Volume 48, No. 2

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Trends in density, abundance, and response to storm damage for Westland Petrels Procellaria westlandica, 2007-2019


1Office of the Parliamentary Commissioner for the Environment, Level 8, Bowen House 70/84 Lambton Quay, Wellington 6011, New Zealand; Museum of New Zealand Te Papa Tongarewa, PO Box 467, Wellington 6011, New Zealand (
2Centre d'Études Biologiques de Chizé, CNRS UMR 7372 - Université de La Rochelle, 79360 Villiers-en-Bois, France
3Department of Conservation, Kawatiri/Buller District Office, PO Box 357, Westport 7866, New Zealand
4Latitude 42 Environmental Consultants, 114 Watsons Road, Kettering, Tasmania 7155, Australia; Institute of Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia
5RD 1, South Kaipara Heads, Helensville, New Zealand
6West Coast Penguin Trust, PO Box 70, Charleston 7865, New Zealand
7School of Biological Sciences, Victoria University of Wellington, Kelburn, Wellington 6011, New Zealand


WAUGH, S.M, BARBRAUD, C., DELORD, K., SIMISTER, K.L.J., BAKER, G.B., HEDLEY, G.K., WILSON, K.-J. & RANDS, D.R.D. 2020. Trends in density, abundance, and response to storm damage for Westland Petrels Procellaria westlandica, 2007-2019. Marine Ornithology 48: 273 - 281

Received 14 April 2020, accepted 19 June 2020

Date Published: 2020/10/15
Date Online: 2020/10/14
Key words: Climate change, seabird population estimate, rare climate event, breeding habitat destruction, endangered endemic species, Westland Petrel


The density and distribution of Westland Petrel burrows was assessed over a 12-year period (2007-2019). During that time, burrow density increased while occupancy remained stable, commensurate with an annual population growth rate of 1.022 (95% confidence interval: 0.971-1.076), as estimated using mark recapture data. From our surveys, we estimated a 2019 baseline population of ~6 200 breeding pairs and a world population of 13 800-17 600 individuals, covering around 95% of the population. Transects were conducted to establish the location and density of 17 petrel sub-colonies in rugged, untracked terrain in Paparoa National Park, West Coast, New Zealand. Major storms in 2014-2018 caused widespread treefall and landslides, destroying breeding habitat throughout the species' breeding range. Demographic effects of the major and ongoing habitat loss may continue in the medium to long term, as birds re-establish burrows and partnerships following loss of their habitat. Our study illustrates the complex effects of climate-related disruption on the biology of a long-lived species. With a single nesting area in the West Coast region, climate change will likely have an ongoing influence on the species' global population, since an increase in the frequency of severe weather events, including ex-tropical cyclones, is expected. However, current indications suggest that the species has some flexibility to adapt and to occupy new areas following habitat disturbance.


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