View from Heifer Hill: Cheeky chipmunk caching for winter
At 2 months old, most of my kids can feed themselves. They are furry, beautiful, and athletic. I like to tease my friends with human babies. They will spend many months changing diapers, feeding and burping, and awaiting those first clumsy steps. My kids are ready to head out into the world within three to five months. This is not to say that wildlife babies do not bring difficulties of their own. Recently, I have been fretting about Cheeky, a chipmunk who has set up housekeeping in a tree.
Cheeky arrived in early September when her mother and siblings were killed by a cat. I was not hopeful at first, but with warmth, a bit of honey, and an injection of electrolytes, the tiny, listless lump of chipmunk began to perk up, and within a day had seized life with a vengeance. Cheeky earned her name long before she began caching food. She had an early and erroneous belief that my ears needed to be bitten. When I put up my hand to cover them, she would squeal in outrage and bat me with her paws. What cheek!
This is a hallmark of chipmunks. Unlike woodchucks (our other ground squirrel), chipmunks do not toddle off to hibernate swathed in fat. While they do enter torpor during the winter, they rouse every few days and trot down a dark corridor to their larder to eat. Winter survival depends upon not just gathering enough food, but upon keeping others from stealing it. They must enter the fray with gray squirrels, red squirrels, and other chipmunks to claim their share of the bounty. They must also be alert to pillagers ready to take advantage of their gathered stores. Chipmunks need to be fierce!
Cheeky honed her fighting skills in mock battles with my fingers. One day her nips and kicks became ferocious, and I realized she was no longer playing. She had stashed some acorns near the site of our game, and I had become a potential thief. Childhood was over. I released her, hoping she would find an abandoned burrow to claim. I planned to watch her, locate her den, and then provide food right near the entrance.
During Cheeky's first days of independence, I saw her boldly chasing other chipmunks. She soon learned that other chipmunks have just as much hutzpah as she does, and they are bigger. She now looks a bit like a moth-eaten taxidermy specimen, with fur missing from a section of her tail and numerous nip injuries. These do not cause me to worry. I worry about a chipmunk living in a tree.
Normal chipmunks live in elaborate burrow systems with large chambers for storing food and a nest chamber down below the frost line filled with leaves. How would Cheeky store enough food in a squirrel nest? Wouldn't she freeze to death if she entered torpor? What to do?
When Cheeky had filled the squirrel nest with seeds, she began stashing them in various places nearby. This change in behavior gave me some hope. Maybe she had not yet committed herself to arboreal life. While watching her, I decided to try to calculate how long it would take her to store a winter's worth of provisions. I was able to find several fascinating articles about chipmunk caching behavior. From these, I was able to glean that 2,500 grams of sunflower seeds would likely be sufficient to get Cheeky through the winter, and 4,000 grams would be ample. I set up a gram scale, measured out 10 grams of sunflower seeds, and invited Cheeky to load up. Over an hour, she made 12 trips to transport seeds. The cargo for each trip averaged 5.5 grams (about 100 black oil sunflower seeds). If Cheeky worked at this rate for 8 hours, she could store 528 grams per day and meet the 2,500-gram goal in just under 5 days. With 10 days of solid work, Cheeky might stow away 5,000 grams of sunflower seeds (11 pounds).
While I was busy weighing the seeds and timing her trips, I tried to figure out where she was going, a task she made challenging since she doesn't trust me not to steal her seeds. She would disappear around one side of the house and then the other, but finally, I caught her! She was shoving her fat cheeks into the tiny entrance of a new burrow! Just six inches away, I saw the portal to a chipmunk burrow that has been in use for years. The two tunnels must merge below the ground. Cheeky now owns prime real estate. To heck with my calculations, now I can pour sunflower seeds and acorns right into her doorway.
Yes, I admit, for a few weeks Cheeky caused me some anxiety, but soon she will be well-situated for a winter of comfort and ease, and my job will be done — in just two months. True, she won't take care of me in my dotage, but aren't you parents of humans a little bit jealous?
Patti Smith is a naturalist and wildlife rehabilitator at the Bonnyvale Environmental Education Center. The View from Heifer Hill, a feature on the nature of our region, appears in this space the first Saturday of each month. She welcomes your feedback at firstname.lastname@example.org.
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