Corvid ecologists

Interesting news on corvid (crow, jay, raven, nutcracker) behavior and the forests they tend. Corvids could save forests from the effects of climate change
Crows, jays, and nutcrackers have co-evolved with trees for good reason.

quote:

---

A raven with a large seed, about to bury it in a field. (Callum Hoare)

​

To you, crows and jays might be noisy, obnoxious birds who eat garbage. But for large-seeded trees like pines, hickories, oaks, and chestnuts, they could be life-saving heroes. That's because these birds can actually relocate forests that are threatened by changing climates and habitat loss.

​

In a new paper published in ornithology journal The Condor, a group of US scientists describe how corvids' unique food-gathering strategies have transformed forests around the world. Now, environmental scientists are actively using the animals as part of their reforestation strategies.

​

Scatter-hoarding

​

Corvids, a family of birds that includes crows, ravens, jays, magpies, and nutcrackers, are called scatter-hoarders. They roam large territories to scavenge seeds, fruit, and even meat, storing as many morsels as possible to eat later. That's the "hoard" part. But they don't have one giant stash full of loot the way squirrels do. Instead, they hide each treat in a separate place, occasionally moving it around to prevent other animals from finding it. That's the "scatter" part. Corvids are incredibly intelligent, with excellent visual memory, and scrub jays can remember up to 200 different cache locations at any given time.

​

Over millennia of evolution, this arrangement has become mutually beneficial. Many large-seeded trees have co-evolved with corvids, developing seeds that contain lots of carbohydrates so the birds fill up faster. As a result, corvids are less likely to gobble up seeds on the spotthey'll be sated and may even fly tens of kilometers to hide the seeds.

​

Forest builders

​

Just look how many seeds this jackdaw has jammed into its beak. Pretty impressive. (John Haslam )

​

Corvid appetites have even helped to improve the fitness of pine and oak forests. The birds carefully select their seeds, often examining them visually and shaking them in their shells to determine whether they've been infested by fungus or arthropods. Though the birds are thinking only of what will be tastiest for them, the result is that the seeds that get scatter-hoarded tend to be the healthiest ones. Combine the corvids' pickiness with their predilection for flying great distances to hide their food, and you wind up with new patches of forest, planted by corvids, whose trees are both healthy and genetically diverse. Even better, many corvids prefer to cache their seeds in recently burned or disturbed landscapes, which are the most in need of reforestation.

​

Corvids have unwittingly become a key part of a virtuous cycle. By planting seeds, they lay the groundwork for entire ecosystems. Many plants thrive in the shade offered by trees like oaks and pines, and animals flock to the area as well. Finally, forest floors are excellent carbon sinks. Scatter-hoarding corvids are, in fact, guardians of the forestor, as the researchers put it, geoengineers.
Human and corvid geoengineers team up

​

Playful behavior could give clues about why they’re so smart.
In our era of climate change and agricultural expansion, trees are threatened by one basic fact. They can't move. If a habitat gets too wet or too hot, or humans decide to build a farm in the forest, the trees are doomed to die in place. That's why the scatter-hoarding corvid is so important to the life cycles of forests. Some corvids can carry dozens of seeds at a time, up to 50 kilometers away from their sources. Given that the trees and birds prefer the same kind of habitats, scientists believe that corvids might slowly bring forests with them to the right kinds of habitats as the old ones become inhospitable over time.

---

So once we understand this behavior we can work with it, provide seeds and let the corvids plant them, saving on labor and benefiting the existing ecological process.This gives me hope that some of the impending doom of global climate change can be ameliorated.Enjoy

And that's why I have 3 types of feeders, the tall cylinders with small perches that suit the little birds, purple finches, chickadees, goldfinches and the like, plus flat open feeders for birds like bluejays, cardinals and morning doves, and then suet for nuthatches, sapsuckers and woodpeckers.The "problem" birds I have are (1) starlings that mob the other birds and try to empty all my feeders in a day, and (2) european house "sparrows" (actually weaver finches) that overwhelm the feeders and drive the shyer birds away, again with large numbers in their flocks. Both these birds are not native introduced species that have spread across the continent. They also steal cavity nests from bluebirds and swifts and the like. Actually it is an evidence based hypothesis that has been and is currently being tested. Corvids are not the only vectors that the trees use, as squirrels and other animals also spread seeds. Bears that raid squirrel hoards also plant seeds along with a dose of fertilizer ...But the corvids take the seeds the furthest distance, and thus are a much larger vector for spreading the trees to new areas.This isn't some much an evolution issue, as it an ecological one -- the interaction of species in habitats and how the behavior of one affects the behavior of the others, and the balance of the whole ecology.So sit back and marvel at the quiet spread of forests by tireless workers while we argue about what needs to be done.Nature will survive global climate change, the question is what species will survive, which species will change, which will perish, and which one of them will we be.Enjoy

There are several types of stick-on window feeders: Put low on an upper window frame you can open the lower one to fill it, or two windows side by side work.A friend of mine has one with a stool inside for the cat ... Enjoy

Curiously, in my book (NatGeo Field Guide to Birds of N. America) American sparrow species are on pages 386-407 in the "Grosbeaks, Buntings and Sparrows" section, and none of them are Family Passidae, while the Eurasian Tree Sparrow (Passer montanus) and the European House Sparrow (Passer domesticus) are on page 432-433 under "weavers" between "weaver finches" and "finches" ... in the finch section of my book, with Tanagers and Orioles in between them: not closely related to American sparrows.Both of them are introduced species and thus are not native, and certainly not American sparrows.So I'll give you "weaver" as opposed to "weaver finches" (like the Java sparrow (Padda oryzivora), another introduced species).One need only look at the nesting behavior (communal nests all woven together) to see that they are distinctly different from American sparrows. They are invasive, opportunistic, and mob bullies chasing away other birds, and taking over cavity nests from other American birds (blue birds, tree swallow, etc). They are destructive and worm their way into small opening in houses.So I have little love for them.Enjoy

My book calls them all "sparrows" and there are lots of native families and geni, all different from the introduced european and eurasian ones that are in the Weaver Finch\Weaver\Finch section as opposed to the Grosbeak\Bunting\Sparrow section for all the "birds you call sparrows in America." With Blackbirds, Orioles and Tanagers between them.If this is muddled, it is so in my book "The National Geographic Field Guide to Birds of N. America" which I find difficult to accept.But this is all aside form the Corvid ecologist issue.

Or to true Scotsman ...So "sparrow" is just a general nomenclature for small seed eating birds and has no real taxonomic basis.Like "warbler" ... or "seagull" ...The point remains that they are not welcome at my feeders ... neither are starlings, another greedy pest introduced from England, because they chase off and displace native species.Enjoy

Exactly the behavior in the article that spreads forests into new areas.I've seen similar with Canadian/Gray Jays (Perisoreus canadensis) and Steller's Jay (Cyanocitta stelleri), the latter taking bits of cheese from my hand and burying them in sand.Enjoy