The last of the lineage of short-faced bears, the spectacled bear evolved as the sole bear species isolated in South America after the end of the last ice age.  Spectacled bears are medium-sized by bear standards, but they are the second-largest land mammals in South America.  Only the tapir is larger.  Its name refers to the light-colored markings surrounding the eyes.  One of its common names in Spanish means “bear with eyeglasses”; another means “the bromeliad eating bear”.

The evolutionary paths that this intriguing bear has followed to reach this niche are paralleled in complexity and variety by the actual trails across landscapes that its ancestors trod to reach their last stronghold in the Andes Mountains.  From early Tremarctine (short-faced) bears in eastern Asia about 15 million years ago, this trail led across the Bering Land Bridge to what is now Alaska.  These were the first bears to make this journey, and we must assume that conditions at that time were not greatly different than during the most recent ice ages of the Pleistocene (see the chapter on brown bears).  Massive ice sheets covered what is now Canada and blocked any travel routes south for several thousand years.  The vegetation was sparse and much of it was growing over permafrost.  Winters were very cold.

We assume that these early short-faced bears were adapted to the cold and were omnivorous like the bear-dogs they evolved from.  They survived in the harsh northern climate and eventually made their way south to a land covered in grasslands and deciduous forests and populated with large predatory cats, mammoths, camels, horses, and other mammal forms which have since disappeared.  For well over ten million years the short-faced bears radiated throughout North America.  Ice ages came and went with a cold period occurring about every 100,000 years.  No new bears migrated from the Old World during this time, but the short-faced bears evolved into several new species as they were able to exploit unique opportunities presented by changing conditions in the New World.  Just as the Ursid bears were able to adapt to warmer climates in tropical Asia where sloth bears and sun bears evolved, the Tremarctine bears were eventually able to adapt to tropical central America and exploit a more herbivorous niche.

Spectacled bears are omnivorous and feed on plants, small mammals, and even birds.  However, they are primarily herbivorous, their preferred foods are fruits and Bromeliads (family Bromeliaceae).  They eat the leaves, bases and hearts of Bromeliads, and spend much of their time in the treetops where they often will build nest platforms for feeding and sleeping.  Because their food grows on many branches that can not support their weight, they will sit and bend the branches inward to reach fruit and Bromeliads.  As the bent branches often break, they are wedged into place to build a rough nest.  Once a nest becomes large enough for sleeping, the bear will add layers of leaves, and may spend several days in the same nest. 

Spectacled bears can occupy a wide variety of habitats, but are most common presently in heavy forest, perhaps because of displacement and persecution by humans.  They are now confined to a narrow strip of habitat along the spine of the Andes; in fact only ten percent of occupied bear habitat in Venezuela is found outside the protection of National Parks.  They are difficult to observe; being largely nocturnal and arboreal in thick forest canopy, and therefore their status and distribution is uncertain in many areas.