Region’s bird population clobbered

Last week the HB Regional Council reported significant findings on the region’s bird population pre-and post Cyclone Gabrielle.

The work undertaken was both hugely impressive and hugely depressing.

Over the 2019-2024 window, HBRC’s biodiversity team has surveyed 292 kilometers of our rivers and 321 kilometers of our coastlines, allowing detailed pre- and post-cyclone comparisons across nearly 150 bird species. 

Among the findings …

• Pohowera/banded dotterel – 17% decline across the region (2.5% decline in national/global population)

• Black-fronted dotterel – 30% decline (15-17% decline in the national population)

• Tōrea / South Island pied oystercatcher – 43% decline (HB’s is the only North Island breeding population)

• Tūturiwhatu / Northern New Zealand dotterel – 36% decline (3.1% decline in national/global population)

The list goes on. And as indicated above, in cases where species are endemic to NZ, our region’s losses constitute global losses.

The team notes that many species appeared to be unaffected by Cyclone Gabrielle, “but this may be due to “lucky’ timing”. For example, the event occurring after breeding season for some species.

Bottomline: “Uncertain whether declines are due to mortality or changing habitat use, therefore speed and likelihood of population recovery is not known.”

When questioned during the presentation, staff indicated that the most likely cause of mortality, where that occurred, would be habitat and food loss, given that our streams and rivers were stripped of the aquatic life on which the birds feed. BayBuzz has produced a video report on this food change impact.

Additionally, cyclone clean-up, given priority in the immediate storm aftermath, would likely have had an adverse impact on bird habitat.

Recommendations from the biodiversity team:

• Repeat these surveys in 3-5 years time to measure population recoveries
  
• Regional climate change adaptation and emergency response plans need to include measures to mitigate adverse impacts on river and coastal ecosystems including:
  
  • Careful management of woody debris inputs and removal
    
  • Landscape-scale predator control on rivers and coast to offset losses caused by extreme weather [In terms of predator control, although large scale efforts are the most efficacious, HBRC staff can identify the most species-dense river and coastal areas where control efforts would deliver the most ‘bang for buck’.]
    
  • Creating artificial nesting and flood refugia habitats in less flood-prone locations
    
  • Carefully managing coastal defences and coastal retreat to create room for 
    landward migration of coastal ecoystems.

The Powerpoint presentation is here. And the HBRC report is here.