Donna - March 21, 2012With Lily’s radio-collar now sending her location to our computers every 10 minutes, we can “see” what she is doing. Today her locations were clustered in and around a damp open area that may be a source of willow catkins. We’ll check for bear foods and bear sign there as soon as Lily and Faith move on. The area is a third of a mile from their den. Yesterday, they were a half mile from the den.
Donna and yearlings leave the den - March 23, 2012With Lily and yearling Faith out foraging, we wondered what Donna and her 3 yearlings were up to. It’s been a week since we visited them on the 20th. We found an empty den with Donna’s radio-collar in it. The trail cam at their den showed that Donna and all 3 yearlings came out and left on March 23 (NOTE: date time stamp on trail cam images is incorrect).
Donna's yearlings play - March 22, 2012In the days before that, the pictures showed the family out playing together at midnight as well as by day. Without a radio-collar, the family’s activities will be a mystery now until we can get a radio-collar back on Donna. We don’t plan on radio-collaring any of Donna’s yearlings.
Five of six mothers with yearlings have now left their dens—Lily, Jo, Donna, Braveheart, and Ursula. We hope to check on June soon to see what she and yearlings Aster and Aspen are doing, how far they are from their den, and if the den is flooded.
Jewel rakes bedding - March 27, 2012Meanwhile, Jewel is raking more bedding into her den. The cubs are still wobbly and tipping over when they walk, so they will likely remain in the den a little longer. Perhaps to make the remaining days as comfortable as possible, Jewel left the den 12 times today and returned several times with bedding. She brought in a big clump of running clubmoss (Lycopodium clavatum) that she bit into smaller pieces inside the den, a piece of log that she bit to shreds, and smaller pieces of wood which she also shredded.
Jewel breaks up club moss - March 27, 2012Video of Jewel and cubs from yesterday is posted at http://www.youtube.com/watch?v=naPu2KbF-sg.
You asked which bears we intend to have radio-collared this year. They include the 11 mature female clan members we have monitored for years—Dot (12), Donna (12), June (11), Braveheart (10), Colleen (8), Juliet (8), Cookie (7), Ursula (7), Lily (5), Jo (4), and Jewel (3)—plus the matriarch of the clan, Shadow, for a total of 12 mature females.
Donna plays with yearling - March 21. 2012One reason we are monitoring these mature females is to determine land tenure and territoriality in this study area where bears have access to supplemental food. The purpose is to compare the data with what we found in a previous study area without supplemental food (Rogers 1987 Effects of food supply and kinship on social behavior, movements, and population dynamics of black bears in northeastern Minnesota). A priority this year will be getting a radio-collar on the matriarch Shadow (25) to document where she fits in.
Donna's yearling pulls down a branch - March 21, 2012As new yearlings come into the population, we need to make choices about which ones to radio-collar to document how they work into the social system. For this, we must now concentrate mainly on June’s offspring. Our data on movement history and social relationships is most complete for this lineage. We plan to radio-collar Faith and June’s yearling female Aster (if she will let us). This would bring us to 14 radio-collars and give us one collar to hold in reserve for any special need that might arise. If we can collar Victoria we might temporarily collar her to help monitor family break-up.
Donna's yearling plays with branch - March 21, 2012One of the data sets we’re pulling together for a paper is ‘family break-up’—the behaviors that lead to mothers and yearlings that have played and nursed for more than a year splitting apart. At family breakup, mothers split from their yearlings and the yearlings usually split from each other. We are finding, as with everything we have studied, that there is great variability in how this happens. With this being the year of mothers with yearlings, we had planned to boost our sample size for this kind of data by temporarily radio-collaring a number of yearlings to monitor during May and June. The data would have increased our sample size for publication. As part of the variability, all members of a family may split at once, yearlings may leave separately, mothers may leave and travel far outside their territory leaving scent trails for males to follow, or a male may join the family and force the mother to choose between him and her terrified yearlings as in the BBC documentary Bearwalker.
One of Donna's yearlings - March 23, 2012To collar Faith, Aster, and the matriarch Shadow, we must remove radio-collars from the young females we have been studying. We already removed the radio-collar from 2-year-old Shirley— Sharon (2) and Star (3) are the next logical choices.
We’ll write more about research topics we are pursuing in future updates.
Your thoughtful heartfelt comments on last night's update are very much appreciated and the YouTube video by Madelene Ostrowski (http://www.youtube.com/watch?v=JHrQ4FNCvbU) brought back a flood of good memories.
Thank you for all you do.
—Lynn Rogers and Sue Mansfield, Biologists, Wildlife Research Institute and North American Bear Center