Monday, March 28, 2011

Busy Little Beasts

The amphibians and reptiles kept me busy last week.  Still have a ton of camera trap photos to share with you all.

So I'll get back into those with a little tale about a big rodent.  In fact, the biggest rodent in North America:

Castor canadensis.  The North American Beaver.

The labors of this little critter are well-known, even among Homo sapiens.  So much so that their legendary labors are the basis for a commonly used expression meant to describe an equally hard-working human. 

I should post the expression here, but I wont.  I just wont.  It's so obvious.  You all know what it is, right?  :)

The Fur Trade and the Near Extinction of a Species

What you may find interesting is that the toiling rodent of which I speak was nearly driven to exctinction in North America.  Prior to European settlement, the Beaver population here was estimated to be anywhere from 60-400 million (Seton 1929).  This is obviously a very broad range, but even if the true number lies more towards the lower end.....that's still a hellavalotta beavers!  It was also very widespread in it's distribution, with the potential to occupy any aquatic habitat found from the arctic tundra to northern Mexico. 

But it was their pelt.....their soft, warm, luxurious fur.....that got them in trouble when Europeans landed in the New World.  In previous centuries staying warm meant standing near a fireplace to roast your frontside, while your backside froze becuase you lived in a structure with no insulation.  Thus, wearing animal furs, such as beaver, made a miserable winter slightly more tolerable.  Beaver pelts, therefore, had a more utilitarian function at first.  Later wearing garments made of beaver became a status symbol among Europeans.  Felt made of Beaver wool was most importantly used to make hats (Carlos and Lewis 2008).  The review by Carlos and Lewis is an outstanding historic summary of fur trading in North America.  As they point out, for centuries hats were a required part of daily garb for both men and women.  A hat was a symbol of social status or authority during Colonial times.  Unfortunately for our giant rodent, from the late 15th century to the 19th century, the most desired hats were made from beaver wool felt.  By the 16th Century, the European Beaver (Castor fiber) was already nearly extinct, probably due in large part to the demand for hats (and castoreum).  As a result, Beaver wool was hard to come by in Europe.  Thus, it should come as little surprise that once Europeans landed in the New World and saw the prevalance of the North American Beaver, the exploitation of this resource began.

Beaver pelts are the most "desirable" when they are dense and luxurious.  The most luxurious pelts come from Beaver living areas with extreme winters.  As a result, the most severe harvests apparently started in Canada.  In the New World, pelts were obtained from Native American and transplanted European trappers who exchanged them for goods with commercial trading operations.  These commercial outfits then shipped the pelts to Europe for their final sale.  Thus, the trade in Beaver pelts spanned the Atlantic: demand being driven from Europe, while volume and price being dictated in North America.  To meet this demand, Beaver pelts were shipped back to Europe in high volume.  For example, it has been estimated that the potential market for hats in England alone was 5 million in 1700.  These demands did not abate or level off over time and, in fact, they increased.  For example, 69,500 beaver hats were exported from England to the rest of Europe in 1760 this number rose to 500,000 beaver hats (and 370,000 hats made of a combination of beaver wool felt and the felt from another animal's wool).  Again..this data is nicely summarized by Carlos and Lewis (2008).

The very high demand for beaver pelts....a demand that was increasing....led to a high harvest rate for North American Beavers.  Hays (1871) estimated that 80,000 Beavers were harvested annually from 1630-1640 in the area of the Hudson River and western New York.  The accuracy of estimates based on historic records may be questionable, but this number is staggering!  This high harvest rate (especially along the eastern Sea Board of the U.S.) led to population declines.  As eastern populations dwindled, trappers moved further inland to seek Beaver pelts....which resulted in the formation of the Hudson Bay Company who traded in that bay of the same name.  One good thing about the formation of the Hudson Bay Company is that they kept close records on their trade in Beaver pelts starting in 1700.  As a result, it's possible to get some appreciation for the numbers of Beaver harvested and traded through them at that time.  For example, records from one of their main trading posts at Fort Albany from 1700 to 1720 indicate that an average of about 19,000 beaver pelts a year were processed.  From 1721 to the late 1740s, the annual average pelts traded were about 14,000.  After a period of stability, and even increase in the late 1740s, the numbers of pelts recieved dropped drastically.  By 1756 less than 6,000 pelts were recieved and in 1770 only 3,600 beaver pelts were recieved.  Remember...these records are only for Fort Albany.  Hudson Bay Company had other trading posts and they weren't the only gig in town.

Couple the extreme harvest pressure on Beavers with the loss of suitable habitat that has occured over time (for example, Shaw and Fredine 1971 estimated a loss of up to 260,000 km-squared of wetland habitat in the U.S. since the time of European settlement).

Today, trapping regulations and an absence of Beaver predators (which is also the result of human activity) has allowed Beaver populations to rebound slightly.  For example, according to Naiman et al. (1988) the US Beaver population is estimated to be between 6 and 12 million.  Great.  Although this estimate may be a tad dated and on the low's a far cry from the historical estimates of 60 to 400 million!

The Influence of Beavers on Aquatic Ecosystems

Beavers are often refered to as "ecological architects".  They have the ability to massively alter aquatic habitats by busily building their dams.  Interestingly, their removal and near extinction must have drastically changed freshwater habitats in North America. This obviously occurred before modern limnologists (people who study freshwater) started to conduct their research.  As a result, as Naimen et al (1988) point out, "our understanding of stream ecosystems is derived from sites that lack the influence of this previously abundant and ecologically important herbivore". 

Beavers alter the landscape in several ways.  The most obvious way is by daming the stream, and transforming it into and "impoundment" (or Beaver pond).  In other words, they build their dams in a stream, the water backs up and what was once a swift flowing stream...becomes a slow moving, backwater wetland habitat.  Beaver dams reduce annual water discharge and velocity substantially.  As water backs up, the area of flooded soils increases, as does deposition of sediment and organic material.  Naiman et al. (1986) report that a even small dam (4-18 meters-cubed in size) retained 2,000 to 6,500 meters-cubed of sediment.  Beaver ponds can also substantially change the way nutrients, such as nitrogen and especially carbon, cycle within aquatic ecosystems compared to a stream.  As a result of the massive differences in nutrient cycling and hydrology, these two habitats (streams vs. wetlands) have very different assemblages of species that associate with them.  Furthermore, the physical and chemical characteristics of a Beaver pond change over time!  So, there is further variation in how Beavers influence their environments.

Yet, Beavers don't just alter aquatic habitats.  To create their dams, Beavers must take something from the nearby riparian zone (or zone associated the stream banks).  Any ideas as to what it is that they take?  Naiman et al. (1988) reviewed work by others and found that in northern latitudes, Beavers can be responsible for the removal of up to 1 metric ton of wood annually within 100 m of their ponds.  In fact, Beavers can almost completely eliminate the trees in a riparian area that is comprised mostly of tree species they prefer.  You may imagine that this can have a profound effect on the structure and function of terrestrial ecosystems adjacent to Beaver ponds.  For example, removing many trees increases light penetration to forest floor, giving smaller plant species access....changing plant assemblages in the area, which can change the animals species that use the habitats created by the vegetation.

So, Beavers come in, change water flow, nutrient-cycling, and hydrology of an area.  They also alter the associated terrestrial landscape.  These activities drastically alter the species found in these areas after Beavers become established AND drastically alters ecosystem function.  As more Beavers move into a watershed, the more impact they have.  As Naiman et al. point out: "A Beaver-impounded landscape is thus a mosaic of different vegetation types, due to the dynamic hydrology of beaver ponds, the diversity of pre-impoundment vegetation, and the changes caused y beaver foraging in the riparian zone."

Therefore, Beavers can exert incredible influence on, not only aquatic ecosystems (i.e. turning streams into wetlands), but also adjacent terrestrial ecosystems!  Some suggest that no other animal species (especially one that is only found in small family groups) has as great of an impact on their surroundings.

That's alot of impact for a big rodent!


Finding the Busy Beast

Alright...alright.  I know!  I know what you are saying: "C'mon with the pictures, chump!"  But, once I start talking about something of's easy for things to get out of control!

So, about three weeks I wandered along stream banks at one of my study sites, I came across a mud slide down to the water.  I was not very far from my otter latrine site, so I assumed it was an otter slide.  However, as I inspected the slide more closely, it became apparent that this was not a slide confined to the stream bank.  It appeared to be drag that plunged back into the adjacent scrubby woodland behind me.  What the hell an otter would be doing such a thing for was beyond me.

Above: the drag marks I followed that lead me away from the stream.

Although I was sort of pressed for time on that given day, I couldn't help but I followed the strange "slide".  Within seconds I saw something that made me exclaim to myself..."Well, duh..ya idjiot! Of course this isn't the work of otters!"  There, along the trail, was a freshly gnawed-off tree about the diameter of a sapling. 
Above: obvious evidence of Beaver activity along the trail I followed

I continued along the trail, which I now knew had been created by Beavers dragging trees down to the water.  Soon the trail began splitting off into various other directions...and more evidence of fresh beaver activity starting showing up.
Above:  A tree trunk with both fresh and old beaver activity present.  Note also the shavings at the base.

Finally, the trail lead into an opening....which was a great example of how Beavers can almost clear-cut an area comprised of trees they prefer. 

Above: a small clearing in the shrubby woodland, created by Beavers.

Dang, I thought, I need a camera in here!  I didn't have an extra camera with me at that time....but I knew I had one at home that I could jimmy-rig to work somewhere in the vacinity of the beaver activity.  So, after investigating the area a bit more, I headed for home.

The next day, I came back...extra camera in-hand....looking to trap me some Beaver (pictures of Beavers, that is).  Now, anyone who uses camera traps knows, more often than not you have to secure them to trees.  This is especially true if you are working in areas where theft can be a problem.  What is the difficulty with this when Beavers are involved, you ask?  Well....should our giant chewing rodent decide he wants the tree that your camera is attached to, you may (1) fail to get Beaver pictures because (2) your expensive camera was incorporated nicely into the dam of the busy little critter! 

All of this went through my mind as I tried to find a suitable location to mount my camera.  The Bushnell I was going to use had a sluggish trigger at I couldn't put it perpendicular to the trail.  If I did that the Beaver may lumber past too fast for the Bushnell to snap a good shot.  I also didn't want to put it in the woodland clearing.  Mostly because the only suitable tree for mounting a camera was the same species the Beaver seemed to be fond of chopping!  The camera had to go on the trail somehow.  But, it had to be facing up or down the trail (not perpendicular to it).  It also had to be on a tree that the Beaver appeared to be passing by, for whatever reason.

I found a tree that appeared useful.  It looked like the same species of tree that the Beavers had been focusing on.  However, they had passed this particular tree by again and again when dragging branches back to the water. 

Not a great option, but better than none.  So I mounted the camera, and with alittle trepidation, left the site.

Above: a test photograph from the location I mounted my camera trap along the Beaver drag.

Well, I waited...and got nervous...and started thinking the worst. 

What if the Beavers decided suddenly to take the tree I had my camera on?  I'd be out the cash and didn't have any to replace the missing unit.  Man I was an idiot!  What was I thinking?!

Ultimately, circumstance dictated that I had to go to my site about four days later (usually, I'm out weekly in the winter/early spring).  Immediately upon my arrival, I marched to my Beaver camera set and breathed a sigh of relief.  The camera was still there! 

So, I opened the camera and noticed it had taken 400 plus pics in that four day period.  Very exciting!  Upon arriving home, I anxiously scrolled through the pics.  Sure enough, I had gotten a ton of Beaver pictures!

But not at first......

The first visitor was an eastern cottontail (Sylvilagus floridanus).

March 11, 2011 (Evening) through March 12, 2011 (Morning):
About an hour later, our busy little friend came calling....
A few hours later, another one enters along the same path.

Not long afterwards, one of the Beavers is on the way out, and he's dragging a tree with him (appears to be a cedar of some kind). Note the tree branches in the lower right of the field of view beind hauled out by the beaver.
Several hours after that, the second Beaver is on his way back to the water with a small tree in his mouth.

A few hours later, one of our little friends returns yet again!
But, he is apparently less-than-satisfied with what he has to choose from, and leaves empty-handed.

March 13, 2011:  A Beaver returns, ready to work...
...and leaves soon after with some wood that is to his liking....

....not long before he's back.....
This is a quick trip, though.  Within a few minutes, he's leaving with branch in-mouth....

March 14, 2011: the Beaver returns as predicted.
....and this time, there's a co-worker on his heels.....

They both quickly find what they are looking for and head back to the water one-after-the-other (I love the first picture below). In the second picture, we see only the tips of the branch that the other Beaver is hauling by.

March 14, 2011 (evening): The Beaver is back!  This time, though, he plunges down a new side-trail directly in front of the camera.
....and he returns with some wood for the dam....

This is the last picture I got of the Beavers that night.

Next came the ubiquitous white-tailed deer (Odocoileus virginianus).

And finally, a pair of thumpers....

I pulled the camera in the late morning of March 15, 2011.

I'm hoping to find more good Beaver spots in the future.  Most that I find, however, are close to the water....given the "flashy" nature of streams in this area, placing a camera too close to water is hazardous...should an unforseen rainstorm hit.  The beaver set discussed above was as perfect as it gets!  I hope I can find another spot this good!

Literature Cited

Carlos, A. and F. Lewis. 2008. Fur Trade (1670-1870).  EH, Net Encyclopedia, edited by R. Whaples. URL:

Hays, W.J. 1871. Notes on the range of some animals in America at the time of arrival of the whiteman. American Naturalist 5:25-30.

Naiman, R.J., C.A. Johnston, and J.C. Kelley. 1988. Alteration of North American streams by beaver: the structure and dynamics of streams are changing as beaver recolonize their historic habitat.  Bioscience 38:753-762.
Naiman., R.J., J.M. Melillo, and J.E. Hobbie. 1986. Ecosystem alteration of boreal forest streams by beaver (Castor canadensis). Ecology 67:1254-1269.

Shaw, S.P. and C.G. Fredine. 1971. Wetlands of the United States: their extent and value to waterfowl and other wildlife.  United States Deptartment of the Interior, Fish and Wildlife Service.  Circular No. 39.  Washington, DC.

Seton, J.R. 1929. Lives of game animals. Vol. 4, Part 2, Rodents.  Doubleday.  Garden City, NY.

Saturday, March 26, 2011

No Explanation Required!

I think this picture I got of a Raccoon (Procyon lotor) is funny enough to need no further discussion.

Thursday, March 24, 2011

Another Good Day For Herps (i.e., Amphibians and Reptiles)!

I put the clarification in the title as to what a "herp" is....just in case folks not familiar with this word mistakenly thought my post had something to do with an S.T.D.  I thought about this after my post from yesterday (A Good Day for Herps, posted on March 23, 2011). re-interate....a "herp" is a generic term for amphibians and reptiles (the study of these critters is called Herpetology).  Whereas a "herpe" is something you'll never read about on this blog.


Yesterday, I posted about my first good haul of captures in my survey equipment this year (drift fences and coverboards).  The scaly and slimy goodness continued today, much to my happiness!

We had several massive thunderstorms blow through the area last night.  I was hoping the rain would stimulate some amphibians to move around alittle...and they did!

But, let me start with my drift fence capture from yesterday (as promised in my last post).  This one was in the "pitfall" trap along one of the fences I have in an upland deciduous forest.  I have one pitfall trap associated with each drift fence.  It consists of a 5-gallon bucket dug into the ground so the lip of the bucket is flush with the surface of the dirt.  The fence then leads critters to the bucket and they fall in.  It's a live trap.

Above: the drift fence leading up to the pitfall trap

The volunteer yesterday was a nice little wormsnake (Carphophis amoenus).  These critters were a common occurrence in the drift fences last year.  They must exist in large abundances in dry/mesic upland forests in our region.  Despite this, there is relatively little known about these docile little snakes.  In fact, that I know of, there are only five manuscripts that have studied the ecology of these critters in any depth (Aldridge and Metter 1979, Clark 1970, Fitch 1999, Russell and Hanlin 1999, Wilson and Dorcas 2004).  The reason why they have been the subject of so few rigorous ecological research projects is probably becuase they are small, secretive and fossorial (i.e. below ground). They're not easy to find without the use of specific survey equipment.

The wormsnake is easy to identify.  Their dorsal (upper) surface is brownish-red, with sleek scales.  Their ventral (lower) surface is often rosy or pinkish in color.  The head is very small (likely becuase they eat primarily soft-bodied invertebrates, such as worms), as are the eyes. 

Above: the small head and eyes of the wormsnake, buried beneath its coils.

The most unique character is the hardened, pointed tail-tip (sometimes called a "tail spine").  They often press this tail tip into the hand of anyone that attempts to restrain them.  This defensive behavior is almost laughable, as it causes no discomfort whatsoever to a human.  However, perhaps it is effective against other smaller predators that may threatened these snakes in the leaf litter of the forest floor.

Above: the hardened "tail spine" of the wormsnake.

Behavioral observations of this species are uncommon.  However, some unique anecdotal reports exist in the literature regarding their defensive behaviors.  Pressing the "tail spine" into the hand of a would-be captor is the most commonly reported defense.  Kapfer and Slone (In Press) also report a bizzare bit of defensive behavior involving an individual that partially buried the front 3/4 of it's body in leaves, lifted its exposed tail and wagged it's tail in a serpentine fashion.  In addition, Diefenbacher and Pauley (2009) observed an individual hiding its head beneath it's coils, while holding the tip of it's tail vertically.  The assumption is that the head is buried in the coils and the tail is presented to the predator in the hopes that the tail tip is focused on, rather than the head.  In theory, a predator damaging the animal's head is more likely to result in death than if the predator focuses on the tail.  I  don't know how effective this defense mechanism is.....I don't see many wormsnakes with damaged tails.

I had never seen this head-hiding behavior before. 

In any event, while trying to photograph the wormsnake I caught yesterday, it presented me with half of the defensive behavior reported by Diefenbacher and Pauley, it hid its head beneath its coils (it didn't raise its tail in a vertical position, however).  When I would touch the snake in the hopes of repositioning it for a better picture, it would bury its head further into it's coils.  Eventually, I gave up....took a picture of the "headless" snake, buried it under some leaves nearby and went on about my business.

Above: a wormsnake exhibiting the defensive behavior that involves hiding its head beneath its coils.


So the wormsnake was all I got in my drift fences yesterday.  Yesterday was the day for coverboards being effective.

Today, it was just the opposite.  The coverboards yeilded nothing, but the drift fences were crawling (literally).  The massive lightning storm we had last night (and associated rain) may have gave the salamanders under the coverboards the moisture they needed to mosey along to some nice subteranean refuge.

So...I'll go through some of the highlights from the drift fences today.

The first captured critter I encountered today was in one of my grassland drift fences: the Common Gartersnake (Thamnophis sirtalis).  I captured two individuals in the same fence.  One in one of my wooden box traps and the other in a funnel trap.

Above: box trap associated with a woodland drift fence

Above: a funnel trap placed along a woodland drift fence

So, the first gartersnake was found in one of the box traps.  The heavy rain had lead to a drop in temperature, and it was cooler this morning.  The snake wasn't moving very fast and I was able to snap a shot of him in the box (normally they are shooting out as soon as its open!).

Above: my first encounter of the day, a common gartersnake (Thamnophis sirtalis) in a box trap

Above: two pictures of a Common Gartersnake (Thamnophis sirtalis) captured in a drift fence.

Common Gartersnakes are....well......common.  They are probably the most commonly encountered snake throughout the eastern and midwestern USA. We even caught them in huge numbers back home in Wisconsin.  They can withstand human disturbance, they are very general in their habitat needs and diet.  So, I'm not shocked to have caught them today. 

But that doesn't mean it isn't always a treat to catch snakes!

I next moved into check some of my woodland drift fences and was in for a treat.  One of my favorite native frogs was waiting for me in a funnel trap: Cope's Gray Treefrog (Hyla chrososcelis).  Cope's Gray Treefrogs are another species that I was familiar with from my work in Wisconsin (although there it is less common than the related (and very similar) Gray Treefrog (Hyla versicolor).  In fact, these two species are so similar they can only be easily differentiated by hearing the call of the breeding male for each species.  While the call for both is a quick trill, the Gray Treefrog's trill is more bird-like and melodic....whereas the Cope's Gray Treefrog has a trill that sounds more like an insect, almost sounding like a flourished buzz.

There is another definitive way to distinguish these two frogs, but it is much more cumbersome: counting chromosomes.  The Gray Treefrog is a tetraploid, and has double the chromosomes (48) of a Cope's Gray Treefrog, which is a diploid.

Not many people are going to go to this extreme, however!  I've only ever heard Cope's Gray treefrogs calling in our I'm going to assume that's what I caught (I forget my portable chromosome analyzer in the car most of the time, anyways ;) ).

Regardless of all that thing is for certain: they are cute as heck!

Above: note the obvious toe pads. They can climb up sheer surfaces and the toes feel sticky to the touch!

Above: Talk about camoflauge!

Above: the yellow in the groin upper thigh region is typical of H. chrososcelis and H. versicolor.


So after finishing up my work at the first study site, I moved on to site two.  Starting with the grassland drift fence, as I had did at Site 1.  Again, I was in for another treat!

You may recall that yesterday, I found a juvenile Racer under one of the coverboards (which I mentioned was patterned, unlike the adults).

Today I captured a large adult Racer (Coluber constrictor) in a funnel trap.  Now you can see how the juveniles and adults differ in their appearance.  The adults are a beautiful sleek black, with white chins. 

They also can be alittle nippy!

Interestingly, after I set it on the ground and harrassed it for a while (trying to position it for a good picture, while dodging it's angry mouth) went through the same head-hiding behavior that the wormsnake did yesterday.  In fact, it was so committed to protecting it's head, that I was able to pick up my gear and prepare to move on for a good three minutes and the snake remained in that pose for the entire time.  I eventually had to move it off into bushes for fear a hawk would nail the snake if I left it where it was.

Above: an adult black racer protecting its head with its coils.


I'll round this out with some salamanders.  Yesterday, I found two species: the slimy salamander, and the spotted salamander.

Today, when I checked on my woodland fences at site 2, I found a third species the Marbled Salamander (Ambystoma opacum).  Although I found this species commonly last fall, they are a beautiful little salamander and I always enjoy seeing them.  This one was in a box trap.

So long as I'm on a defensive behavior kick, why not show you some cool salamander defensive behavior.

Above: a Marbled Salamander exhibiting defensive posture.

This defensive posturing is cool as heck!  As soon as I touched the salamander, it instinctively rose it's tail and dug its head into the ground (well, as much as it could in this box trap).  What this accomplishes is (1) protecting and hiding the head, making it less of a target and (2) focusing the predator's attention on the tail.  This makes alot more sense for the salamander than it does the wormsnake because, unlike the wormsnake's tail, the salamander's tail would make a particularly undesirable meal.  When harrassed further, the salamander secretes a whitish substance from glands on its tail.  This secretion is incredibly sticky (it will even cause your fingers to stick together for a few seconds).  The secretion is also noxious.  Brodie et al. (1979) found it will deter a common woodland floor predator: the shrew. 

So, the sally protects its head, while presenting a foul, sticky tail.  Brilliant!

Above: whitish secretions from glands on the salamander's tail

Above: the salamander's sticky secretion on my thumb!

Above: a handsome little salamander

I also picked up two more adult slimy salamanders, three white-footed mice (Peromyscus leucopus), and a nice little Carolina Short-tailed shrew (Blarina carolinensis).  Didn't get very good pictures of them, though.

Literature Cited:

Aldridge, R.D., and D.E. Metter. 1973. The reproductive cycle of the western worm snake, Carphophis vermis, in Missouri.  Copeia 1973:472-477.

Brodie, E.D., III and R.T. Nowak and W.R. Harvey. 1979. The effectiveness of antipredator secretions and behavior of selected salamanders against shrews. Copeia 1979:270-274.

Clark, D.R. 1970. Ecological study of the worm snake Carphophis vermis (Kennicott). University of Kansas Publications, Museum of Natural History 19:85-194.

Diefenbacher, and Pauley 2009. Carphophis amoenus defensive behavior.  Herpetological Review 40:94-95.

Fitch, H.S. 1999.  A Kansas Snake Community: composition and changes over 50 years.  Krieger Publishing.  Malabar, FL.

Kapfer, J.M., and C.Slone. In Press. Carphophis ameonus (eastern wormsnake) defensive behavior. Herpetological Review.

Russell, K.R., H.G. Hanlin. 1999. Aspects of the ecology of worm snakes (Carphophis amoenus) associated with small isolated wetlands in South Carolina. Journal of Herpetology 33:330-344.

Wilson, J.D. and M.E. Dorcas. 2004. Aspects of the ecology of small fossorial snakes in the western Piedmont of North Carolina. Southeastern Naturalist 3:1-12.

Wednesday, March 23, 2011

A Good Day for Herps!

The posts will come more frequently in the spring, I imagine. 

Especially now that the herps are active, as I'll have more to talk about in between camera trap photos!

As a little background, let me tell you about this project.  I have two study sites that I'm comparing mammal and herp communities at.  The camera traps are part of that project, but I've also got a suite of other survey equipment deployed for small mammals and herps.

At each site we are surveying three habitats.  In each habitat we have a transect of 10 cover boards and a drift fence (200 ft of fencing with three types of live trap: funnel traps, box traps and pitfalls). 

So, for those of you keeping track, that's 60 coverboards (hauled out on the back of your's truly last year) and 1,200 ft of fence dug in (again, by your's truly).  The boards create cover, and a microclimate beneath that are attractive to herps and small mammals.  They are passive, so you can go out and flip them whenever.  The drift fences also capture herps and small mammals.  Problem is, they are not passive.  If the traps are engaged, you have to check them every 24 hrs and release the critters captured.

We are also supplementing with sherman traps (only for small mammals).

So, I run the surveys in the summer and off semesters, and in the semesters that I teach Wildlife Ecology, the students run the surveys as part of their lab exercises.

Two weeks ago, the drift fences were opened for the first time (no class this it's done by me, or any student willing to volunteer).  Because the semester is still in session, time is limited, and we are only opening them for one or two 24 hr perios per week.

In the first week: no captures.
In the second week: a single cricket frog and a white-footed mouse (and that's it for ALL of that survey equipment!).

Clearly, stuff was not ready to start hopping yet.

Today, I had the first good haul of herps to indicate the season is upon us (I hope!).

First, in one of the grassland coverboard transects, got a cute little juvenile racer (Coluber constrictor).

Although the adults are typically a sleek black (with a white chin), hatchling racers are patterned.  This pattern is retained by juveniles (as seen in the pics above) for a time and fades as they grow to adulthood.   Racers are aptly named.  They can move like the dickens and even an experienced herpetologist can loose them in long grass or brushy edges should they take off.  Luckily it was cool this morning when I checked the boards, and this guy wasn't moving very I was able to snap a few pics!  Although the specific epithet "constrictor" implies....well...something that constricts, racers typically don't.  They often prey on animals they can overpower without constriction....although bigger prey may be held down with a coil or two.  They hunt by smell, but also by sight.  Nussbaum et al. 1983 report that they are able to detect crickets up to 50 METERS away, and can see larger prey at even greater distances!  Their dietary choices are not narrow. 

In fact, Uhler et al. (1939) reported the prey occurence (by volume) in the stomachs of racers surveyed in Virginia as follows:
  • snakes=26%,
  • birds=18%,
  • shrews=12%,
  • caterpillars and moths=10%,
  • frogs=9%,
  • moles and lizards=6%,
  • squirrels=5%
  • other insects/arthropods=5%
Hamilton and Pollack (1956) found the percent occurrence of food types selected by racers in Georgia to be as follows:
  • Lizards=65%
  • Snakes=28%
  • amphibians=9%
  • mammals=3.5%
  • insects=1.7%
In North Carolina, Brown (1979) found that reptiles, mammals and insects made up roughly 80% of selected prey.

Interestingly, a different trend was observed in Illinois by Klimstra (1959):
  • insects = 48%
  • mammals = 43.5%
  • birds = 16.5%
  • THEN reptiles= 12%.
A similar trend was also reported by Fitch (1963) for racers in Kansas:
  • Insects = 77%
  • mammals = 15%
  • snakes = 5%
So, not only do they have broad dietary interests, they also vary greatly by geographic location.


My next coverboard discoveries occurred in the woods, specifically in lowland deciduous woods.  There is a wooded riparian area (stream corridor) nearby, and a number of ephemeral wetlands in the general vicinity.  That means one thing!  GREAT SALAMANDER HABITAT!

The first volunteer was a very young white-spotted slimy salamander (Plethodon cylindraceus).  He was under a board located within 15 ft of an ephemeral pool.  He was so small that I actually almost didn't see him.

I had found many young slimy salamanders at this site last year, but no big adults.  That changed today, however!  I found a big male under a different board in the same transect.

Slimy salamanders are members of the family Plethodontidae, which are generically referred to as the "lungless salamanders".  The name is accurrate, as members of this Family truly have no lungs!  They absorb oxygen through their skin (called cutaneous respiration).  The taxonomy of the "slimy salamander complex", specifically, is amazingly confusing and constantly in flux.  Members of this "complex" are found throughout the southeastern and eastern USA.  According to Beane et al. (2010), all slimy salamanders in our region were once thought to be a single species (P. glutinosus).  These have now been split into 4 species that exist in the state: P. glutinosus, P. cylindraceus, P. chattahoochee and P. chlorobryonis

Luckily, in my particular part of the state, I only have to worry about one (P. cylindraceus, the white-spotted slimy salamander).  Whew!


I round out this post with another coverboard encounter: the spotted salamander (Ambystoma maculatum). 

A member of the family Ambystomatidae (the "mole salamanders") these chucky little salamanders are fairly common in this region of the state.  Amazingly, I had not found one until today!  So, I added a new species to the list for one of my sites.  The breeding season for this species is late winter, early spring and has already passed.  I imagine this fella was taking advantage of the nice cover created by the board and will soon move on to his permanent borrow for the summer.

Drift fence captures to be reported in the future!

Literature Cited:

Beane, J.C., J.C. Mitchell, W.M. Palmer, and J.R. Harrison III. 2010. Amphibians and Reptiles of the Carolinas and Virginia (2nd edition).  University of North Carolina Press.

Brown, E.E, 1979.  Some snake food records from the Carolinas. Brimleyana 1:113-124.

Fitch, H.S. 1963. Natural history of the racer Coluber constrictor.  University of Kansas, Publications of the Museum of Natural History 15:351-468.

Hamilton, W.J., Jr., and J.A. Pollack. 1956. The food of some colubrid snakes from Fort Benning, Georgia. Ecology 37:519-536.

Nussbaum, R.A., E.D. Brodie, Jr., and R.M. Storm. 1983. Amphibians and reptiles of the pacific northwest.  University of Idaho Press.

Klimstra, W.D. 1959. Food of the racer, Coluber constrictor, in southern Illinois. Copeia 1959:210-214.

Uhler, F.M., C. Cottam, and T.E. Clarke. 1939. Food of snakes of the George Washington National Forest, Virignia. Transactions of the North American Wildlife Conference 4:605-622.