Colorado has 8.3% of the U.S. population of Violet-green Swallows, coming in a close 3rd after Alaska (10.5%) and Washington (8.5%). VGSWs—-especially the males—-are lovely, graceful, chattery birds. It’s a challenge to find a photo on the Internet that does justice to the eponymous violet and green areas of the adult male. Heaven knows we tried our darnedest this year. While neither of these is ideal, you can at least get a hint of the colors. You will need to enlarge the photo (click on the photo once) to see the green on the shoulder and head in the first one and the overtail covert violet patch in the second.
The females are much less spectacularly colored. Here’s one waiting not so patiently while we bother her box, with an insect in her mouth. (You will need the larger format to see that also.)
You can find information about the natural history of VGSWs at the Sialis Web site.
This year, we had 17 VGSW nests in nest boxes—-the most frequent occupant by a factor of 3. (The next highest number was 6 Mountain Bluebird pairs.) We caught this female trying out a box for size and location—-I love the feather smile.
VGSWs are the latest of the cavity nesters in our area. This year, the first signs of nest construction occurred in early June. Their nests are usually easy to differentiate from the other species starting nests at the same time—-for us, typically just the Ash-throated Flycatchers—-because they always incorporate feathers. Lots of feathers. Some are rather skimpy, structurally, especially those started from scratch as the one below was.
Some refurbish the nest of an earlier cavity nester, adding their own touches—-and feathers—-to the structure. This year, VGSWs took over a used MOBL nest, a JUTI nest, an MOCH nest, and 2 WBNU nests. Here’s a photo of the JUTI conversion.
This year, a very industrious VGSW went a bit crazy with feathers. Just as the VGSWs were starting their nests, we also had a large number of Band-tailed Pigeons (BTPIs) coming to our feeders. Sky-darkening flocks of BTPIs. With such large birds moderately close to the house, we not surprisingly had a number of window strikes—-producing a large number of BTPI feathers available for VGSW nests. The nest of this female looks as if she had murdered a BTPI and stuffed all of its feathers in her nest. She was “caught in the act” with a feather in her mouth in the midst of a sea of other feathers.
VGSW eggs are small and unmarked–almost translucent until just before hatching. Here’s a photo of an unhatched egg left in a nest after the nestlings had fledged, using the “universal size tool”—-the penny.
Here’s a nest with eggs in it. The nests in our boxes this year had 2-6 eggs, with an average of 4 eggs per nest.
These hatchlings are less than 1 day old. Seeming to mug for the camera (“All right, Mr. DeMille. I’m ready for my close-up”), the fellow on the far right (the first to hatch) really shows off the “clown lips” of the large (relatively speaking) mouths and white gape flanges (edges of the beak).
Next, the same nest when the nestlings are about 6 days old.
And again, the same nest at age 15 days.
Here is a clearer photo of a different group of nestlings around the same age—-17 days old. (Rather than using the hand mirror to get a better photo, Zell had to use the mirror to keep this adventurous dude from hopping out.)
Here’s a different nest of soon-to-be fledglings—-about 22 days old. These kids probably fledged the following day or so.
And finally, a soon-to-be-fledgling, getting ready to take the plunge. (Its nestmates had fledged the day before.) It looks very much like an adult female except that the white gape flanges are still apparent, making the beak appear to be light with a dark tip rather than all dark.
For those who might be curious, the entrance hole in this box is a variation of our typical 1.5″ round hole. Zell had read that swallows sometimes like diamond-shaped holes. So, he adapted a 1.5″ hole to this diamond shape. He extended a line from the horizontal diameter 3/4″ on each side. He then drew a triangle on each side with the 3/4″ point as the apex. Using a saber saw, he removed the material within those triangles and—-voilà! A diamond-shaped entrance. He altered the entrance holes of 2 of our boxes; one was taken by this VGSW family and one was taken by a chipmunk. Both seemed pleased with it. But with these 2 boxes representing just 2% of all of our boxes, we can’t really say anything definitive about the VGSW preference at this point. It should be noted that this design might not be advisable if your area has European Starlings; I believe they like this shape as well and can squeeze in the opening. (You can see the dimensions of our typical box at nest box monitoring.)
© 2008 Tina Mitchell