Hummingbird bills in the Pacific Northwest

George Walter

Jill Severn | The JOLT News

Those of us who listen to NPR heard recently about research into the bill length of our Pacific Northwest Anna’s hummingbirds.

Apparently, they have been getting longer as their range expands northward. That got me to thinking about just how unique hummingbird bills are, and how long humans have been collecting hummingbird specimens and studying them. 

Imagine for the moment 19th century European naturalists receiving hummingbird specimens from New World explorers. They receive shipments of tiny dead birds with bright throat feathers and long, very thin bills. They are amazed. There are no birds remotely like this in the Old World.  

Those same New World explorers also described how these birds hovered next to flowers, sticking their bills into each blossom to sip nectar. Their description of the humming of these birds’ wings gave rise to their common name.  

An Anna's male hummingbird in flight.

Liam Hutcheson | For The JOLT News

Hummingbirds only exist in the Western Hemisphere. Most species are found in Central and South America.

However, the home ranges of a few species extend into North America, including our own Thurston County. To date, there are 366 recognized species and more continue to be found. A new one was identified in 2017 in Ecuador, and another in 2024 in Peru.  

As with all birds, their bills are designed for eating. But here’s as interesting thing — like their big bird cousins, hummingbird bills also serve as weapons. Male hummers of some species use those bills as mini-swords in their competition for breeding territory.  

Some folks might think of the hummingbird’s bill working like a straw to suck in nectar. But the bill actually contains a tongue that laps the nectar, moving rapidly in and out. By standing very still, you might be able to watch this at your window feeder. Hummingbirds have the longest of all tongues in proportion to the birds’ overall size. 

A close-up of a female Anna's hummingbird.

Liam Hutcheson | For The JOLT News

Hummingbird bills have served as a prime example of evolutionary adaptation with some species having long curved bills (and longer tongues too) apparently adapted to access the long tubular flowers of specific plant species. It is these highly variable bills and tongues that have most intrigued research biologists. 

Which brings us back to our Anna’s hummingbirds. When they were first described by 19th century ornithologists, their range was limited to chaparral (dry brushy shrubland) habitat in southern California and northern Mexico. Anna’s range gradually expanded north, but even in the 1970s, its northern range edge was in the San Francisco Bay area of California. 

In the succeeding 40 years, Anna’s have expanded their range so far north so that they are now common in coastal British Columbia. Anna’s also have become adapted to surviving harsh winter conditions, a feat well documented by increases in the annual Audubon Society Christmas Bird Count numbers, including in our own Olympia count.  

Many writers have suggested this range expansion has been facilitated by the proliferation of hummingbird feeders and ornamental plants that bloom in winter. The ornamental plants also attract small insects that hummingbirds catch on the wing. Nothing like a nice protein snack on a cold winter morning. 

Someone, probably a Ph.D. student looking for a dissertation topic, wondered if the Anna’s in this expanding population were undergoing actual physical changes, especially to their bills. That’s not an unreasonable hypothesis since hummingbirds in general are known for great variation of bill size and shape.  

So, they set about measuring bill length and width (I can imagine measuring length, but width?). It turns out that bill length varies within a population and between sexes, but all that evens out if one has a large enough sample.

And, as it turns out, over the past 200 years a ton of dead Anna’s have made their way into museum collections, and each specimen includes its specific location. 

I have this mental image of an ever-patient Ph.D. student opening drawers full of Anna’s hummingbirds, measuring the length and width of each bird’s bill, entering the data and location into a data table, and then moving on to the next museum. I’m ever thankful that all I have to do is write about the effort. 

Here’s the bottom line: The research shows that Anna’s Hummingbirds in the northern part of the species range have statistically significant longer bills and, very surprising, the female bills have a greater curve. This rapid change is stunning, really, when you consider that these 40 years represent only about 20 generations. In this case, evolution is happening fast. 

And here’s another evolutionary variation: The bills of the British Columbia birds are not as long as those in the rest of the Pacific Northwest, but they are thicker. Perhaps having a shorter and thicker bill provides some degree of protection from winter’s extreme temperatures further north.  

Finally, this study demonstrates the immense value of museum specimens and why maintaining museum collections is so important. They provide important basic information that is essential for future inquiries and therefore are a very worthy expenditure of public funds, even in times when “cost cutting” seems to be a popular political slogan.   

George Walter is environmental program manager at the Nisqually Indian Tribe’s natural resources department; he also has a 45+ year interest in bird watching. He may be reached at george@theJOLTnews.com 

Photos for this column are provided by Liam Hutcheson, a 17-year-old Olympia area bird enthusiast and avid photographer.