Reptile & Amphibian Forums

Eby's post below got me thinking on something, and so I'm hoping to open up some thought-provoking dialog here...

One of those things I've often wondered about snakes that have been caught and then released is whether their subsequent survivorship was effected by the ordeal or not. My guess is that, depending on the time and location of the release, probably so...

But is there a way to measure exactly that without somehow also measuring the average survival rate of the unmolested population? I know that there are equations for wildlife management & methods that allow people to measure the survival rate of many types of animals, but how effective are those on creatures like fossorial snakes? Because finding snakes like gray-banded kings, for instance, is such a luck-involved process (as opposed to random sampling or counting of a herd of bighorn sheep, for example), can you count on such an equation to seamlessly apply to gray-banded kings?

The reason I've given this some thought is that there was a study on movement ecology, retreat-site habitat, and thermal biology of Trans-Pecos Rats in 1996, and the authors used radiotelemetry to track the animals involved. Eight adults were used, and there was, in my opinion, a major flaw in the study because all 8 of the snakes were released and tracked outside of their home range.

Long story short, some of the snakes' daytime "retreat-sites" were "under a rock" and "in a bush". Within 10 days of tracking, three of the eight snakes were found dead...two skeletons were found in the immediate area of some owl feathers, and another skeleton was found without any hint as to the cause of its death. Now we know that places like "bushes" or underneath landscape debris/structures (like 'under a rock') aren't common daytime hiding retreats for happy wild adult subocs, so why were they found there? Was it because the big scary ecologists were almost perpetually right outside of any nook or cranny they decided to slither into and/or was it because they weren't released exactly where they were found and were disoriented? I'd assume both.

I just think it's illuminating that three of eight adult snakes that had fought it out, won territories, found mates, etc for years...all-of-a-sudden were dead within days after being captured.

Now I applaud any person who releases a snake after capture, but I just wonder what might happen to a completely nocturnal, fossorial, and possibly philopatric snake that was released during daylight and not on the same exact crevice on the same exact cut. I'm not picking on Eby by any means, because I've seen other herpetologists do the same thing (including myself, even under the direction of a PhD herpetologist); I'm just thinking out loud is all...and I'd appreciate any comments, opinions, or feedback.

Thanks,

Dusty Rhoads
Suboc.com

BEAUTIFUL Gray-Band, Eby! Congratulations on finding, photographing, and releasing that animal. Gorgeous!

I'm sure the releasing was the hardest part.

DR
Suboc.com

Dusty,

I am not familiar with the siboc study, but between 1994 and 1997 there were studies done at two independent locations in Arizona using radiotelemetry to evaluate the effects of nuiance rattlesnake (Crotalus atrox) relocation. I don't recall the exact numbers but in both groups the mortality rate of the relocated snakes was very high. I think that there were several flaws in this study, but it did offer some enlightment concerning capture and later release/relocation.
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Gerald Keown
Southwestern Center for Herpetological Research
www.southwesternherp.com

Thank you, Gerald. I remember Mike Price telling me about a bunch of nuisance atrox that were relocated, most of which died. I think he said this happened in Texas. Can't remember exactly where.

I just don't want to see us, who love these animals, to ever be ignorantly putting any of them at risk. The only danger that would ever come to an alterna (or any other herp) from a snake lover would just be us "loving them to death". But, I'm just preaching to the choir.

Dusty
Suboc.com

Dusty,

If you would like a copy of that paper, email me your mailing address and I'll pull it out and make a copy for you.
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Gerald Keown
Southwestern Center for Herpetological Research
www.southwesternherp.com

Great topic. I was definitely thinking the same thing during that release (and every non-immediate release I've done).

I normally release at the point of capture, and as soon as possible, but that release was delayed by attempts to coordinate with another herper or the possibility of giving it to a breeder with a locality mate. The other complicating factor was that there was not a cut at the capture sight and I was just not comfortable releasing it on the shoulder. I settled on an outcrop with deep fractures that was as close as I could find to the capture sight. It also happened to be in the direction the snake was heading when captured. I hope, but can't possibly know if the outcrop was within her home range. One thing I should have planned better was a release later in the day or at night. Luckily the outcrop faced east and had been out of the direct sun for at least a couple of hours prior to the release, so the surface temps weren't too high. As she disappeared into a deep fracture, I just prayed it was unoccupied by anything other than a lizard or two.

I strongly suspect your concerns are well founded, and it's something I've often considered myself. I try to release herps as soon (usually within minutes) and as close to the exact locality of capture as possible. I seldom retain a specimen just for the purpose of a later photograph, but when I do I only do so if I'm sure I can release it at nearly the exact spot of capture. This is likely less of a concern with juveniles than adults.
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Brad Chambers
WWW.HCU-TX.ORG

The Avalanche has already started-it is too late for the pebbles to vote....

Releasing the animal in exactly the same spot, say 24 hours later just shot it through a time warp. To us everything seems to be the same. To the snake it could be like throwing it weeks or even months into the future. I think it would be cool to be thrust into the future, myself. I, however am not a snake. We think that moon phase is so relative to their activity patterns. The snakes clock could suffer major discombobulation. Could this greatly effect it well being? I don't know. Dusty wants to provoke thought? This should seriously be considered. Regards, Rusty

Yes-I think minimizing "time in hand" is definitely a worthy goal.

And maybe this explains alien abduction stories. Galactic "recreational collectors" practicing catch & release
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Brad Chambers
WWW.HCU-TX.ORG

The Avalanche has already started-it is too late for the pebbles to vote....

If a person is concerned with a snakes ability to survive and thrive in the wild, the snake should be left untouched and unmolested. The slightest interference could disrupt its well being. The philosophy, "It's best to err on the side of caution" should be observed. Ask Frank Retes about the hila monster he would often see in the same location. Then, one day someone decided to touch it and it was never seen by him again. I'm currently conducting a study on subocs that may shed some some light on just why some of those wild subocs which were re-released outside their capture site didn't fare well. It is a study being conducted in captivity. There is so much behavior we can potentially learn from captive animals that could be attributed to their wild counterparts. First, however we must start thinking outside the box, and remove the snake from its "Box" in order to give it an opportunity to express instinctive behaviors. Two or three years from now I hope to have enough data to support some of my theories. At that time I will share the study and the results. Regards, Rusty

I know Richard Hoyer has captured Rubber boa and kept them for months, maybe more, and returned them to the same board, log, rock, only to find the boa months and even years later.
The Hoyer web site gives an interesting insight to this subject.

If possible, I believe it would be critcal to any succes of the found animal to be placed back in the same area it was found.

Kudos to Eby for his release, I'm not sure I could or would have.

-Dell

there are several studies that I'm aware of . . . the gist is:

1. Catch and release at site of capture within about 24 hours is fine

2. Catch and release after about 3-4 days, the snakes wander about as if "lost" and mortality goes up

3. Catch and release after a couple of weeks, survivorship is the same as if you'd translocated them

4. Translocation of adult snakes, survivorship is very low

Troy

Troy,

Do the release mortality rates appear to be similar for different species, sizes, ages, and genders? Of course, this question assumes there is enough data to hazard a reasonable guess (not sure that is a safe assumption).

My WAG is that active species would do better than secretive species, small species would do better than large, young would do better than old (after adjusting for the naturally higher mortality of younger animals), and males would do better than females.

Interesting topic... It makes me wonder how even 1 out of 100 fresh hatchlings would survive in the same terrain??

~ Mike Russo

Troy, do you think the results of the studies you cite are likely to be applicable to alterna? How about to other species such as subocs, cealanops, and pictigaster? This is a great discussion and kudos to all for even considering it. This is a very conservation-minded group. I wish that the Texas legislature would see the interest and concern behind these posts! --Henry W.

I think Mike has brought us to an interesting conclusion, not a solution to the entire discussion by any means, but an important point.

1 in 100 hatchling probably DON'T survive. Hatchling mortality in many or, dare I say, all snake species is very high. Troy and I were discussing a watersnake mark and release study he did where up to 66 or 75 percent of the marked babies were presumed dead by their first spring. (Troy correct me if I don't remember the numbers exactly.) Baby snakes hatch and wander as if lost, therefore their mortality rate is much higher than established adult snakes. Snakes who are relocated are put into a similar situation as a new hatchling. They wander until they find suitable digs, but in the mean time get eaten, dehydrate, starve etc.

ALSO,
Rduggler said " Ask Frank Retes about the hila monster he would often see in the same location. Then, one day someone decided to touch it and it was never seen by him again."

I read an interesting report of short distance relocation of Crotalus horridus in a park somewhere, if I can find it I'll post it here. ANYHOO, instead of killing or transporting the rattlers that were found in campsites etc. they would radio tag them and re-release them a very short distance from the capture site. The theory being that these snakes would remember the negative experience and avoid the area where it occurred. In a non-peer reviewed and annecdotal way, this woman proved that this method was very effective.

I wonder if your G-I-L-A wasn't displaying a similar behaviour by avoiding the site of molestation?

ALSO ALSO,
rduggler wrote: "It is a study being conducted in captivity. There is so much behavior we can potentially learn from captive animals that could be attributed to their wild counterparts."

This is not meant as a dig, but do you think the herpetological communtiy will take your study seriously? The reason I ask is, it seems to me that many herpetologists I've encountered have this notion that captive behaviour has little to do with wild behaviour. I think your study sounds interesting and I'm interested to hear the outcome, but I thought I'd throw that out there.

Also also also,
EBY WROTE: "Do the release mortality rates appear to be similar for different species, sizes, ages, and genders? Of course, this question assumes there is enough data to hazard a reasonable guess (not sure that is a safe assumption)."

While I think you're right that there isn't enough data to hazard a guess, this subject is one that is worth investigating. Do large active snakes like coachwhips just crawl aimlessly through the desert and rely on fortuity to locate burrows, food and mates, or do they have a home range which they patrol methodically or systematically? If the former is true, do coachwhips take better to relocation than species that use dens or are fossorial? If the latter is true, how do they establish and navigate this territory?
And, how do these behaviours change through the life of the animal. In Kansas, for example, we have two snakes C. constrictor and P. Obsoletus who undergo a color change from hatchling to adulthood. This suggests a change in behaviour or habitat during these life stages. How does that effect these snakes ability to be relocated or to adapt to new environments.
Also, in many species males seem to wander more than females. Perhaps males would be easier to relocate for this reason. Perhaps these relocations would be even more successful if done during the breeding season. Males might find better hiding places, water, and food by following the scent of reproductive aged females?
There's a whole world of stuff we don't know about snakes eh? The discussion goes on and on.

DAN

Maybe I was a bit rash in calling it annecdotal, but I hadn't read it in about 4 years.

http://www.venomousreptiles.org/articles/18
Short Distance Translocation

Dan, I try to be very careful with my words which is why I use words and Phrases such as "Could" and "May Shed Light". No study conducted in captivity can scientifically answer the kinds of questions posed in this thread. My point however, was that subocs are as easy to breed for a herpetoculturist who knows what he/she is doing with them as it is for an experienced corn snake breeder to breed corn snakes. It can easily be done with a sweater box of appropriate size, a hide box and a water dish. If all we do is keep them in this way, all we will learn are their basic husbandry requirements needed for reproduction. There are so many other behavioral characteristics and patterns that can be learned if we provide them with enclosures where they can exhibit behaviors which I believe are instinctive. Do I keep all of my subocs this way? No. But I do keep a study group in special enclosures that I believe are conducive to their requirements in order to allow them to express these natural type behaviors. Why do I do this? Because as I grow older I become more curious. I have questions that I would like to find possible answers to, and there is something very gratifying in discovering answers yourself. I may be spinning my wheels, but it keeps me content. Regards, Rusty

Rusty,

Good on ya! One of my favorite snake setups was an aviary set up with basking lights and bird house type hide boxes, various basking and belly heat locations. You see natural behaviours, but you also see personality traits of individual animals. I'm sure any of us who have had several snakes at once have seen that some eat this way some eat that way, some sleep here some sleep there. Well, in a cage like this they're given the chance to really express themselves. Anyhoo, didn't want that to sound like a dig or discouraging, its just that in academic world, I got a rude awakening to feelings they have for the private hobbyist. You know. great topic.

DAN

Are their any studies that show what happen when a "sick" animal is released into a population? I remember a tortoise study but I was thinking specifically about snakes.

Great Topic!

Best Wishes,

SXO792

Reminds me of a incident similar to what you discuss.Back when my son was a youngster (He is now on his third tour of duty in Iraq so it was awhile ago). He captured a Large green luna moth.Certanly the most stunning moth here in Upstate NY .The next day when I saw this animal in a jar ,I spoke to him about how it would surely perish and not be able to fullfill its role in nature. He agreed and decided to let it go.We took the jar outside he released the moth who fluttered away ,landed on a tree and was imediatly attacked and carried off by a sparrow.
Well I had to ''fix'' that particular tramatic incident by explaining that sometimes a animals role is to be food.
However in my mind I was thinking but not to a daytime seeking bird ....
This certainly fits your scnerio of a nocturnal animals suddenly exposed in daylight .
www.cnyreptileshow.com

happened to me as a teenager-I'd raised a cecropia moth caterpillar, watched it build a cocoon, kept it cold over the winter, then watched it emerge in Spring. Then I took it out in the backyard to release it. It flew maybe 20 yards when a blue jay swooped in and grabbed it! Talk about anticlimax....
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Brad Chambers
WWW.HCU-TX.ORG

The Avalanche has already started-it is too late for the pebbles to vote....

Is this one of those times that it would be inappropriate to laugh.... just a little bit?

It is that cruel kind of funny..... But the point is well made.

I am sure that the impact of the same set of circumstances is very different from one species to the next, even from one individual of the same species to the next. So you never really know what will come a re-release. I assume that the it is like a form of shell-shock that leaves the animal stunned and not responding properly to the environment around them. They may not feed, drink, thermoregulate or avoid predation as they normally would until this passes. And with nature being very unforgiving about such things....

I would even venture to say that captured animals have the same issue, but a responsible keeper provides the care (food / water / temps) and security (from predation etc) to allow them acclimate to the new situation with enough time. How long does it take a newly captured animal to settle in where they feed well, have an interest in breeding, and just in general act “calm”? Some seem to be fine from day one, others can take years or simply never settle in all the way.

Lance
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___________________________
Herp Conservation Unlimited

Just to add another story about touching a snake. My wife and I live where there is a nice small creek in the back yard and for several years we would see a large water snake every day sunning itself. We would slowly approach it and it would do the usual water snake response and either hit the water or go under a big rock. This went on daily for 2-3 years. One day I decided to catch it since it appeared very fat and wanted to see if I could tell if it was gravid. I caught the snake looked at it and then released it right back there. Never left the spot of capture and only held it for 1 minute or so. I have never seen this snake again since then. It has been one full year now. Maybe it will be around this year but I bet it was the same thing as the Retes Gila. We now have a smaller water snake on the top end of the creek we see every day near a log at the creek and yes I leave it alone after what happened to the other water snake.

I wonder if it matters what the animal was doing at the time of capture. Both Retes' gila and your watersnake were out in the open, possibly basking. I know a researcher who finds kingsnakes under rocks, captures, weighs and marks them and then releases them back under the rocks they were found under. He recaptures them all the time, sometimes several times per season. Perhaps if you find them out in the open they simply don't use that basking spot again for a while. I would think that most snakes have several basking spots and methods of thermoregulation that they use at different times.
Still I usually refrain from touching any snake I find out in the open unless it's on the road or something I want to keep.

A friend of mine who worked for TP&W told me there is like an 80% mortality rate for released herps like turtles and snakes. I assume he was quoting a study done, and there is data to back this up. However, the caveat was that these animals were NOT released in the exact area of capture. This perplexed me because I would assume a herp released into suitable habitat would find food, shelter, mates, etc. Apparently they get wanderlust in new territories due to not knowing where best hunting/grazing spots, hide areas, water holes, are located. In their search, they are more susceptible to predation, exposure, or encountering a traffic filled road. So, if you place them back under the same rock they were found, they should do fine as opposed to just chucking them out in suitable habitat somewhere.

"I assume he was quoting a study done, and there is data to back this up".

Based on what we know about TPW and studies these days, that is one big assumption.

DB