Yes, indeed, had you walked into the Yosemite Valley post office on Saturday morning, you would have found bear prints on the floor, caused (apparently) by the bear finding a not-empty cup of hot chocolate.

There have been various other sightings in the last few weeks in Yosemite Valley… at Curry Village, around a few different housing areas, and by Lower Yosemite Fall (where I recently had my first sighting of the year).  The Tuolumne Meadows winter rangers have seen two sets of bear tracks already.

Thus it begins!

Imagine eating as much food as you could, then taking a nap. When you awoke, you’d realize weeks had gone by! What to do? Eat as much as you can and fall back to sleep! Repeat until it’s nice and warm outside. This is what many hibernating animals do, and they do it in order to conserve energy. (Many hibernating animals are small, so they lose body heat much more quickly than larger animals… I could explain, but it involves exponents…)

Bears aren’t typically considered small animals, yet the hibernate. Or do they? This seems to be an everlasting debate, but the current consensus (if there even is one) is that bears do hibernate–just differently from other hibernators. Black bears can maintain their body heat in winter if they choose, but they have a hard time finding enough food to stay alive in most places where they live. Hibernation is their solution to the food shortage. By hibernating, they can make it through the winter with just their fat.

When bears hibernate, their body temperature cools just a bit and their respiration and heart rate slow a little. They don’t eat or drink at all during hibernation (they even develop a fecal plug!) Since bears don’t cache food (like most other hibernators), they eat as much as possible before hibernation–a state called hyperphagia (literally, in Greek: over-eating). During hyperphagia, bears may eat 10,000 to 20,000 calories per day (compared to around 4,000 per day at other times).

So far this year, it seems like all the bears in Yosemite Valley are hibernating. There has been only one sighting this winter. This isn’t always true, and it’s not uncommon for a bear to be active the whole winter if enough food is available. Last winter, several bears remained active–perhaps because there was a bumper crop of live oak acorns that persisted even until spring.

I wonder sometimes… what would it be like to be able to hibernate?

Some of you reading my last post surely picked up on the part where I said that yelling aggressively at a bear will cause it to leave “almost always.”

I’ve only not been able to scare a bear away once. There have been a few other times when I’ve had trouble scaring a bear away, but ultimately succeeded.

One late afternoon in 2000, I (with others) responded to a report of a bear near Upper Pines Campground. The bear, a large male I was quite familiar with at that point, hung out for a while near (but outside) the campground. So, we just kept an eye on him for a while. Eventually, the bear wandered some more and vanished. (Bears are surprisingly good at this.)

So, we all split up and went to various nearby places to see if we could find the bear again. I went to Lower Pines Campground and found the bear in the campground as he walked up to a locker and tried to open it, but it was latched, so he couldn’t. He went to the next locker, which wasn’t completely latched (see Smart Bear Tricks, part 3), and he opened it up and started dragging food out. When I tried to scare him away, he didn’t budge. When I tried harder, he got up from his meal and started walking toward me with what’s often called the “cowboy swagger.” At that point, early in my bear career, I hadn’t ever heard of this behavior, so I was unsure of what to do, other than back up. (We were within feet of each other.) While I had been bluff charged by this bear in previous encounter–to very close–this actually seemed scarier! So, he continued to eat, and I stood there helplessly watching… and waiting for the wildlife crew to show up.

Do you remember the first time you ever saw a bear in the wild? Were you scared? (If you’ve never seen a bear in the wild, would you be scared if you did?)

I was quite scared the first time I ever saw a bear, near the trailhead parking in Yosemite Valley. I’ve spent most of the 18 years since then working with bears in Yosemite and have now seen bears hundreds of times. These days, it takes a lot for a bear to scare me. I’m that comfortable around black bears (in Yosemite, at least).

Bears are the same way. They are born afraid of people. Nearly all of them, even in Yosemite, seem to remain deathly afraid of us, even when they’re big, dominant males. But, if they regularly spend time around people, they slowly get more comfortable around us–just like I got comfortable with bears by working with them so much. This is how bears get into trouble. Once they’re comfortable around people, our abundant, high-calorie food is all that more tempting (and obtainable) to them.

And this is why it’s critically important to scare black bears when they approach people or are in developed areas. (This is true in the national parks of the Sierra Nevada–it isn’t true everywhere, so always heed local instructions.) Bears learn quickly when people are afraid of them, and even more quickly when they get food out of the encounter.

So, how do you scare a bear away? Yell as loudly as possible at it (we usually say “go away bear!” or “get out of here, bear!”) Obviously, it doesn’t really matter what you say, but if you’re yelling something like that at a bear, you’re more likely to mean it. And this is the trick. You have to mean it! You could make all the noise in the world, but if the bear doesn’t think you mean it, it’ll probably ignore you. You can see an example of yelling without meaning it not working very well in this video.

Video by Zack/UTubeLightBulb via Youtube.

It turns out, in my experience, that bears like this one are very good at reading human body language. (I also wonder if, with their superb sense of smell, they can smell fear… or lack thereof.) Confident people yelling at a bear always results in the bear leaving more quickly than when un-confident people are yelling. I’ve frequently shown up at the scene of a bear in a campsite because I could hear lots of people making lots of noise with no effect, but then I, with my lone voice, scared the bear away in a second.

So, to scare a bear away, you want to yell, in your loudest possible voice, “GO AWAY BEAR!” and keep repeating it until the bear leaves. Use your voice aggressively and be mad at the bear, and mean it. Forget the car alarms, pots and pans, clapping, whistles, or whatever else. These don’t work. Yell at the bear like you’re the boss and you’re demanding it to leave, and it will (almost always).

PS: In Yosemite, we tell people not to chase bears because doing so without training can be dangerous. However, walking toward or running just a few steps toward a bear (while already yelling at it) can be helpful if you’re careful and are sure the bear has an escape route.

I saw an article like this one maybe a year ago and was intrigued by the concept that not thinking about a dilemma can lead to a better decision than obsessing over it. In fact, since I read that, I’ve let this process help me out with lots of little, unimportant decisions. It seems true: not thinking about a decision I have to make seems to work better than debating it constantly, whether the decision is big or little.


Why ‘Sleeping on It’ Helps

By John M. Grohol, PSYD,

posted: 26 October 2009 06:59 pm ET

We’re often told, “You should sleep on it” before you make an important decision. Why is that? How does “sleeping on it” help your decision-making process?

Conventional wisdom suggests that by “sleeping on it,” we clear our minds and relieve ourselves of the immediacy (and accompanying stress) of making a decision. Sleep also helps organize our memories, process the information of the day, and solve problems. Such wisdom also suggests that conscious deliberation helps decision making in general. But new research (Dijksterhuis et al., 2009) suggests something else might also be at work — our unconscious.

Previous research suggests that sometimes the more consciously we think about a decision, the worse the decision made. Sometimes what’s needed is a period of unconscious thought — equivalent to “sleeping on it” according to the researchers — in order to make better decisions.

Read the rest of the article…

Studies have shown that people exposed to constant noise are more stressed out. I’m not sure whether that’s true of animals (although I’m not sure why it wouldn’t be), but it does seem that even small amounts of noise might affect how animals interact.

the acoustic ecology institute

NPS study: moderate noise can have major impacts on animals

December 13, 2009

An ongoing research project from the National Park Service Natural Sounds Program is about to publish a groundbreaking paper that outlines the many ways that even moderate increases in human background noise can create major impacts on animals.  The study proposes a new metric for use in bioacoustics research, the “effective listening area.”  This is the area over which animals can communicate with each other, or hear other animals’ calls or movements; as might be expected, animals focus especially on listening for sounds at the very edges of audibility, so that even a small increase in background noise (from a road, wind farm, or regular passing of airplanes) can drown out sounds that need to be heard.  The authors note analyses of transportation noise impacts often assert that a 3dB increase in noise – a barely perceptual change – has “negligible” effects, whereas in fact this increased noise reduces the listening area of animals by 30%. A 10dB increase in background noise (likely within a few hundred meters of a road or wind farm, or as a private plane passes nearby) reduces listening area by 90%.

Read the rest of the article…

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.

My previous post about acorns reminded me of a bear, Green 52, who provides a good example of how far bears will go to get acorns.

Green 52 was a black-colored bear (fairly rare in the Sierra) who appeared one spring and was often seen grazing in the meadows. He caused frequent and long-lasting bear jams, which allowed him to slowly get habituated to people (as he got comfortable as people ventured closer and closer to him). Despite becoming habituated, he didn’t seem to get much (if any) human food. One day, he passed through Curry Village, and followed his nose to a tent cabin (illegally) containing quite a bit of food.

He was never quite the same.

We started seeing him more and more in campgrounds and other developed areas.  He even broke into the Village Store (a grocery store) via an open window. (Later in summer, apple trees have lots of apples in Yosemite Valley, so it’s somewhat amusing that the first food he went for once inside the grocery store was… apples. He later found his way to the pastries.) What goes through a bear’s mind when it finds itself inside a grocery store?

Black bear up a snag, eating acorns

Green 52 picking acorns out of the snag. (NPS photo by Kate McCurdy)

Even the most food-conditioned bears seek out their natural foods, and Green 52 was no exception. With the arrival of fall, he tried to eat as many acorns as possible, although he may have been a bit more ingenious doing this than other bears. One day, the wildlife crew found Green 52 up a snag near their office. It turns out that acorn woodpeckers had converted the snag into a granary (as they do to many snags in Yosemite Valley), where they had stored hundreds of acorns. Green 52 had climbed the tree and was painstakingly removing the acorns from each hole the woodpeckers had pecked and filled with an acorn.

It just goes to show you that bears will leave no stone unturned as they search for food, particularly in the fall, when they’re hyperphagic (very hungry, consuming 10,000 to 20,000 calories per day).

As for Green 52, I don’t remember all the details, but we relocated him north of Yosemite Valley. After that, he left the park and began getting into trouble in areas outside the park near Highway 108. As a result California Fish & Game trapped and killed him.

At this time of year, a black bear could eat 10,000 to 20,000 calories per day as it bulks up in preparation for its winter hibernation (during which time it won’t eat, drink, urinate, or defecate). The typical person eats about 2,000 calories per day. So, if you were to eat as much as a bear, you would need to eat breakfast, lunch, and dinner five to 10 times, each. Every day.


Black oak acorns. (Photo by Steve Ryan)

What kind of tree can feed a bear this much?

The black oak. And, at this time of year, it provides most calories bears in Yosemite are getting.  A bear eating only acorns would have to eat over 1,600 acorns every day!

Aside from feeding bears, black oaks also feed deer, acorn woodpeckers, squirrels, jays, and probably some others I’m forgetting. Before 1851, acorns were the staple of the diet of the people living in Yosemite Valley (and, I imagine, throughout much of California).

Why do people, bears, deer, birds, and squirrels rely so much on acorns? They are incredibly nutritious, being rich in fat, protein, and carbohydrates, and containing a wide variety of vitamins and minerals.

So, aside from entertaining us with its yellow leaves in fall and sheltering us with its shade in the summer, the black oak truly is the tree of life.

Like my friend and coworker, Tori Seher, I’ve noticed that bears seem to like minivans. Frequently, such perceptions are not true–but it turns out that this one is!

Tori and two other researchers decided to look at the data and they found some interesting things. Not only are minivans the most frequently broken-into vehicles, but they’re also disproportionally broken into. That is, they’re not most frequently broken into because they’re more common. During the two years when they were counting both vehicle types and incidents, minivans made up only 7 % of all vehicles, but 29% of all vehicle breakins. On the other hand, sedans made up 28% of all vehicles but only made up 14% of all breakins. My perception is that SUVs are frequently broken into, and, indeed, SUVs were the second most frequently broken-into vehicles (but that mostly reflects their popularity).

So, why are minivans so frequently broken into? I think it’s two things: they’re easy to get into (bears get into a lot of minivans by simply popping the window out–often causing little damage to the glass or the frame–as compared to other vehicles, in which they often have to bend the door frame down). The other thing is that minivans may be more likely to carry children, who are more likely to spill food and drinks–which would also attract bears. (These are two of the hypotheses put forth in the study.)

If you have a minivan, should you worry during your Yosemite visit? No–as long as you remove all your food, drinks, toiletries, trash, and any other scented items from your car. After all, only 9% of the minivans broken into definitely were food-free. (Bears aren’t perfect.) So, if your car is clean, there’s a slim chance a bear will break into it.

You can read the article in the Journal of Mammalogy.

White 60 exiting an SUV in front of me, July 2007. (NPS Photo by Tammy Evans)