Speaking of Nature

The Great Birdseed Heist

Susan thinks Bill is nuts; you can judge for yourself

It’s 4:50 on Sunday afternoon and I am sitting out on my deck. The temperature never really got too high today and with a stiff breeze blowing in a swirling pattern around the yard, the comforts of summer seem long gone. The sky is a bright blue typical of September, but there are now many flat-bottomed clouds moving slowly to the east. They cover more than 60 percent of the sky and they seem to be increasing in number.

Normally, I might be inside watching football, but I’m out here today because I’ve had a curious thought running through my head for some time now. I’ve been wondering how much I’m being swindled by one of my wild little neighbors and I’m out to find the answer. Susan thinks I’m out of my mind.

The little neighbor I’m speaking of is the chipmunk that comes to raid my feeding operation. Actually, there are at least two individuals that I can recognize by sight, but there is only one that seems to “own” the porch. Chipmunks have been raiding my birdseed for years and I’ve often pondered just how many pounds of seed they’ve made off with. With a little (very little) planning, I’ve set up a little experiment to see if I can answer this question.

I’ve prepared two samples of the birdseed that I routinely offer to my feathered friends. One sample is a 1-ounce cup of mixed seed that contains white millet, sunflower seeds, wheat seeds and the occasional fragment of coarsely cracked corn. The second sample is a 1-ounce cup of shelled sunflower hearts. I use the shelled sunflower seeds to keep my lawn alive and keep the mess on the porch to a dull roar.

My experiment is crude, but will offer at least an idea of the extent of the theft. A small offering of seed has been placed out to simply attract the chipmunk’s attention. Once that is gone, I will put out my first sample and start my stopwatch as soon as the chipmunk makes its first appearance. I will stop the timer when the last seed is gone.

This will give me an idea of how quickly an ounce of birdseed can be secured by the chipmunk. All I have to do then is multiply that time by 16 to find the time required to collect up to a pound of seed, followed by an additional multiplication by 40 to calculate the time required for a 40-pound bag of seed. Then by dividing by 60 (for minutes in an hour) and 24 (for hours in a day), I can calculate the daily cost of a single chipmunk’s efforts.

Now, all I need is the chipmunk’s cooperation. It’s 5:15 and I’ve seen neither hide nor hair of the striped bandit, but I do have the company of those chickadees I introduced you to a couple of weeks ago. There appear to be three of them here this evening and their sudden appearance is most welcome. They came in from across the street and seemed to follow the general direction of my driveway. One minute the world was quiet and lonely. The next minute, there was plenty of happy energy. I love chickadees.

Well, the stage is set and I’m going to stop writing for a little while to conserve room for what I hope will be an interesting scientific analysis of mammalian thievery.

5:20 — chipmunks sighted in the driveway.

5:21 — I put out a little extra bait to let them know there is food to be had

5:33 — the bait is gone and the chipmunk is getting closer to my location

5:34 — the game is afoot!

5:40 – 1 ounce of mixed seed is in place

5:55 — has my plan backfired?

5:58 — there is a chipmunk staring at me from the flower pot

5:59 — start the timer!!

I had a little scare there for a moment when the chipmunk was more interested in the widely scattered bait seeds out in the driveway. In just 20 minutes, the blue sky has completely disappeared and the clouds have taken over. All I have to do is hope that the chipmunk keeps at it long enough to clear out the entire pile.

A flock of Canada geese is flying low on the eastern horizon. The stiff wind from the west is keeping the sounds of their voices at a minimum this evening, but there is enough for me to figure out where they are. Nineteen geese flying in tight formation and heading to the south. Fall is most certainly here!

The chipmunk only required 1 minute, 44 seconds to fill its cheeks to capacity. It disappeared for about a minute, but has now returned to resume its harvesting. I don’t know if it’s my imagination, the cold, or the failing light, but the striped bandit definitely seems to be working with an urgency of purpose. I suppose I’ll have a speed that can be estimated to be on the faster side when I’m done.

The little downy woodpecker that has been my constant companion since the winter is now here. My next experiment is to learn Morse code and see if I can’t translate a hidden message in all of her tapping. Wouldn’t it be funny if she was talking to me all along and I just wasn’t smart enough to know it?

The chipmunk is back for a third visit. The pile of seed is about half gone and I am now at the 8-minute, 30-second mark. Conditions being what they are, I doubt I’ll get to do a second experiment tonight.

The chipmunk faithfully returned for a total of six trips, but the design flaws of my experiment made themselves known at the very end. The chickadees often look for food in the same exact place every night and I make sure to put out a nice little handful of seed for them. Apparently, the chickadees aren’t the only ones that are aware of this. At the 19-minute, 30-second mark, the chipmunk suddenly changed its route and went for the chickadee seed, leaving about 25 pieces of sunflower seeds from the 1-ounce sample unclaimed. But I’ve got some data.

Using 20 minutes-per-ounce as a nice round number, I calculate that the chipmunk can remove a 40-pound bag of seeds in a little less than 18 days. Thus, if the chipmunk were not distracted by other chipmunks, or limited by competition from the hungry birds that also come to eat, it could remove about $2.24 worth of seed per day.

I’d have to do a lot more research to confirm these initial estimates, but it feels like it is safe to say that there are literally bags of seed hidden underground around my house and I don’t really want to contemplate the value of that seed. Thank goodness chipmunks hibernate for the winter!

Bill Danielson has worked as a naturalist for 16 years. In that time, he has been a national park ranger, a wildlife biologist and a field researcher. He currently works as a high school chemistry and biology teacher. His Speaking of Nature column runs weekly in The Recorder, except for the first Thursday of each month, which is when his Kids and Critters column for young readers appears. To contact Bill, or to learn more about his writing, visit www.speakingofnature.com

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