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SUMMARY (1) The breeding success and timing of laying of manx shearwaters breeding on Skokholm Island, Wales, are discussed. (2) Newly formed pairs have a lower hatching success (66-2%) than established pairs (79'1%). This is due to the fact that new pairs include birds without prior breeding experience and not to the newly formed pair bond per se. (3) When forming new pairs experienced breeding birds tend to mate with other experienced breeding birds rather than new breeders. (4) Divorce and burrow movement are both more likely after breeding failure than after success. (5) The timing of laying and the size of eggs laid are very constant from year to year, both for the population as a whole and for individual females. (6) The relationship of laying date and egg size to female age is described. (7) It is suggested that birds do not lay earlier than they do because, early in the season, the food supply would be inadequate to enable the adults to maintain continuous incubation. (8) Circumstantial evidence is presented suggesting that conditions for incubation improve during the incubation period.

In June 1977, Karen Bjorndal of the University of Florida collected the pelvis and leg bones of a single shearwater at Tortuguero beach on the Caribbean coast of Costa Rica (10'30'N, 83'30'W). The specimen is on deposit at the University of Florida (GSC 290). I compared the bones with skeletons of the eight species of Puffinus listed by Palmer (Handbook of North American birds, Yale University Press, New Haven, Connecticut, 1962). The following species were eliminated because their bones were smaller than the Tortuguero specimen: assimilis, bulleri, carneipes, iherminieri, puffinus, and tenuirostris. Puffinus gravis and P. griseus averaged just slightly larger than the specimen. The leg measurements for these two species overlap considerably, except for the height of the cnemial crest (Tortuguero Puffinus: 13.8 mm; P. gravis: 14.9-17.6 mm, N = 8; P. griseus: 18.8-20.9 mm, N = 8). The specimen agrees with P. gravis, the Greater Shearwater, in the following characters. Pelvis: the proximal, dorsal edge of the ilium is broad and rounded (narrow and pointed in griseus). Femur: the posterior intermuscular line extends onethird the length of the shaft from the distal end (onehalf the length in griseus). Tibiotarsus: (1) the proximal tip of the inner cnemial crest is more rounded (more pointed in griseus); (2) the internal ligamental prominence is high and rounded (low and ridgelike in griseus); (3) on the proximal end, in external view, the prominence extending distally from the head is indistinct (distinct in griseus). Tarsometatarsus: (1) the anterior lip of the external cotyla dips slightly towards the distal end (dips steeply in griseus); (2) in external view, the external calcaneal ridge is long (short in griseus). The Greater Shearwater ranges in open Atlantic waters from Tierra del Fuego to Labrador and Greenland. The Gulf of Mexico was not included in its range in the Check-list of North American Birds (Fifth ed., American Ornithologists' Union, Baltimore, Maryland, 1957). Arnold (Auk 92:394-395, 1975) first reported this species in the Gulf at Galveston, Texas. Eastern Caribbean records (Trinidad and Los Roques, Venezuela) were reviewed by Collins and Tikasingh (Bull. Br. Ornithol. Club 94:96-99, 1974). It was not listed by Slud (The birds of Costa Rica, American Museum of Natural History, New York, 1964). This then is the first record of the Greater Shearwater for Costa Rica and the western Caribbean. I thank Pierce Brodkorb for checking the identification of the specimen and for loaning comparative material.

Puffins Fratercula arctica were studied on Skomer Island, Wales (51?44'N, 5019'W) during 1972-77. Annual survival of breeding adults was 95%. Each year, 20-27% adults were without nesting burrows, and 2% were absent from the colony. 64% of pairs with burrows fledged a chick, with 5-16% not laying, 22-25% eggs not hatching, and 5% chick mortality. Much of the egg loss was caused by disturbance from prospecting Manx Shearwaters Puffinus puffinus which competed with Puffins for burrows. Data on the feeding and growth of chicks is given. Young Puffina first returned to the colony at two, or more usually three, years old. Four years was the earliest age for first breeding. At least 10-16% fledglings survived to four years old; it was not clear whether enough survived to replace adult mortality.

The distribution of pelagic birds was investigated over the continental shelf off southwestern Vancouver Island in September and October of 1986 and 1987. The California Gull (Larus californicus) had higher densities (average 61 birds/km) than all other birds combined and most gulls occurred in few but relatively large flocks near fish trawlers over offshore banks and the outer continental shelf. California Gulls were seen at more locations and in much smaller flocks in nearshore waters than further seaward. Glaucouswinged Gulls (L. glaucescens), Cassin's Auklets (Ptychoramphus aleuticus) and Common Murres (Uria aalge) occurred more in nearshore waters, while Sabine's Gulls (Xema sabini) and Sooty Shearwaters (Puffinus griseus) occurred mostly over the mid shelf. Pink-footed Shearwaters (P. creatopus) were generally observed to be further from shore than were Sooty Shearwaters. Northern Fulmars (Fulmarus glacialis) were most abundant in the deepest waters (100-200 m) and Common Murres in the most shallow waters (

Systematic field experiments show that procellariiform birds, viz., Black-footed Albatrosses (Diomedea nigripes), shearwaters (Puffinus griseus, P. creatopus, P. puffinus, P. bulleri, and P. tenuirostris), Northern Fulmars (Fulmarus glacialis), and storm-petrels of several species, are consistently attracted to sources of food-related odors under natural conditions at sea with controlled visual cues. They approach predominantly from downwind, in proportions above control levels, when food odors are presented as surface slicks, slicks spread in large shallow pools of plastic floating on the ocean, and by saturated wicks on free-floating rafts. Control stimuli and odorous materials unrelated to food do not attract procellariiforms. Birds of other orders are not attracted by any odorous stimulus, and approach the areas from all directions only when discrete visual stimuli are added. Observations and photographs reveal a flight pattern displayed only by procellariiforms in their apparent foraging approaches to food-related stimuli. Tube-nosed birds are most numerous under conditions of reduced visibility, high winds, large swells, and turbulent ocean surface. The results of this study strongly support the view, previously based on comparative anatomy and uncontrolled observations, that procellariiforms use olfaction in locating food. The ethology of olfaction is still largely unexplored in all vertebrates, and notably so for birds. Among avian olfactory systems, the nasal architecture and olfactory bulbs of the procellariiforms are impressive (Bang 1965, 1966, 1971). Cobb's (1960) measure, the ratio of olfactory bulb diameter to the largest diameter of the cerebral hemisphere, places tube-nosed species in 10 of the first 12 ranks for the 151 species among 23 orders on which measurements have been made (Bang 1971). These high values range from 0.27 for the Northern Fulmar (Fulmarus glacialis) to 0.37 for the Snow Petrel (Pagodroma nivea). The two other highest-ranking species, the Brown Kiwi (Apteryx australis) in rank 2 and the Turkey Vulture (Cathartes aura) in rank 10, have already been shown to respond discriminatively to appropriate food odors (Stager 1964, Wenzel 1969, 1971). The Rock Dove (Columba livia), now thought to be partly dependent on olfactory cues for homing (Papi et al. 1978, Keeton 1979), falls in midrange with a ratio of 0.17. Anecdotal evidence has long suggested that procellariiforms can distinguish odors (for review see Wenzel, in press). Some species can be attracted over long distances by griddle drippings, especially bacon fat, poured on the ocean surface and they often collect more quickly when the fat or oil has been heated (Murphy 1936, Miller 1942, Kritzler 1948). Several species of albatrosses discriminate between slicks of paint or petroleum and bacon fat or whale oil (Murphy 1936, Miller 1942). Two Snow Petrels in captivity accurately found hidden pieces of herring either outside in the snow or concealed inside a room (Jouventin 1977). In addition to feeding, other features of procellariif rm biology also suggest the possibility of olfactory guidance. Many species eject redolent stomach oil when disturbed. Secretion from the uropygial gland is typically odorous, accounting for the wellkno n musky scent of many procellariiforms. Such compounds might serve as olfactory markers to aid in identifying individual nesting burrows, chicks, and mates in densely populated breeding colonies (Stager 1967). Members of several species must find their burrows when they are obscur d by fog, clouds, overlying forests, d rkness, or snow cover. Few controlled experiments have been attempted on the olfactory behavior of procellariiforms. Grubb (1974, 1979) studied th role of olfaction in the return of Leach's Storm-Petrel (Oceanodroma leucorhoa) to its nesting burrow. After approaching their island upwind at twilight or after dark and crashing through the heavy wooded cover, breeding birds typically walked upwind to their burrows, in contrast to the inconsistent orientation of nonbreeders. Grubb found

Food from stomachs of 396 short-tailed shearwaters collected at three colonies was analysed. The main food items found were the euphausiid Nyctiphanes australis, and arrow squid Notodarus sloani gouldi, with fish, other crustaceans and squids forming a minor part of the diet. Plastic particles were common particularly at the beginning of the breeding season but gradually decreased in frequency as the season progressed.

Banding of the short-tailed shearwater or Tasmanian mutton-bird, Puffinus tenuirostris (Temminck), started in the Furneaux group of islands, north-east Tasmania, in 1947, with copper bands. In 1950 the more permanent monel bands were substituted. During the 10 years to the end of the 1956 nesting season, a total of 18,121 birds was marked. Details are given of the objectives of the programme and the nature of the banding, together with a discussion of the recoveries. Young birds return in general to the natal islands, usually from the age of 3 years and onwards. So far recoveries outside the breeding area are very few but two marked birds have been taken in the North Pacific on their contranuptial migration. Suggestions are given for the conduct of marking programmes on petrels to obtain the most productive results.

In 1946 an epizootic disease was found to be occurring among the juvenile Manx shearwaters (Puffinus puffinus) on Skomer Island, Pembrokeshire. A similar outbreak followed in 1947, and this was investigated by Dane (1948a, b). From material sent to Cambridge Miles & Stoker (1948) isolated a virus which appeared to be the causal agent and they suggested that the disease be named puffinosis. Further work on the virus is being published by Stoker and Miles (in the press). Epizootics in wild animal populations have not often been studied because of the obvious difficulties involved. However, in the case of the puffinosis epizootics there were certain features which made a detailed investigation possible. In the first place Manx shearwaters could be caught and examined fairly easily, and much had already been discovered about their life history and habits by Lockley (1942) and others; secondly, Skomer was an ideal place for such an investigation as it is isolated and of a convenient size; and finally planning was simplified by the regularity with which the epizootics occurred. Because of these rather exceptional advantages we decided to continue investigations on a larger scale in 1948 and 1949. In 1950 and 1952 we visited the island again, but on these occasions only to make certain limited observations. Before continuing with an account of our work in these years it will be necessary to give a brief description of Skomer, the Manx shearwater, and the epizootics of 1946 and 1947.

Stock, including sheep, are considered deleterious to ground-nesting birds and have been held responsible for declines in numbers of P. tenuirostris breeding in Bass Strait. Investigations during 1965-68 attempted to study possible interactions existing between sheep and shearwaters on Big Green I., Furneaux Group, Tas. The island has been stocked with sheep for more than 100 years and during this period changes in vegetation and decreases in colony size have been noted. Exclusion of sheep from a portion of a colony did not increase hatching or fledging success, nor was there a decline in either the number of burrows or in burrow utilization, in the sheep-trampled areas. Indeed, sheep activity over colonies appeared to decline during the birds' breeding season and it was concluded that burrow damage was due mainly to the birds themselves, with major damage occurring in the fenced area during the breeding season. Comparison of burrow stability on Green Island with that in another colony, again suggested that birds were responsible for nest destruction but that renovation by the birds tended to nullify the importance of the damage. Though shearwater colonies were once considered to be more widespread on Green Island, experiments have indicated that the vegetation, induced by man and perpetuated by sheep, was not preventing burrow formation and expansion of colony areas. Sheep have not, therefore, been shown to be responsible for past declines and other factors will be considered later.

INCE 1947 an intensive ecological study of the short-tailed shearwater, Puffinus tenuirostris Temminck, commonly known in Australia as the Tasmanian mutton-bird, has been carried out by Dr. D. L. Serventy, of the Division of Wildlife Research, C. S. I. R. O., with the cooperation of the Tasmanian Fauna Protection Board (Serventy, 1958). The study is confined to the breeding grounds of the species in southeastern Australia, particularly the Bass Strait, where birds are exploited for food and by-products such as oil, fat, and feathers. Birds spend the winter in the Northern Hemisphere, over the Sea of Okhotsk and the Bering Sea, in the region of the Aleutian Islands.

From 1947 to 1960,30,336 fledgling and adult short-tailed shearwaters, Puflnus tenuirostris (Temminck), have been banded in their south-eastern Australian breeding stations. Most of the fledglings were marked on commercial mutton-birding islands in connection with a "Lincoln Index" study of harvesting intensity, but 12,020 of these birds are considered to have survived the commercial operations to leave on their first migration. In addition, 1693 adults were banded on various islands. Recoveries at the banding-place confirm earlier work (a) on the degree to which young adults home back to their natal islands, and (b) on the site-tenacity of the established breeders. There have been 10 recoveries of marked birds in the North Pacific Ocean, and 11 along the east Australian coast and in New Zealand during the southward (spring) migration; also 9 recoveries of fledglings that perished at the natal area immediately after their first take-off. Altogether 24 of these recoveries were on birds in their first year of life, but relatively the numbers are small and represent a recovery rate, for that age-group, of about 1.3 per thousand from the time they leave their burrows.

The development of commercial fisheries in the Aleutian area, particularly the catching of salmon in the open sea with drifting gill nets, has stimulated interest in the food of the Pribilof seal (Callorhinus ursinus) in the Bering Sea. Added interest results from the decline in the salmon runs in Bristol Bay. Fisheries investigators believe that at least part of the salmon migrating to rivers entering Bristol Bay pass through areas in the Bering Sea where fur seals feed intensively. No pelagic investigation of the food of fur seals while in the Bering Sea has been made since Alexander's in 1892. This was summarized by Lucas (1899) who wrote that "In Bering Sea during August and September the pollack (Theragra chalcogramma) forms the staple article of food, a squid (Gonatus amoenus) coming next in importance, while some salmon and a few species of small fish are also eaten." Lucas quotes Alexander in stating that "material which has been found in the stomachs of seals taken in different parts of Bering Sea indicates that only a small percentage is composed of fish which inhabit deep water. It is only reasonable to suppose that when seals are in shallow water they feed on both bottom fish and those near the surface." Lucas footnoted the latter part of this statement, saying: There is, however, no evidence of this except in the rare presence of cottoids. . ." On the basis of stomachs collected from the killing fields, Kenyon (1956) has verified Alexander's statement. Most of the content of these stomachs (94 per cent) was composed of sand fish (Trichodon trichodon), which burrow in sand in relatively shallow water. The sturgeo -lik sea poacher (Agonus acipenserinus), second in importance, is also a bottom dweller. Fro 17 June to 20 July 1955, 204 fur seals were collected pelagically in the Bering Sea from Unimak Pa s and Unalaska to the Pribilof Islands. Most of the seals were collected by the authors by shooting with buckshot from the deck of a halibut schooner, the M/S Paragon. On the rare calm days two men worked from a dory powered with a 10horsepower utboard. In good weather this was as effective as the larger vessel, and fewer animals were lost when hunting with the dory. Throughout the period, seals were most abundant in or near Unimak Pass. Near the Pass were also Steller sealions (Eumetopias jubata), numerous humpback whales (Megaptera novaeangliae), and vast numbers of shearwaters (Puffinus spp.). It is reasonable to presume that the rich food supply attracted all thes forms. Pregnant females predominated among the seals collected, comprising 71 per cent of the total. Females without fetuses composed 16 per cent and males 13 per cent of the collection. Table 1 gives the food contained in the stomachs of 204 seals collected pelagically and of three others in the commercial kill at St. Paul Island where empty stomachs are the normal condition among the thousands we have examined. Capelin was the predominant food species in Unimak Pass and near the Aleutian Islands. It appears that concentrations of capelin are available for the seals during extensive portions of their northward migration. Scheffer (in Taylor, Fujinaga, and Wilke, 1955) found that capelin made up more

A collection of Acarina inhabiting the nests of the mutton bird, Puffinus tenuirostris Temminek, on Fisher I., Bass Strait, is described. Fourteen species, belonging mainly to the Mesostigmata are described or recorded of which two genera Laelapsella and Austruropoda, and six species Hypoaspis acme, Laelapsella humi, Gymnolaelaps annectans, Austruropoda tasmanica, Variatipes longisetosa, and Acotyledon (Cosmoglyphus) mykytowyczi are new, Haemolaelaps marsupialis Berlese 1910 is now redescribed in the female sex after a comparison of the type in the Berlese collection in Florence. The male is described for the first time. Of the species found Hypoaspis acme, Laelapsella humi, Gymnolaelaps annectans, Haemolaelaps glasgowi, and Mesolaelaps australiensis can be considered to be ectoparasites and the remainder, except Zachvatkinia puffini which is a true feather mite, are detritus and excreta feeders.

Although the ecology of several species of Procellariidae (petrels, shearwaters and fulmars) has been studied by many ornithologists, of the eleven genera only Fulmarus, Puffinus and Pachyptila have received much critical attention; Pterodroma, which comprises more species than any other genus in the family, has been little studied. This is because Pterodroma is an oceanic genus breeding in the tropics, sub-tropics and southern hemisphere in places difficult of access such as remote islands. In common with most pelagic birds the food and feeding habits of gadfly petrels (Pterodroma spp.) are known only vaguely (see Ashmole 1971). A number of authors have recorded food remains obtained from petrels they handled. Often stomachs were empty but for digestion-resisting fragments of cephalopod beaks and eye lenses, fish bones, crustacean exoskeleton or pieces of stone or pumice. This situation seems to result from rapid digestion combined with infrequent feeding. The following information applies to Pterodroma only; comparisons with some other genera are made in the discussion. Cephalopods have been reported in the diet of P. m. macroptera (Smith), P. m. gouldi (Hutton), P. cooki (Gray), P. leucoptera (Gould), P. neglecta (Schlegel), P. cahow (Nichols & Mowbray), P. lessoni (Garnot), P. solandri (Gould), P. brevirostris (Lesson), P. mollis (Gould) and P. phaeopygia (Salvin) (Sladden & Falla 1928; Oliver 1930, 1955; Falla 1934, 1937; Palmer 1962; Mougin 1969; Harris 1970; Serventy, Serventy & Warham 1971; Wingate 1972). Fish are eaten by P. inexpectata (Forster), P. phaeopygia, P. solandri and P. mollis (Kuroda 1955; Pocklington 1967; Harris 1970; Serventy et al. 1971). Crustacea are taken by P. macroptera gouldi, P. neglecta, P. phaeopygia, P. brevirostris and P. cahow (Sladden & Falla 1928; Oliver 1930; Larson 1967 per Harris 1970; Mougin 1969; Wingate 1972); those eaten by P. cahow include a small scarlet shrimp (Palmer 1962). Other pelagic organisms have been noted among food of P. macroptera gouldi and P. phaeopygia which took pteropods (Oliver 1930; Loomis 1918 per Harris 1970). But none of these workers was able to analyse the composition of the food or to identify food items to a lower level. Thus the food of gadfly petrels (and shearwaters, Puffinus spp.) was known only by generalizations until Ashmole & Ashmole (1967) examined the feeding ecology of Procellariidae, Phaethontidae (tropic-birds) and Sterninae (terns and noddies) on Christmas Island in the central Pacific Ocean. The petrels they studied were the phoenix petrel (Pterodroma alba (Gmelin)) and the Christmas Island shearwater (Puffinus nativitatis Streets). Detailed comparisons of their findings with mine are made in the discussion. In their analysis of samples from Pterodroma alba they identified several

MEINERTZHAGEN1 has described in South Greenland seas (c. lat. 60° N.) flocks of wing-moulting, and often temporarily flightless, great shearwaters (Puffinus gravis) which migrate trans-equatorially northward from their Tristan da Cunha breeding grounds (lat. 37° 6′ S.). He suggests that it “needs to be explained why the Great Shearwater moults in its winter quarters, whilst the Fulmar (Fulmarus glacialis) moults while the young are hatching”. (The fulmar, of course, breeds locally.)

In May and June, 1965, the author made five bird surveys in less known parts of Hokkaido. These are reported here under the headings: 1. Notes on birds along Shiretoko Peninsula (May), 2. Sea-bird survey of Kojima I., off Matsumae (May), 3. Observations of birds of Rishiri I. (June), 4. Bird survey of Cape Esan (May, June) and 5. Birds of Soya area and Rishiri. They are sea bird observations (pelagic census and breeding colonies) and notes on land birds.1. Along Shiretoko peninsula, sea bird colonies were observed from ship at some distance. The main colony was on the west-side cliffs at Iwaobetsu chiefly consisting of some hundreds of Larus schistisagus and Phalacrocorax capillatus with Ph. pelagicus and Cepphus carbo, etc. There were a few other smaller ones but they could not be observed at close range. According to local observer, Mr. Yoshida, there appears to be some colonies of Uria aalge, Lunda cirrhata, Cerorhinca monocerata, and breeding of Fratercula and Brachyramphus marmoratus, possibly also Phalacrocorax urile is suggestive. Summer records so far known for Brachyramphus are listed and two birds were encountered this time. A flock of scores of Larus crassirostris were observed near the tip of the peninsula but the breeding was not confirmed. According to Yoshida, he saw chicks of Histrionicus with an adult bird in June, 1963. A White-tailed Sea Eagle was seen on a pack ice with some Larus schistisagus; it breeds at several places of the peninsula. Two Japanese Robins, Erithacus akahige, were unexpectedly found at rocky tip of the peninsula where there were no vegetations and some snow was remaining. Offshore census of sea birds is given in tables.2. Kojima I. is situated in 139°50'E, 41°20'N, 20km. WSW of Matsumae, the southwesternmost tip of Hokkaido. It is a small volcanic island with a coastal line of about 7km., surrounded by steep cliffs and inhabited only by lighthouse keeper family. The breeding species consisted of Larus crassirostris, Uria aalge, Cerorhinca monocerata, Cepphus carbo and Phalacrocorax capillatus, as on Teuri I. (Kuroda, 1963). Many nest burrows of Cerorhinca were found excavated (by a dog of the lighthouse) and this puffin was apparently decreasing (but increasing at Teuri I.) judging from remains of nests on which grasses were already growing. Gull eggs were still being taken by fishermen and thus protection of the whole island is hoped. The time (May 14) was too early (the season was 10-14 days in retard this year) for Uria aalge which we saw only a few, but on May 31 some hundreds were seen by Mr. Saito. On the island some passerines on migration (both leaving winter bird such as Turdus naumanni and arriving summer birds such as Muscicapa narcissina were found). Scattered Cerorhinca and some flocks of Puffinus griseus and P. carneipes were seen in this sea area and a huge migrating flock of about 3, 000 birds (probably of the latter species) were flying northwestward off Cape Shirakami in an endless line. A flock of 300 birds of this species (definitely identified) had been observed on May 7 all making west the Tsugaru Strait.3. Rishiri and Rebun Is. (See also 5.) situated at a little north of 45N°, west of Wakkanai, northern end of Hokkaido, were visited June 7-9, staying on Rishiri. Cerorhinca was found scattered on the sea between Wakkanai and the islands and many were non-breeding birds without the bill-nob. A small number of Puffinus tenuirostris was seen confined off Wakkanai, a great flock of about 1, 500 of P. griseus consisting of numerous small groups was making a circular movements over the sea area between Rishiri and Rebun

Three marked individuals of the short-tailed shearwater, Puffinus tenuirostris (Temminck), first reproduced at 5, 6, and 7 years of age, respectively. Immature birds (pre-breeders) return to the islands on which they were reared at, usually, 3 years of age. These, and the 4-year old birds, visit the rookeries between January and mid Xarch. The non-breeding 5, 6, and 7-year old birds arrive with the breeding adults in November and cease vis~ting the rookeries by mid January.

A study of the Tasmanian mutton bird or short-tailed shearwater, Puffinus tenuirostris (Temminck), has been in progress at its nesting grounds in islands of the Furneaux Group, Bass Strait, since 1947.