Of mice and bones

Bones are central to our survival: the skeleton of a vertebrate is what keeps it upright and supports it against gravity. But they are also essential for some animals in a more surprising way: when an animal dies, or a deer sheds its bony antlers, all that calcium and bone marrow is a tempting meal for creatures of a range of sizes, including the tiniest.

A field mouse is a very tiny thing, easily caught by any number of altogether larger creatures. This one was caught by a Mackinnon’s Fiscal Shrike in Kenya:

and this one was eaten, and its soft tissues digested, by a coyote (or fox) in Maine, leaving the skeleton substantially intact, including even the tail :

(It didn’t digest the fur either, and once time and rain have cleared away the residue, fur and bones are made visible.)

These tiny creatures eat small seeds, like these beech nuts:

and during the long winters in Maine they emerge from their impossibly small holes, risking life and limb, to forage:

An unlikely food source is a shed deer antler. In Maine bucks grow their bony antlers in March or April, and shed them the following winter. I found this one in October, by which time it had been eaten by squirrels, mice, chipmunks, raccoons, opossums, porcupines, foxes, bears, and even otters, for the 20% calcium, 10% phosphorus and mineral salts content.

The outside is compacted bone, very hard, but rodents have sharp teeth.

The size of the tooth marks is a clue to who has been eating the antler. In the picture above it was something small, squirrels or mice. If it has cracked right through to the inside, it is something bigger:

The interior is spongy bone, well supplied with blood vessels when the antlers were growing. For whatever reason, this doesn’t seem to get eaten much.

These ones (found on a different occasion, but also in the autumn) looked older, but they hadn’t been quite as thoroughly chewed:

So if you view the world through the eyes of a mouse, it has two reasons to be grateful to bones: for giving it the strength to stand and to run, and for nourishing it at the end of a hard winter.

PS Here is Robbie Burns 1785 poem “To a mouse”, a rare literary paean to this timorous beastie:

https://www.poetryfoundation.org/poems/43816/to-a-mouse-56d222ab36e33

And then course there is E.B.White’s masterpiece Stuart Little.

3 thoughts on “Of mice and bones”

  1. Yes, an observant nature lover you are, as I too love and worship nature. “The best laid plans of mice and men”! We got the book of that title and then the movie. All from this blessed poem? I love mice and rats. I am chided for this, and with much disapproval. I took videos of the little guys who live out by the fence and little shed. They used to come in so eagerly to eat from the dropped seeds from my casual bird feeder outside on the porch. I sent these videos to my sister who is friend of yours. It was so interesting to watch their behavior around feeding. I just loved to watch them so happily and freely eating bird seed. More and more of them came. Their beautiful little babies began to join in. This began to feel a little overwhelming as their numbers increased. I felt guilty when I thought about my neighbors and how they might disapprove. So I changed the bird feeding method and they seem to have mostly disappeared. At least I am no longer so blatantly feeding them. They still get some tid bits, so they were not completely cut off. Thank you for bringing attention to these precious and important creatures. After all we like them when scientist use them for so many purposes. We like them to feed our pet snakes and raptors with. All good but horrifying and cruel if they are fed while alive, or experimented with while alive. Then they make interesting small pets for our kids. What is right or wrong.? Not so black and white. I still love them. Thank you Moira.

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  2. I too like mice, and very occasionally I meet one in the woods, but they always disappear much too fast for me to get a photo, so sadly these pictures all feature either mouse traces, or dead mice.

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