So, sadly, many green anoles did not survive the severe storms that brought cold and ice to the Southern states this past winter. It's very sad. I really hope it doesn't take the populations long to recover, but it may.
As for me, I have to head south, where the green anoles are faring better. I've heard that they are relatively plentiful in areas in Florida, so I'm hoping for the best (as always).
A bit about Anolis sagrei (the brown anole)...
I began this journey in Georgia, in part because the green anole is usually relatively plentiful there. I am conducting a study looking at the effects of competition between males within a species. So, it makes sense to study those effects where this species is not competing with another species on a daily basis; where the main struggle these males face is fighting for territories against males of the same species and opportunities to mate (within their own species). Makes sense, right? Keep it simple.
Well, green anoles in Florida face a challenge that those in northern Georgia do not (at least, not yet). This challenge, is the brown anole. The green anole is native to the United States. The species' predecessor arrived here from Cuba millions of years ago (roughly 2.5 to 5 - here's a link to some of the science!). The brown anole, is not. It arrived in Florida around 50 years ago, though it's possible it was in the Keys before then (trying to chase down a time frame gets silly - no one is really sure when the brown anole arrived in Florida, but it was fairly recently ago).
OK, so you have two Anolis lizard species in Florida. No big deal, right? Aren't there like, a bunch of lizard species (5,634 named as of March 2013)? Actually, there a quite a few Anolis lizards in Florida, but here's the problem with the green and brown anoles.
It's two-fold, actually. These species have overlapping ecological requirements, and the brown anole is a highly invasive species. Remember when I said that the green anole was a trunk-crown anole (you remember, member)? Well, the brown anole is a ground-trunk anole. See anything troubling there? Yup, the trunk part. They eat the same food (the same insects - I'm still analyzing those data - I hope to have that manuscript out soonish) and they're competing for many of the same perches. You know how I keep harping on shade and sun and good trees and bad trees? I'm serious about it, and so are they. They can't survive without those perches that provide adequate sun, shade, and food. And if other lizards are moving in and competing for the same perches... Well, times are tough for the green anoles. Not only are they competing amongst themselves for food and perches (and territories and mates), now they have these other guys to deal with. And since the brown anoles' arrival about 50 years ago, they have spread throughout Florida and are now making their way into Georgia, South Carolina, Texas, and probably other northern areas.
And brown anoles are highly invasive. This means they are REALLY good at establishing themselves. A lot of work has gone into figuring out how they manage to out-compete the green anoles (that's how I got started working in Florida with the anole diet work). But, in essence, they are aggressive, and they just take over. They can also cause the green anoles to physically evolve, because in certain habitats the green anoles move up in the canopy in response to the presence of the brown anoles (so their limbs get longer and their toepads get stickier - essentially).
However, in my old field site, there is no place for the green anoles to go. Even though the palms have grown since I've been there, they are still relatively short. I have not been tracking the population year to year, so I can't say for certain, but there are now brown anoles in the park where they weren't three years ago, and there are far fewer green anoles than there used to be. Far, far fewer.
Some other scientists I work with are very angry with the brown anoles. That may sound silly to you. Actually, a lot of biologists get quite upset with (yes, personally) invasive species (of which there are so many it's difficult to keep track, but you know one when you see one because it's the one out-competing everything else - I used to be so proud of them when I was a child. I hadn't been taught that they were the bad guys, yet). But, brown anoles are lizards, too. And I grew up loving lizards. These guys are charming in their own right. They are just surviving. They happen to be doing a better job at it than the green anoles. It makes me sad, but I don't hate them for it. And, it's important to note that green anoles themselves have recently been introduced to areas where they weren't before, like Hawaii. In those areas they seem to be doing well. And so it goes.
The brown anoles, being trunk-ground anoles, are stout, strong, and clumsy. They are constantly underfoot or scampering off noisily. But they have their charm, if you like that sort of thing (and I do). Where the lean, quiet, watchful green anole embodies all the grace a Southern lizard should have, the brash, bold, muscular brown anole is its redneck cousin -- and they are fighting for existence in a post-apocalyptic world with no politics or money, and the one who can get down and dirty, fight, and kill a gator for dinner is the victor. I just wish the two could co-exist peacefully.
Maybe some day.