Little Bits of Sky

Here's a nice find from this morning:

Summer Azure (Celastrina neglecta),
Lyons Woods FP, Lake Co, IL 5/17/2014

This is a Summer Azure (Celastrina neglecta). Well, most likely it's C. neglecta. Not very many years ago, it would have been called C. ladon, the Spring Azure. Today, C. ladon's been split into 8 species, all of them looking very similar to this, and most of them polymorphic, just to confuse things further. In the eastern US, every state has somewhere between 2 and 5 species of azures, all flying at slightly different times and differing in host plants and very minor structural differences. Apparently C. ladon is quite rare up here in Lake County, so even though it's only May, I'll settle for calling this one C. neglecta.

They're called Azures because the males have a bright blue upperside. Females are duller, either pale gray blue or dusky gray depending upon the species. Here's a female Appalachian Azure (C. neglectamajor) showing some of that color. (They rarely hold their wings open when they're perched, making it very difficult to photograph the topsides.)

Appalachian Azure (C. neglectamajor), Powdermill Bird Observatory,
Westmoreland Co, PA 6/13/2004

To better show how closely these species resemble each other:

Lucia Azure (C. lucia), Tussey Mountain Hawkwatch,
Center Co, PA 3/27/2012

This is a Lucia Azure from Pennsylvania.

Echo Azure (C. echo), Mogollon Rim, Coconino Co, AZ 8/2/2005

And this is an Echo Azure from northern Arizona.

These are a great example of what are often called cryptic species. That doesn't mean that they're hard to see, but that they're very hard to tell apart. Obviously, they manage it, but they're likely using clues like UV light or pheromones that we simply can't distinguish. Biologists have found impressive examples of cryptic species in parasitic wasps, finding that what was thought to be one generalist species of wasp was actually a whole host of specialist species, all of which look identical. Each one used just one host species, and they were genetically isolated from each other.

Biologists studying Red Crossbills (Loxia curvirostre) have found that the North American population falls into as many as 9 different groups, which differ by call notes and food preferences and appear to travel in segregated flocks. DNA results across the whole genus show as much individual variation as between-species variation, even though White-winged Crossbills (L. leucoptera) are clearly a good species, and British Ornithologists consider the three forms found in Scotland to all be good species. The American Ornithologists Union has yet to agree to splitting any of the Red Crossbill types, though.

I do suspect that this reluctance isn't something we'd see in entomologists, given the same data, since they're used to the idea of cryptic species. It is true that birds see the world in a way rather closer to our own than insects do, but we've seen evidence of cryptic species in flycatchers already. The ideal of science is to let the data speak while we listen. The reality is that both the questions we ask and the way we hear the answers is influenced to some degree by our backgrounds, both as scientists and as people. That's an important part of the process, but it can make for some interesting quirks in any given field.