FEEDING ECOLOGY OF THE CONCHO WATER-SNAKE, NERODIA-HARTERI-PAUCIMACULATA

The diet of the Concho water snake Nerodia harteri paucimaculata was i nvestigated from 1987 to 1990 by palpation of stomach contents. Prey r emains representing 304 prey items were recovered from 192 individual snakes. Concho water snakes were almost completely piscivorous, feedin g on 19 species of fish from nine families with minnows (Cyprinidae) d ominating numerically. Cricket frogs (Acris crepitans) represented the only non-piscine prey. Diet diversity increased ontogenetically accor ding to snake body size. Observations of foraging snakes suggest an on togenetic change in foraging sites concurrent with a change in diet co mposition. Prey size was positively correlated with snake body size al though some snakes occasionally ingested numerous small prey, possibly due to opportunistic feeding on small prey aggregations. Snakes occas ionally attempted to handle prey too large to be ingested. Feeding occ urred from mid-March to early November. Gravid females fed throughout the spring into mid-July and resumed feeding after parturition. Neonat e and juvenile riverine snakes ingested prey in proportion to apparent availability while adults consumed a disproportionate amount of large r prey species. Lacustrine snakes primarily consumed prey associated w ith benthic or shallow water habitats. However, few individuals of ope n water and top water species were ingested, suggesting that prey habi tat preference strongly influences catchability in lake systems.