01 April 2021

In praise of oak trees

Oaks support more life-forms than any other North American tree genus, providing food, protection or both for birds to bears, as well as countless insects and spiders... With 90-plus North American species and about 435 worldwide, Quercus is the Northern Hemisphere’s largest tree genus, made up mostly of trees that are very large and very long-lived, two factors among several that help explain the oak’s power...

Oak trees support 897 caterpillar species in the United States. At Mr. Tallamy’s 10-acre property in southeastern Pennsylvania, he has recorded 511 — dwarfing the number supported by other native trees there... [but not many butterflies, AFAIK: Hairstreaks, Red-spotted Purples, and Duskywings.]

An oak can produce three million acorns in its lifetime — tons of protein, fat and carbohydrates — and a mature tree can drop as many as 700,000 leaves every year..  The resulting litter is habitat for beneficial organisms...

Oaks and jays evolved together about 60 million years ago, in what is now Southeast Asia. Jays grew so adapted to life alongside oaks that a small hook at the tip of their bill “is designed to rip open an acorn husk,” Mr. Tallamy writes.  The bird’s expanded esophagus (a gular pouch) can hold up to five acorns — each one buried in a different spot.
I didn't know about the mutualism of blue jays and oaks.  You learn something every day.


  1. Oaks are awesome trees, but I could do without their pollen coating everything in greenish dust and making me sneeze my eyes out ever year. Allergies are rough.

  2. You should watch the kids science show Wild Kratts on PBS. They had a whole episode on blue jays hiding acorns. My kids learned a surprising amount from that show.

  3. These too: https://en.wikipedia.org/wiki/Gall_wasp

  4. I cannot find the link, sadly, but I read that the trees in a savanna "communicate". They have evolved against predation of squirrels. They will produce vastly less acorns every 5 or 6 years to prevent squirrels from decimating future generations of trees. I had witnessed this at a local savanna located behind/around my local school. There were so many acorns that the ground crew collected them. I'd guess their September/October haul was 100 gallons or more. The year that followed, minimal. So much so they were not collected at all. I didn't realize what was happening until I read the article. I'm going to search further to see if I can find the article.

    This is some cool reading regarding the interconnectivity of trees and the research driving is. https://mothertreeproject.org/about-mother-trees/

  5. There is a marvelous Mark Twain story about a bluejay trying to fill a hole with acorns. "What Stumped the Bluejays".
    -Jean K.


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