Human exploitation assisting a threatened species? The case of muttonbirders and Buller's albatross.

Susan M Waugh,John P Y Arnould,Jean-Claude Stahl,Colin M Miskelly,Timothée A Poupart,David Hyrenbach

doi:10.1371/journal.pone.0175458

Susan M Waugh, John P Y Arnould + Show 4 more

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https://doi.org/10.1371/journal.pone.0175458

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Abstract

Albatrosses are flexible and adaptable predators, relying on live prey as well as carrion. Use of predictable food sources and reliance on human-produced resources are well-known trait in long-range feeders like albatrosses and petrels. Breeding Buller’s albatrosses studied at Solander I. (Hautere), New Zealand fed their chicks the remains of sooty shearwater juveniles (tītī in Māori), which are harvested from nearby muttonbirding sites. Evidence of this food type was found at over 10% of nests examined, and 17–40% birds that were fitted with GPS loggers visited muttonbirding sites in this and previous studies. Muttonbirding is a traditional practice that has continued for centuries, with up to 120 tonnes of offal discharged to the sea annually during the present day harvest. It coincides with the energetically-demanding early chick period for the albatrosses. Our finding suggests that the offal may be an important, but overlooked element in the albatross diet. As an important supplementary food for the albatrosses it is likely to have contributed to the 3% per annum growth of their populations since the first comprehensive population surveys in 1969.

Highlights

Many pelagic seabirds are opportunist feeders, relying on a mixture of predictable patches of natural prey [1, 2, 3] and as well as scavenging from the carcasses of dead vertebrates [4] fisheries waste [5] or offal from meat processing [6, 7]
We described the observations of bird regurgitates of shearwater remains and tracking locations, and asked these colleagues to assist us in interpreting our findings, to share their experiences and observations in relation to seabirds feeding on muttonbird remains, as well as details of the muttonbirding discarding practices at sites they were familiar with
Our observations indicated that Buller’s albatrosses are adaptable feeders, and in addition to feeding extensively on fisheries waste, as reported in the literature, there is evidence that around 10% or more adults and chicks fed on tītī remains from our direct observations

Summary

Introduction

Many pelagic seabirds are opportunist feeders, relying on a mixture of predictable patches of natural prey [1, 2, 3] and as well as scavenging from the carcasses of dead vertebrates [4] fisheries waste [5] or offal from meat processing [6, 7]. Muttonbirding is a centuries-old practice [8, 9] undertaken by New Zealand Māori, and refers to the harvest of petrel chicks. / Rakiura (47 ̊S, 167.84 ̊E), the tītī harvest is undertaken by members of Ngai Tahu people [8] at the tītī islands [8, 11, 12] from 1 April to 31 May. Tribal elder, Rakiihia Tau, stated “Ngai Tahu’s relationship with the Tītī Islands (sic) is undoubtedly a most important cultural, social and political facet of Ngai Tahu tribal identity” [8].

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