Notes on Rough Green Snakes

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salamanderhunter
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Notes on Rough Green Snakes

Post by salamanderhunter »

In 2014 I did an 'unofficial' study of Rough Green snakes. The purpose was simply to increase my own understanding of the natural history of this species, but I decided to share my notes here on the forum because 1) There are some great herpers and biologists here, and I would love to get your comments, hear what you have to teach, and incite some good discussion, 2) I believe education should be free and accessible where possible, and 3) the more we know, the better we can manage and conserve. I learned a ton this last season, but after 5 nights per week from April until Oct, I was more than ready for these guys to go down for the winter. :)
By the way...I am no photographer. Photos were intended to show roosting position of the snake and perch plant taxa.


Notes on an Opheodrys aestivus mark/recapture study at the Buzzard’s Roost Nature Preserve
Ross County, Ohio
2014

William J. Letsche
Ross County Park District
roostpreserve (at) gmail.com

The Buzzard’s Roost Nature Preserve (BRNP) is a 1200 acre preserve located on the edge of the Glaciated Appalachian Plateau in Ross County, Ohio. The terrain is hilly and covered primarily by broadleaf deciduous forest. The study area is an approximately 5 acre opening that is composed mostly of overgrown fields with dense woody vegetation (mowed once per year), but also contains manicured walking paths and lawn, and a small pond. Dense edge vegetation of various species of shrubs, vines, and saplings are continuous around the border of the clearing and the pond. A short section of an old dirt road abutting the clearing and bordered by dense edge vegetation, was also included in search efforts.
I began searching the study area with a flashlight five nights per week in late March to locate Rough greensnakes on their roosts. The snakes were photographed on their roost as found, and the type of perch plant and estimated height above the ground was recorded. Gender, SVL and TL were also recorded. Snakes were marked on the ventral scutes by medical cautery, and the location of each encounter, including recaptures, was marked on hand drawn maps.


Recorded encounters at the Buzzard’s Roost-137
Individual snakes marked- 29 adults, 9 juveniles. 38 total.
Total encounters with marked snakes- 105
Total encounters with status unknown- 29 (Too high to reach)
Total recaptures-67
22 adults and 1 juvenile were recaptured at least once.
7 adults and 8 juveniles were not recaptured.
SVL and TL recorded on 22 snakes.
Gender recorded on 18 snakes. 11 male, 7 female.

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- I began systematic searches of the study area in late March. The first snake was encountered on 10 April, and was observed several times both during the day and roosting arboreally at night over the following two weeks. Encounters with additional new (unmarked) snakes occurred on 21 Apr (1 snake), 26 Apr (2 snakes), 27 Apr (3 snakes) and 30 Apr (2 snakes). A mass emergence then appears to have begun the last week of April.
- Snakes used privet and honeysuckle bushes very early in the season before other tree species were fully leafed out, and in autumn when other foliage was thin or in fall color. Otherwise, snakes were rarely found in these vegetation types.
-Snakes rarely used berry and rose bushes for roosting, even though these were common in their activity ranges.
- Neonates and young juveniles were more likely than adults to wrap around vegetation stems ‘candy cane’ style to roost at night, and hence, are more difficult to locate. There is a question in the literature concerning the arboreality of young juveniles, as they are seldom found off the ground in vegetation. My hunch though is that they are simply more difficult to see—I had at least one hundred encounters with adults before I ‘learned’ to see the juveniles roosting arboreally.
- One snake (N-5-8) had a single anal plate.
- 4 of 29 (14%) snakes exhibited Type 1 ventral scute anomalies as described by Peters (1960). Plummer (1980) found that 15% exhibited anomalies in an Arkansas population.
- #47 presented with a sizable gash on its dorsum just above the cloacal region, and was encountered roosting within 5’ of the original encounter location eleven nights in a row, after which it wasn’t seen again.
#13 was encountered roosting arboreally on two different nights in nearly the same location when frost appeared on the ground in the early morning hours. Daytime temps were above 60F.
- Snakes appeared to use different habitats within the study area seasonally, apparently following peak prey densities. Snakes were most often found higher in edge vegetation and in larger trees when the caterpillar density seemed to peak there (June, early July). Snakes were most often encountered in the overgrown field when the density of orthopterans suddenly peaked in that habitat in late July. (A garter snake was encountered roosting in the same vegetation on two occasions during this time as well). Finally, Neoscona crucifera, an orb-weaver spider in the family Araneidae, suddenly appeared in abundance in the edge vegetation, at which point snakes were most often found roosting in that vegetation strata.
-Snakes were found as high as an estimated 60 feet. Maximum height appears to be limited only by the height of the thick, dense vegetation structure that this snake prefers.
-Peak encounters in late July was due to snakes being concentrated in certain areas of overgrown field.
-Peak encounters in late September was due to snakes being concentrated around hibernacula locations.
-The last week of May and the first two weeks of June resulted in almost no adult snakes. The three encounters recorded in early June were almost certainly the same juvenile. A neighbor called me and reported that he ‘scared up’ two green snakes from a small ditch with knee high grass while cutting the lawn surrounding the ditch. This might indicate that the adults during this time period were on the ground, perhaps hunting some prey item found there.

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For the information below, snakes were considered to be near hibernacula if they were roosting within approx. 5m of one of four presumed hibernacula locations.

-5 of 29 adults were shown to be philopatric to hibernacula:
#12 and #104 were found at the Wood Shed hibernacula post-egress and pre-ingress.
#15 was found at the Oak/Cedar hibernacula post-egress and pre-ingress.
#93 was found at the Cabin Trail East hibernacula post-egress and pre-ingress.
#38 was found at the Outhouse hibernacula post-egress and pre-ingress.

#17 was encountered at the Outhouse hibernacula on 10 May, just after emergence, then was encountered at the same location again on 20 Sep. I assumed the snake would remain there in preparation for ingress, but was then encountered at the Oak/Cedar hibernacula on 28 Sep and 03 Oct, suggesting the possibility that it moved to a new hibernacula just before ingress.
#24 emerged at cabin trail east hibernacula on 27 April, then encountered at oak/cedar hibernacula on 20 Sep, again suggesting the possibility it entered a different hibernacula for the winter of 2014.

-At least some snakes appear to brumate communally. 22 snakes were found near one of four presumed hibernacula locations:
Number of snakes found near hibernacula locations post-egress (late Apr-early May):
-wood shed: (3) #14, 12 and 104
-oak/cedar: (2) #15 and 35
-Cabin trail east: (2) #24 and 93
-Outhouse: (3) #19, 17 and 38

Number of snakes found at hibernacula locations pre-ingress (Late Aug-early Oct)
-Wood shed: (2) #12 and 104
-Oak/cedar: (7) #24, 25, 48, 46, 45, 17 and 15.
-Cabin trail east: (1) #93
-Outhouse: (2) #17 and 38

10 individual snakes were found at one of four hibernacula locations at egress.
12 individual snakes were found at one of the same four hibernacula locations at ingress.
#38 was the first snake encountered for the season. It remained within 25’ of presumed hibernacula for 2 weeks (observed daily), and then was encountered approximately 100’ away from hibernacula on the edge of the study area on 27 Apr. Was not encountered again until 6 Sep at the same hibernacula location. Likewise, #12 was last encountered on 06 May at woodshed hibernacula, then not seen again until 02 Oct at same hibernacula. I suspect both of these snakes moved out of the study area to adjacent areas of appropriate habitat for their active season. Further, there was a sudden increase in new, unmarked snakes in late August and early September, most of which were found at or near one of the four recognized hibernacula, also supporting the contention that some snakes immigrated into the study area to brumate, but did not use the study area for their active season. It’s possible that these snakes moved through mature forest to enter/exit activity ranges (edge zones) for the season. In at least two cases elsewhere on the preserve, this was certainly the case as there was no other way into the forest openings where the snakes were encountered except through mature forest. Carl Brune recorded an encounter with a rough green snake on the forest floor under a mature canopy with no understory vegetation present.
-Although I didn’t record the data to support this, snakes were sometimes found in ‘pairs’ (within say, 10m of each other). Some were much closer to each other, even within 5 feet. In three instances, a snake was found roosting on the same branch where a different snake had roosted 1 to 2 nights previous. These ‘pairs’ were encountered before and after the presumed courtship/oviposition season, and some were same sex pairs. This ‘pairing’ behavior, as well as the apparent movement of a snake from one communal hibernacula to another suggests that scent trailing plays a larger role in this species natural history than simply as a courtship behavior.
-I don’t think this species roosts arboreally every night, or even most nights. The individual I maintained in captivity commonly roosted under the mulch substrate. The snake would stick its head out of the substrate when hit with direct sunlight in the morning—the same behavior I observed for snakes roosting arboreally in the study area, suggesting that it probably does this in the wild as well.
-I have a hunch that the ambient temperature at the time the snakes are ready to move to nighttime roosts influence whether they roost arboreally or on the ground (If they do indeed regulary roost on the ground as I suspect). I found few snakes roosting arboreally on nights when the ambient temperatures were less than 68 to 70f at the time the snakes would be moving to roosting locations (about an hour or so before sunset).
-I suspect this species is much more common today than it was before European settlement, simply due to the fact there is much more edge vegetation. If the necessary vegetation structure (edge) was largely limited to riparian areas before Europeans dissected the forests, this would account for the evolution of aquatic behaviors documented for this species. The snakes suddenly found a new and suitable niche along roads, field edges, power line ROW’s, etc. So, this species may not necessarily prefer riparian edge zones over non-riparian edge. Both types provide an adequate prey base.


A big thank you to Tiffany Bond, Brad Prall and Sarah Purdum for helping me find snakes! To Jeff Davis for patiently reading and commenting on the “Daily Green Report”, and to the Ross County Park District for hosting, and for purchasing flashlights for the study.

Citations:
Peters, J. A. 1960. The snakes of the subfamily Dipsadinae. Misc. Publ. Univ. Mich. Mus. Zool. 114:1-224.
Plummer, M. V. 1980. Ventral Scute Anomalies in a Population of Opheodrys aestivus. Journal of Herpetology, Vol. 14, No. 2, p. 199.

Other species were sometimes found roosting off the ground...
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Sometimes the greens didn't give you much to see.
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Sometimes they are obvious...like before the foliage leafs out in early spring, or when they are against a background of blue-green foliage (sassafras for example).
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Where greenbrier (smilax) invades dense stands of young broadleaf saplings...you have prime green snake habitat.
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A neonate in greenbrier
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Some other shots...

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This is the injured snake referred to in the notes.

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It's amazing how fast they can wrap their tails around tree branches and such.

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About 30 feet up.

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Thanks for looking!
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John Martin
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Location: North end of Lake Okeechobee, Florida

Re: Notes on Rough Green Snakes

Post by John Martin »

Wow, kudos to you on a very interesting study! Do you plan to continue this in 2015? That's a lot of work, my hat's off to you :beer:
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regalringneck
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Re: Notes on Rough Green Snakes

Post by regalringneck »

... very fine piece of work there & im hoping some of our academian's will pm w/ you to offer collaboration on 1 or more papers/ntrl histry notes for peer reviewed publication (assuming you dont want to do it). I'd start w/ a lit search 1st & see whats known; then your pop structure,+ estimated density data would be a solid stand alone paper for the sps. in that habitat, & the roost heights would make for a gr8t ntrl histry note, all in Herp Review. I'm presuming you have a gr8t boss(es) but they should be aware of your work too : }
Looking up at night @ the bright yellow bellys of florida greens are some of my fondest herp-memories; way out east of the west!
Greensnakes seem to be rather under represented/discussed on forums, especially those little smooths .. i wish they were easier to maintain in vivaria ... ya gotta have access to lots of soft caterpillars.

Thnx for taking the time to share w/ us / rxr

edit ... yes i triple chkt ... that i typed lit search ... b4 i hit submit :p
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LouB747
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Re: Notes on Rough Green Snakes

Post by LouB747 »

Great post. Nice work. I spend a couple weeks in Kansas City midsummer each year and have always wanted to try and find rough greens out in the trees. You've motivated me into having a serious look this summer. It's all the chiggers and ticks that seem to deter me. Are they less active at night?
Jimi
Posts: 1955
Joined: December 3rd, 2010, 12:06 pm

Re: Notes on Rough Green Snakes

Post by Jimi »

Lou - permethrin on your clothes is the solution to chiggers and ticks; it works like a charm, I promise. "Willy Pemer, make you a believer!"

You can absolutely get chiggers and ticks at night. Screw that - permethrin on the clothes, picaridin or DEET on the skin, you're good to go. I can't believe you don't use the stuff in Malaysia etc. (Or maybe you already do?) The stuff has probably already saved my life a few times!

cheers,
Jimi
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LouB747
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Re: Notes on Rough Green Snakes

Post by LouB747 »

Thanks,

On my trips to Singapore I only see mosquitoes, and only at certain times of the year. I spray a little "Off" on me and I'm good to go. I'm not sure if there are chiggers or ticks in Singapore. They do have small ants that have a pretty good bite (sting?).

I never knew what a chigger was until I went to Kansas. Those things are awful. Can't say that I've ever seen one, but I have a few scars on my ankles from them.

Finding snakes in trees at night is a hell of a lot of fun. That's mainly how I find most species in Singapore. Can't wait to try it in the USA.
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mfb
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Re: Notes on Rough Green Snakes

Post by mfb »

This is really great stuff! I also enjoyed the video you posted a while back of a rough green snake eating a spider. I have only seen one rough green in the wild myself, so can't add anything to your observations.

Will you be presenting any of this at the Feb 28th Ohio Biological Survey Natural History Conference?
http://www.ohiobiologicalsurvey.org/

Mike
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walk-about
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Re: Notes on Rough Green Snakes

Post by walk-about »

salamanderhunter - This is some fantastic field work you and your colleagues have endeavored. Yes, I have lots of questions. And btw when you said "By the way...I am no photographer...." Well let me just say you got some fantastic photos here. I too see these in Greenbriar and Sassafras. So at some of the low observation levels in late May and early June, were you just unable to reach the snakes with your flashlight to observe them?? I am guessing they were too high in the trees? Or was there another explanation for their wherabouts?? Did you notice a preference for any arachnid or was it primarily the Orbs? Most species of Orb Weavers I encounter are low to ground. So I am guessing it was the catapillers that maybe drew them higher up in the trees??

Dave
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salamanderhunter
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Re: Notes on Rough Green Snakes

Post by salamanderhunter »

Thank you for your kind words everyone. It's good to get a pat on the back after so much work. :) Walk-about...in late may and early june, the snakes just disappeared. poof. nowhere to be found. except for juveniles. I had another location approx 20 miles away that I or one of the folks helping me checked occasionally. Same deal there, although the proportion of adults was slightly higher, but still mostly juveniles. I think they were on the ground, rather than higher in the trees. I didn't learn much in the way of their diet, as the vast majority of my observations were at night. I think they are opportunistic though...they'll eat whatever they can find. (but they won't eat stinkbugs). And yes, when they moved higher into the bigger oaks and hickories, the caterpillars were booming up there. Caterpillars, as well as some other arthropods show up well in a bright flashlight. Mike...negative on the Natural History Conference. I'll be doing some presentations locally in southern ohio throughout this year though...also probably half day workshops on how to find them in the field...hoping to get folks searching their back yards so we can get a better idea of their distribution in Ohio. LouB...I have a suggestion if you (or anyone) have seen few or no rough greens...go to a place where they are known to occur (the exact location of a DOR is a good bet you're in the correct habitat) and start there. You have to develop a search image for them...which you can only do by seeing a few. And I had very few problems with chiggers and ticks...although it was a pretty cool summer...and they are apparently less active at night when the temps are down. Regalringneck...yes, very little is known about them...and virtually nothing in the northern portions of their range. I would LOVE to see a few of those big Florida rough greens! John Martin...I plan to continue with the rough greens at least a little this season...the study area is in my front yard...so it's too easy to get out for an hour at night. ha ha.
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