Eating fruits & seeds

The main problem that confronts bears in their pursuit of fruits and seeds is getting them off the bushes or out of the tree tops either before other competitors get there or before the fruits decompose.  After finding a suitable patch, a bear may face more immediate problems such as gaining access to fruits and seeds elevated above the ground, removing seeds from some undigestible protective covering, gleaning fruits from out of a less digestible matrix of leaves and twigs, or simply the rate at which it can consume and digest readily accessible berries.  But ursids are as well equipped as any organism to deal with these difficulties and draw upon an acute sense of smell, relatively well-developed color vision, facile lips, paws, and tongue, and varied climbing capabilities to ingest sometimes phenomenal amounts, 10-45 kg, of energy-rich fruits and seeds in a given day.


The simplest foraging scenario for a bear eating fruits is probably the removal of berries from ground-hugging or nose-level bushes.  In this case the bear often tries to maximize the number of berries ingested relative to leaves and twigs.  This endeavor is obviously limited by energetic considerations and, at some point, it is not worth the extra time and effort to be picky.  However, this break-even point clearly varies among individual bears (depending upon their skills and tolerances) and with the abundance and type of berry being consumed.  Although it has not been clearly demonstrated, there are observations supporting the logical expectation that bears are more selective when sated or when foraging upon large abundant berries.  Observers have thus reported behavior ranging from the sloppy to the fastidious.  Some bears wrap their lips around a stem and indiscriminately strip off leaves, twigs, and berries.  Other bears daintily pluck berries out from among less desired portions by a combination of lip and tongue work, sometimes aided by manipulation of stems with their paws.  Accordingly, we find berry feces that sometimes contain nothing but the remains of fruits and others that contain mostly leaves.


Bears also consume a substantial number of tree fruits and seeds that have fallen to the ground, either by their own efforts (as described below), wind and natural dehiscence, or the efforts of competitors.  They detect such things as acorns and whitebark pine cones by sight and scent, and move along alternately nose to the ground and scanning the nearby forest floor.  They typically use their lips and tongue to pick up nuts from the ground litter, crush the shells in their mouth, and spit out the hull.  Acquisition of seeds from whitebark pine cones can be a little more complicated, but can be as simple as chewing and swallowing the cone, seeds and all.  At the other extreme, bears often break the cone bracts off with their claws or teeth, after bracing the cone with another paw, and facilely lick the seeds out of the debris with their tongue.  The opportunity to indulge in this more fastidious consumption of seeds seems to be greater when bears are raiding cone caches made by red squirrels compared to when they are scavenging sometimes rancid seeds from cones dispersed over the forest floor.  We accordingly see feces that consist wholly of crushed seeds when bears are using squirrel middens and messier feces containing lots of other cone remnants when bears are engaged in the energetically more costly pursuit of wind-thrown cones.


A number of berries are produced towards the top of tall bushes.  Mountain ash, elderberry, chokecherry, and hawthorn are good examples of this type of fruit that is potentially quite abundant but often beyond immediate reach of tongue and lips.  Bears resolve this problem quite simply by squatting or standing on their hind legs and pulling more flexible fruit-laden stems to within range of their mouth.  More robust stems may be subdued by either grabbing them with the paws and pulling on them until they break or walking along them from proximal to distal end until either the branch breaks or the fruit is reached.


Bears employ variations on this technique to get fruits and seeds out of trees.  There are many incentives to make a trip into the tree tops, including potential meals of sugar-rich cherries and fat-rich acorns and beechnuts that would otherwise have to wait until later in the year, or be sacrificed altogether to competing rodents and birds.  The option of arboreal foraging is largely denied to grizzly and brown bears, and is perhaps the price they pay for being able to live in austere northern habitats where digging and large body size are important to survival.  This not to say that grizzlies never climb trees, and, in fact, some closely-related European brown bears have been observed to forage for fruits or leaves in tree canopies in Norway, the Alps, and Afghanistan.  Nevertheless, tree foraging is the definitive domain of the smaller-bodied black bear, whether in North America or Asia.


Once in a tree, bears most often try to get the items of gastronomic interest down from the canopy by either breaking or chewing off branches or by simply shaking the fruit off.  They then descend to eat on the ground.  Under other ill-defined circumstances, bears will stay in the canopy to feed.  This type of foraging is characterized by the bear securing itself in a fork or on a broad branch near fruit-laden stems, and then consuming the fruits from branches that have been pulled inward with the paws.  Branches thus handled often break, and are then either dropped or accumulated in a pile beneath or near the bear.  This accumulation has often been described as a "bear nest," but has nothing to do with either rearing young or resting, and is simply an artifact of feeding.  In any case, bear foraging in trees is usually clearly betokened not only by claw marks on tree trunks, but also by broken limbs on the ground and dangling in the canopy.