Abstract
Simulation of seed passage through a bird's gut is an important tool for comparing the effect of bird digestion and thus the potential for plant dispersal by endozoochory. However, sufficient methodology is missing.
Thus, we subjected seeds of 20 plant species to seven different simulations of gut passage and to the real passage through a pigeon's gut to determine which simulation type best reflects the effects of real bird digestion. We also measured various seed traits to identify the traits responsible for differences between species.
Results show that four out of seven simulations were significant predictors of seed survival after gut passage. The fit between direct digestion by the pigeon and the different simulation treatments was, however, species-specific and depends not only on the commonly tested traits such as seed mass and water permeability, but also on other unmeasured traits.
Seed mass was the best predictor of differences between real digestion and simulation. Selecting one type of simulation to be a good predictor of seed survival after gut passage is difficult.
The strongest simulation (24-h scarification and 240-min acid immersion) is the best predictor and may be used to compare the ability of seeds to be dispersed by bird endozoochory. Such knowledge can be included in databases of species traits, as is currently done for many other species traits.