prove useful in the field.
So to get this topic moving (this topic could eventually become a Chat Happens Feature Article) let’s talk Juvenile or female Tree Swallow(TS) vs. Northern Rough-winged Swallow(NRS).
I’ll begin with breast and belly color: Both are brown swallows, but more importantly, TS are two-toned being dark on top and light on the bottom. NRS to me appear to be uniform in color near the head and breast. The belly becomes buffy but not usually white.
What do you think? please let us know.
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May 13th, 2006 @ 11:41 pm
Ryan,
Yeah, swallow ID is often a difficult process, particularly if one is viewing birds under poor conditions, which with swallows can be more frequent than other birds due to their foraging methods which can often place them in harsh lighting causing strong washouts of color, or in extremely backlit situations with little color being viewable (e.g. Cave Swallow in NY on a overcast day). All of this, like you said, results in the usage of color being a good first step in identifying species, but not always useful. So what do we use?
Flight patterns for me, and many birders that I have been around is extremely important, as is tail shape (think Barn Vs Tree). Recent discussions with Rich Stallcup over separation of Tachycineta swallows (Tree, Violet-green), and Hirundo swallows (particularly Cliff and Cave), led Rich to give his “observations” on swallow ID, and one of the main features he used in both sets of swallows was the opaqueness of the wings strongly backlit, and how “twinkly” the birds appeared flapping. Now, he is without a doubt a very astute observer and takes with him many, many years of combined knowledge to reach these conclusions, but it is obvious that more should go into swallow ID than just color or silhouette.
As far as the separation of Northern Rough-winged Swallows (NRWS) and Tree Swallows (TRES) is concerned, there is an obvious size difference (0.5 inch) and flight style difference, but the overall color is a major indication that I go for (if I can get a good look at it). I feel that Tree Swallows in any plumage live up to their species name (T. bicolor), and show a strong difference of brown and white. For Rough-wings I feel that the brown is separated from the white, however there is a blending effect on the chin and upper breast with a diffuse gray-brown that appears as if an artist smudged pencil from the birds back onto the white of its breast.
Once again, I have more observations on this and would like to add more to it, but perhaps a combined effort for an article, or a series of articles, would be best for these thoughts; something along the lines of Kenn Kaufman’s articles in Birder’s World for separation of ‘look-alike’ species. Let me know, and I’ll consider it more (on top of all the other articles I have brewing).
Until next time,
Chad
PS Another great ID aid when viewing swallows is of course their calls. I often have a hard time remembering them from season to season, yet with a little bit of exposure I regain this knowledge, and as I walk in the field I often can know the swallow flocks foraging above me even without looking.
May 19th, 2006 @ 6:40 pm
My last encounter with NRWS left me with the following impressions:
-A smaller swallow
-More “fluttery” in flight than the nearby TRES and Barn Swallows (BASW?)
Ry
May 25th, 2006 @ 8:52 pm
Peterson says the NRWS’s flight is like that of Barn Swallow (BARS-> Not BASW due to Bank Swallow), while Sibley claims the Rough-wing’s wingbeats smooth and flight flowing. So I guess that may contradict your observations…haha. But seriously I know what you mean when you say more “fluttery”. It is one of those things where describing a bird’s flight is anything but easy.
June 25th, 2006 @ 8:27 pm
That’s interesting, on one of my spring field trips, someone described the NRWS’s flight as “more like a bat than anything” and I agreed, It seemed to have quick wingbeats… I’ll have to pay more attention next time. I have not even seen a bank swallow yet this year otherwise i would shift the comments to the other swallows.
bird on, ryan