Food Hoarding Behavior in the Short-tailed Shrew Blarina brevicauda

Abstract

Short-tailed shrews Blarina brevicauda cached most (86.6%) prey captured. Few were consumed immediately (9.4%) or left where killed (3.9%). Shrews most often ate the first prey captured but normally cached subsequent prey. The smallest prey offered, mealworms, was the only type of prey eaten more often than cached. Shrews returned to and consumed cached prey, including those cached by conspecifics. INTRODUCTION Storage of food for later consumption, commonly called caching or hoarding, is done by a wide variety of mammals and birds (Ewer, 1969; Lack, 1954). Two main categories of hoarding are distinguished: (1) larder hoarding is storage of food in a concentrated area of an animal's home range (Stapanian and Smith, 1978); (2) scatter hoarding is burying each object separately at dispersed sites in an animal's home range (Morris, 1962). Larder hoarding may have originated from the need of the animal to find a safe place to consume prey (Bindra, 1948; Morris, 1962) and is common in animals with protected burrows (Ewer, 1969). The tendency of laboratory rats to carry food to the nest to eat is increased by making the feeding place more exposed and decreased by making it more protected (Bindra, 1948). Scatter hoarding appears to have evolved in connection with an increase in mobility within the home range (Morris, 1962) or where loss of cached food to conspecifics or other species is prevalent (Shaffer, 1980). In scatter hoarding, individuals have food buried all around them and are less dependent on one large cache which may be endangered in some way. Size of food also may be an important factor initiating hoarding behavior; the larger a piece of food, the greater the chance there will be something left over after the animal has become satiated (Ewer, 1969). The purpose of this study was to examine experimentally the food caching behavior of the short-tailed shrew Blarina brevicauda. Blarina is a nonhibernating, nonmigratory insectivore which feeds as a carnivore (Brooks, 1908). Responses to prey of different size and type and to prey cached by conspecifics were tested. METHODS AND MATERIALS Ten short-tailed shrews were collected on the E. N. Huyck Preserve, Rensselaerville, Albany Co., New York. Nine were collected fromJune to August 1977 and one inJuly 1976. Shrews were housed individually in 10-gal. aquaria (507 mm x 260 mm x 320 mm) with commercial canned dog food and water available ad lib. Amphibian prey, Desmognathus ochrophaeus and Rana clamitans, were collected in Albany and Ulster counties, New York; the crickets and mealworms were obtained comercially. Test chambers were constructed of wood. The chambers used in Sets A-D and G-H were 1 x 1 x 0.23 m and painted with white enamel. Set refers to a series of identical experiments or trials conducted with individual shrews. A 30-mm horizontal overhang of aluminum flashing was attached to the rim of the chambers to prevent escape of shrews and prey. Chambers used in Sets E and F were 2.28 m2, 1.2 x 1.8 x .4 m and varnished. A 73-mm horizontal overhang of aluminum flashing was attached to these chambers. These chambers could be partitioned in half by a piece of wood. 1 Present address: Philadelphia Zoological Garden, Philadelphia, Pennsylvania 19104