Hiding from the Ghost of Herbivory Past: Evidence for Crypsis in an Insular Tree Species

Abstract

The color of many animals matches that of their preferred habitats, making them difficult for predators to locate. However, quantitative examples of crypsis in plants are comparatively rare. We conducted morphometric and spectrographic analyses of a heteroblastic tree species that is endemic to New Zealand (Elaeocarpus hookerianus Raoul) to test whether it is cryptic in appearance from the perspective of birds, who were once dominant browsers in New Zealand. The leaves of smaller, juvenile plants are highly variable in size and shape and are mottled brown in color from the perspective of birds, which would make them difficult for herbivorous birds to locate against a background of leaf litter. However, once plants grow to above 3 m in height, beyond the reach of the largest herbivorous bird known to inhabit New Zealand, plants suddenly produce leaves that are ordinary in size, shape, and color. Results provide quantitative support for the hypothesis that E. hookerianus is cryptically colored when within reach of flightless browsing birds.