Stasis and turnover in small shearwaters on Bermuda over the last 400 000 years (Aves: Procellariidae: Puffinus lherminieri group) STORRS L. OLSON* Division of Birds, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7012, USA Received 1 September 2009 accepted for publication 28 October 2010bij_1393 699..707 The extinct species Puffinus parvus Shufeldt of Bermuda is shown to be synonymous with the living taxon Puffinus boydi of the Cape Verde islands. This species occurred on Bermuda throughout the last 400 000 years, during both glacial and interglacial intervals, and into the Holocene up until the arrival of humans when introduced predators evidently caused its extirpation. Subsequently, the island was colonized briefly by the Caribbean species Puffinus lherminieri, which in turn was extirpated from the island in the 20th Century. The indications are that P. boydi successfully outcompeted P. lherminieri on Bermuda until it was removed through human agency, thus closely paralleling the situation documented for two species of Megadyptes penguins in New Zealand. Thus P. lherminieri and P. boydi have long functioned as biological species and should be considered as full species along with the cold-water species Puffinus baroli of the North Atlantic. Restoration efforts for small shearwaters on Bermuda should now focus on P. boydi rather than P. lherminieri. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 699–707. ADDITIONAL KEYWORDS: Cape Verde Islands – competitive exclusion – fossil record – Pleistocene – P. boydi – P. parvus. INTRODUCTION In a family of seabirds with notoriously difficult generic and intrageneric systematics, the smallest shearwaters in the genus Puffinus have long been regarded as being the most intractable aggregation of taxa. Recent discoveries of new populations (Louette & Herremans, 1985 Shirihai, Sinclair & Colston, 1995 Bretagnolle & Attié, 1996 Shirihai & Christie, 1996 Le Corre, 2000 Merton & Bell, 2003), and a reasonably comprehensive molecular study (Austin, Bretagnolle & Pasquet, 2004), have added more layers of complexity to an already very intricate problem. The following analysis and discussion is confined to the populations of the North Atlantic Ocean. An extinct fossil population of a small shear- water is known from St Helena (Olson, 1975) and other populations have recently been found off of Brazil, although South Atlantic birds will be treated elsewhere when more data become available. Murphy (1927) distilled the long-held concept of two species of small shearwaters in this complex, each with numerous subspecies: the Audubon’s shear- water Puffinus lherminieri Lesson (1839 – type local- ity Antilles) of warm tropical and subtropical waters characterized in general by brownish–black upper- parts and pinkish-coloured feet, and the little shear- water Puffinus assimilis Gould (1838 – type locality Norfolk Island) of temperate and subantarctic waters characterized by blacker upperparts and bluish feet. These two groups may be further distinguished by the fact that P. lherminieri-type birds have long wings and tail, whereas birds of the assimilis group have short wings and tail (Lee, 1988 Carboneras, 1992). This pattern of short wings and tail in antarctic or subantarctic waters and longer wings and tail in warm tropical waters appears to be a morphological *E-mail: olsons@si.edu Biological Journal of the Linnean Society, 2010, 99, 699–707. With 2 figures © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 699–707 699

response to environmental conditions, especially wind strength, that is exhibited throughout the family Pro- cellariidae (Spear & Ainley, 1998). Three named living populations of small shearwa- ters are found in the North Atlantic. The islands of the Caribbean and the Bahamas are inhabited by P. lherminieri by definition and this species winters mainly in the western North Atlantic in the vicinity of the Gulf Stream at the latitude of North Carolina (Lee, 2000). An historically known population from Bermuda, first reported in 1906 (Bradlee, 1906), was correctly identified as P. lherminieri (see below) but was subsequently extirpated by the early 1980s (Amos, 1991). A second taxon, baroli Bonaparte (1857), occurring in the Azores, Canary Islands, Sal- vages, and Madeira, is much smaller than P. lher- minieri and has the short wings and tail and dorsal and foot coloration characteristic of the assimilis group and has always been referred to as Puffinus assimilis baroli subsequent to the two major groups being distinguished. As documented by the syn- onymy below, the relationships of the third taxon, boydi Mathews (1912), of the Cape Verde Islands, have long been in dispute. As Murphy (1927) estab- lished, it has the proportions and dorsal coloration of P. lherminieri, with which he placed it, reversing his previous stance (Murphy, 1924), although its much smaller size and bluish foot coloration, among other characters, have caused it to be associated with assimilis or with baroli when that taxon is separated from assimilis. In a recent molecular analysis, Austin et al. (2004) concluded that the North Atlantic populations of small shearwaters were more closely related to each other than to the remaining taxa and united all three under P. lherminieri. Such a treatment was foreshadowed by Fleming (1943: 125) who percep- tively concluded that it ‘would appear that these two north Atlantic races, baroli and boydi, have no relationship with the southern hemisphere assimilis group except through the intervening species group lherminieri’. Another named taxon in the North Atlantic is Puffi- nus parvus (Shufeldt, 1916) described from fossils in Bermuda that were at one time wrongly synonymized with P. lherminieri but that were assessed as belong- ing to an undetermined smaller species (Olson, 2004). The identity and history of this taxon sheds new insight into the relationships among the small shear- waters of the North Atlantic. MATERIAL AND METHODS Measurements were taken with dial and digital cali- pers and rounded to the nearest 0.1 mm. MATERIAL EXAMINED Puffinus parvus: Fossil bones in the original series studied by Shufeldt (1916, 1922) in the Carnegie Museum (CM) as discussed in Olson (2004) and many more additional fossils in the collections of the Department of Paleobiology (USNM) from the follow- ing localities in Bermuda (site numbers as given in Olson et al., 2005): 4, Calonectris Quarry 9, Govern- ment Quarry (Finch Cave, Wilson’s Cave, Fissure fill upper level) 11, Admirals Cave 12, Convolvulus Cave 13, Sibley’s Cave 15, Devil’s Sinkhole 16, Fern Sink Cave 17, Walsingham Cave 18, Walsingham Sink Cave 19, Church Cave 20, Jane’s Cave 22, Terrapin Cave 23, Tropicbird Cave 24, Spittal Pond 26, Cockroach Island. Puffinus boydi: Subfossil bones collected on Isla Sal, Cape Verde Islands (Boessneck & Kinzelbach, 1993), SAPM lot AV-00501 two modern skeletons MNHN CG 1964-92 and CG 1966-862. Skins YPM 43694- 43700, 43702-43703, 43707, 43710-43716, 43718- 43720. Puffinus baroli: Three modern skeletons MNHN uncataloged, CG 1981-1023, CG 2004-421. Skins YPM 24090 BMNH 81.5.1.6016, 81.5.1.6014, 90.5.7.8, 90.5.9.42, 95.7.1.20, 95.7.1.117, 95.7.1.119, 1905.12. 22.354, 1905.126.29, 1913.10.22.210, 1913.10.22.212, 1913.10.22.215, 1914.12.1.246, 1934.1.1.96, 1949. 17229, 1960.26.1, ‘253’ uncataloged. Puffinus lherminieri: Modern skeletons Bermuda USNM 17724, 428929, 428931-428935, 428937- 428938, 428941-428945 Bahamas USNM 613790- 613793 Virginia and North Carolina at sea USNM 560756, 620719-620720, 620725-620726 (all collected after the species had been extirpated on Bermuda). Skins Bermuda: AMNH 349275, 708863, 783741- 783743 BMNH 1914.12.1.240, 1917.2.16.11 MCZ 321421. Skins Bahamas (11), Bequia (1), Saba (2): USNM 80978, 110651, 110654-110658, 220358, 223117, 323168-323170, 353482-35348. SYSTEMATICS FAMILY PROCELLARIDAE GENUS PUFFINUS BRISSON, 1760 PUFFINUS BOYDI, BIOLOGICAL SPECIES RANK Puffinus lherminieri boydi (Fig. 1) Mathews, 1912 Bannerman, 1914 Murphy, 1927 Bannerman, 1930 Peters, 1931 Jouanin & Mougin, 1979 Lee, 1988 Warham, 1990 Austin et al. 2004 Brooke, 2004 Onley & Scofield, 2007. Puffinus assimilis boydi: Hartert, 1920 Murphy, 1924 Witherby et al. 1940 Vaurie, 1965 Bannerman & Bannerman, 1968 Cramp & Simmons, 1977 Bourne & Loveridge, 1978 Nørrevang & den Hartog, 1984 Bourne, 1986 den Hartog, 1990 Carboneras, 1992. 700 S. L. OLSON © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 699–707