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Conspicuousness of terrestrial birds from a distribution study using 100 ha squares based on the New Zealand map grid was investigated. Logistic regression was used to determine the amount of time observers should spend in each square to have a 50% chance of detecting any given bird species if it was present. The analysis was conducted for 3 habitats. For 14 species of native and introduced birds, the length of time necessary to determine presence was 1 – 631 min. To ensure that most species are accounted for in future distribution studies using similar grids, it is recommended that observers spend 1 h in each square.