Migratory Seabirds Research Articles

Effects of climate variability on breeding phenology and performance of tropical seabirds in the eastern Indian Ocean

We compared 20 yr of seabird breeding data with oceanographic variables (sea level, sea-surface temperature) and a climate index (Southern Oscillation Index; SOI) for the lesser noddy Anous tenuirostris, brown noddy A. stolidus, sooty tern Onychoprion fuscata and wedge- tailed shearwater Ardenna pacifica at the Houtman Abrolhos, eastern Indian Ocean. We found that timing of breeding and performance of these species is related to climate variability, mediated by oceanographic conditions within the eastern boundary Leeuwin Current (LC). The 3 migratory species have breeding parameters which are correlated with sea level and the SOI, while the first egg date of the resident lesser noddy is correlated with SST during their pre-breeding phase. There was poor breeding performance for each species during El Nino Southern Oscillation (ENSO) conditions; moreover, poor breeding success was recorded for all species outside of (ENSO events in the latter years of the study. In addition, breeding was delayed for all species dur- ing the time of the present study. The environmental conditions contributing to this appear to be fewer years of strong LC flow with associated high sea levels, warmer SSTs, stronger eddy energy and increased productivity. Migratory seabird species breeding at this location appear less able to respond to climate variability — and its influence upon prey availability — than the resident spe- cies. It is suggested that the resident lesser noddy may have an advantage due to its response to a localised environmental cue, SST, in the pre-breeding phase, which may be correlated with prey availability in the waters surrounding the Houtman Abrolhos.

Reproductive success of South American terns (Sterna hirundinacea) from Cardos Islands, Florianópolis, SC, Brazil

Sterna hirundinacea (Lesson, 1831) is a migratory seabird that breeds in the Pacific Coast (from Peru to Chile) and along the Atlantic coast of South America from Espírito Santo (Brazil) to Terra del Fuego (Argentina). This paper describes the reproductive success of South American Terns on Cardos Island, Florianopolis, Brazil in the breeding seasons of 2003, 2005 and 2006. The colony was formed in mid-May in 2003 and early April in other years, with the total number of nests ranging from 1,852 in 2006 to 2,486 in 2005. Hatching success was estimated at 76.39% in 2006, 62.73% in 2003 and 41.1% in 2005, the lowest value that could be attributed to predation by hawks Caracara plancus, lizards Tupinambis merianae and black vulture Coragyps atratus. The chicks hatched in July in 2003, and in June 2005 and 2006, and fledging success was 50.94%, 35.96 and 53.47% respectively. Cardos Island has been constantly used as a breeding site by South American Terns, and therefore represents an important area for conservation of this species. This success could be attributed to low pressure of Kelp gulls (Larus dominicanus), the main predator of seabirds along the Brazilian coast.

Migratory Birds: Ecology and Conservation. A report on the BOU’s Annual Conference held at the University of Leicester, 5–7 April 2011

In April 2011, the British Ornithologist’s Union’s annual conference took place at the University of Leicester. The theme of this year’s conference was the ecology and conservation of migratory birds, and talks ranged from those focussed on either breeding, migration or wintering ecology, to those linking two or more of these and trying to build a more complete picture of the complex problems faced by long distance migrants. Talks also covered recent technological advances, which are increasingly allowing us intriguing new insights, particularly into the seasonal movements and wintering areas of some of the most declining species. Finally, talks examined the policy challenges associated with protecting migratory species and how best to tackle flyway-scale conservation of migratory birds.

Recoveries of juvenile Giant Petrels in regions of ocean productivity: potential implications for population change

Explaining long-term population change for migratory seabirds such as Giant Petrels (Macronectes spp.) has proven elusive because only aspects of adult life-histories have been studied. There is a paucity of demographic data for juveniles however; there is a considerable amount of leg-band recovery location data for younger age-classes. Nestlings were leg-banded at two sub-Antarctic islands, and at two higher latitude Antarctic breeding colonies. Bands were most often recovered in winter within six months of liberation. Banded fledglings were recovered in known productive upwelling biomes. The birds had travelled between 350 and 6150 km downwind from their natal colonies to reach these biomes. The distances fledglings travelled to reach the biomes were correlated with the observed population trends at their natal colonies; negative/positive population trends were correlated with great/lesser distances travelled. This study highlights the potential importance juvenile life-history attributes when considering population change for long-lived seabird species, and identifies rich upwelling regions such as the Humboldt and Benguelen Currents that might be important foraging areas for this and other Procellariiform species with high conservation values.

Early Migratory Fishermen and Newfoundland's Seabird Colonies

Abstract The migratory fishery at Newfoundland was a key step in the expansion of the European world system and was, for centuries, one of the largest industrial enterprises in the New World. But large-scale predation of cod was only part of the impact Europeans had on the northwest Atlantic. The shore-based salt-cod fishery involved a complex interaction with local ecosystems, creating predatory pressure on animals used as bait. Cod fishers were large-scale predators of seabirds as well as cod. Use of the Great Auk from the Funk Islands off northern Newfoundland for provisions is well known. It is less often recognized that early fishers preferred seasonal stations close to seabird colonies, in order to use nesting birds as bait. By 1600, human predation in Newfoundland's coastal ecosystem was already a complex business, involving local seabirds and several of the largest marine mammals, as well as fish. Even if only a relatively minor factor in the marine ecology of the northwest Atlantic, industrial-sc...

Global climate patterns explain range‐wide synchronicity in survival of a migratory seabird

AbstractTo predict the impact of climate change over the whole species distribution range, comparison of adult survival variations over large spatial scale is of primary concern for long‐lived species populations that are particularly susceptible to decline if adult survival is reduced. In this study, we estimated and compared adult survival rates between 1989 and 1997 of six populations of Cory's shearwater (Calonectris diomedea) spread across 4600 km using capture–recapture models. We showed that mean annual adult survival rates are different among populations along a longitudinal gradient and between sexes. Variation in adult survival is synchronized among populations, with three distinct groups: (1) both females and males of Corsica, Tremiti, and Selvagem (annual survival range 0.88–0.96); (2) both females and males of Frioul and females from Crete (0.82–0.92); and (3) both females and males of Malta and males from Crete (0.74–0.88). The total variation accounted for by the common pattern of variation is on average 71%, suggesting strong environmental forcing. At least 61% of the variation in survival is explained by the Southern Oscillation Index fluctuations. We suggested that Atlantic hurricanes and storms during La Niña years may increase adult mortality for Cory's shearwater during winter months. For long‐lived seabird species, variation in adult survival is buffered against environmental variability, although extreme climate conditions such as storms significantly affect adult survival. The effect of climate at large spatial scales on adult survival during the nonbreeding period may lead to synchronization of variation in adult survival over the species' range and has large effects on the meta‐population trends. One can thus worry about the future of such long‐lived seabirds species under the predictions of higher frequency of extreme large‐scale climatic events.

Levels and pattern of polybrominated diphenyl ethers in eggs of Antarctic seabirds: Endemic versus migratory species

Chinstrap and gentoo penguins are endemic species that live year round south of the Antarctic Convergence. South polar skua is a migratory seabird that can be observed in Antarctica during the breeding season (i.e., austral summer). This study compares concentration and pattern of polybrominated diphenyl ethers (PBDEs) in eggs of seabirds breeding at King George Island, Antarctic Peninsula. PBDEs in south polar skua eggs are approximately 20 times higher than in penguin eggs suggesting that skuas are more exposed to contaminants during the non-breeding season when they migrate to waters of the northern hemisphere. The pattern of PBDE congeners also differs between south polar skua and penguin eggs. The latter exhibited a pattern similar to that found in the local biota. In contrast, the congener pattern in south polar skua eggs suggests that birds breeding at King George Island may winter in the northwestern Pacific Ocean.

William Graeme Laver PhD, FRS (1929–2008)

William Graeme Laver PhD, FRS (1929–2008)

Environmental contaminants in bald eagle eggs from the Aleutian archipelago

We collected 136 fresh and unhatched eggs from bald eagle (Haliaeetus leucocephalus) nests and assessed productivity on eight islands in the Aleutian archipelago, 2000 to 2002. Egg contents were analyzed for a broad spectrum of organochlorine (OC) contaminants, mercury (Hg), and stable isotopes of carbon (delta13C) and nitrogen (delta15N). Concentrations of polychlorinated biphenyls (SigmaPCBs), p,p'-dichlorodiphenyldichloroethylene (DDE), and Hg in bald eagle eggs were elevated throughout the archipelago, but the patterns of distribution differed among the various contaminants. Total PCBs were highest in areas of past military activities on Adak and Amchitka Islands, indicating local point sources of these compounds. Concentrations of DDE and Hg were higher on Amchitka Island, which was subjected to much military activity during World War II and the middle of the 20th century. Concentrations of SigmaPCBs also were elevated on islands with little history of military activity (e.g., Amlia, Tanaga, Buldir), suggesting non-point sources of PCBs in addition to point sources. Concentrations of DDE and Hg were highest in eagle eggs from the most western Aleutian Islands (e.g., Buldir, Kiska) and decreased eastward along the Aleutian chain. This east-to-west increase suggested a Eurasian source of contamination, possibly through global transport and atmospheric distillation and/or from migratory seabirds. Eggshell thickness and productivity of bald eagles were normal and indicative of healthy populations because concentrations of most contaminants were below threshold levels for effects on reproduction. Contrary to our predictions, contaminant concentrations were not correlated with stable isotopes of carbon (delta13C) or nitrogen (delta15N) in eggs. These latter findings indicate that contaminant concentrations were influenced more by point sources and geographic location than trophic status of eagles among the different islands.

Ixodes philipi (Acari: Ixodidae): Phylogenetic Status Inferred From Mitochondrial Cytochrome Oxidase Subunit I Gene Sequence Comparison

Ixodes philipi ticks were collected from the nest burrows of streaked shearwaters, Calonectris luecomelas, on 3 different islands of Japan (Awashima: 38 degrees 45'N, 139 degrees 24'E; Mikurajima: 33 degrees 52'N, 139 degrees 36'E; and Omorijima: 36 degrees 8'N, 133 degrees 10'E). The mitochondrial cytochrome oxidase subunit I (COI) gene sequence was determined for each tick. The COI sequences of 9 other ixodid tick species also were determined, and they were used for taxonomic positioning of I. philipi. A metastriata tick, Amblyomma triguttatum, was used as an outgroup reference for the analysis. Phylogenetic examination indicated that the I. philipi ticks are on the branch with Ixodes turdus and Ixodes acutitarsus weakly, and the bootstrap value of this branching was low. Three different analyses, maximum parsimony, genetic distance, and maximum likelihood, support this conclusion. To further refine this analysis, 2761 base pairs (bp) of sequence, which included the genes for tRNA(Met), NADH dehydrogenase subunit 2 (ND2), tRNA(Trp), tRNA(Cys), tRNA(Tyr), and COI, were determined and compared for 6 I. philipi ticks from the 3 different collection sites. Although a base substitution (T to C in the ND2 gene for an Awashima tick) and 2 transitions (G to A in the COI gene for 1 Omorijima tick) have occurred, the overall sequences were highly conserved. Preserved mitochondrial sequences in the ticks from 3 widely separated locations suggest the possibility of gene flow, which was probably accomplished by migratory seabirds.

Black beak tip coloration as a signal of phenotypic quality in a migratory seabird

Many different seabirds including terns have black color at the tip of their beak, but a yellow, orange, or red color of the rest of the beak. The tip of the beak of Arctic terns Sterna paradisaea is black, while the rest of the beak is deep red during the breeding season. We hypothesized that the black coloration of the tip of the beak is a reliable signal of phenotypic quality maintained by the costs of deposition of melanin. In this paper, we tested a number of predictions arising from this hypothesis. Consistent with the hypothesis, we found that (1) Arctic terns mated assortatively with respect to beak color score; (2) early breeding adults had larger beak color scores than late breeders; (3) clutch size was larger in adults with large beak color scores; (4) adults with a small beak color scores were more likely to die in the immediate future than individuals with large scores; and (5) beak color score was related to environmental conditions at the breeding grounds, as reflected by the North Atlantic Oscillation and the amount of fertilizer used in agriculture, and hence, leaking to coastal waters and environmental conditions at the Antarctic wintering areas as reflected by the Southern Oscillation. These findings suggest that beak color score provide reliable information about individual phenotypic quality.

Seabird Guano Is an Efficient Conveyer of Persistent Organic Pollutants (POPs) to Arctic Lake Ecosystems

Migratory seabirds have been linked to localized "hotspots" of contamination in remote Arctic lakes. One of these lakes is Lake Ellasjøen on Bjørnøya in the Barents Sea. Here we provide quantitative evidence demonstrating that even relatively small populations of certain seabird species can lead to major impacts for ecosystems. In the present example, seabird guano accounts for approximately 14% of the contaminant inventory of the Lake Ellasjøen catchment area, approximately 80% of the contaminant inventory of the lake itself, and is approximately thirty times more efficient as a contaminant transport pathway compared to atmospheric long-range transport. We have further shown that this biological transport mechanism is an important contaminant exposure route for ecosystems, responsible for POPs levels in freshwater fish that are an order of magnitude higher than those in Arctic top predators. Given the worldwide presence of seabird colonies in coastal marine areas where resources are also harvested by humans, this biological transport pathway may be a greater source of dietary contamination than is currently recognized with consequent risks for human health.

First Detection of Rickettsia in Soft‐Bodied Ticks Associated with Seabirds, Japan

Rickettsia was first detected in seabird soft-bodied ticks, Carios capensis and C. sawaii in Japan. According to sequence analysis, Rickettsia in Japan was identical to Rickettsia scc31 in C. capensis in the U.S.A. This suggested that an environmental circulation had consisted among microorganisms, ticks and long distance migratory seabirds around the Pacific Ocean.

Spring-time distributions of migratory marine birds in the southern California Current: Oceanic eddy associations and coastal habitat hotspots over 17 years

Abstract We used a 17-year time series of shipboard observations to address the hypothesis that marine birds associate with persistent hydrographic features in the southern California Current System (CCS). Overall, approximately 27,000 km of ocean habitat were surveyed, averaging 1600 km per cruise. We identified mesoscale features (eddy centers and the core of the California Current), based on dynamic height anomalies, and considered habitat associations for seven migratory seabird species: black-footed albatross ( Phoebastria nigripes ), Cook's petrel ( Pterodroma cookii ), Leach's storm-petrel ( Oceanodroma leucorhoa ), dark shearwaters (mainly sooty shearwater Puffinus griseus , with a few short-tailed shearwaters Puffinus tenuirostris ), northern fulmar ( Fulmarus glacialis ), red phalarope ( Phalaropus fulicaria ), and red-necked phalarope ( Phalaropus lobatus ). We explored associations (presence/absence and density relationships) of marine birds with mesoscale features (eddies, current jet) and metrics of primary productivity (chlorophyll a and nitrate concentrations). Mesoscale eddies were consistently identified in the study region, but were spatially and temporally variable. The resolved eddies were large-scale features associated with meanders of the equatorward-flowing California Current. Cook's petrel was found offshore with no specific habitat affinities. Black-footed albatross, red phalarope, and Leach's storm petrel were found in association with offshore eddies and/or the core of the California Current, but the functional relationship for these species varied, possibly reflecting differences in flight capabilities. The more coastal species, including the shearwaters, fulmar, and red-necked phalarope, were positively associated with proxies of primary productivity. Of the hydrographic habitats considered, the upwelling region of Point Conception appears to be an important “hotspot” of sustained primary production and marine bird concentrations. Point Conception and other similar coastal locations (upwelling cells) may warrant protection as key foraging grounds for seabirds.

Decline in the distribution and abundance of flesh-footed shearwaters ( Puffinus carneipes) on Lord Howe Island, Australia

The flesh-footed shearwater ( Puffinus carneipes) is a migratory seabird that ranges widely across the Pacific and Indian Oceans. The principal breeding populations are in Australia and New Zealand. The only breeding site in eastern Australia is on Lord Howe Island. Despite it being afforded a high level of legislative protection, the population on Lord Howe Island has declined substantially during the last few decades. The total extent of nesting habitat in 2002 was 24.3 ha, a reduction of 13.4 ha (35.6%) since 1978. Loss of nesting habitat was associated with increased urbanisation, the adverse impact of which extended beyond the footprint of buildings and gardens. In 2002, overall burrow density was 0.123 per m 2 and the total number of burrows was estimated to be 29,853 ± 5867, a decline of about 19.0% since 1978. A substantial decline in burrow density was evident in the colony where loss of habitat to urbanisation had been greatest. In 2002, 58% of burrows were occupied by breeding birds, and the total population size was estimated to be 17,462 breeding pairs. Breeding success (the proportion of eggs that produced fledglings) was 50%, but was lowest in the most urbanised colony. To avert further declines in the population of flesh-footed shearwaters on Lord Howe Island major changes in land use practices, enforced through appropriate legislation, are needed, together with reductions in the level of seabird bycatch in fisheries operations and in the amount of plastics that litter the world’s oceans.

Harvest rate of sooty shearwaters (Puffinus griseus) by Rakiura Māori: a potential tool to monitor population trends?

Sooty shearwaters (tītī, muttonbird, Puffinus griseus) are highly abundant migratory seabirds, which return to breeding colonies in New Zealand. The Rakiura Māori annual chick harvest on islands adjacent to Rakiura (Stewart Island), is one of the last large-scale customary uses of native wildlife in New Zealand. This study aimed to establish whether the rate at which muttonbirders can extract chicks from their breeding burrows indicates population trends of sooty shearwaters. Harvest rates increased slightly with increasing chick densities on Putauhinu Island. Birders' harvest rates vary in their sensitivities to changing chick density. Therefore a monitoring panel requires careful screening to ensure that harvest rates of the birders selected are sensitive to chick density, and represents a cross-section of different islands. Though harvest rates can provide only a general index of population change, it can provide an inexpensive and feasible way to measure population trends. Detecting trends is the first step to assessing the long-term sustainability of the harvest.

Mitochondrial Sequence Variation in Carios capensis (Neumann), a Parasite of Seabirds, Collected on Torishima Island in Japan

Partial mitochondrial 16S ribosomal ribonucleic acid gene sequences in the ticks Carios capensis collected from black-footed albatross. Diomedea nigripes, colonies on Torishima Island, Japan (30 degrees 28'N, 140 degrees 18'E), were examined. The sequence was compared with those of C. capensis from Hawaii, South Carolina, and Texas. The sequences were all identical in ticks from Torishima and 2 from Hawaii. There were 2-3 transitions between the other Hawaiian and Texas ticks and Torishima specimens. Two transitions were also observed when compared with the ticks from South Carolina. The results suggest the possibility of gene flow between tick populations at each of the 2 geographic sites, which probably was accomplished by tick-infested migratory seabirds at their breeding sites. Sequence comparison analysis indicated that the C. capensis ticks are on the branch with C. marginatus and C. mexicanus ticks and not with Ornithodoros. This supports the revision suggested by Klompen and Oliver (1993).

Using stable-isotope analysis of feathers to distinguish moulting and breeding origins of seabirds.

To determine whether stable isotope measurements of bird feathers can be used to identify moulting (interbreeding) foraging areas of adult seabirds, we examined the stable-carbon (δ13C) and nitrogen (δ15N) isotopic composition of feathers of chicks and adults of black-browed albatrosses (Diomedea melanophrys) from Kerguelen Islands, southern Indian Ocean. Albatross chicks are fed primarily fish (75% by mass), the diet being dominated by various species of the family Nototheniidae and Channichthyidae which commonly occur in the shelf waters in the vicinity of the colony. δ13C and δ15N values in chick feathers, which are grown in summer in the breeding area, were lower than values in adult feathers, which are grown in winter (δ13C: -19.6‰ versus -17.6‰ and δ15N: 12.4‰ versus 15.7‰, respectively). No differences in δ13C and δ15N values were found in adult wing feathers moulted in 1993 and 1994 and in adult feathers formed at the beginning, middle and end of the 1994 moulting period. These data are consistent with adults moulting in the same area and feeding at the same trophic level from one year to the next and with no major changes in foraging ecology within a given moulting season; they suggest that foraging grounds were different in summer and winter and that these differed in their stable-isotope signature. Changes in both feather δ13C and δ15N values indicated feeding south of the Subtropical Front (STF) during chick rearing, which is in agreement with the known foraging ecology at this time and feeding north of the STF during moult. This, together with band recoveries from adult birds, indicates that black-browed albatrosses from Kerguelen Islands wintered in subtropical waters off southern Australia. The stable-isotope markers in feathers, therefore, have the potential for locating moulting areas of migratory seabird species moving between isotopically distinct regions and for investigating seabirds' foraging ecology during the poorly known interbreeding period. Such information is needed for studies of year-round ecology of seabirds as well as for their conservation and the long-term monitoring of the pelagic environment.

Molt of Cory's Shearwater during the Breeding Season

We studied the molt of adult Cory's Shearwater Calonectris diomedea borealis breeding at Vila Islet, Azores. Breeders appear to undergo a complete annual molt that overlaps considerably with the breeding season. Molt is minimal during most of the prelaying and early incubation periods (March-June). The cycle starts at middle incubation (main period July), with ventral body feather replacement at a locus on the upper breast that progresses downwards and laterally to the belly and flanks. Dorsal body molt apparently follows similar topographical and temporal patterns to those of ventral body molt. Primary renewal seems to be simple and descendent and it is estimated to take a mean of 207 days for completion, between 28 August and 22 March. Rectrix renewal apparently starts on the wintering grounds since it is advanced but not completed in March-May; then it is apparently suspended until August, when the renewal of the few remaining old rectrices is concluded in most birds by September. Such an overlap of wing molt and breeding has not been previously described in a pelagic and highly migratory seabird as the Cory's Shearwater. We suggest that the timing of molt in the species is dictated by intrinsic rhythms acquired by evolution rather than imposed by nutritional or energetic constraints.

Virological quality of the Ria de Aveiro: Validity of potential microbial indicators

The summer occurrence of human enteroviruses and rotaviruses in the bacteriologically clean area of the Ria de Aveiro, a coastal marine lagoon, prompted the question of the assessment of the virological quality of recreational waters and shellfish raising beds. Enteroviruses were present in surface water at a density of 3 pfu 10 l−1 and were accumulated in sediments and, especially, in cockles where they reached concentrations 2 to 310log units greater. Rotaviruses were detected at one10log unit below the density of enteroviruses in sediments and cockles and were not detected in water. Four bacteriophage systems were assayed as indicators of human enteric viruses: somatic coliphages ofE.coli C, sexual and sexual-RNA coliphages plated onSalmonella WG49 and phages againstBacteroides fragilis HSP40. The results obtained from 2 lagoon stations sampled in summer, autumn and winter showed that the four systems failed to indicate the presence of enteroviruses and rotaviruses in water, sediment and shellfish samples. The absence of phages ofB. fragilis HSP40 in all types of samples taken from the lagoon, but not from the residual waters of the treatment station, suggests that they may suffer a strong negative pressure in this ecosystem as their proportion to the coliphages in the cockles deviated strongly from the ratio of 1∶100 to 1∶1000 observed at the sewage outfall. In fact, no correlation was observed between these phages and enteric viruses or coliphages. Alternatively, it is possible that the importance of diffuse faecal pollution and the interference of faecal pollutants of animal origin, including migratory sea birds which are abundant in winter, can alter the proportions of the faecal bacteriophages beyond recognition. It is apparent that bacteriophage monitoring of the health risk linked to the occurrence of viruses in the marine environment is not yet fully resolved, what may leave viral quality assessment dependent on direct detection of human enteric virus.