Ingesta particle size, food handling and ingestion in the tammar wallaby (Macropus eugenii Desmarest)

The particle size distribution of stomach contents From 25 tammar wallabies (Macropus eugenii Desmarest) shot in the Okataina State Forest and adjoini ng farmland near Rotorua, New Zealand, were determined. There was a greater percentage of finer, and a smaller percentage of larger, particles than re ported in the stomach contents of larger macropods. The: chewing and biting activities of four free-ranging tammars fitted with radio-microphone colla rs were monitored. Chewing rates (chews per minute) were similar to those o f other small herbivorous vertebrates. There were significantly lower rates of chewing and higher chew-to-bite ratios when browsing than when grazing. Observations of browsing by three captive tammars showed inefficient handl ing by mutually opposed palms and digitopalmar grip, resulting in low rates of ingestion. We suggest that tammars lower the time necessary for ferment ation of food by reducing the size of food particles, and that their choice between graze and browse is influenced by food handling and chewing invest ment.