Soil disturbances increase songbird use of monotypic re-established Grasslands

Abstract

Extensive conversion of natural areas for agricultural production has had many consequences, including reduced habitat for nesting birds. Increasing focus on habitat re-establishment has led to the establishment of patches of perennial herbaceous vegetation in these agricultural landscapes, although these often consist of monotypic grass fields with little vegetation diversity. In 2001 and 2002, we assessed songbird responses to mowing followed by a soil disturbance (disking) meant to increase vegetation diversity and abundance of arthropod food resources in conservation easements in East-central Iowa, USA. We randomly assigned fields to disking and control treatments and collected data on breeding bird density and species richness in these habitats before and after treatments were applied. Disking increased density of all species combined, several individual species including dickcissel (Spiza americana; a declining species of concern), and overall conservation value of bird communities in treated fields. Total bird density increased with disking when the size of disked area was relatively small, and dickcissels and American goldfinches (Spinus tristis) responded positively and negatively to block-shaped treatments, respectively. Most species either showed no response or increased in density with disking. Changes associated with disking treatments were likely related to changes in both vegetation structure and increased abundance and biomass of arthropod food resources. Disking appears to be an effective management practice for maintaining herbaceous habitats, increasing vegetation diversity and food availability for insectivorous birds, and increasing habitat quality for priority bird species. Given the increasing availability of monotypic grasslands in agricultural landscapes, this practice may provide a relatively inexpensive way to improve re-established habitats. © 2013 The Wildlife Society.