Cyclone Gabrielle: Hawke’s Bay Regional Council report finds weather event impact caused decline of bird species

A new report shows Hawke's Bay's coastal and river bird species, such as banded dotterels, have seen a significant decline as a result of Cyclone Gabrielle. Photo / Adam Clark

A new report suggests the impact of Cyclone Gabrielle’s caused Hawke’s Bay’s largest recorded decline in river and coastal bird populations.

Between 2019 and 2021, Hawke’s Bay Regional Council conducted baseline surveys to monitor and understand trends in the numbers and distribution of coastal and river birds.

From October 2023 to February 2024, 321km of the Hawke’s Bay coastline and 292km of land along the Tukituki, Ngaruroro and Tūtaekurī Rivers was re-surveyed.

Ecologist Nikki McArthur said those recent surveys found significant decreases across several bird species compared with pre-cyclone results.

“Pohowera/banded dotterel numbers fell by 15% across the three rivers. Specifically, there was a 51% decrease on the Tūtaekurī River, and a 20% drop on the Ngaruroro River.”

Pohowera populations were also reduced by 31% along the coast, and combined with the rivers, this represented a 17% drop in the regional breeding population.

“This equates to an estimated 2.5% decrease in the national and global population, assuming these declines were the result of mortality, rather than a change in distribution,” McArthur said.

The regional population of the river-breeding black-fronted dotterel declined by 30% across the three rivers, and the coastal-breeding tūturiwhatu/New Zealand dotterel regional population declined by 36%.

This represented the most significant population decline observed for these species in Hawke’s Bay.

McArthur said these historic population decreases were “very concerning” as the Department of Conservation classified many of the species surveyed as at-risk and threatened.

“The Tūtaekurī, Ngaruroro and Tukituki River catchments support internationally and nationally significant populations of indigenous shorebirds, including 13% of the global population of pohowera.

“These endangered birds are an essential part of our coastal and freshwater ecosystems and contribute to healthy biodiversity, but they face many threats to their survival. These surveys highlight the high degree of vulnerability these species have to extreme weather events and climate change, in addition to existing threats like predators and disturbance.”

McArthur said the community could do their part to help offset losses by protecting and enhancing habitats.

“Implementing wide-ranging predator control, minimising disturbance from people and vehicles, and keeping dogs on leads and cats inside at night during the nesting season are all things we can do to help.

“In the long term, the regional council will need to look at planning coastal defences and coastal retreat to allow room for coastal habitats to retreat inland with climate change.”