I can hear the cicadas buzzing outside, so I know it must be hot. The predicted high on NPR at dawn this morning was 99 degrees Fahrenheit. Not so warm for June in the Sonoran Desert, but uncomfortable. My fieldwork for several summers involved starting at dawn, but staying out all day in this, marking little seedlings on exposed hillsides. (You can see very preliminary – not peer reviewed yet – results of what I found at the Southern Arizona Buffelgrass Coordination Center website.) All summer. It was, well, tough. I have a rather unique data set as a result.
I was listening to the NPR weather report at dawn today because I was on my way to a field site to retrieve some plastic trays of seeds coated in fluorescent powder I had left out all night before. I am interested in the places nocturnal seed-eaters go. The wind picks up during the day, so I wanted to minimize the powdery spray between the time the seed eaters tracked it around, and when darkness falls and I can return to trace their pathways with blacklights (and friends!). I explained a little about the goals of the project in my previous post.
This dawn and dusk schedule is much more comfortable, convenient for me getting other writing done during the day, and also for attracting volunteers. Many animals adopt this schedule in hot deserts. The schedule even has a name: crepuscular, although I call it the siesta schedule. This will be key because I am detecting fewer pocket mice per night than I had hoped. So I may be in for many more crepuscular days of leaving little offerings to the desert, trying to increase my sample size.
Here is a teaser of the pocket mouse (genus Chaetodipus) jamming the fur-lined pockets next to its mouth full of seeds, then burying them nearby like a pirate with treasure, or a squirrel with nuts. Most animals that “scatterhoard” their seeds in many small caches near the source later return to move them to secondary caches, or even eventually to their “larder” in their burrow. I suspect these pocket mice behave in a similar way.
And as a bonus, when the little guy (or gal) first showed up, before eating anything, it did my favorite “dancing” behavior:
Was it marking this resource for itself? Attracting a mate? Doing an instinctive behavior in response to positive stimulus? We need an animal behavior specialist to get on testing this.
And a few last gratuitous shots of the experimental set-up during a beautiful Tucson sunset: