Tuesday, August 4, 2009

Amazing Jays

For a guy like me who has trouble finding my car in the parking lot of a mall, jays are amazing. Each year the average jay collects and buries more than 4,500 acorns, each acorn in a different spot, every one buried in good soil to the correct depth, every one covered by leaves, twigs or pebbles to discourage scavengers from raiding their cache.

So how many of those acorns does the jay find? About 1 in 4. That's a pretty amazing feat of memory on the part of the jay. They are highly skilled at using landmarks to find their caches. But it's an even better deal for the oaks! That means that 3 out of every 4 acorns buried by jays are not found, and while a significant portion of those will be found and eaten by various animals or succumb to infection or rot a much larger portion will germinate and grow (at least until the deer browse them).

What's more, jays make better oak planters than most humans. They don't plant acorns in the deep shade of the woods (where they would never thrive), because they'd also be very difficult to find again. They plant them along forest edges where the jays have landmarks to find them, and the new oaks get full sun but also get some shelter from the wind. They don't plant in compacted or wet soils, because they would be difficult to bury properly. In short, they plant oaks in exactly the places where they have the best chance to thrive.

William Bryant Logan says, "the fact is that the jays are the world's great cultivators of oak and a principal tool in the oak's spread and dominance."

Co-evolution is pretty cool.

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