I’ve recently encountered two bits of good news about Yosemite’s bears and what they eat.

In an article published in the November Ursus (not available online, as far as I can tell), researchers published their results from studying 500 bear scats in 2001-2002. Yes, they actually picked up as many bear scats as they could find, then picked them apart to see what food items they contained. They did this to determine what bears were eating. Another scientist did the same research in the late 1970s, when the National Park Service was just beginning to reduce human food availability.

Compared to the 1970s, Yosemite Valley’s bears are now eating far less human food (and apparently replacing it with greens)!

Bear scat

Bear scat containing mostly grass.

Item 1970s 2000s
Human food 21% 6%
Fruit and acorns 53% 51%
Roots, grasses, etc.
17% 29%
Animal matter 2% 3%
Debris 7% 10%

Another study that hasn’t been published yet finds basically the same thing by looking carbon isotopes in the hairs of bears through the decades. According to that study, and if I’ve understood it correctly, it seems that bears in Yosemite Valley are eating as little human food as they did in the earliest years of the 20th century–before the open dumps.

So, everyone’s work to improve food storage has really paid off in a big way.