Procellariiform Seabirds Research Articles

Seabird bycatch in New Zealand trawl and longline fisheries, 1998-2004

Fisheries bycatch is a threatening process for populations of procellariiform seabirds, and is of particular importance for the conservation of albatross, an especially threatened group at a global scale. There is a high level ofendemism of albatross and petrels in New Zealand waters, and around one-third of the world's species of procellariiform seabirds breed in this area. Therefore, understanding the levels of mortality of these species in the New Zealand Exclusive Economic Zone is important for global conservation of the order. For New Zealand fisheries for the 1998-2004 fishing years, we estimated total seabird bycatch using data from scientific observers with model-based estimation procedures. Although sectors of the fishing activity were not evenly covered by observers, we were able to estimate seabird bycatch for large scale fisheries by vessel size (split at 28 m length), season, area and year. Approximately 5500 seabirds (credible interval between 2000 and 10 000) are estimated to be landed in New Zealand trawl and longline fisheries annually, as a result of interactions with fishing gear. Few data were available for the small vessels, thus estimates are highly uncertain. Mortalities are likely to be most common in trawl fisheries at approximately 2000-3000 seabirds annually, with the greatest contribution coming from large vessels. Around one half of these birds were albatross. For large surface longline vessels we estimated that fewer than 500 seabirds were killed annually during the main tuna fishing season. For large demersal vessels, seabird mortality was estimated to have decreased from around 1800 seabirds in 2001 to 600 seabirds in 2004. We report observed captures by species for each fishing method and area for the fishing years 1998-2004. Thirty-one species of Procellariiformes were identified during this period, over half of which are threatened species. For some species, such as White-chinned Petrel, Procellaria aequinoctialis and White-capped Albatross, 1halassarche steadi, several hundred individuals were caught. For 15 species, fewer than 10 individuals were identified. However, the unrepresentative deployment ofobserver coverage across fishery areas makes it difficult to interpret the conservation implications of species captures. A high proportion of the petrel species was observed caught primarily from areas surrounding their breeding sites while albatross were caught across breeding and non-breeding areas. Greatly improved observer sampling ratios, and studies of population status and trends, are needed to understand the conservation implications of the effects of New Zealand trawl and longline fishing mortalities on seabird populations.

Lack of host‐dependent genetic structure in ectoparasites ofCalonectrisshearwaters

We compared patterns of mitochondrial DNA (mtDNA) differentiation in three host-specific lice (Halipeurus abnormis, Austromenopon echinatum and Saemundssonia peusi) and one generalist flea (Xenopsylla gratiosa), parasitizing 22 colonies of Cory's and Cape Verde shearwater (Calonectris). The shearwater hosts show distinct phylogeographic structure corresponding to the three taxa Calonectris d. diomedea, C. d. borealis, and C. edwardsii. The host-specific lice appeared undifferentiated among the three Calonectris taxa, whereas the more generalist flea displayed significant levels of population differentiation. Neither genetic distances among host populations, nor their spatial distribution explained the patterns of genetic variability observed in the ectoparasites. The lack of differentiation among lice is unexpected, given that previous work has found evidence of cospeciation between procellariiform seabirds and their lice, and lice typically have an elevated rate of mtDNA evolution with respect to their hosts. Our results suggest that either rates of evolution in seabird lice are not always as high as previously thought, or that the magnitude of movement of lice between seabird hosts has been substantially underestimated.

The influence of developmental environment on the evolution of olfactory foraging behaviour in procellariiform seabirds

The evolutionary origins of foraging behaviour by procellariiform seabirds (petrels, albatrosses and shearwaters) are poorly understood. Moreover, proximate factors affecting foraging ecology, such as the influence of environment on the development of sensory systems, have yet to be addressed. Here, we apply comparative methods based on current procellariiform phylogenies to identify associations between sensory modalities and the developmental environment that may underlie the evolution of complex foraging behaviour. We postulate that, for burrow-nesting species, smell is likely to dominate the sensory world of the developing chick. Alternatively, for ground-nesting species, chicks receive exposure to a range of visual, auditory and olfactory cues. We employ maximum likelihood to test models of correlated trait evolution between nesting habit and olfactory foraging style and to reconstruct the ancestral states of these characters when coded as binary states. Our results suggest that nesting behaviour has evolved in conjunction with foraging style. Based on this analysis, we propose that nesting on the surface was a life-history innovation that opened up a new developmental environment with profound effects on the foraging ecology of procellariiform seabirds.

Lipids from stomach oil of procellariiform seabirds document the importance of myctophid fish in the Southern Ocean

We investigated the relative importance of myctophid fish and Antarctic krill in the diet of adult flying seabirds of the Southern Ocean. The main prey of short‐tailed shearwaters Puffinus tenuirostris (P. ten.), white‐chinned petrels Procellaria aequinoctialis (P. aeq.), blue petrels Halobaena caerulea (H. cae.), thin‐billed prions Pachyptila belcheri (P. bel.), and Antarctic prions Pachyptila desolata (P. des.) were mostly deduced from the lipid analysis of adult stomach oils. More than 97% of the 125 analyzed oils mainly consisted of wax esters (WEs) and triacylglycerols (TAGs) (>70% of total lipids). WE fatty alcohol (FAlc), WE fatty acid (FA), and TAG‐FA profiles clearly segregated P. aeq. from P. ten., with smaller, but still significant, differences among the three other petrel species. P. aeq. and P. ten. therefore preyed on distinct prey species, whereas H. cae., P. bel., and P. des. had a more similar diet, but still with some prey differences. Comparisons between FAlc and FA patterns of oils with those of potential prey species showed that >93% of FAlc and FA patterns of oil WEs had a high probability of resemblance with the myctophid signatures, and similar results were obtained with the TAG fractions. Almost no stomach oil fit the lipid patterns of subantarctic and Antarctic euphausiids, including those of the WE‐rich Thysanoessa macrura and the TAG‐rich Antarctic krill Euphausia superba. This study thus demonstrates for the first time the importance of myctophids in the nutrition of adult flying seabirds breeding in subantarctic islands and foraging in Antarctic waters during the austral summer.

Is basal metabolic rate influenced by age in a long-lived seabird, the snow petrel?

Ageing is associated with a decline in basal metabolic rate (BMR) in many species, including humans. The evolutionary and physiological causes underlying the relationship between age and BMR are poorly understood. Studies of procellariiform seabirds may provide valuable insight because they have a longer maximum lifespan than expected from their body size and rates of energy metabolism. Such studies are rare, however, because there are few populations with a high proportion of individuals of known age. We performed a cross-sectional study of energy metabolism in relation to age in a long-lived seabird, the snow petrel Pagodroma nivea. In an Antarctic population that has been subject to a long-term research program, including annual banding of chicks since 1963, we measured BMR of individuals aged between 8 and 39 years. We show that the BMR of the snow petrel does not decrease with increasing age. BMR seems to be sustained at a fixed level throughout the investigated age-span. We review this result in light of the disposable soma theory of ageing, and we discuss whether species-specific relationships between age and basal metabolic rate can be related to differences in maximum lifespan.

Predatory Behaviour of the Gough MoorhenGallinula comeri: Conservation Implications

The Gough Moorhen is endemic to Gough Island and is classified by the IUCN as Threatened. We present several observations of Gough Moorhens preying on introduced House Mice Mus musculus and on eggs and chicks of burrow-nesting procellariiform seabirds. The incidence of egg predation is almost certainly related to incubation breaks or abandonment. We estimate that Moorhens could access and depredate unattended eggs of at least five species but levels of predation appear to be low and are unlikely to affect population parameters of impacted species. Moorhens hunting live mice and scavenging carcasses presents a significant conservation concern. A possible eradication of mice from Gough Island is likely to employ poisons that are toxic to the Moorhens. Therefore secondary poisoning of Moorhens, by eating poisoned mice, is a threat to the Gough Moorhens. An eradication effort will be required to take appropriate mitigation measures. The introduced Gough Moorhen population on Tristan da Cunha serves as an ex situ population and could, if required, be used to re-stock Gough.

Predictive habitat modelling for the population census of a burrowing seabird: A study of the endangered Cook’s petrel

Inaccurate population data remain a major problem in the conservation of burrow-nesting Procellariiform seabirds. We evaluated the potential of predictive habitat modelling, in contrast with traditional surface-area based strategies, to estimate the population size of the endangered Cook’s petrel ( Pterodroma cookii), breeding on one of two islands in New Zealand. Generalised linear models of burrow abundance using topographic data collected in the field, or extracted from Geographic Information System layers, were developed, and the final model applied to Geographic Information Systems-derived datasets in a population analysis. To compare this result with traditional census methods, population estimates were also calculated by averaging burrow densities across the total area available (simple model) and within vegetation zones (habitat-area model). Results of all models were scaled using rigorously collected burrow occupancy data. The final model, based upon altitude, slope, and distance from ridgelines, explained 31% of the variance in Cook’s petrel burrow abundance and showed an enhanced predictive fit compared with the two area-based models. This model indicated that annually 286,000 (95% confidence interval: 213,000–413,000) pairs of Cook’s petrel breed on Little Barrier Island, approximately six times that previously suggested. Population estimates based on simple and habitat-area models were less accurate, being 10% and 30% greater than the predictive model estimate, respectively. This study underlines the need for accurate population estimates for burrowing seabird taxa by presenting a major population revision for the Cook’s petrel. Predictive habitat models, employing rigorously collected data, offer an improvement on more traditional population census methodologies that are susceptible to scale-induced bias.

Primeiro registro de fósseis de aves marinhas na planície costeira do Rio Grande do Sul, Brasil

The present work presents the first occurrence of seabirds ʼ fossils from pleistocenic fossiliferous deposits submerged along the inner continental shelf of Rio Grande do Sul state. The fossils presented here were collected during field works between 1999 and2003 and consist of three cervical vertebrae and a partial left tibiotarsus. The fossils ʼ morphology and size are similar to those of a procellariiform seabird of the Thalassarche melanophrys Temminck 1828 species (black-browed mollymawk). The fossils are well-preserved, indicating that were not subject to significant re-working during transport from the source areas to the beach. This suggests that the submerged deposits are located near the present shoreline.

PRIMEIRO REGISTRO DE FÓSSEIS DE AVES MARINHAS NA PLANÍCIE COSTEIRA DO RIO GRANDE DO SUL, BRASIL

The present work presents the first occurrence of seabirdsʼ fossils from pleistocenic fossiliferous deposits submerged along the inner continental shelf of Rio Grande do Sul state. The fossils presented here were collected during field works between 1999 and 2003 and consist of three cervical vertebrae and a partial left tibiotarsus. The fossilsʼ morphology and size are similar to those of a procellariiform seabird of the Thalassarche melanophrys Temminck 1828 species (black-browed mollymawk). The fossils are well-preserved, indicating that were not subject to significant re-working during transport from the source areas to the beach. This suggests that the submerged deposits are located near the present shoreline.

Sooty Shearwater (Puffinus griseus) on Guafo Island: the largest seabird colony in the world?

Sooty Shearwater (Puffinus griseus) is the most common Procellariiform seabird along the south-eastern South American coast. In recent years the wintering population off California has declined noticeably. This decline has been confirmed on the breeding grounds in New Zealand. In Chile, knowledge of the population is limited. Investigations on Isla Guafo were carried out during two seasons (03/04 and 04/05), beginning an ongoing monitoring and evaluation of the breeding population of this species in southern South America. On Isla Guafo we estimate a population of about 4 million birds that nest above 150 m above sea level (m.a.s.l.) under a forest without understory. Sooty Shearwaters on Isla Guafo prefer north and western slopes that we hypothesise protect them from the predominantly southerly winds. Population of the species from New Zealand and Australia are compared with the Isla Guafo population and the state of its conservation is discussed.

Behavioural responses of blue petrel chicks (Halobaena caerulea) to food-related and novel odours in a simple wind tunnel

As a first step towards understanding the development of olfactory behaviours in Antarctic procellariiform seabirds, we recently showed that blue petrel chicks (Halobaena caerulea) could detect both a food-related and a novel odour while asleep. In this current study, we tested chicks in a simple wind tunnel to determine if exploratory behaviours could be initiated by olfactory stimuli as well. We compared the behavioural responses of 30 blue petrel chicks to cod liver oil (a prey-related odour) or phenyl ethyl alcohol (an unfamiliar, rosy-smelling odourant) against a control (distilled water). Six behavioural indices were measured, including head turns, body turns, bites, preening events, wing-stretches, and distance walked. In response to cod liver oil, we found that chicks increased both turning rates and distances walked whereas chicks preened more in response to phenyl ethyl alcohol. Since only cod liver oil initiated behaviours consistent with searching, our results suggest that chicks are attaching biological significance to food-related odours even before they leave the burrow to forage for the first time.

Copulation behaviour and paternity in shy albatrosses (Thalassarche cauta)

AbstractWe investigated the mating system of shy albatrosses Thalassarche cauta by combining behavioural observations during the pre‐laying period with genetic paternity analysis. Genetic data on the mating systems of several procellariiform seabirds have recently become available, but data on the reproductive behaviour of these species are rarely obtained. Our main aims were to describe the copulatory behaviour of this species and identify how males achieve within‐pair and extra‐pair paternity (EPP). Most copulations occurred on the nest, were unforced and were within‐pair. Females controlled the success of copulations and were observed soliciting extra‐pair matings. Within‐pair and extra‐pair copulations were behaviourally similar. A low frequency (7–10%, n=29 chicks) of EPP was detected despite male use of frequent copulation as a paternity guard. The pre‐laying foraging exodus of female shy albatrosses differed from that in other albatrosses: it was relatively short in length, lasting c. 2 days, and within‐pair copulations occurred after the female's return 2 days before laying. This may reflect the close proximity of feeding grounds to the breeding colony.

The potential role of ammonia as a signal molecule for procellariiform seabirds

Procellariiform seabirds (petrels, albatrosses and shearwaters) navigate vast distances over seemingly featureless ocean habitat by mechanisms that are not well understood. These birds have large olfactory bulbs, and the use of smell has been implicated in both foraging and homing behavior. While many olfactory cues relevant to these behaviors have been identified, ammonia is a potentially significant, biogenic, scented compound that has not been studied in this context. Ammonium (NH4+) constitutes a primary waste product produced by many of the prey species on which procellariiforms forage. Nitrogen waste products, including volatilized ammonia (NH3) also scent the terrestrial landscape of sub-Antarctic islands where newly breeding procellariiform seabirds recruit and raise their young. Since an ability to smell ammonia may be relevant to both prey detection and locating colonies or islands, we used a non-invasive, behavioral assay to examine whether this scented compound is detectable by a candidate test species, the blue petrel Halobaena caerulea Gmelin. Our results suggest that these birds can detect volatilized ammonia within a concentration range that they may naturally encounter (10(-11) to 10(-5) M), and point to ammonia as a potential signal molecule in the sub-Antarctic.

Modelling impacts of long-line fishing: what are the effects of pair-bond disruption and sex-biased mortality on albatross fecundity?

Long-line fishing mortality poses a significant threat to many large procellariiform seabirds. To date, estimates of impacts have concentrated on lower survival rates, largely ignoring the costs to fecundity resulting from disruption of breeding pairs and skews in sex ratio. A comparative, stochastic, individual-based model was used to investigate these costs for the wandering albatrossDiomedeaexulans. Ignoring the time taken to replace a lost mate overestimates fecundity by 13–18%, resulting in annual population growth rates (λ) being 0.006– 0.007 too high. Long-line mortality exacerbates this cost, which becomes more substantial with increasing demographic skew resulting from female-biased mortality. At moderate levels of long-line mortality (2–4% per year), 80% female-biased mortality reduces fecundity by 9–27% and λ by 0.003–0.010 relative to models with random mortality. Biased sex ratios accumulate and, unlike reduced survival, their impacts on albatross demography persist after long-line mortality ceases. Estimates of the demographic costs of long-line mortality should incorporate individual-level effects, especially where mortality is sex-biased.

Using stable isotopes to study resource acquisition and allocation in procellariiform seabirds

Some procellariiform seabirds use a dual strategy for provisioning their chicks by alternating short (ST) and long (LT) foraging trips. Parent birds gain mass during LT but they lose mass while increasing the chick feeding frequency during ST. Self-feeding during LT is crucial for the success of ST because firstly most of the energy used during ST is likely to be derived from the energy stored during LT and secondly self-feeding during ST is presumed to be negligible. Self-feeding by adult procellariiforms is thus a key issue to understand allocation processes but it is still poorly known. We tested these predictions by using the stable isotope (delta(15)N and delta(13)C) technique on birds' plasma and prey with the short-tailed shearwater Puffinus tenuirostris breeding at Tasmania as a model. Parent shearwaters returning to the colony after a LT have an Antarctic/subantarctic delta(13)C signature in their plasma (-23.8 per thousand), thus indicating that they fed in cold waters, far away from their breeding colony, for their own maintenance. Parent birds returning to the colony after a ST also have a distant Antarctic/subantarctic delta(13)C signature in their plasma (-24.3 per thousand), thus verifying that self-feeding is negligible during ST and that birds fast at that time, using energy stores built up in cold waters. Plasma delta(15)N values of adults (8.8 per thousand) indicates they mainly prey upon zooplankton-eating organisms, probably mesopelagic myctophid fishes. A simple isotopic mixing model estimates that they consume by mass 87% myctophids and 13% subantarctic krill when self-feeding. Finally and as expected, the carbon isotopic signature of chick plasma (-22.2 per thousand) was intermediate between those of high- and low-latitude marine organisms and is thus in agreement with chicks being fed with a large diversity of prey species caught by adult birds from Antarctic to Tasmanian waters. One main consequence of this system is that reproduction of a Tasmanian species is controlled by resources available at great distances from the breeding colony that drive allocation decisions of parent birds.

Sensitivity to dimethyl sulphide suggests a mechanism for olfactory navigation by seabirds

Petrels, albatrosses and other procellariiform seabirds have an excellent sense of smell, and routinely navigate over the world's oceans by mechanisms that are not well understood. These birds travel thousands of kilometres to forage on ephemeral prey patches at variable locations, yet they can quickly and efficiently find their way back to their nests on remote islands to provision chicks, even with magnetic senses experimentally disrupted. Over the seemingly featureless ocean environment, local emissions of scents released by phytoplankton reflect bathymetric features such as shelf breaks and seamounts. These features suggest an odour landscape that may provide birds with orientation cues. We have previously shown that concentrated experimental deployments of one such compound, dimethyl sulphide (DMS), attracts procellariiforms at sea, suggesting that some species can use it as a foraging cue. Here we present the first physiological demonstration that an Antarctic seabird can detect DMS at biogenic levels. We further show that birds can use DMS as an orientation cue in a non-foraging context within a concentration range that they might naturally encounter over the ocean.

Top predator distribution and abundance across the eastern Gulf of Alaska: Temporal variability and ocean habitat associations

Abstract We studied interannual variation in marine bird and mammal distribution and abundance in the eastern Gulf of Alaska (GOA) over 8 years, 1996–2003. We identified and enumerated seabirds, pinnipeds and cetaceans along a replicated 1500 km survey path, representing 450 km 2 of coastal and 2000 km 2 of oceanic habitat. Near-surface temperature (5 m depth) fluctuated considerably from year to year, in part due to the timing of the survey, with an early survey in 1996 and a late survey in 2002. Many species were observed across the entire gradient, particularly procellariiform (tubenose) seabirds and Dall's porpoise ( Phocoenoides dalli ). We observed peaks in abundance in the oceanic zone in 1998, 2001, and 2002, owing primarily to influxes of dark shearwaters ( Puffinus spp.) and Leach's storm-petrels ( Oceanodroma leuchora ). Rank correlations indicated similar year-to-year changes in density between species, and species-specific responses to temperature and ocean productivity as indexed by nitrate and chlorophyll a concentrations. We developed topographic/bathymetric models of habitat selection for the coastal zone. Although we found some distinct habitat preferences in this zone, overall we observed a continuum in the marine bird and mammal community across the entire eastern GOA. The strength of the coupling between coastal and oceanic environments as provided by variation in top predator dispersion appears related to large-scale variations in oceanography, though we have yet to fully investigate causal mechanisms.

Lipid composition of stomach oil in a procellariiform seabird Puffinus tenuirostris: implications for food web studies

Some procellariiform seabirds use a dual strategy for provisioning their chicks by alter- nating between short and long foraging trips (LT). Trophic relationships of adult birds are unknown when they feed for themselves during LT because digestion processes preclude direct prey determi- nation. Since stomach contents collected after LT contain oil of dietary origin, we tested the use of oil lipids as prey trophic markers using the Tasmanian short-tailed shearwater Puffinus tenuirostris as a model seabird. The intra-specific variability of stomach oils was investigated through lipid class com- position, and their fatty acid and fatty alcohol profiles. Oils mainly consisted of wax esters (WE) and triacylglycerols (TAG) (49 to 86 and 7 to 41%, respectively). Major fatty acids of TAG were in a decreasing order 18:1n-9, 16:0, 16:1n-7, 14:0, 20:5n-3 and 22:6n-3. The WE-fatty acid profiles were dominated by 18:1n-9 and 16:1n-7 while fatty alcohol profiles were dominated by 16:0. Fatty alcohol and fatty acid patterns were tested as possible descriptors of ingested prey (derived from literature data) through multivariate discriminant analyses. Comparisons of the WE fatty alcohol patterns showed a close association with the alcohol structure of 3 myctophid fish species namely Krefftichthys anderssoni, Gymnoscopelus braueri and Electrona antarctica; these results were corroborated by WE fatty acid analysis. Comparison of TAG fatty acid patterns showed the highest similarity between oils and the digestive gland of the myctophid-eater squid Moroteuthis ingens in association with the myctophid Electrona carlsbergi. Hence, biochemical analysis of both WE and TAG strongly suggested that adult short-tailed shearwaters mainly prey upon Antarctic/sub- Antarctic myctophids when they feed for themselves, thus emphasizing the role of these oceanic mesopelagic fish in the marine ecosystem of the Southern Ocean.

Partner-Specific Odor Recognition in an Antarctic Seabird

Among birds, the Procellariiform seabirds (petrels, albatrosses, and shearwaters) are prime candidates for using chemical cues for individual recognition. These birds have an excellent olfactory sense, and a variety of species nest in burrows that they can recognize by smell. However, the nature of the olfactory signature--the scent that makes one burrow smell more like home than another--has not been established for any species. Here, we explore the use of intraspecific chemical cues in burrow recognition and present evidence for partner-specific odor recognition in a bird.

Phylogeny of “ Philoceanus complex” seabird lice (Phthiraptera: Ischnocera) inferred from mitochondrial DNA sequences

The Philoceanus complex is a large assemblage of lice that parasitise procellariiform seabirds (petrels, albatrosses, and their relatives). We obtained mitochondrial 12S rRNA and cytochrome oxidase I DNA sequences from 39 species from diverse hosts and localities. Resolution of deeper relationships between genera was limited, however there is evidence for two major clades, one hosted by albatrosses, the other by petrels. Based on our results, the genera hosted by albatrosses are excellent candidates for detailed analysis of cospeciation. Our results also suggest that a previous estimate of a 5-fold difference in the relative rate of sequence evolution in lice and their avian hosts is an artefact of limited taxonomic sampling.