By Wendy Langhans
Have you ever taken a bite of something and immediately spit it out? Anyone spending time with a toddler has observed this behavior (and probably cleaned up after it). From a human perspective, rejecting bitter-tasting foods is one way we protect ourselves from toxic chemicals. But plants see things from a different perspective; making themselves taste bitter is one way they protect themselves from being eaten.
Take acorns, for example. These little nuts are full of carbohydrates and fats; just the thing for a rapidly growning oak seedling.
Or just the thing for a hungry squirrel. Which is why acorns are also full of bitter-tasting tannins. Native Americans knew this; they leached the acorns in water before cooking with them. And today’s plant scientists recognize that tannins also have a a physiological effect – they hinder nutrient absorption.
So what about other acorn-eating creatures, such as tree squirrels. How do they cope with tannins? Well, to begin with, not all acorns have the same amount of tannin. Which means that not all acorns taste alike.
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The 20 native species of oaks in California can be sorted into three subgenera: white oaks, intermediate oaks and red oaks. Let’s look look at an example from the two major groups, white oaks and red oaks: Valley oak (Quercus lobata), and coast live oak (Quercus agrifolia).
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Sub-genera |
White oak |
Red oak |
Amount Tannin in Acorn |
low |
high |
Amount Fat in Acorn |
low |
high |
Acorns sprout |
usually right after they fall from the tree |
are dormant in winter and sprout in the spring |
Squirrel behavior |
85% eaten right away |
60% stored for eating later |
We see that choosy tree squirrels eat more of the better-tasting acorns from white oaks. And they’re lower in fat too!
But tree squirrels are choosy, even when eating acorns high in tannins. They ususally eat only the top half of the acorns from red oaks. That’s because the tannin is concentrated in the bottom half, closer to the acorn embryo.
It just goes to show that squirrels and toddlers are alike more alike that we think. After all, don’t toddlers eat the frosting on a cupcake first?
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Upcoming Outdoor Events:
Saturday, September 18, 8:00-10:00 AM. Morning Bird Hike at Towsley Canyon. Bring water and your binoculars and wear closed-toed shoes. Meet at the park entrance. 2 hours. For a map, click here.
Saturday, September 18, 10:00 AM – 3:00 PM. Reptile Festival at Placerita Canyon. For more information, go here.
Tuesday, September 21, 7:00–9:00 PM. Public Comment for the National Park Service’s “Rim of the Valley Corridor Study”. “The purpose of this special resource study is to determine whether any portion of the Rim of the Valley Corridor study area (the mountains encircling the San Fernando, La Crescenta, Santa Clarita, Simi and Conejo Valleys of Los Angeles and Ventura Counties) is eligible to be designated as a unit of the national park system or added to an existing national park unit.” For more information, go here. Meeting to be held at the George A. Caravalho Sports Complex Activities Center Building, 20880 Centre Point Parkway, Santa Clarita.
Thursday, September 23, 7:00-9:00 PM. Full Moon Adventure in Towsley Canyon. The canyon is a whole ‘nother world at night. Bring water and wear closed-toed shoes. Meet at the park entrance. 2 hours. For a map, click here.
Trail Maintenance Schedule. Come join our volunteers as they help maintain our trails. Contact Steve at machiamist@aol.com for time and place.
Wednesday mornings, September 1, 8, 15, 22, & 29.
Saturday mornings, September 11 & 25.
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You can listen to stories like this every Friday morning at 7:10 a.m. on “The Hike Report”, brought to you by your hometown radio station KHTS (AM1220) and by the Mountains Recreation and Conservation Authority.
For the complete MRCA hike and activity schedule and for trail maps, click here or go to www.LAMountains.com.