October, 1951, 8 scats. Hackberry in three, making up nearly all of them; grape in two (all of 1 and most of the other); wild plum in one (100%); mast (acorn?) in one, making up 100%; crayfish in one making up about half; fox squirrel in one making up the remainder of the scat containing crayfish; rabbit in one making up a small percentage.
November, 1951, 12 scats. Hackberry in five, making up all or most of four and a small part of the fifth; grape in five, making up all or most of four and a small part of the fifth; wild crabapple in three, making up all of two and most of the third; and cottontail in one, making up all of it.
January, 1952, 3 scats. Hackberry in all, making up all of two and most of the third; copperhead (scales of medium-sized adult) making up a fraction of the third scat. Pile of more than a dozen scats not individually separable, nearly all consisted mainly or entirely of hackberry fruits estimated at 2000; other contents chiefly crabapple and corn.
September, 1952, 8 scats. Grape in all, making up all of six and 90% of the seventh, and about 20% of the eighth; wild plum seeds in one making up 40%; blue feathers, evidently of a jay, in one, making up a trace; carabid beetles in one making up a trace.
October, 1952, about 14 scats, two separate (both consisting exclusively of grape) and the remainder mixed in two approximately equal piles, one pile consisting of grape, except for small quantity of fine fur; second pile consisting mainly of grape (about 90%) with small percentages of yellowjackets (Vespula, about 6 individuals, all in one scat), toe bones and fur of cottontail rabbit; a few scales of immature copperhead; and a snail.
November, 1952, 2 scats. Grape in both, making up all of one and about 90% of the other.
Sandidge (loc. cit.) found remains of cottontail rabbit in some of the stomachs he examined, but followed Reynolds (1945) in regarding these as carrion since the opossum was considered to be too inefficient a predator to catch and kill cottontails—prey approximating its own size and much superior in speed. Adult cottontails seem to be secure from opossum predation under ordinary circumstances. However, the opossum obtains some of its food by raiding the nests of small animals, including those of rabbits. At the Reservation, on May 21, 1951, at 9:00 P. M., distressed squealing of a rabbit was heard in high brome grass. Investigation revealed that a large male opossum had killed a young cottontail, weighing approximately 150 grams, and had started to eat it. This young rabbit, about the minimum size of young wandering outside the nest, evidently was pounced upon as it hid beneath the high grass.
Live-traps for mice, in lines or grids of 100 or more, often were set on the Reservation, and predators, including opossums, disturbed them on many occasions. Attacks sometimes resulted in release and escape of the trapped animal, and in other instances resulted in its being caught and eaten. In many instances identity of the predator could not be determined, but it is believed that such attacks by the opossum were relatively infrequent and inefficient. Steel traps set beside the mouse traps after consistent raids, to catch or discourage the predator, caught opossums on several occasions. These opossums usually had overturned mouse traps without opening them and when the trapped mouse was missing from the trap no evidence of its having been eaten was obtained. On other occasions raccoons were caught in the steel traps, and their raids were characterized by systematic and dextrous opening of the mouse traps and, frequently, by predation on the small mammals inside them.
Wire funnel traps set for reptiles along rock ledges also were often disturbed by predators, mainly skunks and opossums, both of which were caught on several occasions, when steel traps were used as a protective measure. The opossums often were attracted to the funnel traps by large insects such as camel crickets, grasshoppers and beetles, but also by trapped lizards including the skinks (Eumeces fasciatus and E. obsoletus) and the racerunner (Cnemidophorus sexlineatus). Both Sandidge (1953) and Reynolds (1945) recorded the five-lined skink (E. fasciatus) in opossum stomachs. On the Reservation this common lizard probably is one of the most frequent items of vertebrate prey of the opossum. Flat rocks a few inches in diameter frequently have been found flipped over; larger flat rocks and those solidly anchored in the ground often have been found partly undermined by opossums scratching away the loose dirt at their edges. Flat rocks similar to those found disturbed by opossums are the favorite resting places of the skinks, which, in cold or wet weather, are sluggish when beneath such shelters; this is especially true of female skinks that are nesting. The shape and size of some of the excavations suggested predation on skink nests. Other possible food sources in the same situation, in loose soil beneath flat rocks, include narrow-mouthed toads, lycosid spiders, beetles (mainly carabids such as Pasimachus and Brachinus) and occasionally, snails, centipedes and millipedes.
A pond, a little more than an acre in size, was a focal area for opossums and more were caught there than on any other part of the Reservation. Opossums that were trapped and marked on other parts of the Reservation were likely to be caught here sooner or later. Tracks in the mud showed that the edge was patrolled almost nightly by one or more opossums and this activity was especially noticeable when the pond was drying. Frogs were obviously the chief attraction inducing the opossums to forage there. Of the 8 kinds of frogs and toads breeding at the pond, the bullfrog (Rana catesbeiana), leopard frog (Rana pipiens) and cricket frog (Acris gryllus) were most abundant, throughout the season and especially when drying occurred. All three probably are important foods of the opossum locally.