Breeding Islands Research Articles

Sustainable Exploitation of Streaked Shearwaters Calonectris leucomelas on Mikura Island, off the Izu Peninsula, Japan

For at least 250 years, the harvesting of Streaked Shearwaters on Mikura Island was regulated by a series of traditionally developed and adopted rules based on ecological knowledge of the species that kept numbers at a steady level. The island's breeding population of streaked shearwaters it still one of the largest known in the north western Pacific. The traditional rules for harvesting were as follows: 1) only older chicks were allowed to be taken, 2) fowling was open on only a few days a year, and 3) only minimal disturbance of colonies was permitted during the breeding season. Chicks were taken for non-commercial uses at home and exchange with neighboring islands. Almost all parts of the chick bodies were used. The human population on Mikura Island was kept low due to the low carrying capacity of the island and the peculiar population control in the island society until the late 1800s, which also played an important role in avoiding over-exploitation of the shearwaters. Traditional taking of natural resources based on a good knowledge of ecology is quite different from the plundering of natural resources, which often occurred on other remote breeding islands of shearwaters and albatrosses caused by visitors without ecological knowledge.

SURVIVAL RATES FOR THE HAWAIIAN MONK SEAL (MONACHUS SCHAUINSLANDI)

Abstract: Endangered Hawaiian monk seal (Monachs schauinslandi) pups at all the major breeding islands in the Northwestern Hawaiian Islands have been tagged since the early 1980s. Pups were double flipper tagged as soon as possible post‐weaning. With few exceptions, an extensive tag resighting effort was conducted annually at the same islands. These resighting data were used to estimate seal survival rates from the time of tagging to age one at all locations using the ratio of seals alive in the second year to number of pups tagged. These survival rates among the islands, from weaning to age one, averaged over the years of the study, ranged from 0.80 to 0.90. For young seals over age one, capture‐recapture methods were used to calculate survival pooled through several years, and these rates ranged from 0.85 to 0.98. At French Frigate Shoals and Laysan Island, the higher numbers of tagged pups allowed separate estimates of male and female survival to be calculated. These rates suggested that survival of immature females was better than males. Beginning in 1989, survival of immature seals at French Frigate Shoals declined sharply.

The behaviour of mature male sperm whales on the Galápagos Islands breeding grounds

The behaviour of mature male sperm whales (Physeter macrocephalus) was observed off the Galápagos Islands between 1985 and 1991. The abundance of males peaked in April and May at 3% of the population. Only 1 of the 18 photographically identified males was sighted off the Galápagos in two different years. In their residency periods off the Galápagos and their lack of preferred ranges, and in many aspects of their behaviour, males were similar to females. However, unlike females, males were sometimes seen alone and never performed any aerial behaviour. Although they were occasionally seen or heard together, there are indications that males avoided one another, perhaps by listening for the "slow click" vocalizations made by males approximately 75% of the time. One incidence of possible aggression between males was observed, and many males possessed parallel scars on their heads, presumably made during aggressive encounters. Males moved between groups of females, spending very approximately 8 h with each group. Groups of females were often revisited by particular males over periods of a few days but never over more than 1 week. Males showed no obvious preference for particular groups, although a few close associations between individual males and individual females were noticed over intervals of a few days. When males were present, females showed increased rates of making spyhops and sideflukes (indicating manoeuvring) and codas (a communicative vocalization). Copulation was not observed. The evidence is consistent with males' maximizing their expected reproductive success by roving between groups of females.

A review of the status, distribution and conservation of the Socotra Cormorant, Phalacrocorax nigrogularis

Abstract The Socotra Cormorant Phalacrocorax nigrogularis is endemic to the Arabian (Persian) Gulf, the Arabian Sea and the Gulf of Aden. Based on data available in the literature and on personal observations in Saudi Arabia, the status, distribution and conservation requirements of the species are summarized. The total world population may still consist of 500,000 to 1 million birds. Nevertheless there are only a few important breeding colonies. Several breeding colonies have been lost in the most recent past due to industrial development and an increase in human activity on and around the breeding islands. These pressures are now threatening several of the surviving colonies. Urgent action has to be taken to give effective protection to this highly vulnerable species, A general plan to enhance the conservation status of this species and its breeding colonies is put forward.

Some Life-History Parameters of a Declining Population of Southern Elephant Seals, Mirounga leonina

Mark-resight data were analysed for 13 cohorts from a declining population of southern elephant seals branded at Macquarie Island between 1951-1965. First year survival was essentailly stable during the 1950s at c46% for females and 42% for males. There was a dramatic fall in first year survial during the 1960s, declining to <2% for both sexes in 1965. Post-year-1 survival did not change between the 1950s and the 1960s. Comparisons with a stable population of southern elephant seals at South Georgia indicated that both first year and adult survival were lower in the Macquarie Island population. There were no changes in the age at first breeding of the Macquarie Island seals during the study, but this was on average 1 yr later than at South Georgia. The current decline in elephant seal numbers at several of their major breeding islands may be due to the populations returning to pre-sealing levels after they had risen to abnormally high levels with the end of commercial exploitation early this century. -from Author

Compte rendu ornithologique camarguais pour les années 1986-1987

This bird report covers the years 1986-1987 and is a sequel to the bi-annual reports begun in the 1930’s of the major ornithological events recorded in the Camargue and neighbouring Crau and Alpilles. Several researchers present the results of long-term monitoring programmes and there are observations of rare species (but only those accepted by the Rareties Committee) or the more regular ones recorded in unusual numbers, or outside the normal dates of presence in the region. There were spells of severely cold weather in February 1986 and again, for the 3rd consecutive winter, in January 1987, this latter being the more severe of the two. Flamingos and egrets suffered less than in January 1985 but passerines were hard hit, particularly Cetti’s and Fan-tailed warblers and Bearded Tits. Rainfall over the two years was quite high and as a result the salinity of the Vaccarès lagoon dropped from 33 g/1 to only 20 g/1 by the end of 1987. All european grebes have been recorded in the delta and their numbers have increased on the Vaccarès where 1 000 or more Great-crested and around 3 000 Black-necked were censused both years. The Grey Heron breeding population continues to increase and there were a record 891 pairs censused in the Camargue area in 1986. In winter the Great White Heron is now a regular visitor with up to 35 individuals. Storks are still regular on migration with 8 Black and 43 White in autumn 1987. Record numbers of flamingos were again breeding in 1986 and 1987 with 20 000 and 17 500 pairs respectively and a record 8 590 chicks raised in 1986. In 1987, only 2 200 chicks were raised because of disturbance caused by a child’s balloon blown onto the breeding island during hatching. The banding programme continues and 600 chicks were marked each year. During the cold spell of January 1987 about 100 flamingos died, one of the victims being marked with an Iranian ring from Lake Rezaiyeh. Waterfowl counts revealed record numbers of Shelducks in February, with 2 745 in 1986 and 3 590 in 1987. The Mute Swan breeding population continues to increase in the area and the Bewick’s peaked at 105 in January 1986. A small flock of Grey-lag Geese now winters in the Camargue and one bird has been seen wearing a Swedish ring. Midwinter counts of ducks and coots have now been made over 24 consecutive seasons. Although Gadwall and Shoveler numbers have increased in recent years the overall numbers of ducks have decreased for the thirteenth consecutive winter. This decline is attributed mainly to excessive hunting and an increase in the salinity of Camargue lagoons. Other notorious winter visitors to the delta have been Sea and Booted Eagles in 1986 and 1987, and 7 cranes in 1986. Amongst the rarer waders is the 4th record of a Pectoral Sandpiper, a spring report of Buff-breasted Sandpiper and several observations of Wilson’s Phalarope, Terek Sandpiper and Black-winged Pratincole. Finally, a record 193 pairs of Slender-billed Gulls bred in 1987 and 35 pairs of Mediterranean gulls in 1986.

White Pelican Reproduction in the Molly Islands Breeding Colony, Yellowstone National Park

Compared to other North American White Pelican, Pelecanus erythrorhynchos, breeding colonies, the Molly Islands Colony is a minor colony consisting of 400-600 adults (Lier and Behle, 1966: Diem and Condon, 1967: Sloan, 1973; Diem, 1976). Despite its small size, the colony is unique for these reasons: 1) it is the only White Pelican breeding colony in a national park; 2) the location of the colony at an elevation of 2,357 m is the highest recorded for any breeding colony of the species; 3) discovered in 1890, the colony has had variable surveillance since 1917, with relatively intense monitoring since 1965: 4) the breeding population is composed of birds from both coasts of North America; and 5) the colony's nesting sites on the two Molly Islands change frequently with no predictable pattern. In addition, a cumulative substrate uplift along the north shore of Yellowstone lake appears to have significantly raised the stable water level of the southern arms of the lake. Consequently, the major objective of this project is to continue monitoring changes in the reproductive success of the Molly Islands White Pelican colony and to continue studies of the factors influencing those changes.

Notes on Blue and Kerguelen Petrels Found Beach-Washed in Victoria, 1984

SUMMARYBROWN, R.S., NORMAN, F.I. and EADES, D.W. 1986. Notes on Blue and Kerguelen Petrels found beach-washed in Victoria, 1984. Emu 86: 228–238.Weights and measurements from Blue and Kerguelen Petrels Halobaena caerulea and Pterodroma brevirostris found beach-washed in Victoria between 23 June and 8 September 1984 are given, and details of reproductive condition, items found in gizzards and aspects of feather wear and moult are also presented. Some data from birds held in the Western Australian Museum, and the Museum of Victoria, are also discussed. Whilst body measurements of the 1984 birds were similar to those presented by other authors for birds caught on breeding islands, body weights were reduced by about a third.The gizzards of both species contained cephalopod remains (from eight families), but Blue Petrels had ingested a variety of food items (including freshwater and terrestrial insects), and debris (including plastic pellets, foil and fragments, aluminium foil and pumice), apparently from the sea surface. The probable difference, and consequences, in feeding strategies in relation to diet, bill structure and wing loading are discussed.From feather wear and reproductive parameters we conclude that the wrecked Kerguelen Petrels were of a mixed age, but the Blue Petrels were mostly birds of the year. Assuming an origin to the west and or south of Australia, weather systems preceding their occurrence are discussed. The strong winds which finally drove them onshore may have been the proximate cause of death but it is likely that such birds were already weakened by starvation and depletion of food resources.

A field experiment demonstrating the influence of seabird guano on intertidal primary production

Nutrient concentrations in intertidal rockpools on the shores of seabird breeding islands off the west coast of South Africa are significantly higher than concentrations in similar pools on mainland shores. This is due to the presence of terrestrial and upper intertidal guano deposits which are washed through the intertidal zone. Growth rates of intertidal macroalgae are significantly faster on the rocky shores of seabird breeding islands than on mainland rocky shores, and the extensive, permanent algal mats that develop on island shores are absent from mainland shores. The hypothesis that guano run-off enhances intertidal algal growth was tested experimentally at a site on the west coast of South Africa where no seabird colonies exist. Seawater, artificially enriched with guano, was trickled down an intertidal rocky slope during a period of two months. Algal settlement and growth on artificial surfaces were significantly enhanced by the guano treatment when compared with controls. The conclusion is that increased intertidal primary production on seabird islands, and the consequent modification of intertidal community structure, are due in part to nutrients which are introduced into the intertidal zone by run-off from the guano cap and by direct deposition of guano in the high-shore region by roosting birds.

Group Size in Foraging African Penguins (Spheniscus demersus)

AbstractDiving synchrony was examined for varying group sizes of African penguins (Spheniscus demersus) travelling to their foraging grounds from their breeding islands. Groups of fewer than 12 birds always dived synchronously, whereas groups of more than 17 birds always dived asynchronously. Since travelling penguins do not dive deeply, large groups of birds can remain together irrespective of diving synchronization. Observations from boats showed that foraging penguins rarely occurred in groups of more than 17 birds. We suggest that groups of penguins that do not have synchronized dives cannot forage effectively, because foraging penguins dive deeply.

Seabird guano as a determinant of rocky intertidal community structure

Seabird guano is recognized as a powerful fertilizer and its entry into the intertidal zone of seabird breeding islands off the west coast of South Africa is hypothesized to cause enhanced intertidal algal production. Intertidal nutrient levels and algal production were measured monthly on the shores of seabird islands and on nearby mainland shores where no aggregabons of seabirds occur. The shores of seabird islands were characterized by significantly higher levels of nutrients and significantly enhanced algal production. Nutrient enrichment, in conjunction with the predatory activity of African black oystercatchers on ~nterbdal herb~vorous hmpets, leads to the formation of extensive, permanent mats of foliose algae on the shores of seabird breeding islands. Mussel spat, polychaetes and small crustaceans settle in the algal mats and provide food for small shorebirds. The structures of intertidal algal, invertebrate and avlan communities on the shores of seabird islands are significantly altered by the activities of guano-producing seabirds and predatory shorebirds.

White Pelican Reproduction in the Molly Islands Breeding Colony, Yellowstone National Park

Compared to other North American White Pelican, Pelecanus erythrorhynchos, breeding colonies, the Molly Islands Colony is a minor colony consisting of 400-600 adults (Lier and Behle, 1966; Diem and Condon, 1967; Sloan, 1973; Diem, 1976). Despite its small size, the colony is unique for these reasons: 1) it is the only White Pelican breeding colony in a national park; 2) the location of the colony at an elevation of 7,733 ft (2,357 m) is the highest recorded for any breeding colony of the species; 3) discovered in 1890, the colony has had variable surveillance since 1917, with relatively intense monitoring since 1965; 4) the breeding population is composed of birds from both coasts of North America; and 5) the colony's nesting sites on the two Molly Islands change frequently with no predictable pattern. In addition, a cumulative substrate uplift along the north shore of Yellowstone Lake appears to have significantly raised the stable water level of the southern arms of the lake. Consequently, the major objective of this project is to continue monitoring changes in the reproductive success of the Molly Islands White Pelican colony and to continue studies of the factors influencing these changes.

Distribution and Migration of Smaller Petrels of the Genus Pterodroma in the Northwest Pacific

Pterodroma nigripennis and P. longirostris were observed in the Northwest Pacific during several cruises on R. V. Hakuho Maru from May to November between 1980 and 1984 (the north of 7°N, the west of 180°E). It can be deduced that P. nigripennis and P. longirostris fly regularly every year in the Northwest Pacific, and during these observations there were no species of smaller petrels to migrate in these areas except the above species including P. hypoleuca. With regard to the season of migration of P. nigripennis to the Northwest Pacific, they migrate to these areas in June-July, and in August-September there are great numbers in the waters southesast of Honsyu, then they return to the breeding islands after November. The favoured water temperature of P. nigripennis is in the range 25°-28°C, so it is surmised that they do not move in the waters off Sanriku to the north of 38°N. P. longirostris migrate to the waters far east of Honsyu in May-June and concentrically distribute in the waters off Sanriku between late July and September, in this season they were feeding mainly at the waters in front of Kuroshio Current, and then they beign to return to their breeding islands. The three smaller petrels occurred in areas where surface water temperatures ranged from 16°C to 31°C in June-September, P. nigripennis favour in areas with the highest water temperature in these species and P. hypoleuca next, but when these species distribute in the Northwest Pacific, they devide a feeding area for keeping away from competition. In the Northwest Pacific P. hypoleuca and P. nigripennis formed mixed groups with sea birds which the breeding islands or distribution areas are same with them, on the other hand P. longirostris formed large flocks with the storm petrels in having same feeding areas.

White Pelican Reproduction in the Molly Islands Breeding Colony, Yellowstone National Park

Compared to other North American White Pelican, Pelecanus erythrorhynchos, breeding colonies, the Molly Islands Colony is a minor colony consisting of 400-600 adults (Lier and Behle, 1966; Diem and Condon, 1967; Sloan, 1973; Diem, 1976). Despite its small size, the colony is unique for these reasons: 1) it is the only White Pelican breeding colony in a national park; 2) the location of the colony at an elevation of 7,733 ft (2,357 m) is the highest recorded for any breeding colony of the species; 3) discovered in 1890, the colony has had variable surveillance since 1917, with relatively intense monitoring since 1965; 4) the breeding population is composed of birds from both coasts of North America; and 5) the colony's nesting sites on the two Molly Islands change frequently with no predictable pattern. In addition, a cumulative substrate uplift along the north shore of Yellowstone Lake appears to have significantly raised the stable water level of the southern arms of the lake. Consequently, the major objective of this project is to continue monitoring changes in the reproductive success of the Molly Islands White Pelican colony and to continue studies of the factors influencing those changes.

White Pelican Reproduction in the Molly Islands Breeding Colony, Yellowstone National Park

Compared to other North American White Pelican, Pelecanus erythrorhynchos, breeding colonies, the Molly Islands Colony is a minor colony consisting of 400-600 adults (Lier and Behle, 1966; Diem and Condon, 1967; Sloan, 1973; Diem, 1976). Despite its small size, the colony is unique for these reasons: 1) it is the only White Pelican breeding colony in a national park; 2) the location of the colony at an elevation of 7,733 ft (2,357 m) is the highest recorded for any breeding colony of the species; 3) discovered in 1890, the colony has had variable surveillance since 1917, with relatively intense monitoring since 1965; 4) the breeding population is composed of birds from both coasts of North America; and 5) the colony's nesting sites on the two Molly Islands change frequently with no predictable pattern. In addition, a cumulative sutstrate uplift along the north shore of Yellowstone Lake appears to have significantly raised the stable water level of the southern arms of the lake. Consequently, the major objective of this project is to continue monitoring changes in the reproductive success of the Molly Islands White Pelican colony and to continue studies of the factors influencing those changes.

White Pelican Reproduction in the Molly Islands Breeding Colony, Yellowstone National Park

Compared to other North American White Pelican, Pelecanus erythrorhynchos, breeding colonies, the Molly Islands Colony is a minor colony consisting of 400-600 adults (Lier and Behle, 1966; Diem and Condon, 1967; Sloan, 1973; Diem, 1976). Despite its small size, the colony is unique for these reasons: 1) it is the only White Pelican breeding colony in a national park; 2) the location of the colony at an elevation of 7,733 ft (2,357 m) is the highest recorded for any breeding colony of the species; 3) discovered in 1890, the colony has had variable surveillance since 1917, with relatively intense monitoring since 1965; 4) the breeding population is composed of birds from both coasts of North America; and 5) the colony's nesting sites on the two Molly Islands change frequently with no predictable pattern. In addition, a cumulative substrate uplift along the north shore of Yellowstone Lake appears to have significantly raised the stable water level of the southern arms of the lake. Consequently, the major objective of this project is to continue monitoring changes in the reproductive success of the Molly Islands White Pelican colony and to continue studies of the factors influencing those changes.

Mother-pup separation and adoption in northern elephant seals

The evolution of fostering behavior, parental care directed toward another's young, has been the focus of much recent interest. During a five-year study of northern elephant seals (Mirounga angustirostris) at Ano Nuevo, California, we recorded the frequency of mother-pup separation, reunion, and adoption of orphaned pups in crowded and low-density breeding areas. While most females nursed their own pup exclusively until it was weaned, many females, especially young mothers (age 3–5 years), were unable to raise a pup successfully. In the crowded main breeding harem on Ano Nuevo Island, 24 to 47 percent of the pups born each year were separated from their mothers from 1977 to 1980. Mother-pup separation and pup mortality were associated with the following inter-related factors: 1) female density; 2) weather and tidal conditions; 3) topographical features of the breeding areas (i.e., degree of exposure to high tides and surf); and 4) the proportion of young, maternally inexperienced females pupping in a particular area. Most motherpup separations were caused directly by 1) adult males moving through the harem; 2) pups wandering from their mothers; 3) female aggression; and 4) inclement weather. Most of the separations, as well as adoptions, occurred when pups were quite young. Mother-pup recognition appeared to be based on a combination of acoustic, visual, and olfactory cues, and most mother-pup reunions were effected by the female rather than her pup. On the main island breeding area, 572 orphans were marked. Of these, five percent relocated their mother, 27 percent were adopted or frequently cared for by foster mothers, and 68 percent were not adopted, or rarely fostered. The survival of an orphan was clearly contingent on the amount of care it received; most orphans which were not nursed or protected by females died before reaching 6 weeks of age. Frequently, an adopted orphan's foster mother was in the stage of lactation which corresponded closely to that of its own mother. The most common fostering event involved females that had lost their own pup and adopted a single orphan. Other pupless females attempted to steal a pup, cared for a pup while it was still with its mother, adopted a weaned pup, adopted two pups, or indiscriminately nursed any orphaned pup that approached. Some females kept their own pup in addition to fostering in alien pup. Most foster mothers were young and had little or no previous maternal experience. The formation of large, high-density breeding rookeries, due to a scarcity of suitable breeding sites, results in frequent mother-pup separations, especially during inclement weather and tidal conditions. Many opportunities for adoptive behavior are therefore presented, because of the great number of orphans and pupless females. Increased maternal experience appears to be a benefit associated with adoption. Some instances of fostering behavior may also be based on “reproductive errors” on the part of the foster mother.

Key Lois and Raccoon Key: Florida Islands for Free‐Ranging Rhesus Monkey Breeding Programs

The importance of the rhesus monkey (Macaca mulatta) in biomedical research has resulted in the development of domestic breeding programs to ensure annual quantities for specific research projects. Charles River Breeding Laboratories, Inc. began the establishment of the first commercial, free ranging rhesus monkey island (Key Lois) breeding colony in 1971 within the continental United States. A second island (Racoon Key) was developed in 1977. Operations unique to these free‐ranging colonies with respect to procurement, quarantine, microbiological assessment, transportation, facilities, and daily operational procedures are described.

White Pelican Reproduction in the Molly Islands Breeding Colony, Yellowstone National Park

Compared to other North American White Pelican, Pelecanus erythrorhynchos, breeding colonies, the Molly Islands Colony is a minor colony consisting of 400-600 adults (Lier and Behle, 1966; Diem and Condon, 1967; Sloan, 1973; Diem, 1976). Despite its small size, the colony is unique for these reasons: 1) it is the only White Pelican breeding colony in a national park; 2) the location of the colony at an elevation of 7,733 ft. (2,357 m) is the highest recorded for any breeding colony of the species; 3) discovered in 1890, the colony has had variable surveillance since 1917, with relatively intense monitoring since 1965; 4) the breeding population is composed of birds from both coasts of North America; and 5) the colony's nesting sites on the two Molly Islands change frequently with no predictable pattern. The major objective of this project is to continue monitoring changes in the reproductive success of the Molly Islands White Pelican colony and to continue studies of the factors influencing those changes.

ROSEATE TERN BREEDING BIOLOGY AND FACTORS RESPONSIBLE FOR LOW CHICK PRODUCTION IN ALGOA BAY, SOUTH AFRICA

Summary Randall, R. M. & Randall, B. M. 1981. Roseate Tern breeding biology and factors responsible for low chick production in Algoa Bay, South Africa. Ostrich 52:17-24. Roseate Terns Sterna dougallii were studied in 1977 on St Croix Island, Algoa Bay, South Africa. They are winter breeders in Algoa Bay and remain away from the breeding islands until about three weeks before the first eggs are laid. Full breeding dress is usually attained by the time the chicks hatch, when red appears on the culmen. Reasons are given for regarding the red culmen as an intraspecific aggressive signal. Nest density was 0,2/m2 with a mean nearest neighbour distance of 0,66 m ± 0,27 m. Mean size of first clutches was 1,32 eggs, of replacement clutches was 1,03 eggs. Eggs measured 42,1 mm (39,8-44,5 mm) x 30,1 mm (28,6-31,5 mm). In clutches of two eggs, first eggs had significantly larger volumes than second eggs. Incubation took about 25 days and one of the pair did most of the incubating. Rearing took less than 28 days and ...