Status and conservation of shrubland birds in the northeastern US

Abstract

The suite of birds associated with naturally occurring shrublands and early successional forests in the northeastern US accounts for about 15% of the total species diversity of the breeding avifauna of the region. Most of the species in this habitat suite are common to abundant in occurrence with moderate to high relative abundance in the region. The shrubland suite of birds contributes a relatively large number of individuals but a relatively small proportion (15%) of the total bird species to the avian diversity of the region. The primary risks to long-term persistence of this suite of birds in the northeastern US include long-term population declines associated with long-term declines in amounts of early successional forest and naturally occurring shrubland habitats in the region (currently <15% of the land area). Many shrubland birds also have relatively high proportions of their total breeding populations occurring in the region, indicating the importance of the northeastern US to maintaining source populations of these species. Partners in Flight (PIF), a cooperative bird conservation organization seeking to maintain populations of North American landbirds has developed bird conservation plans for 12 geographic planning units, called physiographic areas, in the northeastern US. In 10 of these 12 physiographic areas, the shrubland suite of birds is considered either a high or moderate priority for conservation action. Most shrubland birds can be considered species of conservation responsibility rather than species of immediate concern. Species of conservation responsibility require long-term conservation planning and population monitoring to ensure that adequate habitat will be maintained and long-term threats eliminated. Fifteen shrubland bird species (45% of the habitat suite) were identified as species of conservation responsibility in the region. In comparison, 40% of the grassland suite and 34% of the forest suite of birds were identified through the PIF plans as species of conservation responsibility in the region. Therefore, the PIF plans indicate that the suite of shrubland birds should receive a high degree of conservation attention within the northeastern US. Using the concept of historic range of variation, managing 10–15% of the landscape for early successional habitat might provide adequate habitat for maintaining minimal populations of shrubland birds in the region, but a greater percentage will be needed if population increases are desired for birds associated with early successional habitats.