From a small town to a big city...
|
A Birding Blog
By Jared Conaway
From a small town to a big city...
|
Hi all! Remember my "300th LIFER" post? Well, despite all that information I would like to clarify a little more on it, plus add some aspects that I missed before. First and for most, let's talk about North America's ecoregions. I don't find it a coincidence that there is a "type" of every species that fills in the 4 most important, largest, and most biodiverse ecoregions. To give you a picture of this, have you noticed that there are interior west, pacific, and eastern/taiga White-breasted Nuthatches in your Sibley Guide? What about the pacific, rocky mountain, and eastern Three-toed Woodpeckers and Hairy Woodpeckers? in North America, the Rocky Mountains, Pacific Northwest/California Coast, Taiga, and East Canada/US represent the most distinct, largest, and biodiverse ecoregions on the continent. Because they are so different from each other, when a type species fills in all 4 of those (like the continent-wide White-breasted Nuthatch), the different populations most reflect on where they are found. In a "type species" (I'll define a type species in a moment) found only in the west, than typically it has a Rocky Mountain/Interior West population, and a Pacific/California Coast population. The reason these populations should represent different ecoregional species, is because a species has its own genes, and "pure blood." OK, remember the Koloa Ducks I talked about? Subspecies don't have dominant or pure genes, therefore they will fade away when its full species counterpart breeds with it. So these so-called regional variations would have to be full species in order for their offspring and the generations to come remain specialized in that ecoregion. For example, the Red Crossbills have 10 different types, each specializes in the dominant tree species' cone in every ecoregion. So, if the Sitka Spruce Crossbill and Hemlock Crossbill were to breed, the offspring's bill size wouldn't be able to fit any cone because it would be inbetween the 2, right? So is it really a coincidence that each has a different call type? I mean, if you look at those same 2 crossbills' ranges, you'll see that their distribution parallels each other. However, their flight calls are extremely different, and their songs,too! It also makes sense that 2 crossbill species are found in that ecoregion, instead of the typical 1 per region. The reason it makes sense; The Pacific Ecoregion has such a huge diversity of conifers, that it's only natural that there's 2-4 conifers that dominate the forests opposed to the usual 1 or 2. From northern British Columbia northward, Sitka Spruce and Western/Mountain Hemlock are the predominant forest types, therefore, it makes sense to have a Crossbill that specializes in Hemlock cones and a Crossbill that specializes in Sitka Spruce cones in that region. So, now I want to define a "type species." A type species is a bird that has populations situated in the main ecoregions of, in this case, North America, that actually represent their own species. For example, the 4 Scrub Jays are all different species, but are also Scrub Jays. There's one Blue Jay, but there's Rocky Mountain and Pacific species of Steller's Jays. All though the Blue Jay, and the 2 Steller's Jays are in the same genus, only the Steller's Jays are types of each other, not with the Blue Jay. So bascically a type species is different populations that have subtle differences, but are still their own distinct species. For example, you could collectively call all the different Crossbill species that are red, Red Crossbill. Get the gist? I'm doing my best to make this extremely understandable. The Hemlock Crossbill must have its own unique song and flight call to stay in contact with and attract ONLY other Hemlock Crossbills. With many type species, contact calls, plumage, song ect. are consistent with the ecoregional populations. but then there's the Song Sparrow. Each variation sing the typical Song Sparrow song, they all make the same calls. Maybe it's because since the species is so adaptable in the first place, if a Southwestern and Eastern breed, the offspring will still eventually be able to specialize in the place it hatched anyways, either the east or in the desert. But does that make the variations subspecies or full species? The Fox Sparrow is far less complex. Each regional species consistently sings and calls differently than the others, plus plumages are all very different (except Thick-billed looks just like a big-billed Slate-colored). Besides, "Fox Sparrow" and "Red Crossbill" are way too generic of names! Lastly, I would also like to mention that there is technically a 5th ecoregion, the Arizona Mountains ecoregion. Because it is intermediate between the Rockies and the Northern Mexican Montane Forests it is a very fine mix of biodiversity from both regions. for example, the Red-backed Junco is a very interseting species of the area, with a range restricted to that ecoregion alone. In fact, it has a smaller distribution than the yellow-eyed Junco! Also, you're probably asking, so what happens to the subspecies after they've bridged into another species? We'll, to avoid compromising purity of the new species(s) (intergration), the subspecies would have to stop advancing forward, as in adapting, and eventually all of them die from age or predation. All, right, now I've covered all the taxonomy I wanted to cover in this post! Yippy! Lastly, on the 24th, I observed 2 VAUX'S SWIFTS flying behind our yard. This time of year is at least a month and a half early for them to be migrating through, but due to the unusually warm summer-winter we've had in Maricopa CO, early migrants are to be expected this year! So that's right, spring migration is going to coming to the GRPs sooner than you and I think!...
I'm Jared Conaway, and stay tuned, for my next post! Expect to see some knew bird names appear on my Blog Life List... I'll explain their meanings next time on my blog.
0 Comments
Leave a Reply. |
About meJared Conaway Month Archives
December 2019
Categories
Life List
Birds |