Uromacer catesbyi and U. oxyrhynchus are diurnal, arboreal colubrids endemic to Hispaniola. Uromacer oxyrhynchus is an attenuate-snouted, slender ambush predator that is morphologically and behaviorally adapted to prey on active lizards (primarily Anolis, but also Ameiva), and it feeds exlusively on them. U. catesbyi is blunt-snouted and heavier-bodied than U. oxyrhynchus and exploits branches of wider diameter. The diet of U. catesbyi is composed of diurnally sedentary hylid frogs (ca. 96% by vol. and 71 % by frequency) and active lizards (Anolis). Trophic niche overlap between catesbyi and oxyrhynchus on Isla Saona is low (0.37). U. catesbyi was encountered with food in its stomach less frequently than U. oxyrhynchus (22.4% vs. 42.8%), but mean prey size (vol.) was 2.8 times larger for U. catesbyi.