Temporal Variation and Habitat Management Influence Arthropod Prey for Northern Bobwhites (Colinus virginianus)

Abstract

Variation in the relative abundance and biomass of arthropods has important potential consequences for insectivores. We studied the influence of temporal variation and habitat management (i.e., burning and strip-disking) on the availability of potential arthropod prey for brooding northern bobwhites (Colinus virginianus) in the mixed-grass prairie of western Oklahoma. Burning changed the composition of the arthropod community by biomass, but disking did not result in any community-level changes. Burning also increased the total abundance and biomass of arthropods collected compared with the control, but disking did not affect total abundance or biomass. Temporal variation exerted a broader influence on arthropods, and total abundance and biomass increased throughout the duration of the sampling period (May-July) at paired burn/control and paired disked/control sites. Ants, which had the highest abundance and biomass of any taxa, appeared to drive these patterns. The response of individual orders to management and temporal variation varied in size and direction, though we observed more and stronger effects of temporal variation than burning or disking. These results support the idea that burning provides benefits to foraging bobwhite broods through increased total availability of arthropod prey, as well as favorable habitat characteristics (i.e., bare ground, structural heterogeneity). Large temporal variation in total arthropod abundance and biomass, as well as that of individual orders, likely also influences the relative importance of individual prey items in the bobwhite diet based on the timing of nest initiation and hatching. A better understanding of how these temporal and management-induced shifts in arthropod availability influence potential nutrient gains and limitations for bobwhites will require data on macronutrient content and digestibility (i.e., exoskeleton) of prey taxa.