A Bunch of Bluets

If all the IDs I got are correct [1], here are 3 different bluets I met last spring. Bluets are damselflies, and most of the time the males have some bright blue coloring. I will try and provide the rationale for these identifications:

  • These damselflies are all about the same size, so even if they had agreed to be measured I might not be able to ID them from the measurement. The Skimming Bluet is 1.0-1.1", the Turquoise Bluet is 1.1-1.2", and the Slender Bluet is 1.2". And each of them has blue on abdominal segments S8-S9, which are the ones almost at the end.
  • All these bluets are considered "common", so it wouldn't be surprising to see any of them in New Jersey. All of them are active in June. And although my field guide suggests that the Slender Bluet isn't in Somerset County, 1) They are known to be in the counties north and south of Somerset County, and 2) My field guide is from 2009, so it might not reflect the exact location of current populations.
  • Probably the best differentiator can be seen in the 3rd 1, the Slender Bluet. If you look at the thorax (between the head and the abdomen, and where the wings are attached) you can see that it's blue with very thin black lines compared to the other 2, a trait of the Slender Bluet.
  • The next differentiator is a little subjective. If you look at the 1st picture, the Turquoise Bluet, you'll see that the abdomen is almost black between the thorax and segments S8-S9. And in the 2nd picture, the Skimming Bluet, you'll see somewhat more prominent blue rings where the segments meet (until you get to the blue segments S8-S9).

You might wonder about hybridization among a bunch of similar looking species occupying similar habitats, especially since some odonate males will try and drive off vaguely similar males of other species as though they were breeding rivals. One thing that's suspected to prevent this (at least a lot of the time) concerns the way odonates breed. The male will use claspers at the end of his abdomen to grab the female behind the head; that clasping action might not happen correctly across species.

Turquoise Bluet
June 13, 2023 at Washington Valley Park
Photo 300986985, (c) jpviolette, some rights reserved (CC BY-NC)		 

Skimming Bluet
June 13, 2023 at Washington Valley Park
Photo 300987254, (c) jpviolette, some rights reserved (CC BY-NC)

Slender Bluet
June 13, 2023 at Washington Valley Park
Photo 300988361, (c) jpviolette, some rights reserved (CC BY-NC)

[1] All these got some support and no dissent from iNaturalist.

Comments

Post a Comment

Popular posts from this blog

Northern Watersnake

Image
This April I went to Great Swamp National Wildlife Refuge with the hope (among other hopes) of seeing the Northern Watersnakes during mating season. There were 2 problems with this: I think it was slightly late in the season for this. The boardwalk trail where I had seen them in the past was partially closed due to repairs. So although I didn't see any of the 2+ intertwined snakes that I'd seen in the past, but there were still Northern Watersnakes warming themselves in the sun: April 13, 2023 at Great Swamp Photo 272117862, (c) jpviolette, some rights reserved (CC BY-NC) And here's another one coming out of the water. April 13, 2023 at Great Swamp Photo 272119139, (c) jpviolette, some rights reserved (CC BY-NC)
Read more

Female Brown-headed Cowbird

Image
Like quite a few birds, this bird is easier to identify when spotted with her significant other ; she's a Brown-headed Cowbird . Due to their tendency to be monogamous plus plain old birds-of-a-feather behavior, I usually see them with prominently brown-headed males around, greatly improving my confidence in IDing them. My understanding is that Brown-headed Cowbirds are the only obligate brood parasites in my area. Obligate brood parasites have essentially lost all their parenting skills, and thus if they were ever unable to fool other birds into raising their young, they would (almost certainly) go extinct [1]. There are, however, other brood parasites in New Jersey. These are called facultative brood parasites, and these birds will usually raise their own offspring, but will also engage in brood parasitism. (Exactly when birds perform facultative brood parasitism seems variable; one source said it occurred when resources were scarce while another said it occurred when resource
Read more

Rooftop Turkey Vultures

Image
I met these Turkey Vultures by just walking out of my apartment. (I theoretically could have gotten a picture without going outside, but that extra layer of glass can degrade picture quality a little.) Although they don't show up on these rooftops daily, they're not an uncommon visitor to my apartment complex. Similar to this spot of the woods , I wouldn't expect this to be a great place to find carcasses. I'm thinking they're here mostly because: They don't have to worry much about predators up there. They get a pretty good view of the area in case something should happen to succumb. (This apartment was near the top of a hill, providing a better view than most of the other apartments.) Since this picture was from February, it's probably a slightly warmer spot, especially near those furnace vent pipes. Although these are Turkey Vultures, it's also not unusual to see Black Vultures up there too. February 28, 2023 at Finderne Photo 264703396, (c) jpviole
Read more