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Co-ordinated counts of waders across New Zealand have been undertaken in November and June since 1983; the consistent timing of counts aimed to reduce variation from the effect of seasonal changes in bird numbers. The Australian Shorebird census and the wider Asian Waterbird Census, however, are conducted in January, making direct comparison with the New Zealand counts potentially problematic, especially if an attempt is to be made to assess total flyway populations. Since 1998 waders on Farewell Spit (40°30.5 ́S, 172°45 ́E to 40°33.5 ́N 173°02 ́E) have been counted in February as well as in November and June. Counts of bar-tailed godwit and ruddy turnstone were on average 20% and 35% higher in February compared to November, respectively. Also, counts of the endemic migratory South Island pied oystercatcher were 15% higher in February compared to June. The improvement of data for overall population assessments is not only important for establishing trends of species but is also important for applying the 1% population criterion for wader site assessments.