Earlier this week I was able to visit University Nacional Autónoma de Mexico (UNAM) Los Arcos in Hermosillo, Sonora. I was thrilled and grateful for the opportunity to visit Dra. Angelina Martínez Yrízar and Dr. Alberto Burquez Montijo, and to meet Dra. Enriquena Bustamente, and to go out in the field with them! I always learn new things while hiking with experts.
The plants in Sonora were familiar, but a little wrong – like a dream where everything is just backwards. We were driving across the Plains of Sonora region of the Sonoran Desert, while I spend most of my time in the Sonoran Uplands region. For example, visitors to Tucson from more temperate regions of the US are often blown away by the spectacularly strange looking plants. A favorite of mine is the ocotillo, Fouquieria splendens, that waves tentacles skyward like a very lost giant kelp:
The shrub (not a cactus, despite its evil looking thorns!) produces leaves only after rains, and in the springtime sports a brilliant red inflorescence like a gas flare in the night:
The red flowers are edible. Many of them have a bitter taste to me if the sweet drop of nectar has already been provided to a pollinator:
I remember how eagerly I stared at the ocotillos the first year I was in Tucson. Now I look mostly to see if they have leaves, if they have flowers. But arriving in Sonora, I found the ocotillos had more than that – they had trunks and branches!
Just kidding, these were not ocotillos at all, but a different species: the Mexican ocotillo tree, or Fouquieria macdougalii. Their flowers were distinct, and even more enchanting, but I was so busy photographing them I forgot to taste.
Guess I’ll have to go back soon. Gracias para una visita muy buena.
Plants may have all kinds of behavior – or maybe they do not, depending on your definition of behavior.
In his documentary, The Private Life of Plants, David Attenborough demonstrates the way they do at least respond to cues from their environment. This we all know: that some windowsill plants will tend to grow toward the light. I learned recently that the majestic saguaro cacti, like barrel cacti and others, grow distinctly differently on their south and north sides, as so in transplanting one, care should be taken to orient it the same way as originally planted.
My point is that plants move and respond to their environment. Sometimes quickly, like the veuns fly trap, which I was able to watch in its native range near Wilmington, North Carolina, at the end of December. Stroking a stick along the hairs of open traps, as seen below, caused them to quickly glide shut, as is the one at the bottom of the frame.
But sometimes plants move more slowly – important competitive and survival behaviors may take place as they grow, but on timescales too slow for us animals to register them. This is where time lapse cameras like Attenborough’s come in. I decided to take a stab at plant behavior in my backyard.
Last November, my housemate moved a big planter behind the house, and started a garden. I placed a relatively robust wildlife camera in the planter to capture the movement and growth of her lettuce, beets, and radishes. The bright reflection off soil during the day meant I had to time my photos only for infrared detection at night, giving the scenes a spooky air. But then something important happened:
The weekend of El Tour de Tucson, a 100 mile bike race around the perimeter of our city, it rained. Not a nice gentle cooling rain for a few hours or even a whole night, the kind that makes me run outside and dance in the puddles because it rains so infrequently here. This was a downpour. And it was cold. Like living in Portland, or Seattle, or anywhere but Tucson, really. This mattered to me (and 9,000 other cyclists signed up for the race) because we almost never ride in the rain – if it’s raining in Tucson, you usually just wait and ride tomorrow instead because it will be sunny and dry. [Note - this applies only to casual cyclists, otherwise known as sane or relatively normal people. Real cyclists are not deterred by snow or hurricanes.] It was also the first time it had rained – really rained – for the race, which has been going on for decades.
So this storm dumped an unusual amount of water. What’s the big deal for the garden, or the plants and animals in general? There are two main takeaways from this for ecologists and population dynamics analyses:
(1) Infrequent events require long time scales to ensure a capture. If I were a plant ecologist studying winter annuals, and I only had time in my PhD to collect 3 years of data and was trying to extrapolate the growth trajectories of a population over the next 50 years, how would I know to include a storm of this magnitude if I never observed one? Only sampling 3 years from any of the last 30 years would rarely turn up a rainstorm like this. I assumed my nice rugged weatherproof camera would be safe getting rained on in the outdoors for a few months. Based on my experience in the last four years in Tucson, I did not expect the garden to turn into a swimming pool, which was not safe for my camera.
(2) But if you happen to capture one in a short window, it will really mess with your estimates of how a system usually behaves. This was only my second time riding El Tour de Tucson, so now I have one memory of a beautiful ride, and one memory of a truly horrific near-hypothermic sufferfest. Weighted equally in terms of frequency in my experience. If my 3 year window included this event, I might naively conclude this system was pretty highly variable – that an event like this might happen every couple of years.
This was an issue I explored in my undergraduate thesis (with Diane Thomson at Scripps College), but that still continues to be an interesting problem today.
I was standing next to an experimental plot high on a ridge in the Rincon Mountains last summer when I looked up and saw the snake. It was winding its way through the vegetation, approaching closer and closer – only feet away! It was about four different colors. Its head was long and narrow, not triangular like a rattlesnake.
My field team and I watched as it snaked its way around us, apparently unconcerned. I pulled out my phone to look it up on Snakes of Arizona, but too many color options confused me. So I took a picture and uploaded it to Facebook, an hour’s hike off trail out into my study site in the National Park. Within minutes, the phone buzzed in my pocket. A graduate student with expertise in herpetology had already commented on my photo with the species name! I could now Google that snake to learn about it while watching it actively hunt in the wild, as long as I stood relatively quietly and did not startle it away. Imagine if it had been a rare or endangered species – or a dangerous one!”
As the earth reaches this point in its revolution around the sun, members of our species, at least in many urban areas around the globe, reflect on the new advances in technology and the way in which they change (or don’t change) our lives. We hear stories about Most Viewed trends on YouTube (spoiler alert: not science and nature!).
I share the snake story above to illustrate how our connectedness and more importantly the mobility of our devices changes my experience as a naturalist in the field. I can instantly have access to the experience and information of other people, even in (relatively) remote locations.
On the other hand, this connectedness in some ways underscores how much has not changed about field work, or academia in general. Some identifications are difficult or even unknown: if I post a photo of the summer germinating seedlings I am studying, I am unlikely to get back a quick ID. I have to make that seedling guide myself. But for something well known like the snake, what really helped me was having a network of experts that I could turn to. If I were still waiting tables instead of studying biology, a snake spotted on a casual hike would be much less easily identified. The public resource I could quickly find for snake identification with a Google search required some additional knowledge to take advantage of it.
But the internet does provide a platform to get help from experts outside my network – it may take a little more time and effort, but not nearly so much as the in person call of a century ago. After questioning everyone I knew who studied pocket mice about an odd dancing behavior I had repeatedly recorded in the field and finding no explanation, I compiled the clips to funny music, and posted it online. I was thrilled to receive responses via this blog, Facebook, Twitter, and email that provided a consensus opinion from experts I had never met in person.
When I read the following email about the reach my blog had had this year, I was blown away:
“The WordPress.com stats helper monkeys prepared a 2013 annual report for this blog. Here’s an excerpt: A San Francisco cable car holds 60 people. This blog was viewed about 3,600 times in 2013. If it were a cable car, it would take about 60 trips to carry that many people. Click here to see the complete report.”
Though science and nature videos may not match views of cats or video games on YouTube, and watching nature unfold on a screen is far less impactful than really being outside yourself, that is still far more people than I would likely be able to tell what I learn through more traditional mediums – and I undoubtedly am able to learn far more from others this way, too!
The program I have been helping to build for the past year and a half has received some good press in the past month, from school district and department newsletters to the University’s news service, to our local public media affiliate!
I find it easy to talk about the UA Sky School with the media because it is important and powerful. That power comes from reality and rigor. This is not nature camp or space camp. The instructors are prepared with knowledge about unique opportunities to emphasize important scientific standards and the resources to investigate them, but our activities are not simulated and our lessons are not canned. Students on the four day stays especially interact with actual scientists, using actual mountains and plants and telescopes, to do actual original research. The potential to have an epic experience in scientific discovery or outdoor adventure is tangible.
The impending end of the calendar year is a season of reflection and envisioning what the future will hold. In an era of decreasing interest in science, an era of increasing time spent in front of screens, increasing urban populations, here’s to envisioning a future network of such university affiliated outdoor science schools across the country – even across the world – that provide this chance for students to get real and get inspired. And seeing the interest in the UA Science Sky School gives me hope we can make that vision real.
This is no Nutcracker. After sundown, the pocket mice of Saguaro National Park are working it like a strip joint. Check it out (second one has my narration):
A brief summary also appear’s on Felicity Muth’s blog (Not Bad Science) over at http://www.ScientificAmerican.com. What started as bored amusement at this energetically costly behavior turned to curiosity as I realized how often I was seeing it. Idle curiosity turned into fascination as I realized how few mammologists had even seen the dance before.
But beyond the novelty and the entertainment factor, does this behavior matter at all to the ecology of the species? Does it affect their population dynamics?
1. What if this is anti-snake flagging behavior? (Cool video.) I have already posted about the ways in which an energetically costly anti-predator behavior can affect the energy flows in an food chain, and the densities of both the predators and their prey. So if this is tail flagging aimed at a snake, it could decrease the population growth rate of the mice.
2. What if mice are marking territories? I actually had more trouble than I expected finding general theoretical conclusions on the effects of territoriality on population dynamics, but please feel free to correct me if you know of some (or have research of your own I overlooked!). A trivial answer is that dividing space into territories is a form of intraspecific density dependence – that means the species is limiting its own population growth. But does that limit growth differently than pure resource competition? What about in a spatially variable environment? Maybe I can contribute something through my own research here eventually.
3. And of course, what if this is sexual behavior? Male mice have been reported to do a butt wiggle before mounting a female (Bret Pasch, personal communication), so these could be males smelling a potential mate and getting excited. If they are wasting energy dancing too early in anticipation of mating before even locating the female, that could decrease their eventual longevity or mating success, I suppose. That might not even matter to population dynamics if there are plenty of males to get out there and mate, though. Especially if dancing is a minimal cost relative to the total effort of running around through the desert searching for females.
Finally, how can I start testing these hypotheses? Proving the presence of an off-camera snake that is triggering flagging behavior might be hard, but a good first step would be to put a mouse and a snake together and video the encounter to compare with what I have. To detect urine spray for territoriality, I have tried placing filter paper around the camera to inspect with a black light in search of urine droplets. No dancing over my filter paper, yet, sadly. Additionally, if I want to find out whether only males do the dance, I could capture and mark mice in a study area before re-deploying the cameras.
Help me out by posting your own ideas about why the mice are shaking their booties, how to test the ideas, and what the important implications are!
[Update 1: I did not speed up or slow down any of the videos. All I did was select the parts of clips where they are "dancing." Nothing else is changed from raw footage.]
[Update 2: Noelle Bitner, a doctoral student (candidate?) in Dr. Michael Nachman's lab at Berkeley, reports she has two female pocket mice who "dance." So much for the male-specific sexuality hypotheses? Also, Vicky Chan, a graduate student in Optical Sciences, reports her captive pocket mouse (unknown gender) often dances after caching seeds. Support for scent marking?]
“1.Why did 5 eat 6?
- Because 1, 2, 3
- Because 7, 8, 9
- Because 5 predates 6″
There is a well-known joke that goes more like, “Why was 6 afraid of 7?” The answer to that is quite obviously, “Because 7, 8, 9!” Such predator avoidance behaviors as 6 being afraid of 7 and perhaps fleeing from it are ubiquitous in animals, as anyone knows who sees sparrows flutter away at your approach in the parking lot. There is a growing body of mathematical theory demonstrating the effect that these avoidance behaviors can have on the actual population dynamics of the prey species, led by scientists such as Peter Abrams and John Orrock. These results are readily demonstrated in experiments: Oswald Schmitz and his colleagues have demonstrated how grasshoppers reduce their feeding and thus slow their population growth rates by avoiding nutritious leaves where spiders may lurk – and the reduced grasshopper population growth rate occurs even when they glue spider mouth parts shut! The effect of fear on the prey species can even transform entire biological communities and their ecosystems.
Well, 7 eating 9 is a great reason for 6 to be afraid of 7, especially if 6 looks anything like 9 (and it sure does to me). But that’s not a good reason for 5 to eat 6. What on earth do we learn about 5 from this other interaction? (Well, it’s prime, like 7, I suppose, so maybe they have similar predaceous traits.) Predators that are coexisting in a community (of integers less than 10?) are quite likely to partition prey in some way as a trade-off that prevents one from excluding another.
But, as Abrams and other theoretical and empirical studies point out, adopting behavior to avoid one predator may make a prey item easier to capture by a predator hunting by a different mode. So if 6 is afraid of 7, it may crowd closer to 5, who, predating it in an ordered number line, can also then prey (or predate) the 6.
Imagine my indignation, then, when I clicked on the end of the quiz to see my answers, only to discover this subtlety completely overlooked by Singh. He had set the answer to this unusually phrased variant of the classic to the well known answer, which frankly, in this scenario, made far less sense.
So since 5 does predate 6, that is a far better reason for 5 to then eat 6, than because some other number like 7 ate the far off 9. I rest my case, sir!
Freezing and frequent fires are both more prevalent in the Sky Islands than in Tucson. Sky Islands are the forest capped mountain ranges dotting the low lying desert sea of the southwestern United States and northern Mexico. Over the last two days, I helped to investigate which would contribute more to weathering: the fires or the freezes?
This project was the work of five Environmental Science students at Tanque Verde High School who spent their fall break attending the new University of Arizona Sky School, a residential science school located at the summit of Tucson’s most accessible Sky Island: Mount Lemmon. It was co-advised by myself (a doctoral candidate in Ecology and Evolutionary Biology) and Phil Stokes (a doctoral candidate in Geosciences). Needless to say, this project built substantially on Phil’s expertise, and I learned a lot.
For example, I learned that weathering is the process of rocks breaking down, while erosion is the transportation of those particles. I learned that having five students lean around a fire and watch intensely through their safety goggles as a crack in a rock widens visibly a millimeter feels like success.
To test the severity of weathering by freezing and by fire, we collected 3 types of rock, and subjected them to 4 treatments. The rock types were schist, quartzite, and granite. The treatments were repeated short freezing cycles, repeated short fire cycles, a long freeze, and a long burn. Rocks were soaked in warm water before treatments, and between freeze or burn cycles.
As the members of Team Tough Schist presented in the Second Sky School Symposium, ice and fire work differently on weathering rock. A very general explanation they provided was that water seeps into existing cracks, then expands when frozen, widening them. Fire, however, heats the many minerals in the rock, busting them apart and creating new cracks. This additional surface area opened by fire allows more weathering.
Armed with this understanding of weathering mechanisms, and the evidence of more cracks in the roasted rocks than the frozen rocks, Team Tough Schist also concluded that schist is not so tough. Anyone who has picked up the papery flakes laced with mica may have also observed this. And when those papery layers curl up when expanding due to heat, they stay crinkled like a book that once wetted, never lies perfectly flat. As you might also imagine, repeated freeze-thaw cycles wedge cracks wider and wider more than one long freeze. But one long and intense fire may expand and crack a rock more than repeated short fires.
Although overall fire was determined by Tough Schist to be a more severe weathering agent, freezing occurs every year all over the tops of Sky Islands, and fires near any given rock are less frequent, even under historical more frequent fire regimes. So they left their audience with further questions: Which weathering agent, ice or fire, should be contributing more to weathering processes on Mount Lemmon overall?
On a final note, I was obviously disappointed none of the students were fans of George R.R. Martin, given their choice of research question.