We thought it would be a good idea to have a page for frequently asked questions about the CubCams with the bears we are monitoring this winter. We’re adding to this all the time, so please feel free to ask questions in the comments that are not answered here. Follow BEAR League and my FB account for the most current videos and updates.
Q: What are all these videos about?
This scene is common at Lake Tahoe, but rarely seen. These bears are denning under homes in the Lake Tahoe region. BEAR League has had cameras inside similar dens for the last three winters, but BEAR League does its best to encourage residents to bear proof their crawl space before the bears enter and claim it as their den. When cubs are born under a home or deck, they can’t be moved without risking the death of the cubs. We have been fortunate to work with understanding homeowners who have agreed to allow us to insert specially-designed, unobtrusive camera rigs under their homes to monitor the new families and ensure they remain safe until they leave in April. Once the camera is in place, we can monitor it remotely without having to keep removing the camera.
Please check out BEAR League’s public service announcement video “Bears Underfoot” on YouTube.
Q: How old are the cubs?
A: Like nearly all California black bear cubs, they were born in mid-January.
Q: What are they nesting in?
A: In many cases, it’s insulation, but not always the fiberglass kind. For those bears who are nesting in fiberglass insulation, we have observed that it doesn’t bother the bears much other than some itchiness. Many bears drag in pine needles to create nests, though.
Q: Isn’t it dangerous for the bears to be near gas/electrical lines?
A: It’s not optimal, of course, but California has strict building standards for gas infrastructure to survive seismic activity. The bear cubs typically don’t weigh more than about five pounds by the time they leave the den, so they’re not going to affect the gas lines. Mom might be a different story, though, which is why we always encourage people to secure their crawlspaces before winter. In rare cases, homeowners have had to shut off their gas service, but many of the homes shown in our project are second homes without full-time residents. With electrical lines, we’ll sometimes work with the homeowner to isolate the specific wiring and shut it off.
Q: Can the homeowner hear the bears?
A: Probably not. The microphone on the camera is sensitive and picks up sound that would be hard to hear further away. But in some cases, that is how the homeowner finds out about the new neighbors. Bear cubs can sound like human infants.
Q: Where are the cameras located?
A: Under houses in the Lake Tahoe region of California.
Q: Who put all the hay in the den for the bears?
A: It’s not hay, it’s pine needles. The bears will drag them in from outside to build a nest.
Q: Why do you blur the ear tags on the bears?
A: It’s to protect the bears. If the California Department of Fish and Wildlife sees the tag number, they can designate the bear a “conflict bear”, which never ends well for the bear or her cubs.
Q: Do the bears know the camera is there?
A: Yes, but the camera uses infrared light that is invisible to the bears. While it looks like the lights got left on, it is almost completely dark in the den. BEAR League uses custom-designed camera rigs to insert into the den with minimal disturbance of mom and cub.
Q: Why did you put an ear tag and collar on the bears?
A: We didn’t. The ear tags and GPS collars are placed by the California Department of Fish and Wildlife to identify and track the bears. We prefer the bears without all these unnatural attachments. The bears are also micro-chipped with PIT tags by the state, but the chips can only be read at very close range—within inches. These PIT tags also do not transmit signals, either by cellular or satellite, so they are not designed for tracking over distance. They are merely for identification. The GPS collars consist of two parts—the actual transmitter, which is on the top of the bear’s neck and sends signals to a satellite, and the battery compartment, which hangs beneath the bear’s neck. The size of the battery is the reason the bottom part is so large. The batteries can last for years, depending on the model of the collar. The GPS collars have a cotton connector that is supposed to disintegrate and drop the collar after a period of time, and some models can be remotely activated to fall off. But in our observation, the collars remain in place long after that time, sometimes cutting into the bear’s neck and causing an abscess and infection. See this image for an example—click on the image to enlarge. The ear tags are typically only for visual identification from relatively close distance. They do not typically have transmitters of any kind for remote tracking, although there are some solar-powered ear tags with cellular capability.
Q: Why is it snowing in the den?
A: That is just dust that reflects off the infrared light from the camera. It would be nearly invisible if it was light in the den.
Q: Why don’t you just build dens in the forest for bears?
A: Aside from the technical issues of construction on public lands or elsewhere, there’s no guarantee a bear would den in something purpose-built for the bear. Dens can be the hole created by fallen trees, under piles of rocks, or even caves, but they can also be unsecured crawlspaces and decks. Bears are opportunistic, and they will look for easy opportunities to create a den out of the wind and the snow wherever they can.
Q: How do you know which cubs are boys?
A: They roll over from time to time and shows us their boy parts.
Q: Why are some cubs different in color than their siblings?
A: They probably have different fathers. Like some other mammals like dogs, black bears are capable of superfecundation. Superfecundation is a reproductive phenomenon in which a single litter of cubs can be fathered by multiple males. This occurs because female black bears are induced ovulators with an extended estrus period lasting several weeks, during which they may mate with several different males. Since eggs can be fertilized by sperm from different partners across this window, the resulting cubs — though born in the same litter — can have different fathers and hence different coloring. Studies using genetic analysis have confirmed that mixed-paternity litters are relatively common in black bear populations.
Q: Do bears typically have more than one cub?
A: The number of cubs is dependent on a lot of factors, but a primary one is food availability during the fall and early winter. Bears have what is referred to as “delayed implantation” where the bears mate in the spring, but the embryo doesn’t implant in the uterine wall until fall, assuming the mother has stored up enough fat to last through the winter. The fetus will not develop if the mom has insufficient fat stores to survive through the winter and provide milk for the cubs when they are born in January or February. If a mom has eaten well during the fall and early winter, multiple cubs are a higher probability. We’ve seen instances of mother black bears having as many as five cubs, but that is rare. And the reality is, the smaller the litter, the more likely all the cubs will survive to adulthood, as feeding four or five cubs and keeping them all safe once they’re out of the den is a big challenge.
Q: Do the mother bears ever eat?
A: Not until they emerge from the den some time in April. They spent all fall and early winter fattening up to carry them through the winter.
Q: How do the mother bears go to the bathroom?
A: Mostly they don’t. Bears can recycle urine and feces internally during hibernation, but occasionally, they will move to a different part of the den off camera to urinate.
Q: Don’t hibernating bears just sleep all winter?
A: No! They’re in a reduced state of activity, but they move around quite a bit, and moms will leave the den from time to time to eat snow.
Q: Do mother bears return to the same den every year?
A: In our experience, no. Because we assist the homeowners in securing the crawlspaces after the moms leave, the odds of the mom returning to the same crawlspace is minimized. Even in the wild, though, based on our observations, bears tend not to re-use the same den site year after year. There may be bears that have done so, but we have not observed that in the Tahoe basin. BEAR League also works with homeowners to secure their crawlspaces after the bears leave to avoid another bear from taking up residence in a future year.
Q: Why do the cubs cry all the time?
A: They don’t. We are posting only a very small portion of the 24/7 footage we monitor. The vast majority of time, both mom and cubs are sound asleep. When they’re crying, it could be for a number of reasons: they’re hungry, they’re mad, or they’re expressing their opinions to mom. Other cubs we’ve observed are really quiet in comparison.
Q: How many teats does a mother bear have?
A: Six, in three pairs arranged along the abdomen. However, with litter sizes of 2–3 cubs, not all teats are used simultaneously. Cubs nurse frequently and grow rapidly on the mother’s milk, which has a very high fat content (around 20–25% fat) compared to many other mammals. Cubs typically nurse through their first summer. Weaning usually occurs around 6–8 months of age, though some nursing may persist longer.
Q: How do you get the cameras into the den if there’s already a bear in there?
A: For the safety of the bears, we do not discuss the actual mechanics of our camera placements. We have been around bears and have responded to bears under houses for many years, so we do not want non-trained members of the public attempting to replicate camera placements in bear dens. We custom build camera rigs for each den reported to us, and there are a number of factors we take into account when designing the camera rig. One important consideration is the bear. We have regular contact with bears all over the Tahoe region, and we are familiar with the behavior and temperament of many individual bears. Yes, they are wild animals, but they “speak” through their body language, something to which we are highly attuned from years of observing and responding to the bears we see on the bear calls we undertake. We work hard to minimize the impact of the camera placement to the homeowner, and more importantly, to the bears. As they say on TV, don’t try this at home.
Q: Is there a live feed of these cameras?
A: We have decided for a host of reasons not to host a live feed of the cameras, but we will continue to post clips. One reason is that we are guests on the homeowner’s internet connection with some of the cams, and we do not want to monopolize their bandwidth with streaming video. Another reason is that streaming video requires a dedicated computer and more expensive camera equipment. We generally try to keep the cost of our camera equipment to a minimum as we have lost multiple cameras to curious bears in the years we’ve been doing this project. If you’ve ever watched the Explore.org cameras in Katmai, those cams are extremely expensive to maintain on an ongoing basis, and those cameras are in a fixed location purpose-built for that use. In our case, we have to custom-build each camera rig based on the location of the bear’s nest, the availability of power and internet, and other issues. While theoretically we would love to install expensive, high-quality camera equipment to live stream, our first concern is the well-being of the bear, so we don’t want to disturb the bears with complicated equipment installations.
