The role of invertebrates in the diet, growth and survival of Northern bobwhite, Colinus virginianus, chicks in the Southeastern United States

Abstract

Invertebrates are the primary component in the diet of northern bobwhite, Colinus virginiamus, chicks during the first two weeks of life. Despite this, few studies have described the composition of invertebrates in the diet of wild chicks and none have examined their effects on chick-growth and survival. Here, a three-year study was conducted to examine the role of invertebrates in the diet of northern bobwhite chicks in the southeastern United States. Initially, laboratory feeding-trials were conducted to evaluate the use of faecal analysis for studying the invertebrate diet of northern bobwhite chicks. Then, by accounting for differential recovery of prey items, the diet of bobwhite broods on farmland and forested plantations in Florida and Georgia was determined by analysing g faeces collected from their nocturnal roost sites. These broods were also captured at 10-days old to provide data on chick-growth and survival. Invertebrate-selection by bobwhi was studied by comparing the composition of invertebrates in the diet of chicks to that found in broodrearing habitats. In addition, the invertebrate-selection of human-imprinted chicks in the same habitats was also examined and compared to that of the wild chicks. Finally, because cotton is a major crop in the southeasterm United States, a field-scale study was conducted to examine how crop-management differences between insect resistant and non-insect resistant cotton varieties affect the abundance of bobwhite chick-food invertebrates. Invertebrate selection by both wild and human-imprinted chicks was non-random. Although invertebrate composition in the diet of chicks differed between all sites, the three invertebrate groups most selected by wild bobwhite chicks, Hemiptera, Coleoptera and Hymenoptera, collectively formed over 70% of the invertebrate-diet on all study sites.