Invertebrate Use of Natural Tree Cavities and Vertebrate Nest Boxes

Abstract

Thirty-nine taxa of invertebrates used nest boxes and natural cavities in three mid-South forest habitats. Twelve of the 16 genera identified used nest boxes more frequently than natural cavities. Only carpenter ants (Camponotus sp.) (Formicidae) and termites (Kalotermitidae) used natural cavities more frequently than nest boxes. Wood roaches (Parcoblatta spp.) (Blattidae), southern green stink bugs (Nezara viridula L.) (Pentatomidae) and paper wasps (Polistes spp.) (Vespidae) were the most common invertebrates found in nest boxes. Four species exhibited preference for one or more of 16 characteristics of cavities and the surrounding habitat. Greater use of nest boxes than natural cavities by invertebrates may be due to a desirable nest box microclimate. INTRODUCTION Natural tree cavities are used as nesting, resting or feeding sites by many species of invertebrates; but availability of natural cavities is decreasing because bottomland hardwood forests are being replaced with soybeans (Glycine max (L.) Merrill), and plantations of eastern cottonwoods (Populus deltoides Marsh.) and American sycamore (Platanus occidentalis L.), and upland forests are being more intensively managed for timber production. Removal of trees with natural cavities in a stand removes the habitat necessary for invertebrates which require natural cavities, thereby reducing their populations and perhaps the populations of their predators. Maintenance of some natural cavities in a stand may be necessary to provide habitat for invertebrates which could be important food sources for other wildlife such as carpenter ants (Camponotus spp.) (Formicidae) for pileated woodpeckers (Dryocopus pileatus L.) (Conner et al., 1975). Nest boxes can supplement natural cavities for many cavity-using species (Bellrose et al., 1964; Nixon and Donohoe, 1979; McComb, 1979). A few investigators have reported use of nest boxes or natural cavities by invertebrates (McAtee, 1931; Nicholson, 1941; Allen, 1952; Klein, 1955; Flyger and Cooper, 1967), but no one has quantified invertebrate use of nest boxes and natural cavities. It is important that invertebrate use of artificial and natural cavities be quantified so habitat loss by cutting of cavity-bearing trees, as well as the benefits of box erection, can be assessed on the basis of all terrestrial fauna, and not just vertebrates, as is so frequently the case. The objectives of this study were: (1) to compare use of nest boxes with use of natural cavities in a bottomland hardwood stand, a cottonwood plantation and an upland pine-hardwood stand, and (2) to determine what -cavity characteristics were important to cavity-using invertebrates. STUDY AREAS A mature, mixed bottomland hardwood stand (Ben Hur) located on Louisiana State University Ben Hur Research Farm, East Baton Rouge Parish, La., was used as one habitat type. The overstory is dominated by water oak (Quercus nigra L.), pignut hickory (Carya glabra (Mill.) Sweet), American elm (Ulmus americana L.), sugarberry (Celtis laevigata (Willd.) and sweet gum (Liquidambar styraciflua L.); the midstory by box elder (Acer negundo L.) and bluebeech (Carpinus caroliniana Walt.); the understory by switch cane (Arundinaria gigantea (Walt.) Muhl.) and poison ivy (Rhus radicans L.). Ben Hur is an unmanaged forest protected from backwater flooding by the Mississippi River levee system. 'Present address: Department of Forestry, University of Kentucky, Lexington 40546.