Recent Avian Extinctions

BRITISH ORNITHOLOGISTS’ UNION

RECENT AVIAN EXTINCTIONS

THE LINNEAN SOCIETY 1 NOVEMBER 2004

BRITISH ORNITHOLGISTS’ UNION AUTUMN SCIENTIFIC MEETING

This meeting was supported by British Ornithologists’ Club The Linnean Society of London

BRITISH ORNTITHOLOGISTS’ UNION Department of Zoology, University of Oxford, Oxford OX1 3PS, UK Tel & Fax 01 865 281 842 Email [email protected] | Web www.bou.org.uk | Web www.ibis.ac.uk

BOU Autumn Scientific Meeting – Linnean Society, London – 1 November 2004 1

Recent Avian Extinctions

Recent Avian Extinctions A BOU one-day scientific meeting held at the Linnean Society, 1 November 2004.

© British Ornithologists’ Union, 2004

The British Ornithologists’ Union (BOU), founded in 1858 by Professor Alfred Newton FRS, is one of the world’s oldest ornithological bodies. The BOU’s aim is to promote ornithology and a better understanding of ornithology, birds and related issues, within the scientific and birdwatching communities.

To help achieve this aim, the BOU organises regular meetings, seminars and conferences at which ornithologists and others can discuss and learn more about work being undertaken around the world and topical ornithological issues.

The BOU has been organising conferences and meetings for over 100 years, and they provide an opportunity for people, from widely differing professional backgrounds, to explore and relate to a discrete scientific theme of common interest. Recent topics have included Lowland Farmland Birds (in 1999 with follow up conference being held in March 2004), Long-term Studies of Birds and Birds & Public Health. Such meetings help to promote understanding of environmental issues and the sharing of knowledge, the presentation of contentious academic theories to critical public debate and the defence of such ideas lie at the heart of healthy science.

The BOU further achieves its aim by the quarterly publication of our international journal - Ibis. Established in 1859, Ibis - the world’s leading ornithological journal - publishes work at the cutting edge of our understanding of the world’s birdlife, be it behaviour, population dynamics, systematics, breeding biology, taxonomy, habitat use or conservation. Ibis is available in print and online – visit www.ibis.org.uk.

Acknowledgements Recent Avian Extinctions was a one-day meeting organised by Julian Hume and Steve Dudley (BOU) on behalf of the British Ornithologists’ Union.

The BOU is grateful to the financial support from the British Ornithologists’ Club and the Linnean Society of London.

The BOU is grateful to the individual speakers and their respective organisations for presenting their work at the conference.

The proceedings of this conference will be published as in the Bulletin of the British Ornithologists’ Club.

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Recent Avian Extinctions

EXTINCTION ON ISLANDS THROUGH NATURAL, NON-HUMAN CAUSES

Storrs L. Olson Smithsonian Instititution, Washington, D. C.

Only in the past quarter century has the true extent of human-caused extinction of birds on islands begun to be realized through great improvements in the fossil record. The global human-induced catastrophic event on islands has overshadowed the fact that natural factors such as rising sea-level, climate change, volcanism, etc., have also caused extinctions of numerous populations of insular birds in the absence of human influence. Examples, with emphasis on the geological history of Bermuda, will be reviewed with a view towards understanding the effects of past natural events on historically known insular biotas and to try to project what the effects of combined natural and human perturbations may have on insular extinction rates in the future.

Email: [email protected] ______

HOW CONFIDENT ARE WE THAT A SPECIES IS EXTINCT? QUANTITATIVE INFERENCE OF EXTINCTION FROM BIOLOGICAL RECORDS

Dave Roberts Royal Botanic Gardens, Kew, UK

We are now entering a time of immense environmental upheaval were, increasingly, experts are required to provide conservation assessments. In the past a species has been considered extinct when it has not been observed for 50 years. As a criterion, its usefulness was dependent on the characteristics of the species in question. Revision of the categories resulted in species being classified 'extinct' when exhaustive surveys failed to produce any observations over a time period appropriate to the species' life history and throughout its known historical range. Quantitative assessment of trends in range and abundance is costly, requiring extensive field studies over a long period of time. Unfortunately, many species are only known through a few ‘chance’ sightings or a handful of specimens and extinction may be even harder to ascertain. Specimen- based records provide information on the distribution of taxa through time and space, of which there is a wealth held in the biological collections. Using a sightings record, methods have been developed to test the hypothesis of extinction on the basis of the period without sighting and the previous sighting record. The indices produce probabilistic inference of extinction in the absence of biological information. More recently, methods have been developed which also look at the behaviour of the most recent sightings in the record and can reduce the effect of periods where little collection effort has occurred. Methods such as these potentially have wide application as indicators of threat and extinction. These methods are applied here to recent avian extinctions.

Email: [email protected] ______

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Recent Avian Extinctions

NEW APPROACHES TO STUDYING AVIAN EXTINCTION EVENTS

Alan Cooper, Eske Willerslev & James Haile University of Oxford, UK

Recent developments in the study of ancient DNA have revealed how genetic traces are often preserved in sediments of sites, even in the absence of macrofossil remains. While we are still unsure of the exact nature by which the DNA is deposited, the records provide a means to examine faunal diversity through time, as well as species prevalence as extinction events are approached. We will present data from studies of New Zealand cave sites, where two volcanic tephra alter the local ecology and moa species diversity in the area.

New molecular analytical methods also make it possible to estimate evolutionary rates, and population sizes of species through time, simply using DNA sequences from dated specimens. This powerful new approach is far more appropriate than the use of external fossil calibration points, which can generate very inaccurate molecular rate estimates. These methods have been used on Beringian bison to demonstrate a large climatic effect in the run-up to the megafaunal mass extinction event. Such an approach would be equally applicable to studies of avian extinctions.

Email: [email protected] ______

THE RECENT AVIAN EXTINCTIONS ON REUNION (MASCARENE ISLANDS) FROM THE PALEONTOLOGICAL AND HISTORICAL SOURCES

Cécile Mourer-Chauviré, Roger Bour & Sonia Ribes Université Claude Bernard, Lyon, France

The past avifauna of Réunion Island was known from reports of early travellers, but it is only in 1974 that the first fossil bird remains were recovered in some basaltic caves and in a marsh. The extinct species identified from fossils include a night heron (Nycticorax duboisi (Rothschild)), an ibis (Threskiornis solitarius (Sélys-Longchamps)), a sheldgoose (Alopochen kervazoi (Cowles)), a teal (Anas theodori Newton and Gadow), a falcon (Falco duboisi Cowles), a rail (Dryolimnas augusti Mourer-Chauviré et al.), a coot (Fulica newtonii Milne-Edwards), a pigeon (Nesoenas duboisi Rothschild), a parrot (Mascarinus mascarinus (Linnaeus)), an owl (Mascarenotus grucheti Mourer- Chauviré et al.), and a starling (Fregilupus varius (Boddaert)). With the exception of the ibis and the owl, all these species had been mentioned by the early travellers.

These travellers also mentioned a large, whitish-coloured, almost flightless bird, generally designated as “Solitaire”, and from the end of the XIXth century onwards, it has generally been admitted that Réunion, like the neighbouring islands of Mauritius and Rodrigues, also had a dodo-like bird, which became known as the "White Dodo of Réunion". However, during our excavations and despite our expectations, we did not find any remains which can be attributed to a dodo, and we finally realized that the “Solitaire” of the old reports was actually the ibis Threskiornis solitarius. Furthermore the presence of a dodo on Réunion would be very unlikely because the Raphidae lineage separated a very long time ago, as recently demonstrated by phylogenetic

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Recent Avian Extinctions works on DNA, and because of the recent age of Réunion compared to the age of the other Mascarene islands.

Email: [email protected] ______

THE RISE AND FALL OF WILDFOWL OF THE WESTERN INDIAN OCEAN AND AUSTRALASIA

H. Glyn Young1 & Janet Kear2 1 Durrell Wildlife Conservation Trust, Jersey 2 Wildfowl & Wetlands Trust

The islands of the western Indian Ocean (Madagascar and associated islands and sub- Antarctic islands), Andaman, Greater and Lesser Sunda Islands, Moluccas, Philippines, New Guinea, Australia and New Zealand, are home to a large number of endemic wildfowl (Anatidae) – of 68 resident taxa (species and subspecies), 59 are endemic (87 %). Their evolutionary origins vary, many obviously colonising from adjacent continental areas; however, there are representatives of most major wildfowl groups including some that have few nearby extant relatives (e.g. Cygnus, Mergus and Oxyura). There is also evidence of a dispersal of colonising ancestral species (notably Grey Teal and White-eyed Pochards) around the region, groups that did not colonise adjacent continental areas suggesting that during previous geological periods wildfowl habitats were widespread. Rises in sea level following the Pleistocene have isolated a diverse range of taxa.

Eighteen endemic wildfowl taxa (30% of regional endemics) have become extinct during the Holocene, all from the Malagasy faunal region, the sub-Antarctic islands and New Zealand. These islands were the most recently colonised by humans (from 2 000 years ago) and the principal causes of extinction are considered anthropogenic. Those islands with a long established human population, including Australia, continue to exhibit a distinctive wildfowl fauna and have suffered no losses during the Holocene. Two species, the Auckland Island Merganser Mergus australis (extinct 1902) and Madagascar Pochard Aythya innotata (extinct?) have died out recently, and their decline is detailed.

Email: [email protected] ______

USING ANCIENT DNA TO DETECT THE CAUSES OF EXTINCTION AND ENDANGERMENT IN ISLAND BIRDS

Robert C. Fleischer Genetics Program, Smithsonian Institution, Washington, DC, USA

Pacific Island avifaunas have suffered far higher levels of extinction than any others because of direct and indirect human impacts. Waves of extinction have occurred subsequent to both Polynesian and Western contacts, reducing avifaunas by as much as 60%. It is important to understand how these massive extinctions occurred, and how we can prevent additional extinction of currently endangered species. DNA analyses

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Recent Avian Extinctions can contribute to this understanding in a number of ways. First, ancient DNA analyses of extinct and endangered species allow the delineation of units for conservation, and the limits of prior ranges for reintroduction. Comparison of genetic variation in ancient and current populations can be used to estimate effective population sizes and changes in effective population size over time. Use of ancient DNA, in concert with radiocarbon dating, can determine whether the impacts of introduced species, such as the domestic pig, were modified by secondary introductions. Last, ancient DNA can be useful in understanding the timing and impacts of introductions of introduced diseases in Hawaii (e.g., avian malaria, Plasmodium relictum), and its vector (a Culex mosquito), and how the disease and vector may have changed genetically over time.

Email: [email protected] ______

DISCOVERED AND LOST WITHIN 20 YEARS: THE STORY OF THE ALDABRAN BRUSH WARBLER

Robert Prys-Jones Natural History Museum, Tring, UK

The Aldabran Brush Warbler Nesillas aldabrana was discovered in late 1967/early 1968, when a male, female, nest and three eggs were collected on Aldabra Atoll, Indian Ocean, during a year-long Royal Society expedition. The species was not seen again until 1974, in which year RP-J began a two-year field study of a population of circa six individuals, four of which were colour-ringed. The last sighting, of a colour- ringed individual, was in 1983, and the species now appears almost certainly extinct. The presentation will review knowledge of the biology of N. aldabrana and of its status as a species distinct from other Nesillas taxa. The limited data available on the ecology of N. aldabrana itself will then be considered in conjunction with analogous data from other, better-known Indian Ocean island passerines in order to assess the probable cause(s) of its demise.

Email: [email protected] ______

TIME SINCE SPECIATION AND EXTINCTION RISK IN THE WESTERN INDIAN OCEAN ISLAND AVIFAUNA

Ben Warren Smithsonian Tropical Research Institute, Panama

Van Valen (1973) was the first to propose a hypothesis providing theoretical explanation for the observation that the probability of a species becoming extinct is approximately independent of its length of existence. This observation is based on taxonomic survivorship curves compiled from the fossil record. Examination of the molecular phylogenetic placement of sequenced extinct and threatened forms of western Indian Ocean Foudia, Zosterops and Hypsipetes reveals an interesting pattern; contrary to Van Valen's (1973) theory, these forms tend to be the oldest members of their clade. This observation is made on the assumption that the mtDNA-based divergence time of a species from its closest relative is representative of its age. Here

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Recent Avian Extinctions we test the statistical significance of this apparent trend and discuss possible explanations and the problems that undocumented extinction events present in drawing conclusions.

Email: [email protected] ______

GOING OR GONE: DEFINING 'POSSIBLY EXTINCT' SPECIES TO GIVE A TRUER PICTURE OF RECENT EXTINCTION RATES

Stuart Butchart BirdLife International, UK

A total of 129 bird species are classified as Extinct since 1500 on the 2004 IUCN Red List, and an additional four species have gone Extinct in the Wild (with populations remaining in captivity). However, extinction is difficult to detect, and a number of other species currently categorised as Critically Endangered have probably gone extinct too. Conservationists are sensibly reluctant to designate them as such until it is certain that the last individual has died. However, this leads to underestimates of the recent rate of extinctions. BirdLife have recently categorised 18 such species as ‘Critically Endangered (Possibly Extinct)’, defined as 'species which are likely to be extinct, but for which there is a small chance that they may still be extant, hence they should not be listed as Extinct until local or unconfirmed reports have been discounted, and adequate surveys have failed to find the species’. Analysis of the full total of 151 species shows that the impacts of alien invasive species, over-exploitation by humans, and habitat destruction and degradation have been the major causes of extinctions. The majority of extinctions have been on islands. The rate of island extinctions may be slowing, perhaps because so many susceptible island species have already gone extinct. However, continental species have been far from immune, and the rate of extinctions on continents appears to be increasing rapidly as a result of extensive and expanding habitat destruction.

Email: [email protected] ______

ANCIENT DNA REVEALS AN INTERESTING EVOLUTIONARY HISTORY OF NEW ZEALAND'S EXTINCT RAPTORS

Dr Michael Bunce University of Oxford, UK

Prior to human settlement 700 years ago New Zealand had no terrestrial mammals - apart from three species of bats - instead approximately 250 avian species dominated the ecosystem half of which are now extinct. Among these recent extinction events are three raptor species: Harpagornis moorei (Haast’s Eagle), Haliaeetus australis (Chatham Island Eagle) and Circus elyesi (Eyles’s Harrier). Using ancient mitochondrial DNA extracted from fossil bones we have investigated the evolutionary history of these three species. The data shows that one species never existed and is a taxonomic “blunder”, another has a predictable recent ancestor and the third has increased in size by 10-15 times in only a short evolutionary timeframe. This spectacular

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Recent Avian Extinctions evolutionary change illustrates the potential speed of size alteration within lineages of vertebrates and represents yet another example of the remarkable evolutionary processes that occur within island ecosystems.

Email : [email protected]

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