Monday, August 10, 2009

Unusual Shots - Pretending to be Poisonous

I stepped over (literally, camouflage can be quite effective) this Bull Snake (Pituophis catenifer sayi) a subspecies of the Gopher Snake on a trail at Guadalupe Mountains National Park. In the few minutes I had to observe and photograph this specimen, and not being familiar with venomous species in that area, I made the inference that this was a pit viper. While it may be best practice in exotic terrain to assume that all snakes a venomous until confirmed otherwise, I was abnormally fooled by this individual. I found out only later this snake has the ability to flatten its head giving is the distinct appearance common to all pit vipers. Had I not assumed this reptile was poisonous, I might have tried a little harder to locate it after it slid beneath a shrub.

The effectiveness of this adaptation is quite clear. I'm sure it (the adaptation, not this particular individual) has fooled many a potential predator. If it had not, it would not have evolved through natural selection. For me though, it raises a question. As human to snake interaction increases with loss of habitat and other factors, will this unusual ability begin to be selected against. I was recently and proudly told by a family member, "If it has a neck, I kill it." She was referring, of course, to the head shape typical of pit vipers. It seems in this case that the adaptation in question might become an evolutionary disadvantage when the humans are involved.

Wednesday, August 5, 2009

Unusual Shots - Ants with Cicada Wing

On a survey visit to Occoneechee State Park in Virginia, I discovered these ants working together to lift this cicada wing up the side of a tree. It is always exciting to capture images that demonstrate a behavior or behaviors unique to a family of organisms. Most of us have heard of the ability of ants to carry an estimated 10 to 50 times their body weight. Additionally, these photographs provide a limited, but still effective example of the social aspect, the tendency to work together, of these fascinating insects.

I took what turned out to be a series of images that illustrate how the ants worked together, often having to turn, flip, or otherwise adjust the wing in order to raise it to their destination. Two or three times, while I watched, one ant would hold the weight of wing on its own while the other let go and found better purchase. I also witnessed other ants, presumably of the social group, that passed the pair going up or down the tree but all left just these two to their task.

From a photographer's point of view, I try to use my longer lens to capture such behaviors. While I would probably have gotten finer images using a lens with a shorter focal length, I do not want influence the action by getting to close. I want to be an observer of, and not a variable in, the behavior.

Tuesday, August 4, 2009

Unusual Shots - Gulf Fritillary

I apologize for not blogging for a few weeks. I am working to get the images from my latest trip up on the site and make some major changes to EduPic at the same time.

As I've been stuck at home and not in the field, I've decided to post some recent images that for one reason or another I'm calling "Unusual Shots." Like this image of the Gulf Fritillary (Agraulis vanillae) these are not the usual fare. They may not be the most attractive. They may not show the subject in the greatest detail. What they might do, is demonstrate some aspect of behavior, highlight some unique feature of the subject, show the subject from an unfamiliar angle, or demonstrate some informative interaction between the subject and its environment.

In this case, it is the point of view. I have many images of adult butterflies with their wings open from the dorsal view, or of the ventral side with wings folded, but no images of the ventral with wings spread. In fact, I don't recall seeing any images of live specimens in such a "pose." I claim no particular skill in capturing such images, and I don't normally seek out or with forethought compose such a shot. Instead, I attribute my luck to the numerous hours I spend in the field thereby greatly increasing the chances of stumbling upon like displays.