The invertebrate diet of northern bobwhite chicks in Georgia, United States

D A Butler,M P Cook,W E Palmer

doi:10.32800/abc.2012.35.0415

Abstract

The establishment of brood–rearing habitats along field margins has become a popular agri–environmental prescription to help reverse population declines of northern bobwhite (Colinus virginianus) in Georgia, United States. Here, the invertebrate–diet of chicks foraging on farmland with established brood–rearing habitats is examined and compared to those of chicks on an intensively managed wild bobwhite shooting estate. In 2001 and 2002, faecal samples were collected and analysed from nocturnal roost sites of bobwhite broods. Differences in invertebrate composition between the study sites were investigated using compositional analysis. While the diet of chicks on both sites contained similar invertebrate groups, the composition of the diets varied significantly. Although chicks on farmland had eaten 1.7 times fewer Coleoptera, they had 1.7 times more Hemiptera in their diet. These data suggest that although the invertebrate composition in the diet of chicks differed between the two landscapes, both contained high proportions of important prey items.

Highlights

During the past 50 years northern bobwhite (Colinus virginianus) populations have declined rapidly in the southeastern United States (Brennan, 1991)
Predominant crop types on both farms were cotton, peanuts, soya beans and maize. Both farms were participants in the Bobwhite Quail Initiative (BQI) agri–environmental scheme and brood–rearing habitats had been established along field margins
Using a six–part compositional analysis, relative differences in the proportions of Araneae, Hemiptera, Orthoptera, Hymenoptera, Coleoptera, and Others in the diet of chicks from the two study sites were examined. The composition of these invertebrate groups in the diet of chicks varied between the two study sites (Λ = 0.590, F5, 35 = 4.858, P = 0.002)

Summary

Introduction

During the past 50 years northern bobwhite (Colinus virginianus) (hereafter bobwhite) populations have declined rapidly in the southeastern United States (Brennan, 1991). Loss of quality brood–rearing habitat can prevent game bird chicks from obtaining sufficient quantities of prey items and reduce survival rates (Potts, 1986). The daily number of prey–items required by gamebird chicks depends upon the size and nutritional value of the invertebrates within the diet (Southwood & Cross, 2002). Perdix perdix, for example, Southwood & Cross (2002) reported that a nine–day–old grey partridge chick feeding entirely on Heteroptera requires 4,500 fewer items than one eating only Coleoptera. Chicks that are unable to eat sufficient quantities of invertebrates suffer from poorer feather development as well as reduced growth rates (Southwood & Cross, 2002)

Methods

Results

Conclusion