Habitat associations and survey effort for shrubland birds in an urban pine barrens preserve

Inland pine barrens offer the rarest type of shrubland habitat in the northeastern United States and may contribute disproportionately to the regional diversity and conservation of shrubland birds. Testing local habitat specialization and estimating survey effort is needed to inform management of pine barrens for this rapidly declining avian group. We evaluated shrubland bird habitat associations in a heavily urbanized pine barrens of the northeastern United States, and used occupancy-detection sampling and analysis to estimate the number of sample points and surveys for point-based monitoring of shrubland birds in pine barrens. Although forest area was significantly greater than shrubland area, 8 of 11 reliably modeled species showed evidence of association for shrubland, and are thus potentially useful as indicators of pine barrens shrubland quality and management to avert succession. From the analysis of survey effort, we suggest two design options for point-based monitoring of shrubland birds in pine barrens: (1) include enough points to cover at least ∼3% of the study area and survey each point ≥5 times preferably during 05:00–08:00 hr, or (2) reduce the point sample, to no less than about 2% of study area, and increase the survey replication to ≥10 surveys. Three surveys, as suggested by shrubland bird experts for anthropogenic early-successional habitats (e.g., utility corridors) and by others as a general rule, may require too many sample points to feasibly monitor shrubland birds in pine barrens.

Research highlights▶ About two-thirds of shrubland bird species analyzed showed evidence of shrubland association in a highly altered pine barrens landscape. ▶ Correcting for detection probability modified but did not drastically change the main conclusions of a detection-naïve analysis. ▶ We recommend a minimum of five surveys, not three as widely suggested, for shrubland bird point counts in pine barrens. ▶ The sample of point count stations should cover at least ∼3% of the study area.