In summer months, they range within about 5 nautical miles (9 kilometres) from shore, moving further out in winter – up to 15 nautical miles (27.5 kilometres) from land.
The dolphins live for about 20 years.
Females begin to breed when aged between 7 and 9 years, and wait until each calf is fully independent before giving birth again – they have just one calf every 2-3 years – a 2% growth rate.
That means, a population of 100 Hector’s would grow to 102 (at the most) in one year – which is why any human-induced deaths have such a devastating impact.
Are they healthy animals?
Like dolphin populations all over the world, Hector’s dolphins have diseases and parasites.
One bacterium (Brucella) has been found in every dolphin species examined so far, including Hector’s.
It’s a bit like the common cold in humans.
In the past, diseases and parasites were not a major problem for Hector’s dolphins – they have lived with them for millions of years.
What has changed is that our actions (especially fishing) are depleting dolphin populations so they are now less resilient and less able absorb the impacts of disease, climate change, pollution and habitat loss.
Dolphin fact sheets
Read more about the dolphins' ecology by downloading our factsheets.
