I’ve been meaning for quite some time to point readers to Natural Current Events, the photoblog by Emily Jones (who, to disclose fully, is a postdoc with one of my doctoral committee members). It’s a photoblog with nice natural history notation, mainly focused on insects, their host plants, and their predators — but really covering anything that will stand still long enough for Emily to catch a photo. Each post is like a short walk through your neighborhood woodlot with a natural-history-savvy friend.◼
The camera on my iPhone (4, not even S) is really pretty lousy. But when I’m on the last long run before a marathon, it’s the camera I have with me. And it does give you some sense of how colorful things have become in the parklands that line the Mississippi River from Minneapolis to Saint Paul, my regular running route. More photos after the jump!
I like these cities.◼
Like pretty much anyone else writing about this, I’m in it for the headline. Well, maybe 30% for the headline — this is also just freaky natural history. A paper in Biology Letters reports that great tits (Parus major — basically big chickadees) will hunt and eat hibernating bats [$-a] if they can’t find other food sources.
The paper reports on ten years of recorded bat-eating by a population of great tits in Hungary, capped by two years of systematic observations and a couple simple experiments. Are the tits hunting bats because other food is scarce? The authors put out birdseed and bacon near the bat cave, and observed that the birds killed many fewer bats. Do the tits use audio cues to find their prey? The authors played a tape recording of bats calling, and watched as the birds oriented to the sound and approached the speaker. There are also a number of grisly photos of tit-killed bats.
This is really the kind of work that attracts most field biologists to science in the first place — a wild, interesting observation that provides an excuse to do some really unusual (and thorough) birdwatching. More complicated science will follow, I hope, like an estimate of the selective advantage this new food source provides to the birds. But it all starts with an incredible story.
You might want to count your fingers after hand-feeding a great tit. Photo by joyrex.
Estok, P., Zsebok, S., & Siemers, B. (2009). Great tits search for, capture, kill and eat hibernating bats Biology Letters DOI: 10.1098/rsbl.2009.0611
The first half of the walk between my apartment and campus goes downhill through a slightly shabby, crowded college-town residential neighborhood that is much improved by the presence of large, shady trees lining the sidewalk. Almost at the bottom of the hill, my walk takes me past a tree whose owner has decided to feed squirrels. The tree is close to the sidewalk on the left as I walk toward campus, and it has two trunks that diverge almost at the ground; nailed to each of these at about the height of my chin is a wooden box about ten inches by ten inches, with an open face looking across the sidewalk to the house of the probable squirrel-feeder and the bottom surface forming a tray, which usually contains seeds or nuts or such. Many times I’ve forgotten that I’m nearing this tree as I walk to campus in the morning, and many times I’ve been jolted by the explosive scutter of squirrels evacuating the feeder as I approached.
Yesterday this didn’t happen. Yesterday, I didn’t think about the approaching feeder until I was right on beside it. Remembering it, I turned left for a glancing look as I passed. And I came eye to eye with a squirrel.
It was sitting atop the farther of the two boxes, right about at my eye level, frozen in that twitchy way that largish rodents sometimes freeze when they’re threatened, as though you might go away if they don’t do anything cute. It was a fox squirrel, I think, rusty gray above and just rusty below, fixing me with a pair of black, shining eyes.
I stood still and looked at it. It twitched its tail.
Then, incredibly, it jumped to the other box, just a foot or so from my face. I could see its handlike little paws gripping the edge of the box, paws that called to mind words like “cunning” and “clever”. The black little eyes stared at me, blank and shiny as freshly-washed chalkboards. The squirrel made a twitchy advance, then backed off, then advanced again. I tried not to move; but this was unnerving.
It advanced again, and I must have stepped back a fraction – the squirrel made an instant U-turn and scuttered up the tree trunk. I was left blinking at the feeder box, listening to the sounds of traffic on the street at the end of the block.