Monday, October 29, 2012

Snakes in the freezer

My husband holding a rattlesnake
- he tells me he know what he is doing
In addition to tasty delights, my freezer often ends up the temporary home for animals that have died and are on their way to join the scientific collection at the local museum where my husband is a curator. It is sad that these animals have died, especially since it is often the result of humans like getting hit by a car or birds not seeing windows. At least collecting them puts them to good use - plus it prevents having to kill animals for science. I only accept the recently dead - I’ve put my foot down against rotting carcasses after a unpleasant decomposed swan incident. We’ve temporarily housed various song birds, a mink, a hawk, owls, wall lizards, newts, garter snakes, squirrels, toads and more. Perhaps a spare freezer in the carport would not be amiss.

Half a days drive from the coast can put me in rattlesnake country. Only once, have I seen a wild rattlesnake. It was so young it only had its button rather than a full rattle. It looked small and helpless when we cornered it on the bank of a stream. Then it put on an aggressive display, striking at us with it’s mouth open. We could clearly see its fangs, but managed to stay clear of them. We thought it was harmless, only later did I discover that baby rattlesnakes have very potent venom.

What makes a rattlesnake scary is its venom. Venom is saliva that has been modified over evolutionary time. It contains a complex assortment of components that differ between snake species. According to Munekiyo and Mackessy (1998) : “lethality of venom results from a synergistic interplay of venom components, including enzymes, peptides and specific toxins.”

The venom of a Fer de Lance acts differently than rattlesnake venom, which is why it is important to identify the snake that bit you - so you can get the right antivenin.

Snake venom is on my mind because my husband and I recently went to rattlesnake country. My husband has a long history of picking up rattlesnakes - including, Prairie, Eastern Massasauga, Timber, Dusky Pigmy, Northern Pacific Rattlers, and Eastern and Western Diamondbacks. So I was expecting a road-killed rattlesnake to come home with us and spent time in the freezer. I started to wonder if frozen rattlesnake venom is still toxic.

Fortunately, the toxicity of frozen rattlesnake venom has been studied by researchers (Munekiyo and Mackessy, 1998) looking at how to best preserve the venom for scientific research. The answer is yes, a frozen rattlesnake’s venom is still toxic - I’ll need to handle them with care. Munekiyo and Mackessy (1998) went on to speculate that their results should apply to all front-fanged snake venoms (both vipers/rattlesnakes and cobras and their relatives have front fangs). However, this still needs to be studied. I won’t worry about it as I don’t expect a cobra in my freezer - although I wouldn’t be surprised if I found one there. Presumably a cobra in the house would arrive with some warning or at least a big colourful sticky note on the freezer lid.

Reference: Munekiyo, S.M., and S.P. Mackessy. 1998. Effects of Temperature and Storage Conditions on the Electrophoretic, Toxic and Enzymatic Stability of Venom Components. Comp. Biochem. Physiol. 119B, 119-127.

Thanks to G. Hanke for the photos

Friday, October 26, 2012

Garter Snakes

A Wandering Garter Snake
In my opinion, if you mess with an animal and it bites, scratches or pees on you, you deserve it. Currently, I try to let wild animals be; however, as a kid, I often tormented garter snakes in the garden. They would bask in the heat on the black plastic we used to control weeds. This preferred location made them easy to find and I never had any difficulty snatching them by the tail as they tried to slither away. Once caught, their typical defense mechanism was to pee. This potent musky-smelling pee would persist on my hands even after thoroughly washing them in soap and hot water.

Even though they are carnivores, garter snakes don’t want anything to do with people. Wikipedia claims that a garter snake may coil and strike - but I’ve never seen them do anything like this (I've just discovered that a friend and my husband have seen a snake do this - especially when garter snakes are cold). Generally, they retreat from humans as people kill more snakes than snakes kill people.

Since, garter snakes play an important role in keeping pests down, I’d love to have them in my current garden to control the slugs. These streamlined snakes can be quite colourful with black or brown bodies and stripes that range from blue, to yellow or red (the San Francisco Garter Snake is pink).

Garter snakes have saliva that acts like a mild venom, which is dangerous to a frog, but not a person. Only once was I bitten (I totally deserved it). I had the snake by the tail, but moved my hand in range of its mouth. I ended up with two tiny pricks on my hand which healed cleanly without even a hint of infection.

As an aside, I always let the snake go and I still feel bad that I was once keen on interrupting their day.

Thanks to G. Hanke for the photo

Wednesday, October 10, 2012

Circling Vultures

They didn't photograph as well as I hoped
Since it was sunny on the long weekend, my significant other took some time to wash the car. I came out to check out what he was doing. In the still damp and shiny clean back window, I saw the reflection of a mass of black birds circling the house, an scene reminiscent of a horror movie. A nice thermal must have formed above the house as I’m not about to expire any time soon.

Looking up, I saw that each individual had a bald head. Identifying them was easy - they were turkey vultures, common to my area and a bird I’ve been able to identify since I was a kid. There were too many birds to accurately count, my best guess was there was more than thirty.

More vultures joined the group as they shifted their spiral slowly away until the mass was out of sight. This time of year they migrate south in groups. I had no idea they did so in such a large group. Turkey vultures migrate down to southern California or even as far as South America.

There was a time, when I was growing up, I was fascinated by the idea of birding. I’ve never been a serious birder as the hours don’t agree with me and I think going to extremes over a life list of birds can get a little silly, but I still like to identify the birds I see. I scraped together allowance money and bought the ‘Birds of North America’ in the early 80’s. It is still my only bird field guide. Every time I don’t bring my bird book out on a hike with me I see an interesting bird and regret not having my book.

My bird book doesn’t have a lot to say about turkey vultures. It describes them as “ a common carrion eater, scavenging in fields and along road sides.” Carrion eaters have many benefits. According to the The Turkey Vulture Society, these birds prevent spread of disease by cleaning up dead things - no food is wasted in nature. Since they might have to stick their head inside a carcass to get a tasty morsel, being bald means they don’t have to mess up their feathers for a meal.

Turkey vultures don’t make the haunting cry of a hawk, or even the peep of a chick. They have to resort to hisses and grunts as they lack the vocal cords other birds have. I’ve never hears a turkey vulture make a sound. 

As a tangent: I'm always amazed that there is a society for everything.