New Zealand Garden Bird Survey – analysis of the first four years
The New Zealand Garden Bird Survey started in 2007 primarily to monitor long-term trends in common garden bird populations. The method was based on the Big Garden Birdwatch in the UK. Volunteers spent one hour in midwinter each year recording for each bird species the largest number of individuals detected at any one time in their gardens, as an index of abundance. A large number of species was recorded, the two most numerous being house sparrow (Passer domesticus) and silvereye (Zosterops lateralis).