Trapping, Restraining, and Marking Arctic Ground Squirrels for Behavioral Observations

Abstract

Methods of trapping, restraining, and marking Arctic ground squirrels (Citellus undulatus) in northwestern Alaska are compared and evaluated. Comparison of captures using large and small live traps placed alternately at the intersections of a 30-meter grid system revealed a significant difference between catches of adults and juveniles in large traps and between catches of juveniles in large and small traps. Adults were captured with equal success in both large and small traps as were adults and juveniles in small traps. Observations indicated, however, that juveniles were often too light in weight to trip the mechanism of the larger traps. Based on trap-days per capture, selective site trapping was two to three times as efficient as grid trapping. Trap sites with freshly exposed soil were visited more quickly and more often by ground squirrels than were undisturbed sites. A girth hitch sling fashioned from nylon parachute cord used for restraining the ground squirrels enables one person to handle and mark squirrels with accuracy. A numbering system for toe amputation is described which provides 899 numbers with the limitation of removing no more than one toe per foot. Nyanzol A and D fur dyes were judged the best of several tried. Our color-marking procedure permitted a high degree of accuracy in field identification of animals. Recognition of an individual animal, usually achieved by artificial markings, is prerequisite to accurate behavioral observation. The methods described here were developed to mark large numbers of Arctic ground squirrels for a field study in northwestern Alaska during the period 1962-64. Although these methods were used only 671 applied only to one population level and could not be used to compare data obtained from varying populations from different areas or different years. If it were necessary to conduct winter surveys as estimates of breeding populations, it might be better to conduct the surveys at night (Lord 1959:459). If this were done, however, wind would need to be considered a factor.