Removing the blinders

"Fear of the dangers of anthropomorphism has caused ethologists to neglect many interesting phenomena, and it has become apparent that they could afford a little disciplined indulgence." (Hinde 1982)

"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." (de Waal 1997)

Many scientists, in their efforts to be unbiased and avoid anthropomorphism (assigning human traits to non-human animals), engage in anthropodenial (de Waal 1997). Anthropodenial is the opposite of anthropomorphism: the refusal to acknowledge humanlike characteristics of non-humans animals, which is just a bias of another sort. As indicated by Hinde and de Waal above, scientists have missed some interesting animal behaviors because of anthropodenial. (For more on this topic, check out de Waal 1997.)

For example, numerous observations of rattlesnake families dating back more than a hundred years were dismissed by the godfather of rattlesnake biology, Laurence Klauber:


Their propinquity, such as it is, does not result from any maternal solicitude; rather it is only because the refuge sought by the mother is also used as a hiding place by the young. (Klauber 1956)

In 1992, Harry Greene, Peter May, David Hardy, Jolie Sciturro, and Terence Farrell published an article on viper parental care in a peer-reviewed book. In it, they present evidence that not only do families aggregate, but mother snakes actively defend their newborns.

Was there some technological advance at that time that finally revealed this behavior to scientists? No. But, it's difficult to see what you don't look for and these authors took the time to look. They also reviewed others' observations of parental care in vipers, demonstrating that this behavior is widespread and more than mere attendance.

When we began our study of social snake behavior in 2010, we were armed with cameras, binoculars, and field notebooks. With these simple tools we managed to document behavior that was once so easily dimissed. How? We were looking for it. And maybe more importantly, we largely left the snakes alone and let them tell their story.

This is Woody's story.



We first encountered Woody (adult female Arizona black rattlesnake, Crotalus cerberus) in a pile of rocks and a jumble of downed pines in May 2010, about 150 yards from any known dens. We visited this area a number of times through the summer, and found her almost every time, relaxing near some rocks or coiled among woody debris (for which she is named). Because of her camouflage, we would have to search around for her, which sometimes brought us in close proximity, but Woody was even tempered, never rattling or attempting escape.

Then one day in late August, everything changed. We discovered several newborn rattlesnakes basking near Woody's favored spot. As we approached to get a closer look, but no closer than we had approached Woody so many other times, we heard muffled rattling from under the rocks. As we started snapping photos of the little ones, Woody poked her head out of her shelter and then proceeded to crawl from her refugetoward us, still rattling, and glaring directly at us. Our once-placid Woody was now fearless and wanted us to know she would not tolerate our advance. Impressed with her maternal instincts and not wanting to distress her or her young, we quickly backed off.



We were more careful in future visits to Woody's nest, but she remained a vigilant mother: rattling from within her shelter if we got too close, or assuming a defensive posture in between us and her kids (as shown in the photo above). The young caught on too, retreating into shelter if mom was upset.

Eventually the babies shed and the family split up, each trying to get a meal before it was time to enter their den for the winter. Since Woody's nest wasn't located close to a known den, we weren't sure when we would see her again. Was Woody's den located at or near her nest site? Would she show up at one of the dens we already monitored?



On the very first day we visited the dens in April 2011, we spotted Woody, basking in a popular spot with several other snakes, including some little ones that were born the previous summer. One of these juveniles turned out to be Woody's baby, Adam.



The photo on the left is Adam (newborn on left) and Woody (right), at her nest in August 2010. Woody's nest was farther away than most in 2010, but Adam found his way to their den (photo on right taken at den basking area in spring 2011). In 2011 we starting using timelapse cameras, which caught Woody and Adam as they basked together:



Although it is not unusual to see adult and juvenile rattlesnakes basking together, Woody's interest in Adam is striking. Does her maternal regard for her offspring's well-being extend beyond the nest? If her mothering is genetic and beneficial to Adam, then such care could evolve. We have seen similar behavior in another female, following a juvenile from the previous year's nest (see this post for another example of this behavior).

Many underestimate the wonders and complexity of the natural world, especially when it comes to snakes. The more we remain open to the possibilities of nature, the more we will be able to see. Even though some of their greatest admirers denied it, rattlesnakes can be caring mothers.


References

de Waal, F. B. M. 1997. Are we in anthropodenial? Discover 18:50-53.

Greene, H. W., P. May, D. L. Hardy Sr., J. M. Sciturro and T. Farrell. 2002. Parental behavior by vipers. Pp. 179-205 in G. W. Schuett, M. Hoggren, M. E. Douglas, and H. W. Greene, eds. Biology of the Vipers. Eagle Mountain Publishing, Eagle Mountain, Utah.

Hinde, R. A. 1982. Ethology: Its Nature and Relations with Other Sciences. Oxford University Press, New York, New York.

Klauber, L. M. 1997. Rattlesnakes: Their Habits, Life Histories, and Influence on Mankind. 2nd ed. University of California Press, Berkeley, California.

Teardrop & TIE Fighter

Awhile back we dedicated an entire post to the lucky or skillful young rattlesnakes that survived their first winter. In this population neonate (newborn) rattlesnakes have less than a month to find their first meal and locate a safe place to spend the winter. Of course it helps when your mom gives birth a couple yards away from her den (overwintering site), as Sigma did.

10 April 2012: Today we encountered two first year juveniles (rattlesnakes born last fall) near one of the dens, one basking and one hunting. They seemed very familiar, and sure enough, they are the son and daughter of Sigma, famous for her interactions with a squirrel.

Sigma and Teardrop, 6 September 2011.

Teardrop, 10 April 2012

TIE fighter, 6 September 2011.

TIE fighter, 10 April 2012.

Congratulations TIE fighter and Teardrop – you’ve cleared the first major hurdle of your life. We hope to see much more of you in the future.

Related posts:
Survivors
Sigma vs. the squirrel

Drinking

Cap Mama takes advantage of some rain to take a drink of water dripping off the rock above.

Drinking is a behavior rarely seen in wild snakes. In fact, some would say that snakes don't need to drink. While it is rare to see this behavior, snakes do drink and likely need water in addition to what they acquire from their food. How important drinking is to snakes became very clear to me one day in March 2006 (Repp & Schuett 2008). Despite cold, rainy, windy, and even snowy weather, we saw more than a dozen western diamond-backed rattlesnakes drinking rain and snow outside their dens!

A poor quality video of rattlesnakes drinking snow during the long, dry winter of 2005-2006. Ugh - glad we have upgraded our cameras!

Last summer was pretty dry at our field site; the monsoon did not amount to much. In the photo at the top of this post, you can see Cap Mama snagging a drink about nine days after giving birth. The following videos were taken by our time-lapse cameras while the snakes were still pregnant:

This is Cap Mama again, about a week before she gave birth. Shortly after the rain starts, she emerges and drinks rain as it falls on her body.


Meanwhile on the other side of this rock outcrop, another pregnant female (Stache) also sneaks out for a drink. Unfortunately there is some grass in the way, but you can still get an idea of what a drinking snake looks like.

For more information on drinking and water harvesting in snakes, check out this paper:
Repp, R.A. & Schuett, G.W. 2008. Western diamond-backed rattlesnakes, Crotalus atrox (Serpentes: Viperidae), gain water by harvesting and drinking rain, sleet, and snow. Southwestern Naturalist 53: 108–114.

Survivors

It is always a little sad to say goodbye to the rattlesnake families at the end of the nesting season. It’s a difficult time for the neonates (newborns); in this population they have less than a month to find their first meal and locate a safe place to spend the winter. That’s a tall order for a two week old snake. So when the little ones disperse from the nest, we can never be sure that we’ll see them again. Today, we share stories about some of the lucky (or skillful?) neonates that survived that first winter.



Eve (large brown female rattlesnake) nested with another female, Peach (not pictured), in 2010. Together they cared for about 10 neonates, although Eve was the one most often seen on the surface with the little ones. Above you can see Bozo basking with Eve in August 2010.


Fast forward to April 2011, when the rattlesnakes are emerging from their den. Here Eve is captured by our timelapse camera coming out to bask.


Bozo follows about 20 minutes later. They crawled onto a pile of leaves in the sun:

After basking a bit with Eve, Bozo gets restless and heads off camera. A little while later, Eve appears to notice he’s gone, searches for and finds his trail (note how her head is tapping the ground), and heads off in the direction he left.



Another neonate from Eve and Peach’s nest we called Dagger. We haven’t thoroughly examined all the footage from the timelapse cameras, but so far, we have not seen Dagger at the dens in Spring 2011. So either we’ve missed him or he did not den with his nestmates, because….

Dagger was hunting near the dens in late August 2011. He hung around the area for at least a week, trying out several different spots to get a meal. Then on 1 September, our timelapse camera caught him crawling into the rear entrance of Cap Mama’s nest (she gave birth that day).

Unfortunately that is the only footage we have of Cap Mama's nest that day, so we don't know if Dagger interacted with her or the neonates.



The photo on the left is of Adam (neonate on left) and Woody (right), his mother. Woody's nest was farther away than most in 2010, about 150 yards from her den. Regardless, Adam found his way to the den where we saw him in April 2011 (photo on right). Our timelapse camera caught Woody and Adam as they basked together that day:




This is Devil Tail, who nested alone at her den in 2010. Shortly after she gave birth, a large male rattlesnake, who also dens here, visited and basked with the family:
Still image of the group:
The adult male is the large black rattlesnake at the top of the image and Devil Tail is the smaller, brown adult (mostly her tail and rattle are visible). Both of the neonates pictured here were seen at the den the following spring (2011).

Above is '520' in April 2011. Hopefully he'll be adopted and named soon!


And this is Unibrau in April 2011. Unibrau was adopted by Bill Rulon-Miller - thanks!


Barb, another of Devil Tail's neonates, is pictured here with Sigma in April 2011. Perhaps nesting right at the den increases your chances of surviving your first winter, because Devil Tail's kids seem to be doing pretty good!

If you enjoy reading these blog posts, please check out our project on RocketHub and support us financially or by spreading the word. We're raising funds to examine relatedness of this population of rattlesnakes, which will enable us to answer many questions our work has raised, including:
Are Peach and Eve, who nested together in 2010, sisters? Aunt and niece? Mother and daughter?
Was the male that visited Devil Tail the father of her neonates? Their uncle?

Supporting a research project might sound expensive, but it doesn't have to be. Through RocketHub, you can chip in as little as $5 to help us out. So skip one beer/wine/starbucks and support some cool snake research instead! Plus, you can get some cool snake stuff: rattlesnake photos, greeting cards, or adopt your very own social rattlesnake!

OK, maybe you don't have $5. But, it only takes a minute to share the link to our blog or RocketHub project on Facebook or Twitter. You have a minute, don't you? Thanks for whatever you can do to support SocialSnakes!

Support Social Snake Research!

Are snakes social? YES! Do snakes live in groups? SOMETIMES! Are these groups of snakes extended families? Help us find out!

As a reader of this blog, you already know that rattlesnakes are quite gregarious. Their social lives are complex; they recognize and preferentially associate with their siblings, care for their kids, and even help care for their neighbor’s kids. But the big question remains unanswered.

Many of us who monitor rattlesnake dens have speculated that they are composed of closely related individuals. Our goal is to explore this idea by examining relatedness with microsatellite DNA markers. With your help, we will find out if dens really are a rattlesnake family reunion. Our research might reveal a previously undocumented, complex social system in snakes and promote snake conservation by highlighting some very human-like behaviors.

You know you're curious about the relatedness of the snakes you've been reading about here! Check out our project on RocketHub.

And spread the word! This can be just as helpful as a financial contribution.

Sigma vs. the squirrel

Squirrels and rattlesnakes have a complicated relationship. Some squirrels have developed resistance to rattlesnake venom so that an adult squirrel can survive a rattlesnake bite. Juvenile squirrels cannot, so they are often still prey to rattlesnakes. Because of their resistance, adult squirrels will confront rattlesnakes that wander near their colonies and sometimes even kill them!

For more information on rattlesnake-squirrel interactions, check out research from Rulon Clark’s lab and his student Bree Putman’s blog. Now on to Sigma’s story…

We first met Sigma on 23 April 2011 when she was basking near her den. She was named for one of her many weird blotches that is shaped like the Greek letter. Sigma and Barb, 24 April 2011. Barb was born here, to another female (Devil Tail), the previous September (2010).

6 August: We return to the dens and find Sigma at large rock near her den that will be her nest site. Toward the end of her pregnancy, she settles on the west side of the rock as her main basking area, so we set up a timelapse camera there.

Between 3 and 4 September, the squirrel appears to be investigating the nest rock, but never when Sigma is on the surface.

On 5 September, Sigma and the squirrel meet: Sigma (at end of arrow) emerging for the first time that day

The squirrel confronts Sigma

Sigma immediately retreats beneath her nest rock

6 September: Sigma sticks her head out and looks around before emerging (like Cap Mama ). About an hour later, the first of her four neonates emerge from beneath the rock:

The following video captures Sigma’s family’s first day together (warning: its kinda long, 4 minutes). Watch for the squirrel’s appearance at 12:14PM.


The squirrel does not return (that we can see) the following day and the family spends most of it on the surface:



Timelapse video of 8 September:


What starts as a peaceful day for the family was rudely interrupted by the squirrel at 11:27AM. Just before the squirrel appears in the video, Sigma turns and assumes an S-coil defensive posture typical of rattlesnakes: Sigma at rest with her family

Sigma turns, expands her body to look as large as possible, and assumes a ready-to-strike (S-coil) defensive posture.

What you can’t see in the video was captured by our overhead camera; Sigma is posturing to the squirrel just off screen:

The family immediately disappears; Sigma reemerges only after the squirrel is gone. The first neonate to emerge is quickly chased back under the nest rock by the squirrel (~11:54AM–12:01PM in the video).

9 September: After the squirrel interactions, the family seems to spend much less time on the surface (at least where the cameras can see). We recorded only one additional, indirect, interaction between Sigma and the squirrel:
As it often did when there weren’t snakes visible, the squirrel appears to be looking underneath the nest rock. Sigma returns, takes on the familiar defensive posture and appears to be rattling – although it’s difficult to be certain because the timelapse photos were taken at one-minute intervals.

Our camera continued to record at this location until 18 September and the squirrel returned about every other day, usually looking underneath the nest rock. Sigma and her four neonates were never seen together again, but we cannot say if they changed their behavior or if one or more neonates were injured or killed. One limitation of remote photography is that our knowledge is limited to what happened in view of the camera. However, it is unlikely that any of these squirrel-rattlesnake interactions would have occurred if a human observer was present. We never saw anything like this when we monitored rattlesnake families in person – have you?

Scenes from a new den

We were recently told about a new social rattlesnake den in the Galiuro Mountains. We hiked in to check it out, saw one western diamond-backed rattlesnake (Crotalus atrox), and decided to set up one of our timelapse cameras. The video below is from the first two days of our monitoring, and we were a little surprised at all the activity:



That video is a little long and it’s easy to miss all the visitors, so here are stills of all the reptiles we spotted.






This is a juvenile Sonoran whipsnake (Coluber bilineatus). The closely related striped whipsnake (Coluber taeniatus) often shares dens with Arizona black rattlesnakes (Crotalus cerberus; see Are aggregations of Arizona black rattlesnakes stable and complex social groups?).







A gila monster (Heloderma suspectum)! It is not unusual for Gila monsters to share dens with western diamond-backed rattlesnakes and Sonoran Desert Tortoises (Gopherus morafkai). However, this Gila checks out the den only to turn around and leave. Could it be looking for a date? It's awfully late in the year for Gilas to be out and about.







Patch-nosed snake (Salvadora spp.) This is not a snake we have yet seen in any of our other dens. In this video, the patch-nosed appears to be checking the den out before moving on. Future videos may show if this snake continues to use the den.

There were a couple feathered reptiles here too (birds). Did we miss anyone? Who else will show up at the new den? Stay tuned...

A day in the life of a rattlesnake family

Rattlesnakes take care of their babies.

Yep, they really do. But, what does "care" look like in a snake? Do they feed their young like a mother bird? Do they keep them warm? Do they protect them from predators? With the exception of feeding, rattlesnakes care for their offspring in familiar ways. The following is a timelapse video (taken at 1 minute intervals) that illustrates a typical day for a new rattlesnake family. The large, black snake is Cap Mama, a female Arizona black rattlesnake that gestated with four other females and gave birth in late August to seven neonates. This video was taken when the neonates are just two or three days old.


Now let's look a little closer at some of the behaviors in the video:


Before the neonates emerge for the day, Cap Mama looks out as if making sure it is safe for the neonates to come out. Here she looks toward the camera...



And then she looks away from the camera. We have observed this "lookout" behavior by several different females.



The neonate in the foreground of this photo is starting to stray from the group and Cap Mama notices.



A gentle tap from Cap Mama reminds the neonate to stay with the group. We have also observed the females blocking neonates from straying too far (see A rattlesnake helper?).



The neonate responds by returning to the group and Cap Mama heads back in as well.



In this rattlesnake species, adults are darker than neonates and thus may be able to gain heat easier. By allowing neonates to sit on and near her, Cap Mama may be provisioning her offspring with heat (rattlesnakes are ectotherms: they depend on their environment for heat instead of producing their own like we do). And Cap Mama's larger size means she'll garner and release heat, perhaps even into the night when the family is tucked away in their refuge. Keeping warm helps a young snake develop, shed, and get ready to leave the nest and hunt on its own.

Ménage à trois (part 2)

(if you haven't already, see part 1)


When we left our 3 gophersnakes, Bluto had just interrupted courtship between Popeye and Olive Oyl and was biting Popeye repeatedly along his body. Popeye released his bite-grip on Olive Oyl and she fled so fast that we were unable to follow. Bluto continued biting Popeye, making him to wince but not retaliate. Instead, Popeye seeks refuge in a nearby burrow. In his fervid biting, Bluto barely notices that Popeye has escaped, actually biting himself a couple times by mistake. Finally realizing that his competitor is sidelined, Bluto resumes searching for Olive Oyl, who had a 2 ½ minute head start.

Bluto appears to be in a hurry, and while he initially showed brief reactions to close encounters with us, he no longer expresses concern. He flicks his tongue almost continuously, halting almost imperceptibly several times a second to deliver particles into his mouth. Undoubtedly, Bluto is following traces of Olive Oyl, but apparently her trail is not clear. He travels in wide loops, backtracks, and even ascends a pine tree. Perhaps Olive Oyl has passed through this area more than once. And the wind must make his search even harder!

Popeye’s urges can wait no longer. We find him peering from the burrow only 3 minutes after entering. After five more minutes, he locates Olive Oyl’s scent trail, and heads off in the same direction as the other two.

He appears to be a little more careful than Bluto, pausing to hone in on the path ahead. We try to keep tabs on both males as they move about, but we are distracted by a beautiful rattlesnake and Popeye slips away.



After about an hour Popeye reappears, coming within just a few meters of Bluto. He appears to pass Bluto, and we again lose him as he cruises on through the vegetation. Finally, at 1417, 80 minutes after we last saw her, we find Olive Oyl being courted by Popeye on open ground beneath a tree, 113 meters NE of their roadside rendezvous (see part 1). Moments later, Bluto finds the pair, Olive Oyl slips away, and conflict begins anew.

In a repeat of part 1, Popeye is first to find and court Olive Oyl, but they are interrupted by latecomer Bluto, and the female flees. With an enduring calm, Popeye once again slips from Bluto's sway.

To be concluded...