After Masting Aftermath

As I was composing the earlier masting story ("Masting Aftermath", posted 2-3 weeks ago) about our local oak trees, I read an article in the autumn 2012 issue of Living Bird magazine (from Cornell University), on a similar process that is unfolding in the western US. It’s another fascinating tale about the close relationship between animals and trees that periodically mast—this time in the higher elevations of Arizona and New Mexico. It’s a very intimate alliance that has been forged for millions of years between two species that even share the same name: the pinyon pine and the Pinyon Jay. (It’s an interesting byproduct of scientific custom that the bird’s name merits capital letters, while the tree must suffice with lower case letters.)

The symbiotic partnership between the bird and the tree has evolved over time, to the point that today, neither one of them can survive without the other. It is referred to by biologists as a mutualistic relationship—wherein each species derives benefit from their interdependence. The Pinyon Jay’s beak is long and sharp, having evolved specifically to extract seeds from pinyon pine cones. The seeds are very nutritious, but when not available, the birds nearly starve and their chicks—if they have any that year—will not survive.

As part of its bargain, the bird will plant the tree’s large seeds at distant locations, caching thousands of them during the years when the pines mast. The Pinyon Jay has evolved a special throat pouch, into which it can stuff over four dozen seeds! (And any one seed nearly fills its bill!) Monogamous mates will jam their pouch with the plentiful seeds and then fly off, wing-to-wing, and carefully cache the seeds, poking them into the ground. They specifically choose a location where no pinyon pines currently grow. (If that’s not a wonderful example of inherent intelligence, I don’t know what is!) Even though the bird’s memory is so good that researchers have determined it later retrieves some 95% of all its hidden seeds, a few do get forgotten, and some pinyon pines may later sprout in a new location.

This old partnership is in peril, however—threatening both the tree and the jay. Pinyon pine habitat is dramatically diminishing, as development, forest fires, and climate change take their toll on the trees. Recent dry years have fostered more fires; and those fires have worsened because of mistaken forest management in the west, that has discouraged forest fires in recent years and allowed an abundance of dry tinder to accumulate. Conservationists have monitored an alarming decrease in the population of both bird and tree.

The situation is aggravated by climate change—which is causing droughts and heat to worsen. The fates of the Pinyon Jay and the pinyon pine—inextricably linked to each other—is shaky. There is a ray of hope here, however. The mutualistic connection between bird and tree has existed for millennia, and as climate change occurred in past eras, the pines were moved to more favorable locations, thanks to the propensity for the Pinyon Jay to cache seeds in virgin territory.

Will the Pinyon Jay be smart enough (they are a corvid, like crows, and are very intelligent) to find favorable new habitat for the pine, as climate change increases? The future is very uncertain for these two intertwined species. It’s just one more example of the threat to many of nature’s species, as the globe warms and weather becomes increasingly chaotic.