Frequently Asked Questions
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How high can kangaroo rats jump in comparison to their body size?
Kangaroo rats are capable of jumping almost a meter into the air, which is about six and a half body lengths for them!
Are kangaroo rats faster than rattlesnakes?
There is a lot of variability in top speeds of these animals during an interaction, and as you can see in the videos, maneuverability on the kangaroo rat's part appears very important too. When kangaroo rats jump, they leave the ground at an average speed of 3.5 m/s. The snakes, on the other hand, reach average speeds of 3.0 m/s, so these two animals are pretty evenly matched when it comes to speed!
Are there any other bipedal rodents?
Yes, there are four groups of bipedal rodent: kangaroo rats (North America), jerboas (Africa & Asia), springhares (Africa), and hopping mice (Australia). All groups have enlarged hind limbs and small forelimbs as well as a long tail. This bipedal body plan likely evolved through convergent evolution: where distantly related species evolve similar traits because they are adapted to similar environments (like the wing of a bird and the wing of a bat), not because they inherited it from the same ancestor.
Do the snakes anticipate the jump of the kangaroo rat and aim higher?
Typically not, but this also seems pretty variable-- sometimes they might. We have noticed that anticipating the jump and striking higher does not guarantee that the snake will be able to bite the kangaroo rat, and oftentimes the kangaroo rat is jumping so fast that by the time it reaches the snake’s head, it is capable of knocking the snake’s head out of the way.
Why don’t the snakes go for the kangaroo rats while they are in the air?
Strikes in nature are very variable (as our recent articles make clear). Some of the time snakes do strike while the prey is mid-air, sometimes they don't. From our recordings, it doesn’t appear that one strategy is more successful than the other.
Sometimes the snakes look like they are waiting for the kangaroo rat to fall in their mouths. Does that ever happen? Why does the snake do that?
We have only once seen a kangaroo rat fall onto the snake below it, and the kangaroo rat was fine in that instance (to see this video, check out the video page--it's the fifth one down). We aren't sure why the snakes leave their mouths gaping like they do for several milliseconds, but we want to know too! As far as we can tell, they don’t do that when feeding in captivity.
How long can rattlesnakes go without a meal? Is missing one strike the difference between life and death for them?
Rattlesnakes have relatively low metabolic demands, meaning that they don't need a whole lot of energy to keep their bodies fueled. They can even just get one meal a year and be fine for the most part, especially if it's a nutritious meal like a small mammal.
Is the nervous system of a kangaroo rat faster than ours? Is that why they can react so quickly?
Not necessarily. Kangaroo rats are very sensitive to low-frequency sounds, such as those created by a striking rattlesnake or swooping owl (yes, when rattlesnakes strike they make very subtle sounds that can barely be heard by humans). Auditory cues (sounds) are known for having very short processing times in the brain and are able to trigger physical responses in the body quickly. Thus, the reliance on auditory cues by kangaroo rats could be explaining their fast reaction times. We are hoping to explore this question in future work.
Why do the videos actually look really slow?
We recorded the videos at 500 frames per second (a typical hand-held video camera records at 30 fps) and then slow it down 30 times for playback. This video shows a sidewinder rattlesnake strike at a kangaroo rat played back at regular speed and slowed down. As you can see, if we didn't have these high frame rate recordings, we wouldn’t be able to see all the complexities of these interactions!
How is your work unique? Haven’t snake strikes been recorded in high speed before?
Of course, you have probably seen snake strikes in nature documentaries, but our work is unique in several ways. We are filming natural encounters. Chances are those nature documentaries are staging interactions with captive animals. We are trying to record interactions between free-ranging animals, because this is the context in which the behaviors and morphologies of these animals evolved. In our experience, taking animals into captivity can drastically alter their behavior and performance. By studying these interactions in nature we can document abilities that we didn’t know existed, like the mid-air maneuvers and defensive kicking.
How long does a whole interaction take in real time?
Less than one second; in fact, they often take less time than it does for you to blink your eyes (a human eye blink takes 150-300 milliseconds).
Where can I go to get more scientific information on kangaroo rats?
Because kangaroo rats are important ecosystem engineers and very unusual in terms of morphology and behavior, there are a number of research groups that study them. Many of these groups have websites where they post information on their work and links to their scientific papers (including our own research groups at SDSU and UC Riverside). Some of the other research laboratories that study kangaroo rats include Craig McGowan at University of Idaho, Andrew Biewener at Harvard, Angela Horner at CSU San Bernadino, James Brown at University of New Mexico, Burt Kotler at University of the Negev, Joel Brown at University of Illinois, Doug Kelt at UC Davis. Also, Jan Randall, an emeritus professor from San Francisco State University, produced an important body of literature on all sorts of aspects of kangaroo rat biology.