A summer with hummers

Local researcher wraps up seasonal study on Rufous hummingbirds

The perfectly healthy Rufous hummingbird lay motionless in her open palm, in a trance of sorts.


Gwen Baluss, a wildlife technician with the U.S. Forest Service, had just finished banding, measuring and examining the little bird with the care a parent would take with a newborn.

It was May and snow drifts still lingered in the shadows. Despite the still-drab outdoors, the hummingbirds were alive with fervent activity in the chilly air, busily searching out nectar to refuel after a long migration north.

Back in Baluss’ hand, in the warmth of the spring sun, the hummingbird suddenly took flight, zooming into the cover of the surrounding spruce trees. It chattered its annoyance back at the group of observers.

Everyone smiled. Another bird had been counted.

Then, Baluss reached into her jacket and produced a white mesh bag. She extracted its contents — another hummer, another female — and began the process of weighing, sizing and assessing all over again.

Baluss has been recording data on Rufous hummingbirds all summer and now, with the males already gone, she’s wrapping up her research as the last of the birds — the females and juveniles — begin their migration south.

The study had multiple objectives.

“The goal is multifold,” Baluss said. “We want to learn more about the birds, what they do when they’re here and when they’re migrating.”

Specifically, she said they were interested in what native plants they preferred, how far they’d range and how often an individual bird returned to the feeder, to name just a few.

In all, Baluss and her team of volunteers banded more than 130 birds since the study officially began on April 23 at the Jensen-Olson Arboretum. They started a bit later at the Juneau Community Garden. Both places, she said, were chosen because of the prolific blooms that show up during summer months. The hummingbirds, she figured, would know about those places already.

Even with feet of snow still on the ground, Baluss and her team began capturing hummingbirds within the first few weeks.

She said the males arrived first, followed by the females. They were captured simply; a soft net was suspended over a feeder and when the bird arrived for a snack, the net was silently dropped. Baluss would reach in, clasp the bird in her hand and tuck it inside a mesh bag, before stowing it away under her jacket and against her skin to keep the bird from getting too cold and too stressed.

“One interesting thing I found through this study is that these little birds are a lot more resilient than we are in cold weather,” she said. “On those early spring days our hands would be cold and we’d be very uncomfortable, but when we’d get a bird they’d be fine. They didn’t really show signs of stress related of the cold, which is good.”

Baluss said part of that is tied to the Rufous’ unique ability to enter a state of torpor, which means they can lower their body temperature overnight.

“This helps them cope with cold weather and save energy,” she said.

Once captured, Baluss would pluck the bird out of the bag and take measurements. She measured the length of the beak, the length of the wings from “shoulder” to tip. She’d count the number of iridescent feathers on the throat patch, which is like a bird fingerprint — the number, shape, size and coloration are completely unique. She’d snap a photo. Pinch on the tiniest of tiny bands on the leg and jot down the near microscopic number on the metal bracelet. Baluss blew on the feathers of the belly, revealing the paper thin skin beneath. The feathers would spread like parting waves to reveal veins and arteries, muscle and fat deposits. On the females, she’d use this technique to view the vent of the bird — the exit site of the egg. By doing this she could tell if the female had recently mated, laid an egg or was ready to lay. On one female, the perfect outline of a dainty oblong egg could be seen directly under the surface of the skin.

Then, Baluss would lay the bird on a tiny scale, the kind one might find in a laboratory. The hummer wouldn’t budge; it seemed entranced by the process. She’d quickly jot down the number — the females always weighed more than the males — and sweep the bird once more into her hand. In a sunny spot she’d lay her palm flat, opened up to the sky and, after a moment or two, the hummingbird would zip away, often annoyed, but completely unharmed.

“The thing that was really interesting to me is that we kept getting new birds. We wouldn’t get recaptures the same day or even two weeks later,” she said. “We had zero recaptures at the Jensen-Olson Arboretum. All the birds we got there were new birds. That just blew my mind.”

Baluss said she fully expected some males — who were especially territorial — would end up as recaptures. And with the females, who would come and nest, she expected the same. Even the juveniles, she said, must not stray far from the proximity of the nest.

But even at the Community Garden, her recapture numbers were slim. In all, the team had four recaptures.

“On May 7, we initially banded a group, and then we recaptured some of those on May 19,” Baluss said. “I was just happy to see that they were healthy and that the bands were looking good.”

Another recapture happened on July 2.

“That female was probably a local nester, because she did have young around with her,” Baluss said. “She was skinny. Probably busy caring for young.”

Baluss speculates the low recapture rate was because the birds wised up and would avoid the feeder when the net was in place.

“Yet it also shows there’s a whole lot of other birds,” she said. “I often assumed it was the same birds that would keep coming back to my home feeder all day, but clearly there’s more to it than that.”

Generally speaking, Baluss believes her research this summer supports the theory there are more hummingbirds in Juneau during the late spring and summer months than people originally thought. This is a good thing, she said.

“We also know they’re moving around in a wide area, too,” she said.

Baluss hopes, if they repeat a similar effort in the same spot from year-to-year, that a trend will emerge. That trend could be migration timing — how many arrive and at what time. Or, it could be sex-linked — more males than females in an area, for example.

As far as total population numbers go, Baluss said it’s almost impossible to tell how many make their “home” in Juneau.

She said their sampling effort wasn’t huge when compared to other efforts but it’s enough to track when they’re around and already — through observations of local birders and our banding effort — she said the team is going to refine and expand the known spring arrivals and as well as the times the females are here.

“So we’re going to have much better dates on arrival, departure and when the first fledglings are coming out than we have had in the past,” Baluss said. “The other thing we’re interested in is what they’re feeding on. And that’s not related to the banding, but just collecting those observations on what native plants they enjoy.”

That information will be handy to organizations, she said, such as the USFS, on putting out information on pollinators.

“Not only for private gardens, but also restoration projects will be better informed on the proper flower selections for hummingbirds. We want more information for Alaska on that topic.”

For now, Baluss is pouring over her results and logging them into the national database. Next year, she hopes to see some of this summer’s birds again.

“It would be great to get some recaptures so we could see where these birds are going,” she said.

One thing is for sure, all the birds are headed for warmer climes, certainly bursting with the kind of broad blooms only found on Mexico’s mainland and Baja Peninsula.

• Contact Outdoors Editor Abby Lowell at abby.lowell@juneauempire.com.


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