Corvids are efficient nut dispersers

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Rand
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Corvids are efficient nut dispersers

Post by Rand » Sat Feb 13, 2016 12:04 pm

Lawrence woods has a large amount of fallow farmland reverting back to forest. After ~ 15 years I've noticed a rather even scattering of pin oak throughout the old field and I wondered how they got there. Seemed a bit too energetic for squirrels. I think I have my answer:
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.

In Poland, for example, the researchers report that old agricultural fields were reforested with black walnuts over a short fifty-year time span. This boon was entirely because local rooks and crows preferred to plant their larders in the disturbed ground of fallow farmland. A similar kind of restoration happened on two islands in California’s Channel Islands National Park. For 150 years on those islands, oak and pine forests had been ravaged by imported, non-native livestock. But when the animals were taken back to the mainland in the 1980s, the local island jays managed to double the size of the oak and pine forests in just a few decades. Island jays can cache up to 6,000 seeds every year, and the whole ecosystem benefits from their hoarding ways.
http://arstechnica.com/science/2016/02/ ... te-change/


Here's a presentation where a guy tracks the dispersal of american chestnut into the surrounding forest from just 2-3 trees. It's a little long winded though.

https://www.youtube.com/watch?v=I1pp8uNZpFo

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Lucas
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Re: Corvids are efficient nut dispersers

Post by Lucas » Sat Feb 13, 2016 3:11 pm

https://www.sciencedaily.com/releases/2 ... 184109.htm

Jays and crows act as ecosystem engineers

Summary:
A forthcoming review explores how oaks and pines depend on corvids, the group of birds that includes ravens, crows, and jays, to reproduce and spread -- and how birds may be the key to helping these valuable trees weather the challenges of habitat fragmentation and climate change.
We travel the Milky way together, trees and men. - John Muir

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Don
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Re: Corvids are efficient nut dispersers

Post by Don » Sat Feb 13, 2016 8:14 pm

Lucas/Rand-
Your "Summary" put me in mind of the relationships between Whitebark pine, grizzly bears, and Clark's nutcrackers (significant research on the interdependency) and whether the Clark's Nutcracker is in the Corvid family...sure enough! Another one that comes to mind are at the North Rim, Grand Canyon...the Kaibab squirrel, the ponderosa pine and truffles have an interdependency as well, and it may have something to do with dispersal mechanisms too, although the vector here may be the Kaibab squirrel.
In all these interdependencies, it occurs to me that there is likely to be more to the picture...long unnoticed in the big ecosystem picture has been the role played soil biota, fungi in particular...for a casual look at what's going on, on the North Rim, take a peek at:
http://www.wild-facts.com/2012/wild-fac ... -squirrel/
-Don
Don Bertolette - President/Moderator, WNTS BBS
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Rand
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Re: Corvids are efficient nut dispersers

Post by Rand » Sat Feb 13, 2016 11:22 pm

Another insight on blue jays and chestnuts pointed out by a guy in the ACF. When chestnut burs ripen on the tree, the spines harden, the burs break into four petals, and then they fold back on themselves. This exposes the nuts to the air, but presents a wall of spines facing the opposite direction, making them difficult to access by a squirrel climbing along the twigs.

On the other hand, the nuts drop to the ground pretty easily once in this state, so I guess they better be quick.

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Lucas
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Re: Corvids are efficient nut dispersers

Post by Lucas » Sun Feb 14, 2016 1:26 pm

Don wrote:Lucas/Rand-
Your "Summary" put me in mind of the relationships between Whitebark pine, grizzly bears, and Clark's nutcrackers (significant research on the interdependency) and whether the Clark's Nutcracker is in the Corvid family...sure enough! Another one that comes to mind are at the North Rim, Grand Canyon...the Kaibab squirrel, the ponderosa pine and truffles have an interdependency as well, and it may have something to do with dispersal mechanisms too, although the vector here may be the Kaibab squirrel.
In all these interdependencies, it occurs to me that there is likely to be more to the picture...long unnoticed in the big ecosystem picture has been the role played soil biota, fungi in particular...for a casual look at what's going on, on the North Rim, take a peek at:
http://www.wild-facts.com/2012/wild-fac ... -squirrel/
-Don
http://www.amazon.com/Made-Each-Other-S ... W2YMYNW6EM

"The stars of this balletic study are the whitebark pine and Clark's "Crow""

Saw the above while looking at the reference to

http://www.amazon.com/The-Bristlecone-B ... 0878425381
We travel the Milky way together, trees and men. - John Muir

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Lucas
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Re: Corvids are efficient nut dispersers

Post by Lucas » Sat Feb 20, 2016 1:23 pm


Click on image to see its original size

http://www.amazon.com/Made-Each-Other-S ... W2YMYNW6EM

"The stars of this balletic study are the whitebark pine and Clark's "Crow""

I read this last night. Excellent intro to the subject.

I didn't know anything about pine nuts\stone pines and it cleared up a lot.

Bristlecone pines, among others, are planted by Clark's Nutcracker at high elevation.


see also
http://www.bioone.org/doi/pdf/10.1650/CONDOR-15-125.1
We travel the Milky way together, trees and men. - John Muir

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Lucas
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Re: Corvids are efficient nut dispersers

Post by Lucas » Sun Feb 21, 2016 11:01 am

http://arstechnica.com/science/2016/02/ ... te-change/


Here's a presentation where a guy tracks the dispersal of american chestnut into the surrounding forest from just 2-3 trees. It's a little long winded though.

https://www.youtube.com/watch?v=I1pp8uNZpFo
Notes of the Northeastern Naturalist, Issue 22/4, 2015
American Chestnut Caching by Red Squirrels
Bernd Heinrich*

Northeastern Naturalist 21(4):619-629. 2014
doi: http://dx.doi.org/10.1656/045.021.0409

American Chestnut Seed Dispersal and Regeneration
Bernd Heinrich*

Alternate versions of the long winded one.
We travel the Milky way together, trees and men. - John Muir

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