It is currently January 21st, 2019, 6:59 pm

All times are UTC - 8 hours




Post new topic Reply to topic  [ 32 posts ] 
Author Message
 Post subject: USGS Desert Tortoise Project: Part 5
PostPosted: December 16th, 2011, 3:57 pm 
User avatar

Joined: June 7th, 2010, 6:27 pm
Posts: 243
So this post marks my one-year-in-the-desert anniversary! It’s gone by pretty quick. I’m trying something a little different with this entry – rather than posting photos chronologically I’ve organized them by theme into three separate chapters as follows:

Chapter 1: The Un-natural History of the Mojave Desert
Chapter 2: Invertebrates
Chapter 3: Herps, etc.



*Also, I forgot to mention this earlier – all ideas, opinions, etc. expressed here are my own and do not necessarily represent those of the USGS. (This applies to all of my entries).



Image


Image


Image








Chapter 1: The Un-natural History of the Mojave Desert


From looking at photos like the ones above, you might have gotten the impression that I work in some kind of pristine wilderness. Its beauty not withstanding, if you look a little closer (or sometimes not so much…) it becomes clear that this is not the case. I doubt there’s anywhere in the world devoid of all trace of human existence, and the Mojave Desert is no exception. This is something I have alluded to in earlier posts, but would now like to explore in more detail. Some of the “junk” out here is big, some small – some is old, and some more recent… but is it all the same in the end?

Working out in the desert, it’s easy to forget that this place wasn’t always so dry. As recently (geologically speaking) as 10,000 years ago, the climate here was considerably wetter and cooler, and supported a much different array of plants and animals than today. As you might expect, this type of environment would have been more conducive to early human habitation, and I’ve often wondered about what life was like for these people.

The other day we were walking a transect (to survey for tortoises) through some dry mudflats, beside a large playa. I imagined what this place looked like thousands of years ago, when there were permanent lakes and wetlands. For early hunter-gatherers, the resources in the area would have made this a good place to stop by (they were nomadic). This isn’t just my speculation – these people literally left their marks set in stone.

Image




I had heard that there were petroglyphs in the area, but it was especially exciting to basically stumble upon them while conducting our transect. Aside from a small fence and a very uninformative sign, the site was unassuming and could easily be overlooked (did I mention it’s also in the middle of nowhere?). From my experience it’s typical for petroglyph sites to have a low profile in an effort to avoid unwanted attention from potential vandals, which has been a problem (note the bullet holes through the sign).

Image




I was disappointed that there was no educational information about the site provided, and that relatively few people would get to see these petroglyphs in person – but on the other hand it was refreshing to see such an amazing historical/cultural resource not yet corrupted by commercialization, its overall authenticity still relatively intact.

Despite being a small canyon (only a few hundred meters long), this site contains more than 1,000 petroglyphs. The canyon is composed of volcanic basalt, the surface of which has a blackened patina. Chipping or scraping away at the surface, however, reveals a much lighter colored stone beneath, resulting in the contrast seen in the petroglyphs. (Interestingly, the degree of contrast can be used to help date the engravings, as petroglyphs will become “repatinized” by the elements over time, and older images will appear less bold).

Most of the petroglpyhs are located on the southern-facing slope, which gets more sun (there are some on northern-facing slope too, but lichen growth has obscured much of the images on this side). I was impressed with the diversity as well as the concentration of petroglyphs here. While there were some definite themes I recognized among the images, there was also a great deal of variation in terms of style, size, and content. Some of these differences are attributed to the fact that this site was used by different cultures (Archaic hunter-gatherers, Paiute, Shoshone, Kawaiisu) over an extended period of time (12,000 years ago – present).

Stylized depictions of animals (zoomorphs) were a common theme, with Bighorn Sheep (Ovis Canadensis) being one of the most recognizable subjects of petroglyphs across the western United States as a whole. Ironically, O. Canadensis was never that common in this particular area, nor is it believed to have contributed significantly to the diet of native people here. Consequently, scholars think there must have been other factors (i.e. spirituality) responsible for their disproportionate representation in the petroglyphs here and elsewhere. (Notably, other animals that were staple food items for people here [i.e. rabbits] are not represented in the petroglyphs at all).

Image




Others images are more ambiguous – Is this a snake, or just a wavy line?

Image




Some depict humanlike figures/faces (anthropomorphs)

Image




A mask? (and maybe a snake on the left?)

Image




Cave

Image




Technicolor lichen

Image




Abstract geometric shapes and patterns of varying intricacy were also abundant

Image


Image


Image


Image


Image


Image




So what does it all mean? In short, we don’t know for sure, and probably never will, but we do have ideas. There are so many interesting theories regarding the purpose and interpretation of petroglyphs that I’m not even going to attempt to scratch the surface here (haha), other than to say that such images almost certainly played different roles depending on the circumstances of their creation (who, when, where, etc.).

There is a related issue I find especially fascinating and worth mentioning here. During the 1920s psychologist/neurologist Heinrich Klüver studied the effects of mescaline and found that aside from causing bright, saturated hallucinations, the drug also induced the visualization of similar geometric patterns in different users. Klüver called these patterns form constants and organized them into four groups: lattices (including honeycombs, checkerboards, triangles), cobwebs, and spirals (examples below).

Image

Image




Fast-forward a few years. Having studied petroglyphs from all over the world, renowned cognitive archaeologist David Lewis-Williams was struck by stylistic similarities he saw in the images, including those from disparate continents, which he argued could not be accounted for by cultural diffusion or mere coincidence alone. Instead, he contended that the similar geometric patterns evident in many engravings represented an artistic expression of Klüver’s form constants, visualized and transcribed by shamans who were engaged in altered states of consciousness.

While drugs are a well-known trigger for the visualization of form constants, they are one of many. Since Klüver’s pioneering work, a variety of other triggers have been identified, including psychological stress, fever, epilepsy, psychotic episodes, syphilis, sensory deprivation, photostimulation, and migraine headaches.

Because such a diverse range of factors are associated with visualizing form constants, scientists believe there must be an underlying physiological process responsible, relating to the structure/organization of the our visual system. And as you’re probably well aware, we like to scramble up the wiring every now and then!

Since the beginning of time humans have used one or more of the above triggers to intentionally induce altered states of consciousness (again, lots of interesting ideas about the origins of this behavior that I’m not going to get into here), and consequently, visualize form constants. I’m sure there will be those who disagree, but I personally don’t think it’s such a stretch that these petroglyphs could be a reflection of that.

Then again, “form constant-like” patterns are pretty ubiquitous in the world outside our heads, too – just check out these photos from my earlier posts:

Image


Image


Image


Image


Image


Image


Image


Image




So who’s to say these people weren’t simply inspired by the patterns they saw in their day-to-day lives? We’ll probably never know for sure, but it’s fun to think about.




On another note, it’s interesting that despite the manmade origin of these petroglyphs, there still seems to be a general perception that they are part of the “natural” landscape. But when does the transition from trash to treasure occur? What variables are involved, aside from time? And if enough time passes, will all of our trash someday be valued by future archaeologists and anthropologists?

Image




A spearhead that would have been used with an atlatl to hunt wild game (10,000-8,000 years ago!)

Image


Image




.50 Browning Machine Gun cartridge shell (1942); a vestige of U.S. military activities here during World War II.

Image


Image


Image






Image


Image


Image

Image


Image


Image




The Hills Have Eyes

Image




I’ve always been fascinated with nature’s ability to reintegrate itself. Of course this happens everywhere, but the desert must be one of the most unique places to observe the phenomenon. There are a couple of reasons for this. For one, the arid climate has the effect of slowing everything down out here. Things take a long time to grow, and a long time break down. As a result, human artifacts spanning a wide range of time – and in various states of decay – are all on display, sometimes right next to each other. Then there’s the landscape itself – the wide-open space and sparse vegetation don’t leave much to be concealed. The desert has an incredible way of bringing things into focus.

Image


Image


Image


Image


Image





I often wonder about the collective impact of all this human activity (historic and current) on the desert ecosystem. Is our trash leaching chemicals into the soil that would be harmful to plants and animals? Are all of these old abandoned mines acting as huge pitfall traps for unsuspecting tortoises (maybe that’s where all of our missing animals have gone!)? Could some species take advantage of our presence by using artificial cover objects as shelter? Of course there are no clear-cut answers here – human activity impacts different organisms in unique and extremely complex ways. Some species are more adaptable than others. I discussed this a bit in previous posts with regard to coyotes and ravens – here’s another example.

Woodrats (aka “packrats”) refer to any species of rodents belonging to the genus Neotoma. Woodrats are solitary, territorial, and nocturnal. The species we have here is the Desert Woodrat (Neotoma lepida). I’ve never seen one, though I often encounter their dens, constructed from sticks, vegetation, bones, and trash. Woodrats need a lot of water, which they get from fleshy plants, like cactus. Here is a photo of a woodrat nest at the base of a Clustered Barrel Cactus (Echinocactus polycephalus). In addition to offering protection from predators, these nests provide a buffer from extreme temperatures (and in this case, a convenient food source).

Interesting side note – woodrats aren’t as different from us as you might think – they leave their trash out in the desert too, in the form of middens (aka garbage piles) where they place unwanted debris. Middens can be preserved for thousands of years (they have been carbon dated at >50,000 years), and provide valuable information about past environments. Read more about them here.

Image




In the absence of cacti or rocky outcrops, which offer structural support for their homes, woodrats will get creative. Here’s an example of a less-traditional woodrat den in the remains of an old vehicle. Even when natural construction sites are readily available, these guys seem no less eager to take advantage of artificial refuse. So, were the woodrats just using the car because it was convenient, or could this piece of trash have facilitated the movement of this species into a habitat they wouldn’t normally occupy?

By considering life history traits, it makes sense that an animal like a woodrat might (theoretically) be better equipped to adapt to change than a tortoise. Tortoises take 15-20 years to reach sexual maturity, whereas woodrats can reproduce in a couple months. Woodrats also produce multiple litters a year, while tortoises usually have one clutch, and sometimes none at all. Because evolution is dependent on the accumulation of random genetic mutations, one would expect that within a set period of time (and excluding other variables), woodrats would have a better chance of acquiring potentially beneficial mutations than desert tortoises on the basis of their shorter generation times.

Molecular evidence corroborates this idea. Avise et al. (1992) reported that when DNA sequences from six species of turtles were compared, very little divergence was found, indicating a slower evolutionary rate relative to other vertebrates at the molecular level. In addition to turtles’ long generation times, the authors suggest that slower evolution could also be influenced by turtles’ lower metabolic rates.


Image




A different kind of midden. I wonder if scientists will be studying these 50,000 years from now?

Image




I was somewhat surprised when I tracked a tortoise to this spot. I guess I had assumed they would prefer to reside in more scenic locales.

Image


Image




Here is another tortoise I found beside the scattered remains of some structure.

Image




In both of these cases the animals appeared normal. No, they weren’t actively taking advantage of human activity as the woodrats did, but on the other hand, they were not experiencing any obvious ill effects from their surroundings. I do not wish to imply that human disturbance is not having a significant negative impact on this species – there is plenty of evidence to show that it is. But, such influences are not always direct, nor easily observed. Perhaps, when this area was experiencing more human activity in the past, tortoises did suffer, but the relics of such activity (i.e. trash) don’t bother tortoises there now one bit. On the other hand, maybe increased cover objects elevate rodent populations, attracting more potential predators like coyotes to the area. Or maybe the animals aren’t as healthy as they look. Hopefully the data we collect will help to answer such questions and better understand the changing desert ecosystem and our involvement in it.

Image




As a child I had always wanted to be a paleontologist. Though I eventually realized I’d rather work with still-living dinosaurs, the allure of constructing a narrative from old dusty bones has remained with me, and so has my imagination. When I stumbled upon the scene below while tracking a tortoise, I was not filled with disgust as some might have been at the sight of trash tainting the landscape. Yes, part of me immediately recognized the manmade origin of the objects sprawled about before me, yet in their various states of decay, the line between natural and artificial was blurred. It felt more like I was studying the fossils of some extinct beasts than a pile of rusty metal, and each had a story to tell.

Image


Image


Image


Image


Image




I think all conservation biologists wonder, at some point or another, if their efforts are in vain. It’s easy to look at the world around us, throw up our hands, and surrender to the idea that our planet is damaged beyond repair. Every now and then I get a much-needed reminder that this is not the case.

The decomposing car pictured below wasn’t much different from any of the others I’d seen, but as I stared at it something amazing happened – riddled with bullet holes, its paint faded and chipped away, and engulfed by amorphous blotches of rust – the car began to gradually vanish from my view, and from my mind. The longer I stared, the less discernible it became from the rest of the landscape.

The colors, patterns, textures, and even contours of the old truck so perfectly complimented the surrounding environment, it was as if it had somehow acquired the ability to camouflage from some of the desert’s other inhabitants (i.e. sidewinders, horned lizards; see examples in Part 2). The vehicle seemed to be paying a final homage to the desert before breaking down into its most elemental parts and disappearing completely.


“Without us, Earth will abide and endure; without her, however, we could not even be.”
Alan Weisman, The World Without Us (2007)

Image


Image








Chapter 2: Invertebrates


I must admit, while I miss water and trees, it is nice to not have to worry about mosquitoes, ticks, etc. While some of the invertebrates out here appear more formidable then the ones I’m used to, in reality, they’re much more respectful of our personal space and don’t really bother us at all. In fact, it wasn’t until the fall that I really started to see more invertebrates.

This was one of the first ones I found. We were unloading supplies into the garage when I noticed this Giant Desert Hairy Scorpion (Hadrurus arizonensis) stuck in a spider web. At first I thought it was dead, but then I saw it twitch a little bit. We untangled it and nursed it back to health for a week before releasing it.

Image




H. arizonensis is the largest species of scorpion in North America, capable of reaching lengths of 14 cm.

Image




It stays burrowed underground during the day, and comes out at night to hunt for other scorpions, and small lizards and snakes.

Image




The hairs on its body help it to detect vibrations. Its venom is not very potent, and has been compared to that of a bee sting.

Image




My first tarantula sighting was unfortunately this big dead guy, Aphonopelma iodius.

Image




First live tarantula of the season was a different species - Mojave Desert dwarf (Aphonopelma mojave). You are most likely to see tarantulas in the fall, when males roam around in search of females.

Image


Image


Image




Defensive posture

Image




Close-up of the fangs

Image


Image




First live A. iodius.

Image


Image




Agile/Ground Mantis (Litaneutria minor)

Image




Again, a familiar pattern… This one is a bit of a mystery. I found the shell (Sonorella sp.[?]) beside a woodrat nest/midden at the top of a hill. At first I thought it was a fossil, but on closer inspection it seems fairly recent. Someone suggested a bird could have dropped it. Anyone have any other thoughts on where it might have come from?

Image









Chapter 3: Herps, etc.


While it is not uncommon to find two tortoises sharing a burrow, I was surprised to see three tortoises (2 marked, 1 unmarked) inside this rock den at the top of a hill, but apparently up to 17 tortoises have been found sharing a den!

Image




Back in Nevada, AJ checks on the eggs we collected at the Desert Tortoise Conservation Center (DTCC) a few months back (see Part 4).

Image




First hatchlings

Image




It usually takes 1-3 days for the baby tortoise to hatch

Image


Image


Image


Image




Out in the field I found some eggshells at the mouth of a burrow – not sure if they hatched or were eaten.

Image


Image




This baby Yellow-backed Spiny Lizard (Sceloporus uniformis [formerly grouped as a subspecies of S. magister]) had fallen into this tub and couldn’t get out

Image


Image


Image




I’m guessing Red-tailed Hawk (Buteo jamaicensis)?

Image




A really nice looking horned lizard (Phrynosoma platyrhinos platyrhinos)

Image


Image


Image


Image


Image


Image




P. platyrhinos range:

Image






Reptiles have long been perceived as “dumb” animals, only capable of the most rudimentary and predictable behaviors. We’re only just recently realizing this isn’t the case – while their behavior may be much different than that of the “higher” mammals, it is no less impressive, and there is much we can learn from them. So why is this field still largely unexplored? Well, it’s a lot easier to miss something if you believe there’s nothing to be found. Science has certainly come a long way over the years, yet the scientific community continues to reinforce some pretty antiquated ideas, a big one being the unparalleled awesomeness of our own species.

As biologists, we’ve been taught from early on not to anthropomorphize, but sometimes I wonder how feasible this request really is. No matter how hard we may try, we are, after all, human, and possess an inherent drive to connect with and make sense of our world on a human level. This tendency has undoubtedly played an integral role in the evolution of our species. But is the act of attributing one’s own characteristics to others unique to humans? One way in which desert tortoises communicate is by bobbing their heads. Sometimes, tortoises may even direct head bobs at a human, in a failed attempt at communication. In such situations it’s easy to scoff at such “dumb” behavior, without realizing that we are guilty of the same thing, even within our own species!. Just as we have evolved to relate with our environment from a human point-of-view, tortoises do so from a tortoise point-of-view. (Yes, at times the tendency to attribute one’s own qualities to others will cause problems, so we expect that the benefits associated with this behavior must be great enough to outweigh any negative consequences).

I agree with the importance of maintaining objectivity in science, but as we go to such great lengths in the name of scientific integrity, is there a point where we begin to hold ourselves back, missing the forest for the trees? I wonder if anthropomorphisation has become almost excessively stigmatized, not because it challenges scientific objectivity, but because it threatens our position in the grand hierarchy of life. If our tendency to anthropomorphize can be likened to “overestimating” animals’ capabilities, I would argue that underestimating is equally obstructive to science, but ironically this is the norm. I wonder how many times novel behaviors have been overlooked in animals on the basis that such behaviors were “too advanced” to be what they appeared?


"To endow animals with human emotions has long been a scientific taboo. But if we do not, we risk missing something fundamental, about both animals and us.”
Frans de Waal, Are We in Anthropodenial? (1997)

Image




Desert tortoises are curious animals – probably too curious for their own good. In the warmer months, tortoises will often emerge from their burrows if they sense activity outside the mouth of the burrow (i.e. USGS personnel). While both sexes exhibit this behavior, males are generally bolder. Individuals also have their own unique personalities – some tortoises are content to just sit and watch you from the mouth of their burrow, whereas I’ve had others come out and walk circles around me a couple times before getting bored and heading back into their burrow. I’m curious about the origins of this behavior. I assume it relates to territoriality, but it seems counter-adaptive for a tortoise to just waltz out and greet whoever’s come to visit, regardless of that visitor’s size/intentions. I wonder if they act any differently in response to, say, a coyote? Perhaps they’ve evolved long enough with some predators that they’re able to recognize cues alerting them of their presence, and humans just haven’t been on the scene long enough to induce such an aversion? (If anyone knows anything more about this behavior please chime in).

Image




On a related note, some of the most interesting behavior I’ve seen in desert tortoises has involved situations with multiple individuals. Despite wild tortoises readiness to approach humans under certain circumstances, after we mess with them a bit (i.e. attach a transmitter, conduct a health assessment, etc.), they generally have had enough, and will either walk away (and on rare occasions run; a hilarious sight if you’re lucky enough to witness it) or withdraw tightly into their shells until they consider it safe to come out. An exception is if there are two or more tortoises present, as there are occasions when we process multiple animals from the same burrow. In these instances, the tortoise not being processed is generally within view of our activities. Rather than trying to escape, as you might expect, this individual often shows pointed interest in what’s going on. From a few feet away, he extends his neck as far as it will go, and looks on with what appears to be remarkable focus. Every few minutes he may take a few slow, tentative steps closer in what I imagine to be a tortoise’s best attempt at stealth, his gaze never wavering. He may watch for ten minutes or more before eventually deciding to head off.

At times like this I have to wonder who’s really studying who, and what – if anything – is going through these animals’ little heads. Again, I’m baffled by the tortoises’ apparent lack of fear for people. Why would this animal hang around, potentially putting itself at greater risk, after seeing that we had captured its burrow-mate? In these scenarios it can be easy (and let’s admit it – fun) to anthropomorphize. Was this tortoise angry that we had taken his girlfriend? Was he concerned? To a casual observer, this kind of behavior could look a whole lot like empathy, a trait only known to exist in mammals. (For a long time empathy was considered a purely human characteristic; later it was discovered among other primates, and most recently a study has revealed that even mice empathize). Non-mammals (including herps) do, however, exhibit behaviors such as altruism, which can give the illusion of true empathy, and distinguishing the two can be tricky. The difference is that altruistic behaviors are often governed by a more selfish (though inconspicuous) incentive – the spread of one’s own genes.

To illustrate: while it might have appeared that this animal was genuinely concerned with the plight of a fellow tortoise, had we investigated the relationship of these two further, we might have discovered that the male tortoise had previously mated with this female and was thus exhibiting a simple, pre-programmed behavioral response to defend his genetic investment. (Consequently, some argue that this type of behavior, known as kin selection, does not represent “true” altruism, but it’s important to remember that the definition of biological altruism differs from the common usage of the term).

Of course, because we don’t know anything about the relationship of these tortoises this is all purely theoretical, but potentially altruistic behavior has been documented in desert tortoises before. Patterson (1971) reported that an overturned tortoise may give a call that elicits another tortoise to roll it back over. Check out this video that allegedly shows this behavior. (For another example of altruism in reptiles, see this amazing video).

All in all, my take away message here is that non-human animals are a lot more complex than we’ve been giving them credit for (and/or we’re not as amazing as we think). While new discoveries are being made each day, much is still unknown, and I think that’s pretty exciting.

Image





Spiny lizard in a crevice

Image




My first decent shot of a Long-nosed Leopard Lizard (Gambelia wislizenii). This is a larger species (8.2-14.6 cm), with females attaining a greater size than males (I believe the one pictured here is male). This species is unusual among lizards in that during breeding season, the females become more colorful than the males. Their diet consists of invertebrates, lizards, snakes, small rodents, flowers, leaves, and berries.

Image


Image




G. wislizenii range:

Image




Great Basin Whiptail (Aspidoscelis tigris tigris)

Image


Image


Image




Caught one!

Image


Image


Image


Image




Notice the smooth, granular scales – much different than the pointed, keeled scales of other local reptiles (i.e. spiny lizards, rattlesnakes), and similar to those of the Western Banded Gecko (Coleonyx variegatus variegatus ).

Image




First rays of sun

Image




A juvenile Mojave Green (Crotalus scutulatus scutulatus) takes advantage of the early morning light. This is the first one I’d seen since spring.

Image


Image


Image


Image




Coyote (Canis latrans) drinking from a puddle in the road after a rain – it must have been really thirsty because we were able to get pretty close before it finally ran off.

Image


Image


Image


Image


Image




I mentioned earlier that you can’t always tell how healthy a tortoise is just by looking at it. So to get a better idea of how these animals are really doing, we conduct health assessments and collect tissue samples to be analyzed in a lab.

Image




Weighing the tortoise

Image



John works on getting the head out

Image


Image




Getting a nasal lavage sample

Image


Image




Preparing to take a blood sample

Image


Image




Blood!

Image




They may be slow but no one can say tortoises aren’t tough! If they can beat the odds and make it through their first few years without getting gobbled up, they have a good chance of living a long time. Tortoises have an incredible ability to persevere and recover from even the most severe injuries. Take this guy for example – despite losing an eye and having his nose torn off, this tortoise otherwise seemed to be doing ok!

Image




Another survivor with a big battle scar – this one had its scutes chewed off entirely in one spot, exposing the bone underneath. (Note the sutures, which have become partially separated).

Image




Western Side-blotched Lizard (Uta stansburiana elegans). One of the most common lizards out here. The blue speckling indicates this one is a male.

Image


Image


Image


Image




U. stansburiana range:

Image




Living mosaic. This kind of tiling pattern in which shapes fill a plane with no gaps or overlaps (once again, very similar to Klüver’s form constants) is called a tessellation

Image




M. C. Escher is well known for his use of tessellations, and I don’t think it’s a coincidence that reptiles figured prominently in his work.

Image


Image


Image




Reptiles have adopted a wide range of life histories. While species like desert tortoises may take up to 20 years to reach sexual maturity and can live over 50 years in the wild, others, like side-blotched lizards mature rapidly (9 months) but don’t live more than a year.

Image


Image




Mojave/Redspined Fishhook Cactus (Sclerocactus polyancistrus)

Image




Hatchling Desert Banded Gecko (Coleonyx variegatus variegatus). Females lay 1-3 two-egg clutches between May and September. If you look back at the adult pictured in Part 3 you’ll see that the banding is much more defined when they’re young. This kind of change in pattern/coloration that occurs over an organism’s lifetime is referred to as an ontogenetic shift, and is common among reptiles and amphibians. The adaptive significance of an ontogenetic shift varies by species, but is often associated with changes in size, vulnerability, habitat use, etc. If you’re interested in learning more about this phenomenon check out these articles:

Blue tail and striped body: why do lizards change their infant costume when growing up? (Hawlena et al., 2006)

The adaptive significance of ontogenetic colour change in a tropical python (Wilson et al., 2007)

Image


Image


Image




Punctured Bract (Oxytheca perfoliata)

Image


Image




Now that it’s getting cool out the snakes are hunkering down, and tortoise burrows make convenient hideouts. This is why it’s important to always look before reaching into a burrow!

Image




There are some really cool rock formations out here

Image




Molted snakeskin, probably from a coachwhip (Masticophis flagellum piceus).

Image


Image


Image




A nice looking cave

Image




Pretty spacious

Image




I wonder if anyone used to live here

Image




Looking out from inside

Image





One of the rare rainy days in the desert – it was actually a nice change of scenery.

Image




The cacti were especially vivid after being dusted off by the shower.

Image




Image








Thanks for looking!

-Zach








Image





Part 1
Part 2
Part 3
Part 4
Part 5
Part 6
Part 7


Top
 Profile WWW 
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 16th, 2011, 5:08 pm 
User avatar

Joined: June 7th, 2010, 6:11 pm
Posts: 745
Location: cape cod ma.
That was GREAT!! :thumb: Thanks for taking the time to put it all together.


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 16th, 2011, 5:49 pm 
User avatar

Joined: May 14th, 2011, 11:16 pm
Posts: 1132
Location: Santa Cruz, CA
Wow, that was a great series of posts. Thank you!

JimM


Top
 Profile WWW 
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 16th, 2011, 6:32 pm 
User avatar

Joined: November 23rd, 2010, 6:44 pm
Posts: 406
Location: Mesa, Arizona
Thanks Zach that was amazing.


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 16th, 2011, 6:32 pm 
User avatar

Joined: November 23rd, 2010, 6:44 pm
Posts: 406
Location: Mesa, Arizona
Sorry double post.


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 16th, 2011, 6:35 pm 
User avatar

Joined: June 7th, 2010, 10:22 am
Posts: 485
Location: Athens, OH
Nice post. I enjoyed the scenery, history, art, etc... as well as the herps.


Top
 Profile WWW 
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 2:29 am 

Joined: July 2nd, 2010, 5:48 pm
Posts: 688
Location: AZ.
Nice work, you really applied yourself here. Regarding the snail, I don't know anything about it, but I reacted like you did when I found similar shells in the Anza/Borrego-Canebrake area. I think your job is fascinating, and I am happy someone is getting valuable information on tortoises. They have declined drastically in my life time, I sure hope your repatriation/breeding efforts pay off. Sometime I hope you will comment on that.

Vic/Imperial Valley, CA.


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 5:27 am 

Joined: June 7th, 2010, 10:35 pm
Posts: 172
Truly an outstanding post. Being so thoroughly immersed in a place for so long seems to have paid off for you (and us, your readers). You've left us with much to ponder and appreciate.

Cheers,

BH


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 8:05 am 

Joined: June 8th, 2010, 7:12 am
Posts: 8025
Location: Hesperia, California.
Awesome post Zack!
Pretty sure I know that place well... it's one of my favorite places to go. I'm surprised you didn't see any chucks in that 'little canyon'... I see them there often..
Image
I have to believe that the glyph on the left here represents a rattlesnake...
Image
Speaking of which, would you be surprised to know that that is the precise location of my Helleri range extension?
Image
I've been monitoring a pair of Torts in my area for about 3 yrs now, with the female wintering in her human-made burrow for the last several years... :o
Image
And the male in his burrow, bout an 1/8 of a mi away... :)
Image
jim


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 9:10 am 
User avatar

Joined: June 7th, 2010, 6:09 pm
Posts: 1211
Hi Zack:
Nice report. I too recognize the area with the petroglyphs that you posted. I have been there several times. Regarding their meaning: my own personal opinion is that they may have just been a way for ancient individuals to make their presence known to others that were traveling through and just left hints to others of what could be found in the area. Perhaps a primitive form of communication on the same plain as hobo signs. Yes, we can say there are reccuring definitive patterns present in Nature, but whether they have that much impact on subconscious influence on the formation of petroglyphs who's to know for sure. The same can be said for Mandelbrot Sets; which according to the artistically inspired researcher are patterns that are widespread in natural forms. The shack you depicted is most likely owned by some older established desert rat rockhound prospector type or huntsman. They are scattered throughout the Mojave Desert and even though they are private domiciles, unless they are locked, many transients may utilize them for temporary shelter while passing through. There is an unspecified sharing courtesy regarding some of these shacks. If they are left open, that means others may use them so long as they keep everything intact and replace any water or food they use that is left in the house for the next traveler. I think your first tarantula photo may actually be a shed cast of one rather than a dead one. They can be hard to discern from each other at first glance. The amount of trash I have encountered while working in the western Mojave was astounding sometimes. I am surprised you haven't included any couches; there is usually a variety of old couches along with the cars, fridges and televisions. It's really sad to see all that illegal dumping. I too am curious to see what type of impact that trash will have over an extended period of time on wildlife. Will they become 'domesticated' and adapt to utilizing the trash more regularly as refugia? I have found everything from ground squirrels to tortoises under the trash as well as snakes, lizards and inverts. The raptor feather maybe from a Cooper's Hawk. I found a an entire mummified one in Nye County. Those hatchling torts are adorable! Be warned that the desert is a place that can hypnotize you into states of abstract reflection and over stimulate the imagination; especially if your periods of idle time increase...


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 9:23 am 

Joined: June 8th, 2010, 7:12 am
Posts: 8025
Location: Hesperia, California.
I don't know...
I think that canyon is and was a 'spiritual' place, and although I no longer take mind-altering drugs, if ever there was a place to take peyote... that's the place. Although some may be 'hobo signs' I have to believe that it was also a primitive religious site. jim


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 10:01 am 
User avatar

Joined: June 7th, 2010, 3:40 pm
Posts: 353
Fantastic post! I enjoyed your ruminations about the abandoned cars and many times have had the very same thoughts (as well as if it were possible to get a few of them running again - a former hobby of mine). You'd like a Desert Woodrat if you came across one - they aren't half-bad (for a mammal).

Tim

Image

Image


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 10:39 am 
User avatar

Joined: June 7th, 2010, 7:36 am
Posts: 590
Location: Sydney, Australia
Great post! I really like your narrative regarding the history and "trash" vs "relic" concepts in the desert. I've been struck by similar feelings rummaging through abandoned homesteads in the southeast. Two houses in Georgia stand out. Both were still completely furnished, but had obviously been deserted for at least a decade, if not more. Inside one, everything was laid out as its owner had left it, including a closet full of suits. At the other, most of everything was still there, but right in front of the door was a card table with a shoebox full of mail and old photographs. It was really sad to see that in both cases, an elderly person had likely died but their family had not taken the time/effort to take care of their belongings. Its spooky seeing things like that, but I always thought the superimposition of rural history and field herping would make a great Nat Geo article.

Van


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 10:48 am 
User avatar

Joined: June 7th, 2010, 6:09 pm
Posts: 1211
VanAR wrote:
Great post! I really like your narrative regarding the history and "trash" vs "relic" concepts in the desert. I've been struck by similar feelings rummaging through abandoned homesteads in the southeast. Two houses in Georgia stand out. Both were still completely furnished, but had obviously been deserted for at least a decade, if not more. Inside one, everything was laid out as its owner had left it, including a closet full of suits. At the other, most of everything was still there, but right in front of the door was a card table with a shoebox full of mail and old photographs. It was really sad to see that in both cases, an elderly person had likely died but their family had not taken the time/effort to take care of their belongings. Its spooky seeing things like that, but I always thought the superimposition of rural history and field herping would make a great Nat Geo article.
Van

Any stills on the property? :lol: :beer: J/K. Having worked around abandoned homesteads out in the desert, it's always so tempting to look inside. One house we inspected had photos left in a box that we rummaged through. One of the field techs surmised the house was owned by some religious cult with a weird matriarchal figure. She was the only woman (middle-aged) and the photos showed her surrounded by at least a dozen young guys (in their twenties) living in the house with her. WEIRD...


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 11:06 am 
Well put together report, thanks for sharing.
Like the "extras" from the spearheads to the shell cartridge.
The guy with the green bandana looks familiar.


Top
  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 1:43 pm 
The snail, maybe something like Sonorella sp.


Top
  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 2:46 pm 

Joined: June 8th, 2010, 7:12 am
Posts: 8025
Location: Hesperia, California.
tspuckler wrote:
Fantastic post! I enjoyed your ruminations about the abandoned cars and many times have had the very same thoughts (as well as if it were possible to get a few of them running again - a former hobby of mine).


No doubt... that 1st one posted looks like a 70/71 Cutlass (Malibu equivilent)... great car... :D jim


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 17th, 2011, 7:26 pm 

Joined: March 26th, 2011, 3:12 pm
Posts: 21
Hahah, Zach. There are so many pictures of tortoises and trash. It makes it look like the study area is a garbage dump.
Of everything in this thread, the thing I'd most like to see is a ground mantis.

John


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 18th, 2011, 8:59 am 
User avatar

Joined: June 7th, 2010, 3:44 pm
Posts: 2648
Location: Ventura, CA
Zach Cava wrote:
I agree with the importance of maintaining objectivity in science, but as we go to such great lengths in the name of scientific integrity, is there a point where we begin to hold ourselves back, missing the forest for the trees? I wonder if anthropomorphisation has become almost excessively stigmatized, not because it challenges scientific objectivity, but because it threatens our position in the grand hierarchy of life. If our tendency to anthropomorphize can be likened to “overestimating” animals’ capabilities, I would argue that underestimating is equally obstructive to science, but ironically this is the norm. I wonder how many times novel behaviors have been overlooked in animals on the basis that such behaviors were “too advanced” to be what they appeared?

"To endow animals with human emotions has long been a scientific taboo. But if we do not, we risk missing something fundamental, about both animals and us.”
– Frans de Waal, Are We in Anthropodenial? (1997)


...thanks for that Zach, well written! The term "anthropomorphism" is based on the chauvinistic assumption that humans are wholly apart from the rest of the animal kingdom while every aspect of biology screams otherwise. We are rather, wholly connected and inseparable. The better we understand that, the better we'll understand ourselves and fulfill our potential as a species.


Top
 Profile WWW 
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 18th, 2011, 12:48 pm 
User avatar

Joined: June 7th, 2010, 6:27 pm
Posts: 243
Thank you all for the feedback, I appreciate it and I'm glad you enjoyed.

Vic: I'd like to emphasize that this actually isn't part of a breeding/repatriation project, but rather a translocation project as a consequence of military expansion. I talk a bit about this more in earlier entries. The baby tortoises were hatched from eggs collected at the DTCC and are being used in a diet/growth study.

Jim & klawnskale: Its nice to see some other people are familiar with this spot! And Jim I had no idea we had C. oreganus here - when did you find that guy?

Gordon: Thanks for the snail ID!


Top
 Profile WWW 
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 18th, 2011, 1:36 pm 

Joined: June 8th, 2010, 7:12 am
Posts: 8025
Location: Hesperia, California.
Zach Cava wrote:
And Jim I had no idea we had C. oreganus here - when did you find that guy?


Actually... it was about a 25 mi Northward range extension for C. helleri (along the transverse ranges). Found in 09, it went to Loma Linda for genetic testing/venom assays, as a possible Helli/Scute X,and was there nearly a year... came back pure 'desert-clade Helli'. This shot shows his unusual markings...
Image
While he was found right at the entrance to that 'little canyon', I believe he came down (for a drink) from the big decomposing granite hill just east of the canyon... much more likely-looking habitat for hellis than the surrounding lava beds, or creosote flats.
He's also my avatar... as Hellihooks's most unusual helli... :crazyeyes: :D
BTW... found this little female tort under wood at the corner of this fairly-recently built homestead...
Image
Image
I believe she was at the base of the building, or halfway under the foundation, when the place was painted... half her carapace is the same color as the building...
Image
You guys hiring??? :crazyeyes: :lol: :lol: jim
Edit... just wanted to add... that helli is the MEANEST, Most Aggressive rattlesnake I've had to deal with in 36 years... :shock:


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 18th, 2011, 1:48 pm 
User avatar

Joined: June 7th, 2010, 6:27 pm
Posts: 243
Ah, I didn't realize C. helleri was its own species now, but very cool, I'll have to keep an eye out for them! Are they known to hybridize with C. scutulatus? That painted tortoise is great! Unfortunately I think we're operating at full capacity right now.


Top
 Profile WWW 
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 18th, 2011, 1:57 pm 

Joined: June 8th, 2010, 7:12 am
Posts: 8025
Location: Hesperia, California.
Zach Cava wrote:
Ah, I didn't realize C. helleri was its own species now, but very cool, I'll have to keep an eye out for them! Are they known to hybridize with C. scutulatus? That painted tortoise is great! Unfortunately I think we're operating at full capacity right now.

Technically... it might be C.o.helleri, but (IMO)Helleri certainly deserve full species status, if for no other reason than the differences in venom composition... :shock: Besides... a Southern 'Northern' Pacific... how dumb is that... :crazyeyes: :lol: :lol: jim
PS.. some folks say helli & scut X naturally... but the guys at Loma Linda have NEVER seen it... :roll: MAYBE in captivity...


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 18th, 2011, 3:07 pm 
User avatar

Joined: June 7th, 2010, 6:09 pm
Posts: 1211
Zack: next time you're out in the field working in this area, if you like Mexican food, check out 'Casa Hemenez' when you drive back through town. Those that are against any kind of hunting might be offended by the ambience, though since the owner is a big game hunter and avid fisherman. Trophies are mounted all over the restaurant. But the food is awesome, and they have a nice selection of beers and tequilas


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: December 18th, 2011, 4:15 pm 
User avatar

Joined: June 7th, 2010, 6:27 pm
Posts: 243
thanks for the tip, it sounds great, and I'm always looking to try new mexican places!


Top
 Profile WWW 
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: October 25th, 2012, 12:42 am 

Joined: March 12th, 2011, 12:40 pm
Posts: 79
Rattlesnakes can and do hybridize regularly in the wild where their ranges overlap, I have personally witnessed the following: Scute X Atrox, Scute x Molussus, scute X helleri, helleri x mitchelli, Helleri x Oreganus, Others have found, Helleri x Ruber, Ruber x michelli.


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: October 25th, 2012, 7:40 am 
User avatar

Joined: April 10th, 2012, 6:27 pm
Posts: 285
Location: San Francisco, CA
WOW what a post!! Thanks for taking the time to include so much!


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: May 12th, 2015, 11:31 pm 

Joined: December 19th, 2010, 7:35 pm
Posts: 2
Hi Zach,

I'm interested in the helminthoglyptid shell you observed. For the last several years I've studied this family of snails in the southwest. I'm an amphibian guy from the pacific northwest, but terrestrial gastropods fill the slime deficiency of salamanders for me in Arizona. There are several genera of desert adapted snails in the Southwest. Sonorella is not known to occur in California or Nevada. There are many species of related snails that occur in the Mohave assigned to genera Micrarionta, Sonorelix, Eremarionta, Cahuilus, Mohavelix, and Helminthoglypta. None are known to occur in Nevada. If you would provide locality data for the shell, I could narrow down the possibilities. This is the picture I'm referring to: http://i562.photobucket.com/albums/ss66 ... G_2172.jpg

Warm Regards,
Nick Waters


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: May 13th, 2015, 7:56 am 
User avatar

Joined: June 7th, 2010, 8:56 pm
Posts: 318
Location: SW USA
Very nice. I know that lil canyon too. Are you working for Jeff Lovich by chance?


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: May 13th, 2015, 10:58 am 
User avatar

Joined: July 8th, 2010, 10:14 am
Posts: 772
Location: Eastern Washington
Image

According to the above Range map Gambelia wislizenii extend into WA?

Further searching brought a bit more detail, so it makes me wonder if they may actually reach into WA.

Image

On an unrelated note a very distant relative supposedly found a red white and black snake on the WA side of the Blue Mts near Walla Walla about a year ago. Still haven't tried to get pics from this person as I haven't even seen them in over 15 years, but my little brother mentioned it to me.


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: May 13th, 2015, 10:21 pm 
User avatar

Joined: June 9th, 2010, 9:57 pm
Posts: 513
Location: North end of Lake Okeechobee, Florida
Wow! One of the most thought provoking posts I've had the pleasure of reading on this forum... :beer: Now I have to go back and play catch-up with the rest of your series. Excellent job!!


Top
 Profile  
Reply with quote  
 Post subject: Re: USGS Desert Tortoise Project: Part 5
PostPosted: May 18th, 2015, 7:47 am 
User avatar

Joined: June 7th, 2010, 6:27 pm
Posts: 243
thanks John, glad you enjoyed it!

@lateralis no, I was working out of the Las Vegas office


Top
 Profile WWW 
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 32 posts ] 

All times are UTC - 8 hours


Who is online

Users browsing this forum: Bing [Bot], Google [Bot] and 34 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: