Data collected and prepared by Beatriz Willink, Esteban Brenes-Mora, Heike Pröhl. Date of collection: 20110701-20111112. No missing data. Data includes measures of color and visual contrasts (as seen by a model bird viewer) for the dorsal and ventral skin of frogs. Contrasts were calculated against natural backgrounds and with the local irradiance (see METHODS). Calculations for color elements (Qt, Hue and Chroma) are given in Endler. 1993. Biol. J. Linn. Soc 41:315-352. Calculations for contrasts are given in Appendix 1 of Pröhl and Ostrowski. 2011. Evol Ecol 25:993-1015. Qt is the sum of reflected light across all 1 nm intervals between 400-700 nm. Chroma and Hue are objective color color space measures. Chroma is the Euclidean distance from the origin of color space to the reflectance spectra. Hue is the angle clockwise from the axis defined by the long-wavelentgh segment of the spectra (Red). Units for contrasts are jnd (just noticeable differences). In column headers, CC means Color (chromatic) contrast and BC is brightness (achromatic) contrast. TR refers to contrasts calculated against trunks (all types of tree bark), MR refers to contrasts calculated against rocks, usually covered with moss, GL indicates contrasts calculated against green leaves and LL indicates contrasts calculated against leaf-litter