Broad-tailed Hummingbird (BTLH)

Broad-tailed Hummingbirds (BTLHs) are a decidedly western hummingbird.  Surprisingly (at least to me), Colorado leads the nation in BTLHs, with 37% of the population.  NM ranks a pale 2nd, with 17%; UT, 12%.  The BTLH is by far the most common hummer in our area, arriving in late April and early May.  In early July, we begin to see Rufous Hummingbirds—our 2nd most common hummer—as they leave their breeding grounds and begin their southern migration.  We usually see an occasional Black-chinned Hummingbird and diminutive Calliope Hummingbird at our feeders late in the season.  But BTLHs are our common breeder.

In mid-June, while checking the nestboxes, I heard a BTLH “whistle” by.  (BTLH wings make a distinctive cricket-like chirp.)  Suddenly, the chirping stopped near a tree I was standing by.  Scanning the tree with my binos, I spotted a female on a nest about 10′ or so above the ground.  I couldn’t believe my eyes.  Even when we were atlasing for the Colorado Breeding Bird Atlas, we never saw a hummingbird nest.  We were able to confirm the species as a breeder simply because we had seen a female disappear into a cottonwood with a large insect in her beak.  I grabbed my camera and snapped a few shots of where I thought I had seen it in the tree, although I really couldn’t see anything through the viewfinder. The photos below give you an idea of the amazing camouflage so common with hummingbird nests.  If you click on the left photo, you’ll see a larger version with a black oval encircling the nest with the female on it.  The photo on the right shows the nest from a different angle; the nest is the dark mass just above the center of the photo.  (Click on this or any photo to see a larger version.  Then use your browser’s “back” button to return to this page.)

I made a note of where the nest was and kept on checking the boxes.  Once I got back to the house, I found Zell and we both motored back out there on the ATV to see if we could find the nest again and if he could get photos.  We were in luck.  I was able to direct Z to the nest; he positioned the ATV under the nest and was able to stretch up to get some photos.  When we first arrived, the female wasn’t on the nest, so he was able to take several photos of the nest and the nestling.

First, a close-up of the tiny nest. The outer covering is mostly lichen, held together by strands of spider webs (which you can actually see in the larger version of the photo). The spider webs let the nest expand as the nestlings grow.

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Here is a look inside the nest, which is perhaps 2″ in diameter and20090612_BTLH_ nest maybe 1.5″ tall.  The light interior is a lining of spider webs and “gossamer”—-strands that various insects use to move from one tree or shrub to another tree or shrub. (Zell got this photo standing on the ATV, using the hand mirror he uses to get photos of the nestlings in the nest boxes. The nest was only about 10′ off the ground.)

BTLH nests generally have 2 eggs. Although it’s hard to see in the cropped photo on the left, 2 nestlings are curled up in there.  (You 20090612_BTLH_ 005rccan get a hint of some strange-looking spiky down on what I think are their backs.)  On the left side of the next—perhaps at about 8:00, if you think of the nest as the face of an analog clock—you might see a beak pointing to the right; there’s a hint of a head on the right side of the nest, but it’s not very clear. (Again, click on the photo to see them better.) The babies are born dark-skinned, unlike many other baby birds (which tend to have lighter skin). Perhaps that’s a disguise strategy. In this (relatively speaking) deep nest, they can hardly be seen. (I had to lighten this photo quite a bit.) I haven’t been able to find much information describing the development of BTLH nestlings, so I’m not sure about the age. If you go to this page and scroll almost to the bottom, you can see photos of nestling hummingbirds. (I’m guessing they’re the eastern species, Ruby-throated Hummingbird, since most westerners differentiate which hummers they’re talking about because the choices are myriad.) Using these photos, I’d say the nestlings we found might be between 3 and 5 days old. Birds of North America Online says that by 10 – 12 days old, the nestlings are feathered and big enough to fill the nest when they are huddled together. These guys don’t even quite fill 1/2 of the nest. So, “young” is a safe assessment for now…

Mom zipped in just as we were wrapping up the nest shots and plunked herself down on the nest.  The photo op was officially declared complete.  Something that many people don’t realize about hummingbirds in general is that they not only eat nectar, but they eat lots of insects too.  This is especially true during breeding season, when they and the nestlings need a lot of protein.  The mother feeds the nestlings by regurgitating food from her crop into their mouths (veeeerrrrrryyyy carefully, given her long beak). In a week or so, she’ll feed them insects directly, regurgitating food less and less as the kids mature.  (The males have nothing to do with raising the young; they just provide fertilization and then spend the rest of their time defending territories and making appearances at various feeders and wildflowers.)

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Here’s a photo of the nestlings 9 days later—still too small to show above the nest. So perhaps the age I guessed when we first found them was 20090621_BTLH_1rc a bit old—maybe they were only 1-2 days old? If you click on the photo below to see the enlarged version, you can see the tip of a small beak at about 2:00 on the nest edge; when I zoom in on the photo, I think I can see the hint of the yellow gape flanges and a small beak at about 8:00. Maybe. (I guess the classic hummer beak is one of the last thing to start to grow. If they had those daggers before they were big enough to get their heads above the nest edge, they’d constantly be skewering each other.) This photo makes it look as if Zell were in the tree above the nest, but have no fear—again, he was standing on the ATV, stretching to his full 6’+ height, shooting into the hand mirror I use for nest box monitoring.  As before, the female zipped in as we were wrapping up and eyed us from the top of a nearby tree. Always good to see a vigilant parent!

Five days later and getting big now, looking more hummer-like. These hummer-lettes are perhaps 16 -17 days old. You can see one still-not-quite-adult-sized beak across the left side of the nest; the 2nd nestling may have its beak under the other’s, so it looks truncated. Still some growing left to do, but this would be the last time we’d see them.  At the next check, all that was left was the stretched-out nest and some great memories for me.

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One Response to Broad-tailed Hummingbird (BTLH)

  1. Pingback: Greenwood Wildlife Rehabilitation Center - Saving Colorado's Orphaned and Injured Wildlife

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