Food Habits and Dietary Overlap among Six Stream Collector Species

Food habits were determined monthly over one year for six species of invertebrate collectors in a Colorado trout stream. Detritus formed the bulk of the diet for each species with an algal contribution that was usually < 10%. The vast majority of particles in the foreguts were < 75 μm in size and coincided with the most abundant size class of detritus in the stream. Dietary overlap as measured with Horn's Coefficient of Dietary Overlap was usually > 0.90 for type of food (algae vs. detritus) and particle size. This would indicate that no significant partitioning of food resources occurred among these six species of stream collectors.