Beck on Artificially Feeding Bears

A Monologue on Colorado Division of Wildlife’s Policy to Not Feed Black Bears during environmentally stressful years.

By:  Tom Beck, CDOW Wildlife Researcher


During both 2000 and 2001, CDOW (Colorado Division of Wildlife) has received an unprecedented number of calls inquiring as to why we do not feed black bears during years of natural food failures.  Although we have clear direction via Commission regulation to not feed black bears, this explanation is seldom fulfilling.  Invariably the callers mention that CDOW does feed deer and elk in severe winter, in spirit of the regulatory prohibitions against feeding big gaming animals.  This document will discuss the practical and philosophical basis for the CDOW position of not feeding bears.

There are two different motivations of people proposing that we feed black bears.  One group is concerned for the population welfare of the bears while the other hopes that feeding will reduce or eliminate human-bear conflicts.  It is critical to understand the natural feeding patterns of Colorado black bears as one assesses the practicality of accomplishing either objective.

Black bears have a basic carnivore gut; it is characterized by having high pass-through rates and relatively low digestibility of plant parts.  Black bears compensate for this by eating large amounts and by being very selective of food items to maximize nutrient intake.  When feeding on grass or forbs, black bears select the newest growth to maximize digestibility.  Once forbs flower, bears will select the flowers over the leaves as they are both more nutritious and digestible.  Throughout much of North America and Colorado, this period of feeding on grass and forbs results in black bears continuing to lose weight during spring and summer.  However, in many southern Colorado black bear habitats, the abundance of forbs allows black bears to gain weight during this period.  The two primary causes of spring-summer food shortage for black bears are lack of moisture and early blooming of plants.  Lack of moisture is obvious in that succulent green plants dry up, thus becoming less digestible and lower in abundance.  A mild, early spring causes plants to grow, flower, and set seed earlier than normal.  Once seed set occurs, digestibility is very low for black bears.  Thus while forbs may still be abundant in volume, they are not digestible.

The most critical feeding period is late-summer or fall when berries and acorns ripen.  The daily activity of black bears changes and feeding is ongoing for up to 20 hours per day.  Nearly all of the nutrient intake is diverted into fat deposition.  Large fat deposits are necessary to provide energy during the long period of hibernation and to provide milk for newborn cubs.  The timing of this hyperphagic period is keyed to the ecology of local fruit-producing plants.  Again, black bears are seeking highly nutritious, highly digestible foods since their gut efficiencies are relatively low.  The amounts of food eaten can by prodigious; 20 to 30 pounds of food intake per day.  When food is abundant, weight gains of three to five pounds per day are possible.  This amounts to a lot of berries; 20,000 to 30,000 per day (chokecherries average 1,070 berries per pound).  Black bears will make long seasonal migrations (20 to 30 miles) to obtain fall foods as the areas with abundant berries and acorns are often spatially and/or elevationally separate from the spring-summer feeding areas.


Food failure impacts to black bear population welfare:

Black bears have evolved with periodic food failures.  They are relatively immune to annual changes because of their long lives (20 to 25 years), delayed maturity (four to six years), high adult survival of females (greater than 90%), and infrequent litters (only 40% of adult females give birth each year).  Short-term consequences of food failures primarily effect cubs and yearlings.  Cubs born in years of large fall food failures will suffer higher-than-average mortality during the denning period or soon after den emergence in the spring.  Yearlings which survive poor food years may delay onset of reproductive behavior until they are older and larger.   Population modeling suggest that massive food failures at a frequency of one per decade would have no measurable effect on a black bear population.  Adult females that lose a litter or reabsorb blastocysts prior to implantation just cycle back into having offspring the next year.  With a 40% pregnancy rate of adult female black bears, one expects each adult female to have four litters over a ten-year period.  A one-year delay may change the timing of litters but will have little impact on her lifetime productivity.

Black bear populations are quite resilient to infrequent massive food failures.  While food conditions for black bears have received much attention the past two years, it does not appear that massive food failures sufficient to alter births and young bear survival occur much more frequently than one to two per decade.  Should such failures occur more frequently in a localized area, the kill of black bears by hunters should be closely monitored to look for an increase of adult females in the hunter kill.  Such an increase would warrant a more conservative hunting objective.

Even if the welfare of a local black bear population is not threatened, some people will advocate supplemental feeding to increase survival of cubs and yearlings simply from humanitarian concerns.  While it is easy to believe that such concerns result from a naive view of the natural world, it does not change the conviction of those concerns.  Practically it would be most difficult to target a feeding program to reach cubs and yearlings.  Any supplemental feeding program will eventually attract a large portion of the resident bears.  Such aggregations can be risky places for young bears because of intraspecific aggression.  Often adult female black bears are reluctant to bring cubs into such areas and when they do often the cubs are sent up trees for protection.  This would allow the mother to feed but not the cubs.  Most of the food would be consumed by larger bears; thus you would have to feed a large amount to get to the few individuals that you wanted to help.  The short-term gain, if any, would be negated by the long-term problem of habituation.  Cubs and yearlings are easy to habituate.  Habituations will be discussed in more detail in the following section.


Food failure impacts to human-bear conflicts:

Black bears are naturally wary of humans.  Black bears are driven to find nutritious, highly digestible food in large quantities.  High quality food is nearly always available around human habitations.  In normal food years, the wariness of bears keeps most of the bears foraging away from habitations.  Those bears less wary, or those which have habituated to human presence, will still forage around houses and camps even in good food years as the benefit in terms of food is excellent.  However, in food failure years, wariness of humans too often loses out to the need for digestible food in large quantities.  In these situations, the number of human-bear conflicts escalates dramatically as does the amount of property damage inflicted by black bears.  Interestingly, injuries to humans by bears does not escalate during years of natural food failures.  Injuries to humans by black bears seems to be most strongly associated with food-conditioned black bears.  The CDOW policy formulated in 1994 seeks to eliminate access to human and livestock foods as the first line of defense.  This policy must be consistent in all years since once a black bear learns of a food source, they rarely forget it and successful feeding around habitations leads to habituation.

Critics of this policy often advocate supplemental feeding of black bears in areas distant from human habitation in hopes of keeping bears “away from conflicts.”  Such an approach, in my opinion, is misguided and harmful to both bears and humans.

Artificial feeding of bears will contribute to bears becoming less wary of humans.  In a review of bear populations throughout Europe, researchers concluded that access to human-derived food was the principal factor in loss of wariness among brown bears.  The presence or absence of hunting was not a factor.  North American experience in national parks and open garbage dumps provide ample evidence that black bears can be attracted to artificial food sources.  Such unnatural scenes resulted in changes in bear behaviors and a lessening of respect for bears by humans.

In addition, there is a large program of organized supplemental feeding of black bears on industrial forest lands in western Washington.  The goal of that program is to minimize black bear feeding on tree cambium in the spring, which kills the tree.  Coniferous forests in this area have little forb or grass under-story so spring bear food is quite limited.  The program is most successful at reducing tree deaths in local areas suffering high damage from a low density bear population.  As damage becomes more dispersed or the bear population density increases, the effectiveness of the supplemental food program declines.  Even though the supplemental food is provided ad libitum, all black bears studied also foraged away from the feeders.  Not all bears used the feeders and the amount of time spent at feeders was quite variable.

Would an artificial feeding program reduce bear-human conflicts?  Would such a program make conflicts more common?  Definitive answers are lacking, but I have some reasoned thoughts.  First, any feeding program will lead to a lessening of wariness of black bears to humans.  The bears know these concentrated feed sites are not natural and they will know that humans bring the food.  They trade off wariness for energy.  The more times this happens without a bad event happening to the bear, the less a bear will be concerned with the presence or actions of a human.  You just made a habituated bear and now you have a behavior problem for life.

Second, such feeding sites will only attract black bears if placed into natural habitats where the bear has learned to travel. Thus, in mid-August, black bears in southern Colorado move to low elevation regions where Gambel oak, chokecherries, serviceberry, and pinon pine are dominant.  Placing food at high elevation sites will not keep bears from making this move.  They make these moves each year even when food is still abundant on summer areas.  So the feeding sites have to be mixed in with the natural habitats.  These lower elevation sites are also where the bear-human conflicts have been occurring, as black bears will still attempt normal foraging even if abundant food is provided.  This also has its roots in the natural behaviors of black bears.  In wild situations, black bears will feed until their stomach is full, then wander in search of new feeding areas.  The fast passage of food through the carnivore gut means the bear will be looking for food often.  Bears do not stay at a single berry or acorn site until all the food is exhausted.  They fill up, move on, perhaps come back.  Thus many bears use each site and the bears are constantly mobile.  Such mobile bears will still contact human habitations and while their hunger may be less than without the artificial food, so also has their wariness lessened.

Currently we try to manage bear-human conflicts to keep conflicts tolerable in the average year, knowing that the fall food failure years will be very stressful for both bears and people.  Perhaps artificial feeding might reduce the number of conflicts in the bad years.  However, I strongly believe that the habituation would lead to an increase in conflicts during the average years.  More importantly than the property damage levels is the safety of humans.  The evidence is very strong:  food-conditioned black bears are dangerous and prone to injure people. The long-term consequences greatly outweigh the short-term gains.

There are other problems with artificial feeding. Once you begin, you are stuck with it every year. Black bears will quickly make the feed stations part of their “habitat.” They will return the following year, and the year after. How realistic is it that we can find feeding sites distant from human activity? Black bears regularly forage for five to ten mile distances during a single day. How many places in fall bear habitat are that isolated? Feeding sites will cause locally high black bear densities. Human access to these areas would have to be carefully controlled. There would be a strong advocacy to allow humans access for viewing. This would further contribute to habituation. Feeding would have to continue throughout most of September, which is our fall bear hunting season. What are the ramifications of hunters, either knowingly or unknowingly, hunting at or near feeding sites? What would be CDOW liability should a backpacker unknowingly camp near such a feeding site and subsequently be injured? Not just the legal liability but the moral culpability. Once you establish an artificial feeding program, you must accept the consequences of altering the wild behavior of the bears. You will need large quantities of highly digestible foods high in fat and sugars. Spread of exotic weeds is a major and growing problem. In several locations, spread of weeds has been clearly related to foodstuffs used to bait bears for hunting. Any large scale feeding program would need an exotic plant control component.

Current CDOW policy is firmly rooted in the notion to Keep wild bears Wild. The last three decades have seen significant change in how the general public, hunters, and wildlife managers perceive black bears. These changes have come about, in no small part, because of the committed efforts of members of all three groups to elevate the status of black bears. Any action that results in the habituation of bears and the consequent reduction of wariness of humans is harmful in the long term. A bear with his head in a blue plastic food trough isn’t the same as a wild bear; such activities lead to a loss of respect for this remarkable animal.

Finally, a few thoughts on the deer and elk winter feeding policy may help inform the public. In contrast to black bear populations where food failures mostly impact only cubs and yearlings, severe winter conditions can cause large moralities across all age classes. Large losses of deer and elk herds has a serious financial implication to businesses and towns based on a hunting economy. Thus, while it may be ecologically poor policy to feed deer, it is sound economic and political policy. From the humanitarian perspective, starvation is a disruptive event to witness. Both elk and deer are highly visible species which have a propensity to winter near highways. Thus their demise to starvation is witnessed by many. It is hard to believe this is not a factor.