Northern New Zealand dotterel are classified as a Conservation Dependent species, this means that without human help they will go extinct (usually because of predation from introduced predators like rats & cats). So how do you know if your local dotterel are going extinct or not?
Well first you need to work out their productivity rate. Productivity is measured by the average number of chicks fledged per breeding pair (per season). Fledglings divided by pairs. So if you had two pairs and they fledged one chick you can say the site averaged half a fledgling (0.5) per pair.
1 fledgling / 2 pairs = 0.5 productivity
0 fledgling / 2 pairs = 0 productivity
1 fledgling / 3 pairs = 0.33 productivity
Management is considered effective if productivity values are greater than 0.5 for three consecutive years or longer (Dowding & Davis, 2007).
I help manage dotterel at three sites, I can not claim effective management and any of them. This means that over time these sites are a population sink. It’s important to track and share this metric to help conserve the species.
Update April 2025:
New research published by (Dowding & Chamberlin 2025) has found that Variable Oystercatcher have higher survival rates than Northern New Zealand dotterel, so they require a lower productivity rate—0.22 chicks fledged per pair per year or more—for the population to be sustainable and management to be considered effective.