Roaring Fork Valley Phenology | August 12, 2013

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More Abundance!

Chokecherry, Prunus virginiana are beginning to ripen this week. This picture was taken August 10 on the Rio Grande trail near Aspen. The incredible flower display of late June has transformed into many sweet, yet often astringent (bitter/puckery) berries. Chokecherry attracts birds and mammals that eat the berries then pass the seeds through their digestive tract, depositing the seeds at new sites for germination. Viable seeds can be moved long distances this way.

During the next couple of weeks black bears will come down from the surrounding high country looking for ripe berries on chokecherry and serviceberry, and acorns on oaks. This signals the beginning of  “hyperphagia,” which is a period when bears eat excessively in order to put on huge fat reserves required for hibernation. Bears may consume 20 to 30 pounds of berries per day during a good berry/acorn period according to expert Tom Beck, a long time researcher on black bears, in his monologue for Bear Smart Durango entitled “Beck on Artificially Feeding Bears.” During such times bears feed for 20 hours per day putting on 3 to 5 pounds consuming 20,000–30,000 berries.

~ Jim Kravitz, Director of Naturalist Programs