buffalo ecology

Sometimes I have been asked to identify plants that have poisoned horses and cattle. Were buffalo also susceptible to the same poisons as livestock? Did locoweed cause buffalo to hallucinate, wildly leaping over pebbles and shy at the passage of butterflies? Did shin oak’s new leaves constipate them enough to stunt their growth?

Did the young growth of cockleburs kill them in an hour? If they ate larkspur did they twitch, stagger, and wheeze? Did buffalo drool copiously if nightshade was ingested? Did groundsel cause them to walk non-stop until dead from exhaustion? Many plants accumulate nitrates, which becomes nitrite in the bloodstream of grazers, turning the blood brown, and stimulating the heart to race alarmingly. Did a buffalo’s heart do so?

Grazers have a problem. Grass is mostly cellulose, difficult to digest. Many grazers have microorganisms in the digestive tract that chemically split cellulose. Grasshoppers and caterpillars do not have bacterial digestion, so their feces is plentiful and bulky. Ungulates eat dirt as soon as they are weaned, thus acquiring the proper bacteria. Rodents and rabbits eat the maternal feces to become properly inoculated.

Grazers usually have similar mouthparts. Ungulates and rodents both have incisors (though differently shaped), then a diastema - an opening before the grinding molars. The diastema gives space for the tongue to move the food as needed.

Grazing is inefficient. Considerable amounts of food must be eaten. Bison (as well as cattle and deer) are ruminants, able to regurgitate their food for further mastication. When first swallowed the food goes to the first stomach, the rumen where cellulose digestion begins. After the cell walls of the grass begin to break down it is regurgitated to be chewed very thoroughly.

Large grazers are herd animals. Since so much time is needed for grazing and digestion, predators could easily catch lone grazers. Herd grazers develop social structure and sophisticated communication systems. For example, the pronghorn’s white rump hairs are lowered or raised, and the resulting white flash can be seen for a mile or more, instantly communicating to scattered grazing pronghorns that danger has arrived.

Buffalo ranged in clans, in extended matriarchal family groups. Sexually mature bulls ranged in their own small bunches. During the October mating season bulls claimed a group of cows and their young. Great fights would occur as the bulls fought for dominance. Losers stayed near, hoping to luck out and mate when the toughest bull was asleep or very tired.

The buffalo managed the grassland. Ungrazed or unburnt grass deteriorates, choking itself with litter. The litter gives a protective mulch for tall weeds. Their summertime six-foot bloomstalks shade the grass, further weakening it. Fire and grazing prevent this alteration of habitat.

Buffalo defeated hopeful mesquite seedlings advancing from their refuges. Mesquite has a weak crown, susceptible to fungus. Buffalo brushhogged the mesquite, stomping it, pulverizing the new growth, and allowing decay organisms to slow down the regeneration of the mesquite. Fungus and rot organisms are part of a healthy biotic community, flourishing easily in the microclimate of the grass sea’s floor. Prairie dogs, of course, did their part, nibbling germinating seeds.

Thousands of hooves broke the hardened soil, tilling grass and forb seeds to planting depth, the litter of old stalks provided subtle niches for the seedling’s nourishment. The ecological cycles of grass, forbs, and grazing have only recently been studied, with one result being the modern grazing practice known as Holistic Resource Management (HRM).

Two aerial phenomena could direct the daily travel of the buffalo. Smoke and clouds are semaphores of change. On the flat Llano the horizon is fifteen miles away, but a thunderstorm or the smoke from a prairie fire can be visible for a hundred miles and more. Grass greens within hours of a rainfall; water swelling plant cells designed to “disconnect,” go dormant without the injury of drought stress. Grass green rapidly after a fire. In a week bunchgrasses grow six inches.

Five million buffalo once ranged from the Concho River to the Pecos River to the Canadian River. Five hundred million or more prairie dogs also utilized that same range, as well as a million pronghorn. Summer heat urged a northward drift, winter’s blue northers sent each band and clan plodding south.