Friday, May 27, 2016

Are Rattlesnakes Mindless Killing Machines? Dr. Bree Putman Says No Way.


   We all know that snakes have a bad reputation, especially rattlesnakes. Although many people think of rattlesnakes as mindless killing machines, I think they are one of the most fascinating group of animals in North America. Because rattlesnakes are so difficult to study, they likely have lots of secrets to reveal about how they find food, interact with each other, and thrive in many different kinds of habitats. All this was in the back of my mind when I read a recent scientific paper about how rattlesnakes may actually move vegetation around to create better spots to ambush prey. I recently spoke with the author of this research, UCLA Postdoctoral Fellow Dr. Bree Putman, about this work and other developments in the quest to better understand rattlesnakes.

When did you decide you wanted to study rattlesnakes? What makes them interesting and/or worthwhile study subjects?

    Ever since I was a little girl, I have loved reptiles. I think it was Jurassic Park that started my fascination because I was first obsessed with dinosaurs. This prompted my parents to buy me pet reptiles because, unfortunately, dinosaurs were not available for purchase. As an undergrad in college, I knew I wanted to become a wildlife biologist and so I searched for research credit my junior year. Most professors’ work seemed so boring to me at the time (who wants to work with fruit flies?!), but then I found Emily Taylor who studied rattlesnakes and I applied to work in her lab. She accepted me and I worked on a project radiotracking a population of rattlesnake for two years. This resulted in my first publication and I fell in love with the creatures. I found that they were much different than I had perceived. My first encounter with a wild rattlesnake was so uneventful; it just sat there staring at me from a burrow. This is what makes them my favorite study animal. Many people have these preconceived notions of how rattlesnakes behave and then when they actually go into the field and observe them in their natural habitat, they find that most of the myths are untrue. After tracking the same individual snakes for multiple years, I get to learn their personalities and quirks and it makes the snakes endearing (although they probably don’t find me endearing).


You’ve done a lot of work studying the foraging behavior of rattlesnakes. When I hear the word “foraging” I think of an animal moving around looking for prey. I thought rattlesnakes were sit-and-wait predators in that they typically stayed in one place and waited for prey to walk by; is this considered foraging?

    I would define “foraging” as the act of trying to acquire food, and animals can accomplish this task using several strategies. Many predators roam around looking for prey, but other predators are ambush hunters that use surprise attacks to capture prey. Rattlesnake use an ambush strategy where they select an ambush spot, wait there for several hours to days, and then launch a surprise attack on unsuspecting prey that wanders by.


What are the attributes of a good ambush spot for a hunting rattlesnake? How long will a rattlesnake stay in one place waiting for prey?

We are still trying to figure this out, but so far we know that rattlesnakes 
rely heavily on chemical cues (similar to scent) to select an ambush spot. They prefer spots that indicate prey presence, and also the presence of multiple types of prey (but this probably depends on the rattlesnake population as some are more specialized than others). Interestingly, they also prefer to set up ambush in spots where other rattlesnakes have been. Perhaps if it was a good spot for the previous snake, it will be a good spot for them too. Rattlesnakes also prefer to hide in some sort of cover: thick vegetation, under logs or rocks, or inside small mammal burrows. Rarely do we find snakes hunting out in the open. Rattlesnakes could wait for several hours to days for prey to wander by.


You observed that some snakes don’t just look for good ambush spots, they help create them! Could you elaborate on this and explain why it is surprising?

    For my doctoral research, I used security cameras to record the foraging behaviors of wild rattlesnakes. While reviewing hours of footage, I noticed two different snakes behaving strangely. These snakes suddenly jerked their heads upward while in ambush. They were hiding in thick grass and it appeared as if they were using their heads and necks to push vegetation away from the intended strike path (see video below). This was very exciting because first, rattlesnakes rarely do anything while in ambush so any movement excites me (even tongue-flicking), and second, this could suggest that rattlesnakes can learn from past mistakes or plan for future events. We’ve only recorded this behavior from two individuals, but I’ve spoken with other researchers who have observed the same behavior and so this may be more common than we think. However, more studies are needed to determine whether the snakes were actually manipulating their ambush site to increase their strike success. 




What happens after a rattlesnake bites a prey animal? How far away does the prey get before it dies and how does the rattlesnake find it? How long does it take to find it?

    This depends on the prey and probably on the population of rattlesnake as each population seems to have a unique relationship with the local prey species. In the foothills of San Jose, California (where I work) rattlesnakes specialize on California ground squirrels, although they are opportunistic and will capture other prey such as mice, lizards, and birds. If not targeting a squirrel, snakes are more likely to hold onto the prey item during a strike. Then, it just waits for the venom that it injected to kick in before consuming the animal (rattlesnakes will not eat something unless it is completely dead). However, squirrels are bigger beasts to battle. They are resistant to rattlesnake venom (but NOT IMMUNE!) and so it can take a very long time for them to succumb to the venom (sometimes a couple of hours!). Rattlesnakes tend to release squirrels after a bite because the likelihood of a squirrel retaliating and hurting the snake, if held in the snake’s mouth, is extremely high. Snakes imprint on the squirrel’s scent during the strike and then they try to follow the scent trail to the presumably dead prey animal that they released. However, because of their venom resistance, squirrels often run very far away from where they were attacked and the snake has to spend considerable time searching. We’ve recorded several instances when snakes were unable to locate their released squirrel. These snakes spent more than 5 hours searching for their prey and never found it. This suggests that the benefit of eating a large juicy squirrel outweighs the costs of prolonged searching. These missing squirrels may have had enough resistance to fight off the venom, thus leaving behind very confused rattlesnakes.


I think some people perceive snakes as mindless killing machines, does your research suggest we should be thinking about them differently?

    Like any predator, rattlesnakes must overcome prey defenses across a series of stages that occur during the predator-prey encounter. First, they must not be discovered by the prey. Then, they must launch a successful attack on unsuspecting prey. Then, they must successful kill the prey. And finally, they must be able to find and consume the killed prey. Because prey have evolved defenses at each of these stages, predators (including snakes) are unsuccessful most of the time. This puts tremendous pressure on them to evolve counter-offenses (aka better hunting tactics) because if a rattlesnake is unable to consume enough energy, it will not be able to mate and pass on its genes (because reproduction is dependent on body condition), or in the worst case scenario, it could starve to death. Thus, rattlesnakes need to process multiple sets of information to make the “right” decision at every stage of the prey encounter or they won’t be successful. As mentioned above, rattlesnakes integrate several types of information when selecting their ambush site. We also found that they only strike prey during approximately 20% of all encounters, suggesting that are waiting patiently for the “perfect” moment to strike. However, we are still trying to figure out what factors influence the strike. Even in the rare instance when a rattlesnake decides to strike, it is only successful about 50% of the time. It’s a tough life for a hungry rattlesnake!


Will snakes behave differently depending on how easy it is to find food? Are there any other features of the environment that might affect a snake’s foraging behavior?

    First, I don’t think it is ever easy for a rattlesnake to find food (see above). Second, I believe that a rattlesnake’s hunting success depends less on environmental factors and more on the local prey populations’ anti-snake defenses. Many people think that temperature could have a huge influence on hunting success because as ectotherms, rattlesnakes’ activity is dependent on ambient temperature. Temperature could influence how long a snake is able to stay at an ambush spot; it will need to seek shelter if it gets too hot. Many laboratory studies have found that strike speed and presumably success increases with temperature. However, we examined this on our wild rattlesnakes and found little support. Snakes were able to launch successful strikes (where they successfully killed and consumed the prey item) across a wide range of ambient temperatures, even below 14°C! This would never be considered an optimal temperature for rattlesnakes. Snakes are basically successful when prey are completely unaware of the presence of the snake and do not perform an evasive maneuver and snakes are unsuccessful when the opposite is true. However, I am interested in understanding if the environment affects the anti-snake defenses of prey, thereby influencing rattlesnake strike success.


You have helped pioneer the use of video cameras to monitor rattlesnakes while they are hunting. Have you recorded anything surprising not directly related to your research questions?

    OMG, yes! I have seen so many behaviors considered unusual for rattlesnakes. We published a note on a non-rattling tail display that we recorded three individual snakes performing. The snakes slowly raise their tails and wave it from side to side. We have no idea what the function of this behavior is, but it is so distinct and interesting! 



    We also find that rattlesnakes often use the same refuges and interact with each other. They will follow each other into squirrel burrows or hang out together under a log. It’s interesting because we only observe them during the summer foraging season (no mating or overwintering in hibernacula) so why are they hanging out? You would think that this would lower their hunting success if they are competing for the same resource. I’m very interested in understanding the social lives of rattlesnakes.



What are some interesting questions that emerged while you were conducting your research that you hope to answer in the future?

    I would love to further understand the function of rattlesnake-rattlesnake interactions. Some research has been done using social network analysis to investigate associations between snakes, but this work is really in its infancy. It’s just a tough topic to study because rattlesnakes are so secretive and it takes a lot of time, money, and effort to follow them around and observe their behavior. It’s also hard to get funding for something like this. I’m also interested in understanding what limits the venom resistance of California ground squirrels. In other words, what prevents squirrels from evolving full immunity? There are many other questions that intrigue me and I hope to continue to work on this system in the future, but now I’m starting a postdoctoral research position working with urban lizards in Southern California (in collaboration with the Los Angeles Natural History Museum). Eventually, I hope to become a professor, and when that time comes, I will continue to understand the secret lives of rattlesnakes.

Tuesday, May 24, 2016

These Hikers Came Across a Rattlesnake in Texas: You Won't Believe What Happened Next


Other considerations come to mind. Arches National Monument is meant to be among other things a sanctuary for wildlife—for all forms of wildlife. It is my duty as a park ranger to protect, preserve and defend all living things within the park boundaries, making no exceptions. Even if this were not the case I have personal convictions to uphold. Ideals, you might say. I prefer not to kill animals. I’m a humanist; I rather kill a man than a snake.
–Edward Abbey, Desert Solitaire


This year in Texas the Sweetwater Rattlesnake Roundup reported bringing in a record 24,281 pounds of snakes for unregulated slaughter. About 40,000 people attended the event, many of them children receiving their first impressions of wildlife at this grim spectacle. In west Texas, snakes are considered vermin by most. Around here they come up in small talk when you first meet somebody; folks like to recall the local oddities and dangers and the giant rattlesnake they saw stretched across both lanes of the highway. You overhear talk of rattlers at the local lunch spots and it’s generally negative and uninformed. Last year I found four western diamondbacks (Crotalus atrox) out on the highway, their heads bashed in and their rattles gone. When you live in a place like this—where rattlers still have that Western cowboy novel stigma; where mountain lions still prowl yet the Texas Parks and Wildlife Department trap and kill them without mercy or regulation—It’s easy to get caught up in the negativity and lose your optimism.

We awoke to an overcast and serendipitously cool day in Big Bend National Park. The class I was leading was to hike the high Chisos Mountains looking for mammals. Really these hikes are just an excuse to take students on a long walk; a valuable lesson in and of itself. We saw Carmen Mountains whitetails (a diminutive deer subspecies found only in these and neighboring mountains) and rock squirrels, a small haul for a 14 mile hike. My students routinely tell me that I took them on the longest walk they’ve ever taken. They complain about it, but I nod my head smiling.

At one point we passed a group of middle aged hikers. They said they saw deer and rabbits, but the conversation quickly turned to rattlers. One of them stepped near a rattlesnake. He said it was a diamondback but at this elevation it was more likely a blacktail (Crotalus ornatus). I hammed enthusiasm, told him he was lucky, and asked him if it rattled or struck at him. He said no but looked visibly shaken. Like he had just got in a car accident or came home to find his house burgled. I told him he had nothing to worry about and that his car ride down was more dangerous. I doubt he agreed, but the statistics prove it.

My temples pounded as we ascended the trail leading to the top of Emory Peak, the tallest in the Chisos Mountains. I was leading the two fittest students in my class, and they were on my heels. I’ll be honest, I was walking pretty fast because I didn’t want them to pass me. I wanted to win and get to the summit first. And when you’re on the way up a steep slope it’s usually better not to stop because starting again after a rest is even harder. Still, when we finally reached the rocky crag of the summit, I had to stop. Lauren, the fit 22 year old former cross country runner, pranced right on ahead, while Alec and I sucked wind. After I caught my breath I walked up to the base of the peak. There, about 20 people were sitting around, some working their way up the three story rock summit, others tip-toeing their way down, and about a dozen just sitting around on the rocks blocking our path. It was like the traffic jam Jon Krakauer described on the summit of Everest in his book Into Thin Air, only slightly less dramatic.

I wormed my way through the crowd, past Lauren, and headed straight up the rocks—they are deceptively tilted and do not require much finesse on the way up. You can get up pretty quickly using the craggy andesite like a ladder. I last climbed to the top about 15 years ago when I was the fit, 22 year old student that had recently run track. I caught my breath at the top and looked out across the panoramic view: yellow rocks thrown and tortured for miles to the west, Santa Elena canyon visible 20 miles away as a triangular cut carved into three thousand foot limestone cliffs. To the south, the uplift of the tall and mysterious Sierra Del Carmen in Mexico. To the north, dark pimples of volcanic intrusions and cinder cones emerging from Paleozoic strata belonging to the Appalachians. To the east, more pink-yellow rock. A geological kaleidoscope unrivaled anywhere in America. The outlying tip of the great Sierra Madre Oriental.

Lauren joined me after slowly making her way up the slope (youth is no substitute for experience), and Alec huffed it up a few minutes later. He told us he’d just seen a rattlesnake. I asked him where and what kind, and he thought it was a blacktail—the same kind we’d collected dead on the park road the night before. I believed him, because Lauren and Alec are not only the fittest students in my class, they also consistently ace my tests. He said it was back down at the base of the rocks, near the dozen or so people. I decided I better get down there, to make sure nobody got hurt and nobody hurt the rattler. I glanced once more at the Del Carmens and scrambled back down the rocks.

I imagined what I’d do if somebody started to harass the snake. I’ve butted in before when people feed squirrels and that sort of thing. But I also tend to cower in the face of such abuses, hesitant to engage another free American bearing no greater authority than my lack of ignorance. Like the guy humping it up the trail blasting techno music from the radio tied to his pack. I said hello when I really wanted to bash it and him into a thousand pieces. If it came to defending the rattlesnake, I was prepared to pull out all the stops. I quickly prepared a mind-speech about how the park is for the protection of all wildlife, making no exceptions.

A few people warned me on the way down that there was a rattlesnake. I said “cool,” and asked them if somebody was trying to kill it. They said no. I arrived at the base of the rocks, and some kids warned me about the rattlesnake. I asked them what they thought of it, and they seemed excited. “Isn’t it awesome?” I asked. They smiled. From the last ledge I spotted it, a straw-yellow eastern blacktail coiled perfectly among the pinkish talus. Everybody was keeping a safe distance and a few people had their iPhones out taking pictures. Almost everyone thought it was a diamondback, and were surprised and perhaps miffed to hear me say it was a blacktail.

The blacktail rattlesnake was until recently considered a single, variably-patterned species found from Texas to Arizona south into the Sierra Madre of Mexico. They come in two colors: a nice suede grey or a tawny yellow, each overlaid by a handsome pattern of chevrons; the tail is black. I’ve always thought of them as the timber rattlers of the southwest because they resemble them in many ways and occur in rocky forested habitats. There are really two blacktail rattlesnakes, each slightly different in pattern and genetic makeup. They occur along both prongs of the Sierra Madre, which terminate like the tips of a snake tongue in the Southwest. The left tine ends in southern Arizona, where western blacktails (Crotalus mollosus) range. The right tine ends here in west Texas.

I overheard a man say, “look how beautiful it is.” The snake kept its distance, of course, and merely moved its head in my direction when I sat down a few feet away to take pictures. The large family blocking the base of the summit drifted away. A few new hikers came by, admired the snake, and continued up to the top. A man and his wife sat two meters away from the snake eating lunch for thirty minutes.

The snake basked a few minutes more while I unnecessarily stood guard, and then it disappeared back into the rocks.

It’s easy to get caught up in the negativity and lose your optimism. Unless you focus on the times when everything turns out all right.

Saturday, May 21, 2016

Snake Identification Challenge of the Week: Some Serpentine Royalty

Hey there-

I took a picture of this snake a few years ago …but I’ve always wondered what type it was. I am located in Atlanta, GA, and this was taken near Lake Allatoona about an hour north of the city. My guess is Copperhead, but I’m not quite sure because the head looks a little rounder than pics I’ve seen online. I’m guessing he was 3-ish feet long.

Brittany M.
Georgia




Now that the warm weather is upon us, I was able to get a good picture of our snake sunning itself.  I'm guessing the attached photo will make for easy identification.

Thanks for you help.




I've attached another photo.  I thought this was a copperhead, but I was at a parking studying a poster about snakes and now I wonder if it is a banded water snake.  Do you know?

Jackie C.
North Carolina


What Are These Snakes?
-----

Snake Identification Post Ground Rules

-Guesses are welcome and encouraged. Don't worry if you're not an expert, wrong guesses allow us to talk about how to distinguish between the various species and that's why I run these posts.

-If you can't explain why you think a snake is a particular species, go ahead and just say what you think it is. But otherwise please do let us all know how you identified the animal. If you're wrong, we can explain why. If you're right, this helps everyone learn how to identify snakes, which is the point of these posts.

-This is not a pop quiz, any kind of research is encouraged and I hope you will engage with other commenters to try to figure these snakes out. I will eventually chime in with my thoughts.

-Assume I know what kind of snake is in the picture. I run these posts because they are outreach opportunities. Please don't send me private e-mails with your guesses, include them below.

-Remember, the person that sent me the picture is probably reading your comments. Although it is frustrating to know that many of these snakes have been killed, these people do want to learn more about them. More snake knowledge will lead to fewer snakes being killed. Don't hate, educate.

Friday, May 13, 2016

Snake Identification Challenge of the Week!


This snake was seen in Kansas City MO, on 22 April 2016. It was found under a canvas tarp in a field alongside a creek with standing water. It did not show much aggression or open it's mouth, I did stay pretty far away from it. It did shake it's tail very rapidly as a rattler would, but there was no rattle. The head was very distinctly triangular although the picture does not show it. You can see the back of its head right on the edge of the picture. I did not get close enough to see it's eyes as I was afraid it was a cottonmouth. Hoping it is some sort of black snake as there are a lot of mice and rats in that field although I was sure if that coloration would be seen on one?

Hoping to assuage my wife's fears about poisonous snakes on the property as we are building a house and have a young son. Thanks for any help, sorry the pictures don't show better the head.


Kennard M.
Missouri



David , my daughter took this at a park in Kennett square pa. I think it's a water moccasin. What's your thought.

John
Pennsylvania










Can you tell me what this is? I was at the Susquehanna State Park, in Northeast Maryland. 

Thanks!

Deb G.
Maryland



What Are These Snakes?
-----

Snake Identification Post Ground Rules

-Guesses are welcome and encouraged. Don't worry if you're not an expert, wrong guesses allow us to talk about how to distinguish between the various species and that's why I run these posts.

-If you can't explain why you think a snake is a particular species, go ahead and just say what you think it is. But otherwise please do let us all know how you identified the animal. If you're wrong, we can explain why. If you're right, this helps everyone learn how to identify snakes, which is the point of these posts.

-This is not a pop quiz, any kind of research is encouraged and I hope you will engage with other commenters to try to figure these snakes out. I will eventually chime in with my thoughts.

-Assume I know what kind of snake is in the picture. I run these posts because they are outreach opportunities. Please don't send me private e-mails with your guesses, include them below.

-Remember, the person that sent me the picture is probably reading your comments. Although it is frustrating to know that many of these snakes have been killed, these people do want to learn more about them. More snake knowledge will lead to fewer snakes being killed. Don't hate, educate.

Friday, May 6, 2016

Readers Write In: Clyde Has A New Friend, Can You Identify It?

Hello,

Last year I was put into contact with you for help in identifying a rather large Black Snake I had named Clyde. I live on a farm north of St. Joseph, Missouri. (Which is an hour north of Kansas City.)
I was hoping you'd be willing to help me again. I have photos of 2 different snakes.

The first one, I think might be another black snake, but it's belly seems to be a speckled pink, and the top of it seems to have some silver rings on it. This snake is at least 5 feet long- but far skinnier than Clyde was last year, with a much smaller head. It looked similar to a photo of a hog-nosed snake, but I don't think that's accurate. Where Clyde was aggressive, this snake was absolutely passive. Played "possum" the first time I saw it and ignored my dog completely, even thought the hole I think leading to it's den was right beside it and it could have easily escaped before we were aware of it. 


The second snake unfortunately is dead. I must have driven over it when coming home Saturday night around 10 pm. I remember seeing what I thought was a stick on the gravel driveway, until I found it the next day, then thought it was odd for a snake to be out so late at night. I took a photo of it, because it's a snake I've NEVER seen around here. (Neither has my 80 year old mom.) She thought it was a bull snake at first, but thinks the copper color in it is too bright. I'm wondering if it's a milksnake? It was quite short, perhaps 2 feet long. It's so dusty here I had to pour water over it to get a clearer photo. 

Just hoping they're both non-venomous. Thanks so much for your time,

Beth M.
Missouri


Hi,

I live in Bowling Green, KY. I found this snake entering my front yard from the road. It seemed to be full of circular objects as you can see in the pictures. Do you know if it is venomous? Also do you know of any humane snake traps, that I can use to capture the snake and release it into a nearby national park. 

Thanks


Ganesh B.
Kentucky

 (Editor's Note: after learning more about the snake Ganesh was pleased to leave it alone and was not going to attempt to trap it.)


What Are These Snakes?
-----

Snake Identification Post Ground Rules

-Guesses are welcome and encouraged. Don't worry if you're not an expert, wrong guesses allow us to talk about how to distinguish between the various species and that's why I run these posts.

-If you can't explain why you think a snake is a particular species, go ahead and just say what you think it is. But otherwise please do let us all know how you identified the animal. If you're wrong, we can explain why. If you're right, this helps everyone learn how to identify snakes, which is the point of these posts.

-This is not a pop quiz, any kind of research is encouraged and I hope you will engage with other commenters to try to figure these snakes out. I will eventually chime in with my thoughts.

-Assume I know what kind of snake is in the picture. I run these posts because they are outreach opportunities. Please don't send me private e-mails with your guesses, include them below.

-Remember, the person that sent me the picture is probably reading your comments. Although it is frustrating to know that many of these snakes have been killed, these people do want to learn more about them. More snake knowledge will lead to fewer snakes being killed. Don't hate, educate.