R. M. Robinson

Social Behavior in a White-Tailed Deer Herd Containing Hypogonadal Males

During a 14-month period weekly observations were made of the social behavior of a deer herd containing 10% male deer suffering from hypogonadism. Social relationships were divided into two categories: those relationships affected by sexual activities of normal deer and those not so affected. Definite social hierarchy was evident on feeding grounds and was based on frequent aggressive-submissive interactions. Aggression was much more pronounced during the period of sexual activity which coincided with the period of maximum food shortage. Normal males used a sequential pattern of aggressive threats which included the “ear-drop,” the “hard look,” the “sidle,” the “head threat” and the “rush.” Females also used a sequential pattern of threat postures and action similar to that of males, except that a “strike” and “flailing” with the front feet replaced the threats with antlers employed by males. “Velvet-horns” or hypogona-dals were inferior in the “peck order” to all normal deer. Normal males, especially during rut, were more aggressive toward “velvet-horns” than toward any other deer. Normal deer used a sequential pattern of alarm behavior: “stamping” with the front feet, “snorting,” “whistling” and flight with erection of the tail. “Velvet-horns” did not employ any of these alarm actions but merely fled from danger.

PRONGHORN DIE-OFF IN TRANS-PECOS TEXAS'

Pronghorn antelope (Antilocapra americana) numbers on the Marfa Flat, comprising 75,000 acres in Presidio County, Texas, declined from 484 in June, 1964, to 148 in June, 1965. Nearly 60 percent (274) of the original number died from causes other than hunting. Pronghorns were confined on this area by net-wire fences. Three years of below-average rainfall combined with heavy stocking of cattle, horses, and pronghorns caused severe range depletion and forced pronghorns to rely almost entirely on browse species for sustenance. Only tarbush (Flourensia cernua), creosotebush (Larrea divaricata), and snakeweed (Amphiachyris dracunculoides) were readily available. Twelve pronghorns were observed to be utilizing a diet composed almost entirely of tarbush during the winter and spring period. Lesions characteristic of tarbush toxicity were found in 83 percent of the animals examined. Resorbing embryos were found in three of four females that had conceived. Malnutrition coupled with tarbush toxicity was considered to be the cause of the losses. Reproductive rates were reduced from 52 fawns per 100 does in June, 1964, to 17 fawns per 100 does in June, 1965. Pronghorns on ranches with a variety of more desirable browse species suffered only minor losses. Adjustment of stocking rates to forage available, construction of fences allowing pronghorn movement during periods of food shortage, and the possibility of limited, temporary supplemental feeding are management practices that might prevent the recurrence of such losses.

TECHNIQUES FOR COLLECTING BLOOD FROM COLLARED PECCARIES, DICOTYLES TAJACU (L.)

Four methods are described for obtaining blood samples from the collared peccary. This animal lacks prominent superficial veins which makes the procedure of taking blood difficult for inexperienced persons. Large volumes of blood (>20 ml) can be obtained easily via anterior vena cava venipuncture. Moderate amounts of blood (<20 ml) can be obtained from the orbital sinus. Lesser volumes of blood can be obtained from superficial veins located on the ear and the hind limb. The saphenous vein is distended easily due to its unique location across the cranial face of the tibia.

ANTLER MALFORMATION PRODUCED BY LEG INJURY IN WHITE-TAILED DEER1

Field observations of 36 white-tailed bucks with malformed antlers suggested a cause-effect relationship between rear leg injury and antler malformation. Experimental procedures involving six bucks indicated that contralateral antler malformation can be produced by amputation of a rear leg.

VACCINATION TRIALS IN DESERT BIGHORN SHEEP AGAINST BLUETONGUE VIRUS

Immunization of desert bighorn sheep (Ovis canadensis) against bluetongue virus was attempted by inoculation of live virus vaccine with a syringe and needle, by experimentally contaminated Culicoides gnats, the natural biological vectors, by bites of exposed Stomyxis calcitrans, which were considered to be natural mechanical vectors, and by incorporation of lyophilized vaccine in ground dry feed. Only the methods using the syringe and needle and the natural biological vector were effective.