Food of the Red-Backed Salamander

Abstract

T HE following account reports the stomach examination of 169 red-backed salamanders (Pletkodon cinereus Green) collected near Ithaca, New York, from October 2 until November 10, 1942. One hundred and forty-nine contained food while 20 were empty or nearly so. The collections were made at several stations, the majority of specimens being taken in mixed hardwood and pine-hemlock woodlands. Most of these were found under rotting logs and flat rocks. A large number were found under flat stones in dried up stream beds; perhaps the damper soil presents an easier path to the hibernating quarters, wherever this may be. The individuals were solitary, or were sometimes found in groups of 3 or 4. On November 10, one salamander was found, and none were seen thereafter. The salamanders were put immediately into 10% formalin, and examined later in the laboratory. At the same time, the writer made a collection of invertebrates from the habitat of the salamanders in hope that it would assist in the future determination of food items. Once identified, these items were compared with those taken from the salamanders' stomachs.The percentage by bulk of the food elements in each stomach was estimated as carefully as possible, and the results are analyzed in the Table. This paper will serve as a supplement to those of Surface (1913), Blanchard (1928), Smallwood (1928), and Hamilton (1932). Insects made up 73.2% of the total, and occurred in almost every stomach. The order Coleoptera was most important, both adults and larvae forming over 20% of the total stomach contents. Carabids, chrysomelids, staphylinids (Philonthus and Staphylinus), curculionids, and lampyrids were frequently encountered. Elaterids (Melanotus), alleculids, and cryptophagids were found sparingly. Diptera formed 10.5% of the total, and sometimes constituted the entire stomach contents of an individual. Tipulid larvae commonly occurred under rotting logs, and sometimes 6 or 8 form the last meal of a salamander. The larvae of a species of Bibio were often found under stones in large aggregations, and were much eaten by the salamanders. Hymenopterous remains formed slightly less than 10%, about half of which were ants (Lasius sp. and others). Hibernating wasps were frequently found under the same logs as were the salamanders, and the smaller species were sometimes eaten. Lygaeids and tingids (lacebugs) were the most common hemipterans, and the order made up 5.6% of the total. A number of lepidopterous larvae were eaten. Many of the leaf mining larvae listed as unidentified insects are undoubtedly of this order. One might well speculate as to how the salamanders obtained such food; sometimes bits of leaf remained with the insect, making certain their origin. Several red-backs had dined upon the wingless females of moths distended with brown, keg-shaped eggs; and not infrequently the eggs alone served to identify this insect. Thrips