When I initially got into studying the Chignik Drainage’s birds, I thought that a loon was a loon was a loon, a species I knew primarily from seeing Common Loons. I assumed that that is what a loon is. It turns out that there are five species of Gavia, four of which occur in the Chignik Drainage. In order of common occurrence, they are: Common Loon, Pacific Loon, Yellow-billed Loon and Red-throated Loon. (Only the rare Arctic Loon is absent from The Chignik.) It is probable that in the salt waters of the nearby Alaskan Gulf that from fall through spring it is the Pacific Loon that is most common.
We encountered Yellow-billeds as wintertime visitors to the main lake and the river outflow just below the lake. In wintertime, their plumage is rather drab (you’ve got to go to the most northern parts of Alaska, or Siberia, to see them in their stunning breeding colors); however, even in winter these, the largest of the five loons, were easily distinguished from Common Loons by their big, lightly-colored, yellow-tinged bills. We found the Yellow-billeds to be shy and to prefer deep water. The only photos I was able to get were taken using a 600mm lens affixed with a 2.0 teleconverter of far off specimens – and even those images require significant cropping to present a picture such as the one above. Still, Yellow-billeds are uncommon to rare and adding them to the Chignik Drainage List – perhaps a first documentation and almost certainly a first photograph – was a thrill.
Any documentation of this sort is important. As the planet continues to rapidly warm – due largely to a certain overpopulated species’ reliance on burning fossil fuels and turning forests to farmland – things are changing. Fast. (It’s not just that the climate is warming – it’s been doing so for a very long time. It’s the recent rapidity at which it is warming.) Audubon’s climate model projects a 64% loss of winter range for Yellow-billed Loons in coming decades. Not centuries. Decades.
Wherever you live, it is likely that you can see changes in flora and fauna over time. And these changes are not due only do warming. Although in pure numbers countable trees have increased in many areas, most of this new growth is in the form of pulp and timber forests – trees destined to be cut down just as they are reaching maturity. As fewer forests are allowed to reach and sustain maturity, there is less mast (acorns, other nuts, seeds and seed-bearing cones) for animals to forage and often fewer nesting sites as well. Wild grasslands have nearly disappeared from our landscapes. In many locales, streams, rivers and lakes have become warmer, shallower and increasingly over-nutrified owing to run-off from fertilized lawns and farms. So grab a pair of binoculars, a notebook, your iPhone or camera and get out and observe. The regular outings might prove to be a great education, and a daily walk is invigorating.
Anyone who has much studied biology in general, birds in particular, or evolution specifically has undoubtedly encountered “Darwin’s Finches” and the remarkable diversity in bill shape that evolved among a species related to tanagers (not true finches) that became geologically isolated on the Galapagos Islands. Darwin visited the islands, which straddle the equator approximately 560 miles west of Ecuador, in 1835. There he collected (his servant shot) an array of birds featuring 18 different bill shapes. The variation correlated with the different foods each type of food the birds had adapted to take advantage of on the islands. As all of the species Darwin identified originated from a single type in genus Geospiza, Darwin’s Galapagos finches have long been held up as an example of how evolution works. It’s a complex process that occurs over time and I don’t want to oversimplify it. However, for the purpose in this article, it is useful to think of 1) an underutilized food source and 2) genetic isolation. The original tanager-like specimens of a single type in genus Geospiza became isolated on the Galapagos islands. Given an absence of competition from other species of birds and an abundance of various foods – insects & invertebrates, berries, seeds of different size -, various forms of the original type of Geospiza evolved different bill shapes and sizes (and even different body types) as they keyed in on a given kind of food.
Somehow, I think, (speculate), vocalizations must have played a key role in the genetic isolation that concurred with the move toward food specialization among these Galapagos finches. Most species of birds have a variety of calls and songs, each of which conveys a specific meaning. Black-capped Chickadees, for example, communicate with at least 15 different sounds (let us think of them as words) differentiating everything from the approach of different kinds of predators (one vocalization for ground predators, another for aerial predators) to vocalizations used during breeding, to identify food sources, and so forth.
Bird vocalizations play an important role in differentiating similar species. For example, although certain thrushes to the untrained eye appear quite similar, their songs are different enough to easily distinguish. Similarly, the Pacific Wren found in west coast states from California to Alaska is nearly identical in appearance to the Winter Wren which is found in the east and midwest. But the songs of the two species are different. Thus, they are genetically isolated from each other as much by their vocalizations as by geography. After all, they have wings. They are thus able to transcend geographical boundaries. Their songs – agreeable to members of their own tribe, a foreign language to others – helps keep the two populations separate.
Apparently a good bit of the above applies to Red Crossbills. I have photographs of Red Crossbills from Montana that show a recognizable difference from the Red Crossbills we encountered at Chignik Lake. The Montana birds have larger bills. What causes the difference? Probably diet. The Montana birds we saw were feeding on the seeds of Ponderosa Pine cones. My guess is that it takes a more substantial bill to get into the harder, tighter pine cones than it takes to pry apart the looser scales of the softer Sitka Spruce cones found at Chignik Lake and other locales in Alaska.
But, again, crossbills have wings. So, no doubt playing an important part in genetic fidelity among different types of crossbills are their various vocalizations. According to Audubon, there are as many as eight different types of Red Crossbills in North America, and these varying types are most reliable distinguished by their different calls. At least eight. I’ve read elsewhere that there are as many as 11 different types. This is relatively recent insight. In T. Gilbert Pearson’s Birds of America (© 1917), the Red Crossbills of North America are called American Crossbills; there is no mention of diversity among what was then a sparsely-studied species.
So, just as ichthyologists have come to understand the significant genetic variation that can exist among a given species of fish – such as Steelhead or Coho Salmon – as each kind of Steelhead or Coho has adapted to thrive in a given river system – ornithologists are coming to understand that there can be a great deal of intra-species variation among birds as each type within the species has evolved features allowing it to thrive in a specific habitat.
To me, the take-away lesson here is that we should not merely be focusing on the preservation of life forms on the species level, but that instead we should be dedicated to the preservation of each unique biome and ecosystem.
CutterLight 