Cyclone Gabrielle caused significant coastal and river bird species decline, Regional Council report says

Our region’s native river and coastal bird population has experienced the largest ever recorded decline, due to the impacts of Cyclone Gabrielle, says a recently completed Hawke’s Bay Regional Council report.

Between 2019 and 2021, baseline surveys to monitor and understand trends in numbers and distribution were undertaken. Between October 2023 and February 2024, 321 kilometres of the Hawke’s Bay coastline, and 292 kilometres along the Tukituki, Ngaruroro, and Tūtaekurī Rivers were re-surveyed.

Ecologist Nikki McArthur says significant decreases across several species were evident when compared with pre-cyclone results.

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

These are the steepest population declines to have been recorded on these rivers since bird surveys began in 1962. Pohowera were reduced by 31 percent along the coast, and combined with the rivers, this represents a 17 percent drop in the regional breeding population.

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

The regional population of the river-breeding black-fronted dotterel declined by 30 percent across the three rivers, and the regional population of the coastal-breeding tūturiwhatu/New Zealand dotterel declined by 36 percent. Each of these results represent the largest population declines ever observed for these species in Hawke’s Bay.

Mr McArthur says the survey results highlight how catastrophic the cyclone was for river and coastal habitats.

“The Tūtaekurī, Ngaruroro and Tukituki River catchments support internationally and nationally significant populations of indigenous shorebirds, including 13 percent of the global population of pohowera. Many species are classified as At-Risk and Threatened by the Department of Conservation, so to see these historic decreases is very concerning.”

“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.”

“But there’s work we can do in our communities to help offset these losses. Protecting and enhancing habitats by 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.”

Read the full report here.

4 September 2024

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