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Credit & Copyright: Dr. Bruce G.
Explanation: Three trees. With the bark stripped. And cavities. Where are we? And who made these?
We are looking at what can be termed the results of functional vicariates -- that is, very similar ecological roles ("key ecological functions") played by very different animals in different ecosystems.
On the left is a Douglas-fir tree (Pseudotsuga menziesii) in a state park in Oregon, USA. The cavities and wood chip pile were made by a foraging Pileated Woodpecker (Dryocopus pileatus), the largest woodpecker of the region. Pileated Woodpeckers serve as a primary cavity excavator, creating tree hollows for feeding and nesting, in which many other species (secondary cavity users) can take residence. The bark and wood chip pile at the base of the tree is used by other species including clouded salamanders, snakes, lizards, and invertebrate prey.
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Bonus photo: another forest ecosystem, tree species, bark pile, and associated wildlife species! Here is a coast redwood (Sequoia sempervirens) in Prairie Creek Redwoods State Park in northern California. The bark and the wood beneath has been shredded probably by woodpeckers and other animals or naturally sloughed off. It has been gathered and piled here by a dusky-footed woodrat (Neotoma fuscipes) which is native to the area and which creates middens or nests of piles of wood and other material. Not just that, but many other animals use woodrat nests, such as kingsnakes.
So here is a remarkable linkage between tree, birds, rodents, snakes, and other species. This is not a food web; it is what I call a functional web.
Next week's picture: Hoverfly: Nature's Helicopter
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