Successful same-sex pairing in Laysan albatross

Unrelated same-sex individuals pairing together and cooperating to raise offspring over many years is a rare occurrence in the animal kingdom. Cooperative breeding, in which animals help raise offspring that are not their own, is often attributed to kin selection when individuals are related, or altruism when individuals are unrelated. Here we document long-term pairing of unrelated female Laysan albatross (Phoebastria immutabilis) and show how cooperation may have arisen as a result of a skewed sex ratio in this species. Thirty-one per cent of Laysan albatross pairs on Oahu were female-female, and the overall sex ratio was 59% females as a result of female-biased immigration. Female-female pairs fledged fewer offspring than male-female pairs, but this was a better alternative than not breeding. In most female-female pairs that raised a chick in more than 1 year, at least one offspring was genetically related to each female, indicating that both females had opportunities to reproduce. These results demonstrate how changes in the sex ratio of a population can shift the social structure and cause cooperative behaviour to arise in a monogamous species, and they also underscore the importance of genetically sexing monomorphic species.     

Adaptive value of same-sex pairing in Laysan albatross

Same-sex pairing is widespread among animals but is difficult to explain in an evolutionary context because it does not result in reproduction, and thus same-sex behaviour often is viewed as maladaptive. Here, we compare survival, fecundity and transition probabilities of female Laysan albatross in different pair types, and we show how female–female pairing could be an adaptive alternative mating strategy, albeit one that resulted in lower fitness than male–female pairing. Females in same-sex pairs produced 80% fewer chicks, had lower survival and skipped breeding more often than those in male–female pairs. Females in same-sex pairs that raised a chick sometimes acquired a male mate in the following year, but females in failed same-sex pairs never did, suggesting that males exert sexual selection by assessing female quality and relegating low-quality females into same-sex pairs. Sexual selection by males in a monomorphic, non-ornamented species is rare and suggests that reconsideration is needed of the circumstances in which alternative reproductive behaviour evolves. Given the lack of males and obligate biparental care in this species, this research demonstrates how same-sex pairing was better than not breeding and highlights how it could be an adaptive strategy under certain demographic conditions.     

Epidermoptid mange in Laysan albatross fledglings in Hawaii

Mange caused by the epidermoptid mite Myialges nudus (Acari: Epidermoptidae) is described in 31 dead fledgling Laysan albatrosses (Phoebastria immutabilis) from Midway Atoll (Hawaii, USA) sampled from 18 June to 10 July 1990 and from 21 June to 22 July 1991. This is the first record for this parasite from this host. Mites were collected from the skin; were located primarily in the stratum corneum; and were associated with mild to severe granulomatous inflammation, hyperkeratosis, dermal edema, ballooning degeneration of keratinocytes, neovascularization, and subdermal fibrosis. The severity of inflammation in some birds suggested that dermatitis due to M. nudus could be a significant cause of morbidity, or even mortality, in these birds.     

Accumulation and toxicity assessment of polychlorinated biphenyls in black-footed albatross (Diomedea nigripes) from Midway Atoll,North Pacific Ocean

Polychlorinated biphenyls (PCBs) are ubiquitous chemicals that were used as additives in capacitors and transformers; and heavy contamination in the past of Midway Atoll, a national wildlife refuge, puts the wildlife, including the black-footed albatross (BFAL), at risk. In this study, we assess the profiles and toxicity of the individual PCB congeners at a natural equilibrium state in various tissues of 1-month old and 4–5-month old BFAL chicks and black-footed and Laysan albatross eggs found on the atoll. In the 1-month old chicks from Midway Atoll, the major seven congeners PCBs 99, 118, 138, 153, 170, 180 and 183 accounted for 36–78% of the total PCBs in the various body parts, and the total PCB concentrations in the bird samples are inversely related to the total body weights. In the 4–5-month old chicks, these same congeners accounted for much lower percentages (7–26%) than in the 1-month-old chicks, with higher amounts of the less chlorinated congeners. The total toxic equivalents (TEQs) for all of the tissues in the 1-month old chicks ranged from 130 to 11,000 pg g⁻¹ (lipid weight, lw), and the total TEQs for the 4–5-month old chicks ranged from 18,000 to 100,000 pg g⁻¹. The average total concentration was 7.9 and 4.6 μg g⁻¹ lw in the BFAL eggs and Laysan albatross eggs, respectively. The high concentrations could be accounted for by the age and PCB accumulation of the female producing the egg. The average TEQs were 70 and 90 pg g⁻¹ in the Laysan albatross eggs and BFAL eggs, respectively. This PCB concentration and toxicity information can be used to determine the toxicological risk of the BFAL chicks while nesting at Midway Atoll, and the analysis of the albatross eggs is an indication of the contamination of the female albatross at the time of egg formation, with the levels acting as an indicator of the total PCB body burdens that the females are experiencing. The information from this study is indicative of the toxicological risk to the seabirds that nest and feed near Midway and of the overall PCB contamination in the North Pacific Ocean.     

Parent age differentially influences offspring size over the course of development in Laysan albatross

Offspring growth and survival are predicted to be higher for older parents, due to a variety of mechanisms, such as increased breeding experience or greater investment favored by low residual reproductive value. Yet the extent to which parent age affects offspring viability is likely to vary between different aspects of growth and survival, perhaps being most pronounced at the most stressful stages of reproduction. We studied the link between parent age and nestling growth and survival in the Laysan albatross, a long-lived seabird with a mean first breeding age of 8 years. Offspring of older parents were more likely to survive to fledging. Among those that did fledge, nestlings of older parents grew more rapidly. However, parent age did not influence the eventual asymptotic size that nestlings reached before fledging: fast-growing nestlings of older parents reached 90% of asymptotic size roughly 1 week sooner, but slow-growing nestlings of younger parents eventually caught up in size before fledging. Older parents bred c . 2 days earlier than younger parents, but hatch date did not explain observed variation in offspring success. The extent to which parent age accounted for variation in size of individual nestlings was not constant but peaked near the midpoint of development. This could reflect a time period when demands on parents reveal age-based differences in parental quality. Overall, growth and survival of offspring increased with parent age in this species, even though the late age of first breeding potentially provides a 7-year period for birds to hone their foraging skills or for selection to eliminate low-quality individuals.     

Early development and differentiation of the Laysan albatross (Phoebastria immutabilis (Rothschild, 1893): Procellariiformes)

Bird incubation is subdivided into two phases: differentiation (embryonic phase) and growth (fetal phase). Most birds have a relatively short incubation period (20–30 days) with the phase transition occurring midway through the incubation period. The Laysan albatross (Phoebastris immutabilis) is a large pelagic bird with a long incubation period. The purpose of this study was to document the differentiation phase with the aim of ascertaining the impact of a lengthened incubation on embryonic development. Eighty‐two previously collected albatross embryos were examined, measured, and staged. The albatross was found to develop more slowly than smaller birds, with a rate similar to other long‐incubating birds. Legs and wings grow at similar rates but exhibit variation in growth among their anatomical components. While the albatross embryos shared some morphological stages with chickens, they were more similar to ducks and pelicans. Special features of the albatross not shared with the Gallianserae (chickens and ducks) included an alligator‐like curved tail, narial tubes, and a cloacal bulge. Further examination of other larger pelagic birds with long incubation periods are needed to determine the uniqueness of the Laysan albatross embryonic development. Although much embryonic phase growth was documented in the postnatal period, little is known about the later, fetal phase in Laysan albatross. Future studies should involve examination of later (post day 32) fetuses. J. Morphol. 277:1231–1249, 2016. © 2016 Wiley Periodicals, Inc.     

Concentrations,Source and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Soils from Midway Atoll,North Pacific Ocean

This study was designed to determine concentrations of polycyclic aromatic hydrocarbons (PAHs) in soil samples collected from Midway Atoll and evaluate their potential risks to human health. The total concentrations of 16 PAHs ranged from 3.55 to 3200 µg kg⁻¹ with a mean concentration of 198 µg kg⁻¹. Higher molecular weight PAHs (4–6 ring PAHs) dominated the PAH profiles, accounting for 83.3% of total PAH mass. PAH diagnostic ratio analysis indicated that primary sources of PAHs in Midway Atoll could be combustion. The benzo[a]pyrene equivalent concentration (BaP_eq) in most of the study area (86.5%) was less than 40 µg kg⁻¹ BaP_eq and total incremental lifetime cancer risks of PAHs ranged from 1.00×10⁻¹⁰ to 9.20×10⁻⁶ with a median value of 1.24×10⁻⁷, indicating a minor carcinogenic risk of PAHs in Midway Atoll.     

Distribution,Sources and Risk Assessment of Polychlorinated Biphenyls in Soils from the Midway Atoll,North Pacific Ocean

Concentrations of 28 polychlorinated biphenyls (PCBs) were assessed in soils from the Midway Atoll in the central North Pacific Ocean. The analytical procedure involved the application of accelerated solvent extraction (ASE) and gas chromatography coupled with ion trap mass spectrometric detection (GC/ITMS) for identification and quantification. Among the 28 PCB congeners studied, 26 of them, except CB195 and CB209, were detected in the analyzed samples at different frequencies. The total concentrations of 28 indicator PCBs (ΣPCBs) ranged from 2.6 to 148.8 ng g⁻¹ with an average value of 50.7 ng g⁻¹ and median of 39.5 ng g⁻¹. Sources and congeners’ pattern of PCB were investigated in the soil of Midway Atoll. The principal component analysis indicated that the compositions of PCBs in most of the soil samples were similar. The total concentrations of PCBs were used to assess the cancer risk probabilities in humans via ingestion, dermal contact and inhalation of soil particles. Very low cancer risk was found in all soil samples caused by ΣPCBs.     

Dudresnaya babbittiana (Dumontiaceae,Gigartinales), a new red algal species from Midway Atoll,North Central Pacific

Dudresnaya babbittiana I.A. Abbott et McDermid, sp. nov., is described from subtidal habitats at Midway Atoll, among the westernmost reefs and lagoons and series of islets in the Hawaiian archipelago. The new species differs in size, habit, internal rhizoids and auxiliary-cell morphology from the two species that have been previously described from the high islands of Hawaii about 1 400 km to the southeast, D. hawaiiensis R.K.S. Lee and D. littleri I.A. Abbott. Closest affinities appear to be with D. capricornica Robins et Kraft from tropical eastern and western Australia, which differs in having a much greater abundance of medullary rhizoids, more consistently present and larger hexagonal crystals in central-axial cells, a far less regular alignment of surface cortical cells, and differently structured carpogonial and auxiliary-cell filaments.     

Postfledging Survival of Laysan Ducks

ABSTRACT Precise and unbiased estimates of demographic parameters are necessary for effective population monitoring and to parameterize population models (e.g., population viability analyses). This is especially important for endangered species, where recovery planning and managers' decisions can influence species persistence. In this study, we used mark—recapture methods to estimate survival of fledged juveniles (hatch-yr [HY]) and adult (after-hatch-yr [AHY]) Laysan ducks (Anas laysanensis), an endangered anatid restricted to Laysan Island in the northwestern Hawaiian Islands. To better understand population dynamics, we examined how survival varied as a function of Laysan duck density during 1998–2004. Using random effects models, we also quantified process variation in survival, thereby quantifying the appropriate source of variation for future population models. The dataset supported variation in survival that was time (yr), age (AHY vs. HY), and sex specific. Due to small sample sizes, we did not examine time specificity in the survival of HY ducks. Survival of HY ducks was 0.832 (SE = 0.087) for females (n = 21) and 0.999 (SE < 0.001) for males (n = 15) during 1998–2001. Trends in time and density lacked support as sources of variation in the survival of AHY ducks during 1998–2004. After-hatch-year survival ranged from 0.792 (SE = 0.033) to 0.999 (SE < 0.001). Where we modeled survival as a random effect, annual survival for AHY females was 0.881 (SE = 0.017) and process variation (σ_s) was 0.034. For AHY males, annual survival (μ_s) was 0.906 (SE = 0.019) and process variation (σ_s) was 0.040. This information will improve existing population viability analysis models for Laysan ducks. We believe that monitoring the source and translocation populations will be paramount for increasing our understanding of Laysan duck dynamics, recovery planning, and population management.     

Polychlorinated Biphenyls in the Plasma and Preen Oil of Black-Footed Albatross (Diomedea nigripes) Chicks and Adults on Midway Atoll,North Pacific Ocean

Polychlorinated biphenyls (PCBs) are ubiquitous in the environment. Midway Atoll, located in the North Pacific Ocean, was occupied by the military during and after World War II. However, Midway Atoll has become a national wildlife refuge and home to many different seabirds today, including the black-footed albatross (Diomedea nigripes) (BFAL). The profiles and toxic equivalents (TEQ) of PCB congeners in the plasma and preen oil of BFAL chicks and adults were determined in this study. The concentrations of the total PCBs in the plasma samples of chicks and adults collected in Midway Atoll ranged from 2.3 to 223.8 (mean 80.1) and 22.8 to 504.5 (mean 158.6) ng g^-1 (wet weight, ww), respectively. The TEQs ranged from 0.2 to 0.6 (mean 0.4) and 0.4 to 1.6 (mean 0.9) pg g^-1 ww, respectively, in the plasma samples of chicks and adults from Midway Atoll. The major congeners in the plasma samples of chicks and adults included PCBs 31, 87, 97, 99, 118, 138, 153, and 180, accounting for 70% of the total PCBs. The concentrations of the total PCBs in the adult preen oil samples ranged from 1693 to 39404 (mean 10122) ng g^-1 (ww), of which 97% were PCBs 105, 118, 128, 138, 153, 161, 172, and 183.     

Incubation energetics of the Laysan Albatross

Summary The energy expenditure of incubating and foraging Laysan Albatross (Diomedea immutabilis, mean body weight 3.07 kg) was estimated by means of the doubly-labelled water technique. During incubation, the energy expenditure was similar to that of resting birds that were not incubating an egg. The energy expenditure of foraging albatross (2072 kJ/day) was 2.6 times that of resting birds. It was concluded that the energy expenditure of the tropical Laysan Albatross was not less than that of species foraging over cold, high-latitude oceans. An energy budget compiled for an incubating pair of albatross revealed that the energy expenditure of the female was greater than that of the male bird, during the incubation period.     

Habitats, abundance and diets of Muricacean gastropods at Aldabra Atoll

Twenty-three species of predatory Muricacean gastropods are common on the intertidal rocky shores of Aldabra Atoll. Species show a division of the habitat space by vertical zonation along the intertidal gradient, longitudinal zonation around an exposure gradient and by choice of substrate type. Co-occurring species usually overlap very little in size and this may indicate utilization of different parts of the habitat/food resource.
Most species of Thais, Purpura and Morula feed by drilling sedentary or semi-mobile prey and most suitable prey species are exploited. Species show a broad partitioning of the available food resources and overlap between species is usually low. Large species have generally more varied diets than small species. Size variation of some species around the Atoll may be attributed to differences in diet. Species of Drupa do not drill but feed upon eunicid, nereid and sipunculid worms and small Crustacea. Drupella cornus and two species of Coralliophilidae feed upon coral polyps.
The Muricacea occur together with other predatory gastropods, such as the Conidae, Mitridae and Buccinidae, but these families have generally different diets and largely independent food webs.
The Muricacea at Aldabra appear to have narrower habitat ranges than muricids in temperate areas.     

Reproductive endocrinology of the Black-browed albatross Diomedea melanophris and the Grey-headed albatross D. chrysostoma

Gonadal size and the circulating concentrations of two pituitary hormones (luteinizing hormone and prolactin) and three gonadal steroids (testosterone, progesterone and oestradiol-17β) were measured in two closely related Diomedea albatrosses at South Georgia. The Grey-headed albatross D. chrysostoma , if successful in rearing a chick, usually breeds biennially, whilst the Black-browed albatross D. melanophris normally breeds annually. Direct examination (by laparoscopy) of the gonads showed that the testes of both species underwent annual cycles, whilst endocrine data confirmed that those male Grey-headed albatrosses at the colony in the pre-laying period but not breeding in that year (having bred successfully the previous year) were apparently in full reproductive condition with elevated testosterone levels typical of breeding birds. However, the females of the two species differed markedly. Grey-headed albatrosses, in a year following successful breeding, had undeveloped ovaries with low levels of circulating oestradiol but high levels of progesterone, whereas the Black-browed albatrosses showed a pattern consistent with annual ovarian development. The profiles of gonadal steroids through the breeding season were similar for the males of both species but differences existed between the females. In the female Grey-headed albatrosses, transient peaks of progesterone were present throughout chick rearing but these were absent from Black-browed albatrosses. Prolactin had a similar profile in both species, with uniformly high levels throughout incubation and a rapid fall near the end of the brood-guard period. It is suggested that Grey-headed, like Black-browed, albatrosses are intrinsically annual breeders. However, if a female Grey-headed albatross breeds successfully in one year, then nutritional factors operate to ensure that in the following year the female does not show ovarian development, although the ovary is active in terms of progesterone secretion.     

Breeding biology of the Light-mantled sooty albatross (Phoebetria palpebrata) at South Georgia

Aspects of the breeding biology of the Light-mantled sooty albatross Phoebetria palpebrata were studied at South Georgia. Its breeding distribution there is summarized and an annual breeding population of c. 5000 breeding pairs estiamted. Laying, hatching and fledgine dates are given, together with egg measurements and data on the duration of incubation and brooding shift. Chick growth in weight and wing length from hatching to fledging was followed in detail.
Breeding season adaptations of P. palpebrata are compared with those of the other three albatrosses at South Georgia. The slow chick growth of P. palpebrata results in a nestling period even longer than those of the two larger mollymawks and is attributable mainly to the lower frequency of feeding resulting from the highly pelagic existence of adult P. palpebrata .
Comparisons are made with other breeding populations and especially with that on Marion Island. This is basically very similar and differences in chick growth patters are suggested to relate to differences in diet and particulartly to the frequency with which chicks receive food.     

Demography of Bristle-thighed Curlews Numenius tahitiensis wintering on Laysan Island

We studied the nonbreeding ecology of Bristle-thighed Curlews Numenius tahitiensis from 1988 to 1991 on Laysan Island in the Northwestern Hawaiian Islands. Using capture-recapture analysis, we estimated that 300–350 curlews wintered on the island. Annual survival was >85% for adults and 92% for first-year birds. Young birds remained on the island until at least their third calendar year, when some individuals made "exploratory" visits to other islands in the Northwestern chain. Most of the birds marked in their first year migrated north to the breeding grounds when they were 3 years old; several birds remained on the island until they were at least 4 years old. Adults returned to the same discrete home ranges year after year, whereas subadults (which do not migrate) tended to use a greater portion of the island. At least 60% of the subadults marked from 1988 to 1990 returned to the island to winter as adults. Because young curlews arrived after adults and experienced high survivorship while on the island, there did not appear to be intense competition for space at Laysan even though the island is at the northern end of the species' winter range.     

Increased mortality of black-browed albatross chicks at a colony heavily-infested with the tick Ixodes uriae

At Bird Island, South Georgia, we studied the effects of the tick Ixodes uriae on survival of chicks at two colonies of the black-browed albatross Diomedea melanophrys, one where most chicks were infested with ticks, the other where most chicks were tick-free. When the two colonies were compared, it was found that the colony heavily-infested with ticks had significantly greater chick mortality than the colony lightly-infested with ticks. However, within each of the two colonies, there was no significant difference in survival between chicks with ticks and those without ticks.     

Coexistence of Low Coral Cover and High Fish Biomass at Farquhar Atoll,Seychelles

We report a reef ecosystem where corals may have lost their role as major reef engineering species but fish biomass and assemblage structure is comparable to unfished reefs elsewhere around the world. This scenario is based on an extensive assessment of the coral reefs of Farquhar Atoll, the most southern of the Seychelles Islands. Coral cover and overall benthic community condition at Farquhar was poor, likely due to a combination of limited habitat, localized upwelling, past coral bleaching, and cyclones. Farquhar Atoll harbors a relatively intact reef fish assemblage with very large biomass (3.2 t ha⁻¹) reflecting natural ecological processes that are not influenced by fishing or other local anthropogenic factors. The most striking feature of the reef fish assemblage is the dominance by large groupers, snappers, and jacks with large (>1 m) potato cod (Epinephelus tukula) and marbled grouper (E. polyphekadion), commonly observed at many locations. Napoleon wrasse (Cheilinus undulatus) and bumphead parrotfish (Bolbometopon muricatum) are listed as endangered and vulnerable, respectively, but were frequently encountered at Farquhar. The high abundance and large sizes of parrotfishes at Farquhar also appears to regulate macroalgal abundance and enhance the dominance of crustose corallines, which are a necessary condition for maintenance of healthy reef communities. Overall fish biomass and biomass of large predators at Farquhar are substantially higher than other areas within the Seychelles, and are some of the highest recorded in the Indian Ocean. Remote islands like Farquhar Atoll with low human populations and limited fishing pressure offer ideal opportunities for understanding whether reefs can be resilient from global threats if local threats are minimized.