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Den Cam Progress – UPDATE January 14, 2014

JulietMajor progress was made today on a technical issue with the den cams.  Both Holly’s cam and Juliet’s cam have been intermittent—severely testing the patience of viewers and Den Watchers.  Today, the Technical Team came up with a solution that seems to be working.  Fingers are crossed, but both video feeds look great so far.  With Juliet due to give birth within a week, we are grateful for dedicated technicians.

Juliet has been mostly sleeping soundly for the past couple days.  She's barely moved.  She woke and rearranged her bedding this afternoon but settled right back into a deep sleep.  We watch closely for changes in her breathing—looking for anything that might indicate the onset of labor.

Educators interesting in utilizing footage from Juliet’s Den Cam are encouraged to fill out the form at http://www.bearstudy.org/website/educator-signup.html.  We do not yet know what method we will be able to deliver the footage in, but having a list of interested educators will be helpful.

JulietWe had an inquiry from a graduate student who will be studying den emergence this spring.  She will use cameras to check when bears first emerge from the den in spring, how long they stay in the denning area, and the final departure date from the den.  She was worried that what she is defining as the first emergence date may not actually be when the bears begin leaving the den and becoming active.  She had not been aware of our Den Cams and asked if we have seen activity in the dens overwinter.  She wondered when they become active and if they are active in the den before they actually emerge.

We thought our answer might serve as a summary for new Lily Fans.  For old Lily Fans, it might stir some reminiscence.  Here’s what we wrote:

To our surprise, with Den Cams, we found that bears are far more active in their dens than we had ever thought by looking at them with us present or reading the literature based on the same kinds of observations.  They don’t do what they do when someone is standing there watching. 

What we thought was a time of energy conservation turned out to be a time of play, bonding behavior (mutual tongue-licking), removing foot pads, comfort suckling by yearlings daily, frequently rearranging bedding, licking icicles, eating snow, preparing dens for births, 20+ hours of labor, keen attentiveness to cubs and their cries, responding to mice and squirrels that share their dens, eating spiders that might winter in their fur, responding to large mammals that approach the dens, backing out of den entrances to urinate and defecate near the entrances (or off to the side of their beds in large dens), etc.  There are videos illustrating the above among the over 600 videos at http://www.youtube.com/user/bearstudy/videos.

In spring, mothers and cubs begin playing and resting in their den entrances or venturing outside.  In a year of early melt, a mother and yearlings left on March 24.  In a year of delayed melt, a mother and cubs left on April 23.  A mother with especially small cubs left in early May in one of our studies long ago.  If there are big refuge trees near a den, the first move might be to a big tree with the kind of rough strong bark that cubs can safely climb.  Mothers recognize these trees.  If such trees are farther from dens, bears will lead their cubs there when a crust develops on the snow or the snow melts.  We experimentally placed a deer carcass outside a den with a mother and newborn cubs many years ago.  She dragged it to the entrance of her den and partly inside and did not leave until the deer was consumed.  By then, there were just patches of snow.  When melting begins, they come out to lick water from puddles.  Earlier, they’d eat snow from the entrances of their dens. 

During winter, some bears in some regions emerge on warm days.  This behavior varies by region.  Denning behavior is genetically programmed according to the regional norms of food availability—even though black bears in different regions may be of the same subspecies.  In northern regions, emerging in winter would be counter-productive, and they don’t.  In places where food might be available, like in eastern deciduous forests, bears come out during mild periods and some stay out all winter digging down into the snow for beechnuts after an especially good fall crop.

It would be good to know the genetic origins of the captive bears you are studying.  Might they be from wild bears in your state?  If they come from an ancestry of captive bears, they could be a mix of genes from other captive facilities and/or from other areas.

We would love it if your graduate advisor applied for access to our Den Cams or highlight videos for his students at the Educator Signup Tab on the front page of bearstudy.org.    There is a lot of information on denning on bear.org.   We’ll be very interested in what you find.  We always want to compare notes, as we’ve begun here.  Best of luck and keep in touch.

And to Lily Fans, thank you for all you do.

—Lynn Rogers and Sue Mansfield, Biologists, Wildlife Research Institute and North American Bear Center

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