Corella, 1991 , 15(2): 45-52 A11srralasia11 Hird l?<'l'iews - N11111ber 3 THE SHORT-TAILED SHEARWATER: A REVIEW OF ITS BIOLOGY IRYNEJ SKIRA Department of Parks. Wiltllifc and Heritage, 134 Macquarie St.. Hobart. Tas 7000 {<eceived I May /990 The life history of the Short-tailed Shearwater Puffinus tenuirostris has been well documented since it first came to the attention of naturalists. Approximately 23 million birds breed in about 250 colonies in southeastern Australia from September to April. The Short-tailed Shearwater commences to breed when 4 to 15 years. During their completed lifetimes 27 per cent of all individuals produce no young and 19 per cent only one chick. Mortality is age-related with the median survival time for breeding being 9.3 years after first breeding. Many areas remain open for study, with a particular need for interdisciplinary research that includes oceanography. INTRODUCTION The Short-tailed Shearwater was one of the first Australian birds to be banded in large numbers The Short-tailed Shearwater Puffinustenuirostris, (Serventy 1957, 1961) and to be subjected to a commonly known as the Tasmanian muttonbird, long-term scientific study (Guiler et al. 1958). This is one of about I 00 species in the Procellarii­ study was commenced on Fisher Island in the formes. The diagno�tic feature of the order is the Furneaux Group of Tasmania in March 1947 by external nostrils produced into tubes extending Dominic Serventy formerly of the CSIRO onto the bill. Other distinctive features are the (Scrventy 1977) and continues to the present. 42 hooked and plated bill. and the glandular part of years later. Due to the long-term nature of the the stomach which is greatly extended and pro­ study together with the banding of some 92 000 duces the well known 'oil'. actually wax esters birds in Australia, the life history of the Short­ (Warham 1977). Most members in this order have tailed Shearwatcr is one of the best documented a distinctive musky odour. in the world of any bird ( Bradley et al. 1989. 1990: The family Proecllariidac is the most diverse Serventy 1974; Servcnty and Curry 1984: Wooller group in the order and contains 61 species of et al. 1988, 1989. 1990). petrels and shearwaters (Serventy et al. 1971). The majority are nocturnal and nest in holes, EVOLUTION burrows or crevices, which serve to protect them and their young from predators. The genus The Procellariifonncs are an ancient group of Puffinus consists of 15 medium-sized species that birds that probably originated from aquatic birds are among the world's most numerous seabirds. present at the end of the Cretaceous. some 64 Their high nesting densities and their fidelity to a million years ago. The phylogenetic history of particular site has meant that they are highly shcarwaters is little known (Kuroda 1954). vulnerable to exploitation (Serventy et al. 1971). According to Olson (1985 p.211), ·most of the The harvesting of Short-tailed Shearwaters, or modern species-groups, or subgenera, of Puffinus muttonbirding as it is known in Tasmania, is one were in existence by the Middle Miocene. and of the best documented instances of seabird there has been very little morphological change harvesting (Skira 1987, 1990). within these lineages in 15 million years or so'. 45 46 I. Skira: The biology of the Short-tailed Shearwater Corella 15(2) P. tenuirostris has not been found in any _ and Norman 1981), South Australia 600 000 deposits apart from pre-historic archaeological burrows in 33 colonies (A. C. Robinson. pers. sites (Bowdler 1984: Friedman 1934a and b, 1941; comm.), New South Wales 25 700 breeding pairs Vanderwal and Horton 1984). One of the fossil in I 3 colonies (Lane 1979) and Western Australia procellariids. P. conrudi from the Middle 10 000 burrows in several colonies (Johnstone et Miocene of Maryland. USA. seems to have lived al. 1990a and b; Lane 1983). It is estimated that to the Pleistocene. one million years ago. P. 23 million birds breed in about 250 colonies. 1e1111iros1ris may have evolved from a P. conradi­ Recent research by Japanese biologists has con­ type ancestor through the P. inceplor line centrated on mapping vegetation types in several (Kuroda 195--l). /'. inceptor is known from the colonies in Tasmania (Kuroda 1986). Middle Miocene of California suggesting that P. 1e11uirostris and its congener the Sooty Shearwatcr P. griseus which is abundant in MIGRATION New Zealand. were differentiated in the North Atlantic-North America areas. Having settled in The Short-tailed Shcarwater is a circum-Pacific the Southern Hemisphere. perhaps as late as migrant spending the horcal summer in the the Pleistocene. their post breeding migration Northern Pacific region (Fig. l). Sexually may be an instinctive response to return to the immature birds depart from Australia near thc Northern Hemisphere (Kuroda 1954; Marshall end of March. followed by the breeding birds and Serventy 1956). around mid-April, with the Acdged chicks leaving at the end of April to early May. The shearwaters The fossil record left by seabirds in Australia migrate rapidly (Scrvcnty 1956) and arrive in the is meagre compared to that of the Northern Northern Hemisphereon a broad front across the Hemisphere. It spans too short a period of time central Pacific Ocean (Shuntov 1974; Maruyama and is too low in diversity to test biogeographic et al. 1986). hypotheses. The oldest petrel and shearwatcr fossils occur in the late Pleistocene or Holocene Most arrivals to the northern part of the Pacific from coastal deposits around mainland Australia Ocean arc from the end of April to the end of and Tasmania. In these deposits the genera May or the beginning of June. The largest flocks l'terodroma and Puffinus predominate (Rich and can he observed in the eastern part of the Bering van Tets 1982). Sea in the Northern Hemisphere spring and the beginning of summer. In the second half of The interval from 25 000 to 10 000 years before summer many pass into the Chukchi Sea. and present was a period of great fauna! and climatic while birds are still dispersing into the Chukchi change in Australia. Climatic disruptions would Sea migration southwards begins. Some birds have affected the location of Short-tailed Shear­ also migrate along the North American coast water colonies through changes in sea levels. At and others across the Pacific between the times. the coastline was up to 50 km away from I lawaiian Islands and North America (Shuntov its current position (Blom 1988; Jennings 1971). 1974). This results in very large flocks occasion­ ally occurring off the west Canadian coast in May under certain wind conditions (Guzman and DISTRIBUTION AND ABUNDANCE Myres 1983). The Short-tailed Shearwater only breeds in In the Gulf of Alaska. thc Short-tailed and Australia. There are known to be at least 167 Sooty Shcarwatcr arc the dominant birds in colonies around the coast of Tasmania and its spring and they prefer the continental shelf. near offshore islands. The total area of these which is between 100 and 150 km offshore colonies is I 522 ha and the number of burrows is (Harrison 1982). Numbers are greatest in May estimated at 11.--l million (Skira el al. 1986). The and by June their estimated density has dropped largest colonies are in Tasmania. on Babel Island by half. In the north-east of the Gulf. the with 2.86 million burrows and Trefoil Island with Kodiak area. Short-tailed Shearwaters out­ 1.54 million burrows (Towney and Skira 1985a number Sooty Shcarwatcrs by about 1.2: I with and b). Of other Australian States. Victoria has flock �izes numbering 32 000 (Gould et al. I .--l5 million burrows in about 30 colonies (Harris 1982) May, 1991 /. Skira: The biology of the Short-tailed Shearwater 47 ' CANADA ' ' '\ \ \ \ \ \ \ \ I I I California I I IIJ II I I I I I ,Is , I I I I I I I I I / / / ,,/ � ��/ � / ,, AUSTRALIA r-igur<: I. Map cn111pari11g 11ew 111igm1io11 ro111e (A) of Shorr-/(/i/ed Sheanvmers based 011 Japa11ese ship-board s1,r1•eys 10 rhe fig11re­ ofe1gh1 111ove111e111 ( B} of Serve111y ( 1953). Breedi11g areas are srippled. The return journey commences at the hegin­ 1981). The presence of birds along the coasts of ning of September. Many Short-tailed Shear­ Japan and North America led Scrvcnty to pos­ waters have been observed moving through the tulate a figure-of-eight migration (Scrvcnty 1953). western sector of the Pacific (Maruyama et al. However. data from seabird surveys by Japanese 1986). Some flocks pass south and well offshore ornithologists indicate that migration occurs on a through the Gulf of Alaska to off California broad front across the Pacific Ocean (Maruyama before heading across to Australia. but a lack of et al. 1986). Regardless of route. it is apparent sightings indicate that there is no migratory move­ that the movement of shcarwaters between the ment along the Canadian coast after August. two hemispheres occurs on a very broad front. It Some birds remain in the Northern Hemisphere is possible that the route followed varies with the during their first boreal winter (Forsell and Gould age or specific behaviour of the bird. 48 I. Skira: The biology of the Short-tailed Shearwater Corella 1 5(2) FEEDING high phosphorus levels and. thus. a high produc­ Shcarwatcrs commonly form large aggregations tivity. Factors tha t affect these water masses on the sea surfa ce called ·rafts'. These arc affect Short-tailed Shcarwaters be cause the common in calm we athe r and birds may thus abundance and availability of their food is depen ­ den t upon the a ttributes of the individual water assemble either when feeding or resting.