Jays and crows are conservationists for trees

By Joshua Rapp Learn

Mario Pesendorfer with a scrub jay. ©K. Langin

Crows and jays play a vital role in the conservation of some tree species, according to new research.

Birds in the corvidae family hide seeds in small caches across the landscape, effectively saving them for future meals. But the birds are a little too productive in this practice, called “scatter-hoarding,” and don’t always come back to eat every seed they’ve stashed for later, according to a recent review published in The Condor: Ornithological Applications.

The seeds benefit from this, eventually sprouting into trees in areas where the seeds wouldn’t have necessarily reached if it wasn’t for the birds.

Mario Pesendorfer, a researcher at the University of Nebraska-Lincoln and lead author of the review, looked at case studies from around the world to find ways in which corvids spread oak and pine seed species around.

He said that this corvid activity could provide an additional bolster for pine and oak species facing a variety of pressures.

“In light of the globally changing climate and increasing habitat fragmentation, these winged dispersers that transport seeds over long distances are likely to become more important, as they enable plant populations to shift their range,” Pesendorfer said.

Some specific examples the authors looked at include blue jays (Cyanocitta cristata), who help forests recover quickly after wildfires in the eastern United States, and Clark’s nutcrackers (Nucifraga columbiana) and Pinyon jays (Gymnorhinus cyanocephalus), who bolster ponderosa pine tree populations across long distances and maintain the trees’ genetic diversity.

“Since oaks and pines are important keystone species that themselves provide habitat for hundreds of animal species, such dispersal can have ecosystem-wide benefits,” Pesendorfer said.

Some conservationists believe that harnessing this bird activity could speed recovery of forests in some areas. Reintroducing extirpated western scrub jays (Aphelocoma californica) to the Channel Islands off the coast of California could accelerate the recovery of pines and oaks.

Joshua LearnJoshua Rapp Learn is a science writer at The Wildlife Society.

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