Scientists surprised to find all but two of 12 grizzlies were dead within a year of \u2018feelgood\u2019 release, unable to sustain their high-calorie diet and inclined to approach humans<\/p>\n
The orphaned grizzly bear cubs were bulked up with a generous diet of roadkill, watermelon, dog food and snacks donated by the public. Their contact with carers was limited to two people. Then, after up to a year in rehabilitation, they returned home to the wilds of British Columbia.<\/p>\n
\u201cIt\u2019s a feelgood thing \u2013 people feel good when the cage opens,\u201d says Dr Lana M Ciarniello, a bear specialist who tracked the Canadian yearlings in a recent study. There is a perception that bears will thrive in their natural habitat, she says. \u201cThe reality is they\u2019re not followed up on.\u201d<\/p>\n
When Ciarniello studied their fate, she was surprised by her bleak findings. All but two of 12 bears that could be monitored died within a year. Most were killed before their first winter hibernation. The young bears may have unintentionally been set up for failure, she concluded.<\/p>\n
Beefed up so much they were 3.5 times the size of typical wild-reared yearlings, they were apparently burdened by their outsize frames and unable to meet their calorie needs after their release. Some bears also appeared to be unafraid of humans, with one female persistently approaching mine workers in search of food.<\/p>\n
Rescue and release projects often appeal strongly to the public, but the study warns that if such work produces bears that are ill-equipped to navigate the wild then it remains \u201ca form of sympathetic management\u201d rather than an effective conservation tool.<\/p>\n
Teaching a cub to forage and avoid dangers when they have had little or no maternal care \u2013 all while preventing them from growing used to human contact \u2013 is highly challenging.<\/p>\n
Bears have a culture that they learn from their mother over a period of two to three years, says Chris Servheen, co-chair of the International Union for Conservation of Nature\u2019s (IUCN) North American bears expert team. \u201cTheir mother teaches them what to eat and where to go to look for foods at different times of the year, what to avoid, what to be afraid of,\u201d he says.<\/p>\n
\u201cAn orphaned animal of any kind, people want to take care of them.\u201d The problem is, he says: \u201cWe humans are very inept at taking care of baby animals.\u201d<\/p>\n
Broad guidelines, which are shaped by research relating to American black bears, suggest that a larger body mass gives rehabilitated bears an advantage against predators. A target release weight of about 1.5 times that of a wild-reared bear is recommended.<\/p>\n
Ciarniello\u2019s study, which was funded by the Grizzly Bear Foundation, suggests going beyond this could be detrimental. In the bears she observed, which were 3.5 times the weight of wild-reared yearlings, a high calorie intake had increased all metrics: body length, chest girth and neck circumference.<\/p>\n
\u201cThey\u2019re not just fat little roly-poly things. It\u2019s skeletal. Once you\u2019ve got that big frame, now you have to maintain it,\u201d says Ciarniello. This led to what she terms a \u201cmetabolic trap\u201d.<\/p>\n
Two females, released in areas without salmon access, lost on average 0.48kg (1lb) a day. Even in areas with abundant food sources, the bears could not eat enough.<\/p>\n
Giving the bears a small buffer makes sense, says Ciarniello, who is also co-chair of the IUCN\u2019s human-bear conflict expert team. Too much could be counterproductive.<\/p>\n
Experts had previously hypothesised that cutting off contact for two weeks before release would undo familiarity bears have developed with humans. However, the bears continued to associate humans with food, even after much longer periods in the wild without contact. Siggi, a female, spent 59 days in a remote alpine zone before she encountered workers from a mine, whose food supplies she raided. Undeterred even by a noisy helicopter, Siggi was killed after the incident, one of five bears that died in human-wildlife conflict.<\/p>\n