Data Zone
Justification of Red List category
This species has an extremely small area of occupancy since its breeding area consists of a strip of foredunes on a 1-km-long beach on a single island. The species is considered to occupy a single location at risk from the plausible threat of predator incursion causing a rapid population decline. Recent storm surges have destroyed portions of the species's dune breeding habitat. These events are ongoing and have become increasingly frequent since 2003, and as such the area, extent and quality of habitat can be considered to be undergoing continuing decline. For these reasons, this species is listed as Critically Endangered.
Population justification
Population is calculated as 200 adults based on counts of occupied burrows in 2018 (Fischer et al. 2019).
Trend justification
Population trend based on intermittent burrow counts (n = 20 seasons) carried out between 1978 and 2018 (Fischer et al. 2019).
Currently restricted to a small strip of coastal dunes on Codfish Island/Whenua Hou, New Zealand (Fischer et al. 2018). Only known skins originate from either Dundas Island, Enderby Island, or Codfish Island (Fischer et al. 2018). Offshore distribution remains unknown, possible record off New South Wales (Fischer et al. 2018).
Breeds in burrows in coastal sand dunes, preferring foredunes (0-20 m from spring tide line) with steep, seaward-facing slopes (Fischer et al. 2018). Knowledge of breeding and feeding ecology remains largely speculative.
This species has experienced a gradual continuous increase in population size over forty years (Fischer et al. 2019). However, its breeding is confined to a narrow strip of dunes on a 1-km-long beach on Codfish island, rendering it vulnerable to habitat destruction through storm surges (which have become increasingly frequent since 2003, G. taylor in litt. 2019). The population appears to have tolerated the presence of weka Gallirallus australis, brush‐tailed possums Trichosurus vulpecula, and polynesian rats Rattus exulans in the past, experiencing population growth even prior to the eradication of these predatory species (Fischer et al. 2019). However, the potential impact of predator invasion is still regarded as a serious threat to the entire colony: isolated instances of Norway rat Rattus norvegicus incursions have been detected, and this species is known to be capable of decimating breeding seabird colonies on other offshore islands in New Zealand (G. Taylor in litt. 2019). Competition with the Chatham Islands Diving Petrel Pelecanoides urinatrix chathamensis for nesting sites may represent a minor threat (Fischer et al. 2017).
Conservation actions underway.
Only breeding colony is in the Whenua Hou Nature Reserve. Area is subject to aggressive control of introduced animals and plants, and strict biosecurity measures to protect against new incursions of introduced animals and plants (New Zealand Department of Conservation 2012). Burrow counts are carried out during breeding season to calculate population size (Fischer et al. 2019).
Conservation actions proposed.
Translocations to sites within the historical range of the species have been proposed to reduce the threat that stochastic events pose to the species through its sole breeding colony (Fischer et al. 2018). A prerequisite of such an approach would be an improved understanding of the species's breeding ecology and population dynamics (Fischer et al. 2018). If competition for nest sites from the Chatham Islands Diving Petrel Pelecanoides urinatrix chathamensis becomes problematic, measures to exclude this species from burrows may be considered (Fischer et al. 2018).
Text account compilers
Smith, D.
Contributors
Taylor, G.A. & Fischer, H
Recommended citation
BirdLife International (2024) Species factsheet: Whenua Hou Diving-petrel Pelecanoides whenuahouensis. Downloaded from
https://datazone.birdlife.org/species/factsheet/whenua-hou-diving-petrel-pelecanoides-whenuahouensis on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/11/2024.