Brown Booby Sula Leucogaster Research Articles

Trace Metals Analysis in Brown Booby (Sula leucogaster) Collected from Ilha Grande Bay, Rio de Janeiro, Brazil

Concentracoes de metais traco:chumbo, zinco, cromo, cadmio, niquel e cobre foram estimadas em Atoba-pardo (Sulaleucogaster), colhidos na Baia da Ilha Grande, Rio deJaneiro, Brasil. Os niveis medios de concentracao no figado e no rim (μg.g-1 de peso seco), respectivamente foram 6,32955 e 6,57136 (Cd); 78,17409e 96,89409 (Zn); 44,01727 e 65,20864 ( Cu); 41,15091 e 39,62318 (Pb); 2,80091 e4,16455 (Cr) e 9,27182 e 9,91091 (Ni). Os resultados indicam niveis relativamente elevados de contaminacao por metais traco em S.leucogaster e os dados obtidos sao preocupantes pela extensao que pode causar para o nivel trofico da fauna marinha na regiao estudada.

Plunging Behaviour in Chick-rearing Brown Boobies

ABSTRACT Brown Boobies (Sula leucogaster) obtain prey by plunge dives. In order to investigate the foraging behaviour of Brown Boobies underwater, we attached acceleration data loggers to chick-rearing Brown Boobies at Nakanokamishima Island in Japan. We documented, for the first time, Brown Boobies performing many rapid and shallow V-shaped dives and some W-shaped dives during the daylight period. The average and maximum dive depth and duration were 1.03 m and 3.81 m and 1.83 s and 21 s, respectively. Furthermore, Brown Boobies used buoyancy to ascend to the water surface. Our data suggest that Brown Boobies mainly depend on shallow-plunging, contrary to the pursuit divers such as gannets, due to their ecological and/or physiological constraints.

Do mothers regulate facultative and obligate siblicide by differentially provisioning eggs with hormones?

We examined androgens in clutches of two booby species that differ in their sibling conflict. Blue-footed booby Sula nebouxii chicks show an aggression-submission relationship, aggression is normally moderate and siblicide is facultative. Brown booby Sula leucogaster chicks show an aggression-aggression relationship, aggression of both chicks can be relentless and siblicide is obligate. The parental favoritism hypothesis predicts that egg mass, yolk mass and yolk androgens should decline with laying order less in the blue-footed booby than in the brown booby, to promote the survival of the former's junior chick. The eggs of the blue-footed booby had higher yolk concentrations of 5α-dihydrotestosterone (DHT) and lower concentrations of testosterone (T); both species had similarly high yolk concentrations of androstenedione (A). Intra-clutch variation in yolk DHT, T and A failed to support our predictions. In both species, first and second eggs showed similar concentrations of all three hormones and were of similar size, although in the blue-footed booby (only) yolk masses declined with laying order. Brown booby mothers make junior chicks vulnerable to siblicide by hatching them 5 d after their broodmates, but not by differential allocation of egg androgens or nutrients. Blue-footed booby mothers appear to prepare junior chicks for thriving in a subordinate non-provocative role by hatching them 4 d after their broodmates and providing them with 10% less yolk. To orchestrate agonism within the brood, these boobies may rely more on hatch intervals and yolk provision than on androgens.

Sex‐specific foraging behaviour in tropical boobies: does size matter?

Sex differences in the foraging behaviour of adults have been observed in a number of sexually size‐dimorphic birds, and the usual inference has been that these sex‐specific differences are driven primarily by differences in body size. An alternative explanation is that foraging differences result from sex differences unrelated to size, such as sex‐specific nutritional requirements. To examine these alternative hypotheses, the foraging behaviour of parents was compared between two sympatric and congeneric species of seabird, the Brown Booby Sula leucogaster, which is highly sexually size‐dimorphic (females 38% larger) and the Red‐footed Booby S. sula, in which sex differences in body size are less marked (females 15% larger). Using temperature and depth loggers, we found that there were highly significant differences in the foraging trip durations and diving behaviour of male and female Brown Boobies. These sex differences were less marked in Red‐footed Boobies. Thus, our interspecies comparison revealed that the magnitude of the difference between the sexes matched the sexual size dimorphism of the species, providing support for the size hypothesis.

THE CHANGING STATUS OF MARINE BIRDS BREEDING AT SAN BENEDICTO ISLAND, MEXICO

We reviewed the status of the breeding marine birds on San Benedicto Island, Mexico, based on >100 years of published observations and seven of our own surveys conducted between 1978 and 2000. We found that there have been marked changes in the island avifauna with two main trends evident. First, a volcanic eruption destroyed much of the island in 1952. The Wedge-tailed Shearwater (Puffinus pacificus; estimated breeding population 1,000 pairs), Townsend's Shearwater (Puffinus auricularis; probable breeder, small numbers), and Red-footed Booby (Sula sula; 60 pairs) historically had much larger populations, but they apparently never fully recovered from the eruption. The Masked Booby (Sula dactylatra; 2,185 pairs), however, has become much more abundant perhaps due to changes in the vegetation. The second trend is that within the last three decades at least two, and possibly four, species from the central Pacific have colonized the island. The Laysan Albatross (Phoebastria immutabilis; 12 pairs) started breeding in the late 1980s; Black-footed Albatross (Phoebastria nigripes; 1 pair) in 2000. Red-tailed Tropicbirds (Phaethon rubricauda; probable breeder, 10 pairs) may have started breeding in the 1980s, and at least some of the breeding Brown Boobies (Sula leucogaster; 300 pairs) are from central Pacific populations. The reason(s) for this influx of central Pacific species is unknown, but likely involves changes in the marine environment. Other breeding species include the Red-billed Tropicbird (Phaethon aethereus; 200 pairs), Nazca Booby (Sula granti; 50 pairs), Great Frigatebird (Fregata minor; 165 pairs), and Magnificent Frigatebird (Fregata magnificens; 5 pairs).

Observations on the status of the land birds, wading birds and seabirds of Samoa

This paper reports my observations during 1994–97 for both American Samoa and [W] Samoa. New waders added to the Samoan list are Wood Sandpiper (Tringa hypoleucos), Red-necked Stint (Calidris ruficollis), and Red Knot (Calidris canutus). The new breeding records are for the Black-naped tern (Sterna sumatrana), Bridled Tern (Sterna anaethetus), the Common Noddy (Anous stolidus), Crimson-crowned Fruit Dove (Ptilinopus porphyraceus) and the Red-headed Parrot-finch (Erythura cyaneovirens), in Samoa. Crested terns (Sterna bergii), Brown Boobies (Sula leucogaster) and Fairy Terns (Sterna nereis) were also observed with juveniles and so must be regarded as possible breeders in one of the Samoas.

Parental investment, adult sex ratios, and sexual selection in a socially monogamous seabird

Although most birds are monogamous, theory predicts that greater female parental investment and female-biased adult sex ratios will lower the polygyny threshold. This should result in polygynous mating, unless obligate biparental care or the spatial and temporal distribution of fertilizable females constrains a male’s ability to take advantage of a lowered polygyny threshold. Here we present data on the extent of male sexually dimorphic plumage, adult sex ratios and breeding season synchrony in three populations of a socially monogamous seabird, the brown booby Sula leucogaster. For one of these populations, San Pedro Martir Island, we also present data on differences in male and female parental investment, mortality and probability of pairing. The extent of plumage dimorphism varied among populations. Sex ratios were female biased in all populations. On San Pedro Martir Island, parental investment was female biased, females failed more often than males to find a mate, but there was no polygyny. We suggest that on San Pedro Martir: (1) a period of obligate biparental care coupled with a relatively synchronous breeding season constrained the ability of males to take advantage of a high environmental polygamy potential and (2) the resulting socially monogamous mating system, in combination with the female-biased adult sex ratio, caused females to be limited by the availability of males despite their greater parental investment.

Biogeography and Prehistoric Exploitation of Birds in the Mussau Islands, Bismarck Archipelago, Papua New Guinea

SummaryThree archaeological sites on or near Mussau Island (Bismarck Archipelago, Papua New Guinea) have yielded 58 bird bones that represent 17 species (six seabirds, eight resident landbirds, two migrant shorebirds and one introduced species). Four of these (the petrel Pterodroma sp., Brown Booby Sula leucogaster, cockatoo cf. Cacatua sp. and owl Tyto sp.) have not been recorded previously from Mussau. The archaeological samples of birds from Mussau are too small to represent thoroughly the island's prehistoric avifauna. Nevertheless, they are important among avian bone assemblages from the Lapita Cultural Complex (c. 3500–2000 yr BP) for being the westernmost, among the best dated and associated with extensive cultural and environmental information. The Mussau samples also demonstrate that prehistoric losses of birds, such as those well documented in Polynesia, occurred as well in the Papuan region. Compared to avifaunas from Lapita sites in Western Polynesia (Tonga), the lower percentage of extinct/extirpated species from Mussau may be related to the island's more rugged terrain. Alternatively, it is possible that earlier, pre-Lapita peoples lived on Mussau and already had extirpated species.

A Record Crested TernSterna bergiiColony and Concentrated Breeding by Seabirds in the Gulf of Carpentaria

A Crested Tern Sterna bergii colony containing 13 000-15 000 nesting pairs was located on North Bountiful Island in the Wellesley Group, Gulf of Carpentaria. This is Australia's largest known colony and may be the largest documented colony in the world. Breeding birds are thought to aggregate in autumn from foraging areas throughout the vast eastern Gulf of Carpentaria. The outer Wellesley Islands also support major colonies of Brown Boobies Sula leucogaster, Least Frigatebirds Fregnta ariel and a newly discovered colony of approximately 1000 pairs of nesting Roseate Terns Sterna dougallii. Seabird nesting follows the summer monsoonal flooding and is presumably a response to nutrient enrichment of the Gulf by river runoff.

Malaysia's Last Seabird Refuge

The only breeding colony of the brown booby Sula leucogaster in Malaysia is declining steadily due to predation, mainly by fishermen who take eggs and young birds for food. However, if the predation could be controlled, a crop could be taken each year without endangering the colony.

Brown Boobies observed near Ogasawara Islands (Bonin Is.)

In July and August of 1968, "Seiyo maru" (the training and research ship belonging to the Tokyo University of Fisheries) had the research cruises near Ogasawara Islands.As a result: a) Almost all flying Brown Boobies Sula leucogaster were observed within the range of about 10 nautical miles from land. Only one individual of this species was seen exceptionally at about 35 nautical miles from land.b) Above mentioned Brown Boobies were mainly aggregated near Haha-shima islands and Muko shima islands.c) When our ship anchored at Haha-shima Island, some Brown Boobies seen were crowded on the ledges of Cape Inui-saki and Minami-saki, which may be one of the breeding areas of this species.d) Only one Sula dactylatra was seen between Chichi- and Haha Shima Retto.

BIRD RECORDS FROM SOUTHWESTERN ECUADOR

SummaryObservations are given for 25 species of birds seen in southwestern Ecuador or just offshore near the mouth of the Gulf of Guayaquil to supplement the records of Marchant (1958) and Lévêque (1964). Of the 25 species listed, 19 are sea‐birds and a number are species not commonly reported from the area. Two records of the Antarctic Fulmar Fulmarus glacbloides are given, one of which may be the first for Ecuador. The presence of Sooty Terns Sterna fuscata and possibly a few Brown Boobies Sula leucogaster just north of the Santa Elena Peninsula is unusual and was probably the result of an incursion of warm water from the west or north. In May 1966 450 + boobies, 10 Sooty Terns and 350 Brown Pelicans were counted on Isla Pelado (El Viejo) in Bahia de Santa Elena.