Introduction

Acorns in High Park

Acorns in High Park

by Kathleen Keefe

Meet the little nut that powers High Park.

In a good year 10,000 acorns might fall from one tree! Each acorn is loaded with a little root and enough nutrients to sprout into a baby oak. Yet most acorns never become trees. Most become food for creatures in the park.

Acorns are absolutely perfect meals for squirrels, chipmunks, mice, blue jays and insects. Each acorn is a nutritious storehouse of protein, carbohydrates, fat, calcium, phosphorus, potassium and niacin. Squirrels can open and eat acorns in half the time it takes to eat other hard nuts and seeds. In winter, squirrels need to eat twice as much so acorns are their packable lifesavers.

Acorns. Photo: Karen Yukich

Why can’t we eat acorns?

They contain bitter noxious tannins. Native people who first lived on this land figured out ways to remove tannins from acorns. Acorns helped them to survive through long winters. Many animals can tolerate tannins better than humans can, but these animals also have ways to reduce the tannins.

A few kinds of oaks have been dropping acorns on this land for thousands of years:

Acorns hold the Future of High Park's Oaks

Luckily, acorn eaters don’t get all the acorns. A few acorns end up undiscovered or forgotten in natural areas with enough room, soil, sunlight and water to grow into oaks. Since the 1990s, park staff and volunteers have been improving natural conditions for acorn generation. As further insurance, healthy acorns are gathered in High Park every fall and planted in nurseries. A few hundred of these seedlings are then planted in the park where they have the best chance of surviving.

Oak Seedling. Photo: Janice Wilcox

These special acorn efforts are all being made so that one of Ontario's few remaining Black Oak Savannahs can continue to prosper right here in High Park.

 

Last modified: November 12, 2019

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Acorns in High Park

by Kathleen Keefe

Meet the little nut that powers High Park.

In a good year 10,000 acorns might fall from one tree! Each acorn is loaded with a little root and enough nutrients to sprout into a baby oak. Yet most acorns never become trees. Most become food for creatures in the park.

Acorns are absolutely perfect meals for squirrels, chipmunks, mice, blue jays and insects. Each acorn is a nutritious storehouse of protein, carbohydrates, fat, calcium, phosphorus, potassium and niacin. Squirrels can open and eat acorns in half the time it takes to eat other hard nuts and seeds. In winter, squirrels need to eat twice as much so acorns are their packable lifesavers.

Acorns. Photo: Karen Yukich

Why do squirrels eat some acorns on the spot but hide others for later?

When squirrels find the acorns of white oak trees, they usually eat them then and there for two reasons. First, white oak acorns are sweeter and contain fewer tannins. Second, unlike some other acorns, white oak acorns start to root as soon as they fall in October. Once sprouted, acorns lose half the nourishment available to an animal. So, white oak acorns are likely to be eaten as soon as possible.The acorns from red and black oaks contain a lot of tannins. When a squirrel finds these highly tannic acorns, it may nip off just the tops because they contain a very nutritious kernel with low tannins. The little root embryo is at the other end of the acorn. Squirrels bury about 60% of the acorns they collect from black and red oaks. Months of rain and snow then wash away the tannins. Using their incredible memory maps, squirrels return later to collect their “prepared” acorns. 

Grey Squirrel with acorn. Photo: Karen Yukich
Squirrels have a highly developed strategy for hiding and storing their acorns. In order to fool a thieving blue jay that might be watching, the squirrel may actually “fake” hide the acorn and then stash it somewhere else. Squirrels also dig up and move their acorns around to keep their competition guessing.

Why can’t we eat acorns?

They contain bitter noxious tannins. Native people who first lived on this land figured out ways to remove tannins from acorns. Acorns helped them to survive through long winters. Many animals can tolerate tannins better than humans can, but these animals also have ways to reduce the tannins.

A few kinds of oaks have been dropping acorns on this land for thousands of years:

Black Oak acorns. Photo: Ken Sproule White Oak acorns. Photo: Ontario.ca Red Oak acorns. Photo: Ken Sproule

Acorns hold the Future of High Park’s Oaks

Luckily, acorn eaters don’t get all the acorns. A few acorns end up undiscovered or forgotten in natural areas with enough room, soil, sunlight and water to grow into oaks. Since the 1990s, park staff and volunteers have been improving natural conditions for acorn generation. As further insurance, healthy acorns are gathered in High Park every fall and planted in nurseries. A few hundred of these seedlings are then planted in the park where they have the best chance of surviving.

Oak Seedling. Photo: Janice Wilcox

These special acorn efforts are all being made so that one of Ontario’s few remaining Black Oak Savannahs can continue to prosper right here in High Park.

 

A Mast Year for Oaks

by High Park Nature Some tree seeds such as acorns provide a good food source for many animals such as squirrels and blue jays. If the trees provided level acorn production every year, such animals would eat most of them and leave too few to germinate new trees. The trees get around this problem by producing few acorns for about four years and then a bumper crop (known as a “mast year”).There are not enough foragers to eat all the acorns in a bumper crop and the next year there are not enough acorns to support a large population of foragers.The mechanism by which all the trees within a region coordinate their mast years is poorly understood.


Last modified: November 12, 2019

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