An Evaluation of Five Agricultural Habitat Types for Openland Birds: Abandoned Farmland Can Have Comparative Values to Undisturbed Wetland

Abstract

Populations of birds inhabiting wetlands and grasslands are decreasing globally due to farmland expansion and subsequent agricultural intensification. In addition to conserving natural habitats, managing cultivated farmland and abandoned farmland are likely to be important future conservation measures; however, their relative suitability as avian habitat remains understudied. In this study, we evaluated five habitat types (wetland, pasture, cropland, abandoned farmland, and solar power plant) for openland birds in an agricultural landscape in central Hokkaido, northern Japan. Abandoned farmlands had bird species richness and total bird abundance values similar to those of wetlands. These values were generally higher in abandoned farmlands and wetlands than in croplands, pastures, and solar power plants. The per pair reproductive success of Stejneger's Stonechat Saxicola stejnegeri and the amount of its prey (arthropods) did not differ among the five habitat types. Three species (Black-browed Reed Warbler Acrocephalus bistrigiceps, Common Reed Bunting Emberiza schoeniclus, and Japanese Bush Warbler Cettia diphone) arrived earlier in wetlands than in other habitat types. These results suggest that, although protecting the remaining wetlands is of prime importance for the conservation of openland birds in agricultural landscapes, valuing and managing abandoned farmlands would be a promising alternative.