The national annual New Zealand Garden Bird Survey starts today.
The Landcare Research led project asks residents in rural and urban areas to record the highest total of birds they have in their garden in the space of an hour anytime this week.
Spokesperson Eric Spurr said the project aimed to note any general population trends in garden variety birds such as tui and sparrow.
Mr Spurr said the survey results acted as an early warning system if anything drastic was occurring in the eco-system.
"We're wanting to monitor long-term trends in some of the more common native species such as tui, bell bird, and kereru, but that's because we don't know what's happening to the populations, and I'm hoping this citizen science project might act as an early warning system in case these currently common birds do start declining."
Mr Spurr said previous surveys had shown no significant changes in many species over the last eight years, except that tui may be increasing.
However, he said last year there was a mild winter and that meant less birds were driven to gardens in search of food - but this year would be a different picture.
Mr Spurr expected the recent national drop in temperature to drive birds into gardens.
The 2015 survey ends on 5 July.
To find out how to take part in the survey visit the Landcare Research website.