wild andean bears


Andean Bears: A Surprising Discovery

A member of our collaborative field team watches a cliff for bear activity.

This summer my colleague Megan Owen and I were fortunate enough to have an intern working with us. Michael Forney was the John E. and Dorothy D. Helm Summer Fellow, working in our Applied Animal Ecology Division (see Summer Intern Enjoys Opportunities). He extracted behavioral data from videos of wild Andean, or spectacled, bears, living in the tropical dry forest of northwest Peru, where we work with the Spectacled Bear Conservation Society. Some of the videos were collected opportunistically by the field team, when they unexpectedly encountered a bear, and other videos were collected on a more systematic basis. There are more videos yet to review, but the preliminary results are pretty interesting.

These were the first behavioral data ever collected on wild Andean bears, and they delivered some surprises. For example, for most of the year the bears appear to lose weight, suggesting that there’s not enough food available. However, during the period of time when sapote fruit is available, the bears feed primarily on those fruits and appear to gain weight. We’d already seen this pattern, from different sources of data; however, Michael’s results suggest that dry forest Andean bears do not respond behaviorally to a feast and famine cycle like Northern Hemisphere bears would.

Sapote fruit: Does it dictate bear activity?

You may already know that American black bears and brown bears really focus on foraging during the period before they hibernate. Generally, these black and brown bears are driven to fatten up before the months when they won’t eat, so they spend as much time eating as possible. If Andean bears in the dry forest, which don’t hibernate but which do spend months with little food, behaved like these other bears, then you’d expect the bears in the videos to spend most of their time eating sapote fruit during the relatively brief period when it was available. However, Michael’s data show that adult females, with or without cubs, spend relatively little time eating, even when there appears to be a surplus of sapote fruit.

Why don’t these females spend more time feeding? We’ve generated a few hypotheses to address this question, but confirming this phenomenon and testing these hypotheses will require more data from more videos.

This is not just an abstract academic question, without relevance for the conservation of these bears. If weight gain among female Andean bears in the dry forest is constrained by sapote fruit availability, then perhaps an increase in the number of sapote trees would improve the body condition of the bears. However, if weight gain among these females is constrained by something else in addition to food availability, as might be suggested by Michael’s data, then increasing the number of sapote trees would not improve the bears’ body condition. Michael’s work reminds us that we have a lot to learn about Andean bears to further their conservation.

Unfortunately, we’ll have to pursue this question without Michael’s help, as he’s finished his internship with us and has gone south to put his talents to work in Ecuador. Thanks, Michael, and good luck!

Russ Van Horn is a scientist in the Applied Animal Ecology Division of the San Diego Zoo Institute for Conservation Research. Read his previous post, Peru: Conservation Science at Local Level.


Training Andean Bear Field Crew

Meg, at left, conducts a field training session.

I recently spent several days in the dry forest of Lambayeque in Peru working with our collaborator Robyn Appleton and her field crew from the Spectacled Bear Conservation Society and with Dr. Meg Sutherland-Smith, a veterinarian from the San Diego Zoo. Our goals were to reinforce and enhance the field crew’s training in bear immobilization and, with luck, to illustrate everything by immobilizing a female Andean (or spectacled) bear and placing a GPS collar on her. The field crew had recently discovered the den at which a female bear (Pepa) had given birth. This is the fourth den found at this field site, and only the fifth ever described of wild Andean bears (one den was recently discovered in the cloud forest of Ecuador).

Because the cub was still quite young and not able to walk very well or very far, the mother bear was not moving very much in the weeks just before we arrived. However, by the time we were all assembled in the field and ready to go, so were the mother and cub. The cub was able to walk well enough that the two bears moved through terrain that was too steep for a safe immobilization. Rather than risk injury to the bear or the field crew, we decided to wait for a better opportunity in the future. Maybe we’ll have better luck next time!

Heavy fog in the valley of the Río de la Leche separates the Archeological-Ecological Park of Batán Grande (foreground) from the Laquipampa Wildlife Refuge (background).

Although we did not deploy another GPS collar during our visit, we did conduct training, and we did see bears every day from our clifftop overlook. We watched the female bear Laura using different routes to walk to and from one of the few permanent waterholes and walk up incredibly steep cliffs to feed on large land snails. We also watched Pepa eat snails and cactus while her cub complained that they were walking too much and nap in the shade on beds of vegetation that Pepa pulled together.

From where we were camped it was only a few meters to a rock outcrop from which we could look over a valley and see farms and villages along the river below. I’m half-deaf, so I couldn’t hear the noises of the villages below: the music on Friday and Saturday nights and the chickens and donkeys in the mornings. I could see, though, that there’s a risk that human development spreading from the river valley will isolate one mountain range from another, turning them into isolated islands of habitat. I think our work in the new protected area (Archeological-Ecological Park of Batán Grande) will prevent this from happening. If we succeed at this, I won’t mind that we didn’t put a collar on Pepa.

Russ Van Horn is a senior researcher for the San Diego Zoo Institute for Conservation Research. Read his previous post, Notes from Observing Andean Bears.


Notes from Observing Andean Bears

This is the mountainside traversed by the bear and her cub.

I’ve just spent two weeks in northwest Peru, working in the field to study Andean (spectacled) bears with the Spectacled Bear Conservation Society and meeting with several people involved in conservation of the dry forest. As before, I’m impressed that the crew, the bears, and other large mammals in the area can cope with the terrain, the habitat, and the climate. It’s a very different experience than in the humid montane forests of Cusco. I can’t say which is more difficult to work in, because the challenges and constraints are just too different.

One big difference between the two sites is that in the dry forest it is possible, at times, to collect direct observations of the bears. I thought you might be interested in seeing my notes from the afternoon of September 9, 2010. My original notes, the raw data, were written in a type of systematic shorthand, but I’ll spare you the process of translation and tell you what happened, in every-day words.

The researchers' field camp, where the observations were taken.

Four of us (Robyn Appleton, Javier Vallejo, Isai Sanchez, and I) had hiked for several hours from one campsite up to another overlooking a waterhole. The plan was for us to spend the afternoon observing the area around the waterhole to ensure that there were no bears nearby that might be disturbed if we went to the waterhole. We wanted to change the batteries and memory card in a remote camera (i.e., “camera trap”) that had previously been deployed on a trail close to the waterhole. As we were setting up camp and beginning to prepare lunch, Javier spotted two dark specks moving along the cliff face about 1,300 feet (400 meters) away; there were bears to watch!

Here’s what we saw, according to my notes, written every five minutes while the bears were visible. The adult female bear was identified as Laura by her facial markings. Her cub, which is approximately one year old, has been named Martina.

1:35 p.m.: The adult female bear Laura is walking to the left, while her cub, Martina, follows 3 meters behind her.
1:40: Laura and Martina lie down in the shade of a rock outcrop.
1:40 to 3: The bears lie in the shade. We sit in the shade of a tarp.
3 p.m.: Laura walks uphill while Martina follows 1 meter behind her.
3:05: Laura continues to walk uphill, and Martina is now following 20 meters behind her mother.
3:10: Laura stands on her hind legs at the rock face, pulling down snails with her forepaws. We can’t tell exactly what Martina is doing, but she’s 4 meters lower down on the slope.
3:15: Laura is still standing on her hind legs feeding on snails, but Martina is no longer visible.
3:20: Laura walks to the left, while Martina is still not visible.

A cluster of white snails in the shade of an overhanging outcrop.

3:25: Laura has walked 65 meters to the left from where she was feeding on snails, and she has begun feeding on snails again. We can see Martina again, and she’s 10 meters below her mother. We still can’t tell what the cub is doing, but she’s not obviously interested in the snails.
3:30: Laura is walking to the left and uphill, following an obvious bear trail along the rock face. Martina is following her mother, 5 meters behind her.
3:32 p.m.: Laura and Martina follow the trail and go out of sight around the curve of the cliff. We do not see the bears again this day.

What can we learn from these types of notes? We can determine how often, for how long, and during what months adult bears feed on snails. We can document how cubs become less and less dependent on their mothers as they grow up by looking at the distance between the cub and her mother and how often the cubs nurse. We can document when bears are active, and when they sleep, and estimate how long they feed during each day. These, and many other aspects of bear behavior and ecology, can be addressed once we have enough observations of wild Andean bears in the dry forest of Lambayeque.

Russ Van Horn is a senior researcher for the San Diego Zoo Institute for Conservation Research. Read his previous post, Camera Trap Surprise.