Fig. 3. Spectra used in data analyses of spectral discriminability. See text for a description of the model used for this analysis. (A) Irradiance spectra. D65 (standard daylight), D55 (direct sunlight) and D75 (`north' skylight), from Wyszecki and Stiles (1982). Green (light under the natural forest canopy in D. pumilio habitat, Pelican Key), from Summers et al. (2003). (B) Templates representing cone visual pigments of D. pumilio. (C) Spectral sensitivities of avian cones, taken from Parus caeruleus (generously provided by N. Hart). Thin lines indicate visual pigments, while thick lines represent spectral sensitivities computed taking cone oil droplet absorption into account, used for actual analyses. (D) Normalized absorptance of an avian double cone, including the contribution of the associated oil droplet, used in achromatic analyses (provided by N. Hart). UVS, ultraviolet sensitive; SWS, short-wavelength sensitive; MWS, medium-wavelength sensitive; LWS, long-wavelength sensitive.