NUTRIENT AND ENERGETIC CHARACTERISTICS OF SWEEPNET-COLLECTED INVERTEBRATES

As a result of the importance of food resources, primarily invertebrat e biomass, to the understanding of reproductive strategies of grasslan d birds, the nutrient and energy characteristics of invertebrate bioma ss were investigated during late spring and early summer. Sweepnets we re used to collect invertebrate biomass on two sites in eastern Kansas and the collections were separated into order or family groups. Nutri ent and energy characteristics of those taxonomic groups with sufficie nt biomass at the family or order level were measured, Fat contents of families ranged from 8% (dry mass) for Acrididae to 32% for Miridae. Crude protein ranged from 54% for a composite sample of Hemiptera to 7 7% for Araneida. Crude fiber ranged from 5-8% for Araneida to 17-18% f or Hemiptera. Calcium levels varied from 1292 ppm in Diptera to 2560 p pm in Lepidoptera, and phosphorous levels ranged from 5840 ppm in a co mposite Hemiptera sample to 9360 ppm in Pentatomidae. Gross energy con tents ranged front 4906 cal/g for a sample of Acrididae to 6452 cal/g for Cydnidae. Pooled invertebrate biomass collections from the two sit es differed in fat, crude fiber and energy content. Implications of th ese results on studies of the interactions of food resources, foraging behavior, habitat fragmentation and reproductive strategies of birds are discussed.