Yellow-rumped Warbler

Here's a fairly well-known bird that I don't often get a picture of: the Yellow-rumped Warbler. You can actually see their famous yellow rump in the second picture. These birds mostly visit us in the winter, taking advantage of our (relatively) balmy winters (compared to their breeding range that can go pretty far north into Canada).

The Yellow-rumped Warbler may not be a species soon, and this gets to the heart of what we consider a species to be. Prior to 1973 our eastern population of Yellow-rumped Warblers was called Myrtle Warblers [1], and another western population was called Audubon Warblers [2]. But then it was discovered that these 2 populations were interbreeding very readily in one range overlapping area, and so in 1973 they were grouped together into 1 species, the Yellow-rumped Warbler.

But ornithologists have continued to study these birds, and have concluded that while the birds in the overlapping range have a mix of DNA between the eastern/western populations, that mix of DNA doesn't seem to spread out. This suggests that the birds with the eastern genes don't do well in the west, and the birds with the western genes don't do well in the east, which supports the idea that these are better thought of as 2 species that hybridize rather than 1 species with different forms.

So it's possible that Yellow-rumped Warbler will be retired as a species, mostly replaced by the Myrtle and Audubon Warblers. (It's likely that a small isolated population in Guatemala will also become a separate species. It's less clear what would happen to another isolated population in Mexico.)

To me, this also points out the limitations of our taxonomic model. Nature isn't really about distinct buckets that all life fits into, but is really about varying levels of relatedness. Nature actually works more like fuzzy logic than boolean logic. Maybe we shouldn't answer the question: Is this a Myrtle Warbler with a yes/no, but with a 85% (or some similar percentage).

November 3, 2021 at Duke Farms
Photo 168431490, (c) jpviolette, some rights reserved (CC BY-NC)

November 3, 2021 at Duke Farms
Photo 168431511, (c) jpviolette, some rights reserved (CC BY-NC)

[1] They got their name from their rare ability to digest bayberry and other wax-myrtle berries.

[2] Named after the American naturalist John James Audubon.

Comments

Post a Comment

Popular posts from this blog

Tussock Moth Herd

Image
Some caterpillars are usually seen in large numbers (like Armyworm Moth caterpillars and Eastern Tent Caterpillars ), while most are more solitary. The Milkweed Tussock Moth caterpillars (more about them are here ) seem to be slightly social. I'll sometimes see them alone, but more often I'll see them in groups of 2-9 members. In the 1st picture below, you can see there is a clear size difference in some of these individuals. I'm almost certain the little one in the middle is in an earlier instar than the others (though they lack the colorful tufts of fuzz in their earliest instars). August 31, 2021 at Washington Valley Park Photo 167477945, (c) jpviolette, some rights reserved (CC BY-NC) In the picture below, it's clear that these caterpillars don't require a lot of personal space. August 31, 2021 at Washington Valley Park Photo 167477979, (c) jpviolette, some rights reserved (CC BY-NC)
Read more

Copper Underwing Caterpillar

Image
I believe this caterpillar to be a Copper Underwing [1]. At least the coloring and the dorsal hump (near the left end of the caterpillar) seem consistent with the Copper Underwing. These caterpillars are not what you'd consider picky eaters; my Caterpillars of Eastern North America describes their diet thusly: Many wooded plants including apple, basswood, blueberry, cherry chestnut, current, grape, greenbrier, hawthorn, hickory, lilac, maple, oak, poplar, raspberry, rhododendron, viburnum, Virginia creeper, and walnut. Wikipedia adds: Ash, privet, honeysuckle, rose, and service trees. That's a pretty wide range of trees and shrubs. One of the challenges of finding them is that they could be almost anywhere; the other challenges are: Their green coloring blends in pretty darned well with the average leaf. They have a habit of feeding underneath leaves, so they're probably not visible when looking down at their location. They have a tendency to move from leaf-to-leaf; if you
Read more

Eastern Pondhawks

Image
I'm going to try something different today with my Eastern Pondhawk pictures. I'm going to let ChatGPT do my blog today. (ChatGPT is an AI program that you can converse with in a pretty human way; an explanation of it is here .) Me:  Can you tell me something interesting about the Eastern Pondhawk? ChatGPT:  The Eastern Pondhawk (Erythemis simplicicollis) is a dragonfly species that is native to North America. It is a medium-sized dragonfly, with a wingspan of about 3 inches, and can be found in a variety of habitats, including wetlands, marshes, and ponds. One interesting characteristic of the Eastern Pondhawk is its mating behavior. Male Eastern Pondhawks are known for their territorial behavior and will defend their territory from other males. They will patrol their territory and will try to mate with any females that fly into their territory. Another interesting fact about the Eastern Pondhawk is that it is a fast flyer and is able to hover in midair. It is also an import
Read more