Nebraskaland

January-February 2024 • Nebraskaland 77 Horns Horns grow on completely different groups of animals: males, and females in some species, of bovids. The Bovidae family includes cows, sheep, goats, water buffalo, antelopes and gazelles. Unlike antlers that have the same basic shape, the appearance of horns varies widely from one animal to the next. How Do Horns Grow? Unlike antlers that branch out and shed, horns, also called ossicones, do neither of these. In many species, horns never stop growing throughout the life of the animal, which is useful as horns can become worn down over time. Normally, the only reason an animal loses its horns is if they are broken or cut off, and if this happens, horns cannot re-grow. The growth of horns is completely different than that of antlers. The cores begin as small, bony growths underneath the skin and over the skull in the subcutaneous connective tissue. Horns are not attached to the skull — they possess their own centers of ossification and fuse secondarily to the skull bones. In the Bovidae family, horns can grow singularly or as symmetrical pairs, such as those seen on bighorn sheep. Purpose of Horns Although the process of growth is different for horns and antlers, they are similar in function and use. Horns are often used by males to fight and display during the breeding season. These fights include clashes that will ultimately determine the overall strength of the animal and its right to breed. Unlike antlered species, the females of many species of bovids possess horns, especially among larger species. This is most likely due to the tendency of larger species to fight more often; smaller bovids typically prefer to run away and hide. Horns on males are usually thicker at the base and able to withstand more force. On females, they are normally straighter and thinner, which may make the horns better for stabbing for defense. In addition to fighting for dominance, territory or a mate, horns can be used for other functional purposes, such as digging in soil or stripping bark from trees. There is evidence of horns being used as cooling systems: Blood vessels in the bony core of the horn can let off heat to lower the animal's body temperature. Pronghorns, the Exception In the Sandhills and western Nebraska, you may find an animal known as the pronghorn. This animal is the only surviving species of the North American ungulate family: Antilocapridae. Not only are pronghorn a unique ruminant, they also carry unique headgear, which have characteristics of both horns and antlers. True antlers are made of bone and are shed each year, and true horns are made of compressed keratin that grows from a bony core and are never shed. Interestingly, the horns on a pronghorn are neither true horns nor true antlers. Instead, the sheath is made of keratin, yet the horns are shed yearly. True horns normally have only one point, but pronghorn have branched horns. Females also have horns, but they are much smaller than their male counterparts. Pronghorns are the only animals in the world that have forked horns that are shed each year. Male bighorn sheep will often crash into their opponents and fi ght to establish dominance and mark territories. JUSTIN HAAG, NEBRASKALAND Pronghorn have neither true horns, nor true antlers. Instead, they have a combination of both. Their horns are forked and are shed annually. JUSTIN HAAG, NEBRASKALAND

• Cover