Monitoring widespread and common bird species on New Zealand’s conservation lands: a pilot study

Robust monitoring systems are required to improve the ecological outcomes of management actions aimed at preventing biodiversity loss. We present a pilot study that measured assemblages of widespread and common bird species at the national scale in New Zealand. Bird surveys were undertaken at 18 sampling locations (six per land cover class: forest, shrubland and non-woody) randomly selected from a national grid. The full sampling protocol (five count stations surveyed on each of two consecutive days) was implemented at 80% of sampling locations. Each survey consisted of a ten-minute bird count, with distance sampling carried out in the initial 5-min period and any new species recorded in the second 5-min period. Most observations were based on aural cues (particularly in forest and shrubland). On average, one additional species was recorded per sampling location in ten- versus five-minute counts. Analyses highlighted spatial heterogeneity as a major factor influencing detection probabilities both for species present and for individuals of those species at sampling locations. This issue is often overlooked when estimating bird population trends through time. Most endemic species were detected in forest, while native and introduced species were most frequently detected in shrub. Potential uses of the information collected, along with recommendations for improving the sampling protocols, are highlighted.