Origin, age, sex and breeding status of wandering albatrosses (Diomedea exulans), northern (Macronectes halli) and southern giant petrels (Macronectes giganteus) attending demersal longliners in Falkland Islands and Scotia Ridge waters, 2001–2005

A total of 547 sightings of 291 banded wandering albatrosses Diomedea exulans and 21 sightings of 14 banded giant petrels Macronectes spp. were made from toothfish longliners operating on the southern Patagonian Shelf during 2001–2005. This included 25% of the wandering albatrosses with Darvic bands that bred at Bird Island (South Georgia) during this period. Thirteen of the northern Macronectes halli and southern giant petrels Macronectes giganteus had been banded at South Georgia, and there was one sighting of a southern giant petrel from Argentina. Male and female wandering albatrosses of all age classes except young birds (<15 years old) were equally likely to attend longline vessels. Most sightings of all age classes were made during the incubation period and fewest during the brood period. Eighty-six percent of birds sighted had bred at least once before, with half currently breeding and half on sabbatical (i.e. between breeding attempts). Almost half of the wandering albatrosses were sighted on more than one occasion. The data confirms that the southern Patagonian shelf is an important foraging area for wandering albatrosses and northern and southern giant petrels, and that some individuals show consistent associations in multiple years with longline vessels fishing in the region.     

Population size and trends of southern giant petrels (<Emphasis Type="Italic">Macronectes giganteus</Emphasis>) nesting at Signy Island,South Orkney Islands

The southern giant petrel (Macronectes giganteus) has a circumpolar distribution and breeds on subantarctic islands and a few continental Antarctic sites. Although this species has recently been down-listed to “Least Concern” by the World Conservation Union (IUCN), there are strong fluctuations in abundance and variable long-term trends recorded at different sites. Systematic, long-term monitoring is essential to determine drivers underlying its population dynamics. Here, we examine long-term changes in population size and productivity of southern giant petrels at Signy Island, South Orkney Islands. Comparing estimated numbers of breeding pairs over the whole island in 2000/2001, 2005/2006, 2009/2010 and 2014/2015 with historical data revealed several phases of population change: a 64 % decline (6.2 % per annum) from 1968/1969 to 1984/1985, a 162 % increase (6.2 % per annum) to 2000/2001, stability until 2005/2006, a 56 % decline (18.3 % per annum) to 2009/2010 and stability until 2014/2015. This represents a 1.8 % decline per annum between 1968/1969 and 2014/2015. Annual counts within focal study areas suggested a more rapid increase from 1996/1997 to 2006/2007, but the same downward trend from 2006/2007 to present, underlining potential pitfalls in inferring trends from part-island counts. There was also a 20 % decline in breeding success from 1996/1997 to 2014/2015. Our results indicate substantial fluctuations in southern giant petrel abundance at Signy Island over 4–5 decades and a recent decline in breeding numbers and success. As the southern giant petrels breeding at the South Orkney Islands represents ~5–10 % of the global population, continuation of these declines would be of high conservation concern.     

Giant petrels as predators of albatross chicks

Giant petrels Macronectes spp. are not thought to be important predators of albatross chicks, although they are known to kill pre-fledging Thalassarche and Phoebetria albatrosses. We report the first records of predation of healthy great albatross Diomedea spp. chicks, killing wandering albatrosses D. exulans at night on sub-Antarctic Marion Island. Breeding success of this species has decreased markedly in the area where attacks occurred, suggesting that giant petrel predation events are a recent phenomenon. Mouse attacks on wandering albatross chicks may have contributed to the development of this hunting technique. We also report the first observations of giant petrel predation on pre-fledging grey-headed albatross T. chrysostoma chicks as well as additional records of sooty albatross P. fusca chicks being targeted. Only adult northern giant petrels M. halli have been confirmed to kill albatross chicks on Marion Island. Given the threatened status of wandering albatrosses, and the importance of Marion Island for this species, monitoring of their breeding success is necessary to assess whether the predation of chicks by giant petrels spreads around the island.     

An extreme inland breeding locality of snow petrels (Pagodroma nivea) in the southern Prince Charles Mountains, Antarctica

Bird observations were made as part of a preliminary biological survey of the southern half of the Mawson Escarpment in the southern Prince Charles Mountains, Mac.Robertson Land between 26 January and 4 February 1998. A new breeding colony of snow petrels (Pagodroma nivea) is described, together with details of individual snow petrel sightings. At 440 km from the coast, the snow petrel colony is the furthest inland of any confirmed breeding site for this species. Accepted: 1 May 2000     

Hybridization and pre-zygotic reproductive barriers in Plasmodium

Sexual reproduction is an obligate step in the life cycle of many parasites, including the causative agents of malaria (Plasmodium). Mixed-species infections are common in nature and consequently, interactions between heterospecific gametes occur. Given the importance of managing gene flow across parasite populations, remarkably little is understood about how reproductive isolation between species is maintained. We use the rodent malaria parasites P. berghei and P. yoelii to investigate the ecology of mixed-species mating groups, identify proteins involved in pre-zygotic barriers, and examine their evolution. Specifically, we show that (i) hybridization occurs, but at low frequency; (ii) hybridization reaches high levels when female gametes lack the surface proteins P230 or P48/45, demonstrating that these proteins are key for pre-zygotic reproductive isolation; (iii) asymmetric reproductive interference occurs, where the fertility of P. berghei gametes is reduced in the presence of P. yoelii and (iv) as expected for gamete recognition proteins, strong positive selection acts on a region of P230 and P47 (P48/45 paralogue). P230 and P48/45 are leading candidates for interventions to block malaria transmission. Our results suggest that depending on the viability of hybrids, applying such interventions to populations where mixed-species infections occur could either facilitate or hinder malaria control.     

Moult of the giant petrels Macronectes halli and M. giganteus at South Georgia

Moult scores were collected from colour-ringed individuals of known reproductive status of the two species of giant petrel, Macronectes halli and M. giganteus , at Bird Island, South Georgia between 1978–81.
Both species showed a substantial overlap between breeding and wing-moult, unlike most other Southern Ocean seabirds. Males started moult before females and both sexes of M. giganteus moulted at an earlier stage of the breeding cycle than M. halli , which breeds six weeks earlier than its congener.
Changes in moult rate during the breeding season are documented for both species, with Id. halli showing a rapid increase as the chick nears fledging. Male M. giganteus show a notably different pattern to the other three species-sex groups, starting moult much earlier (at egg-laying), with greater individual synchrony and usually suspending primary moult throughout the main chick growth period, whereas only two male M. halli and no females of either species suspended moult. Differences in pattern, timing and rate of moult are interpreted in terms of availability of food resources and the competing energy demands of other activities, especially chick-rearing.
Completion of primary moult could not be observed in the field but was estimated using data frcsm non-breeding birds and failed breeders; the latter started a rapid moult almost immediately they failed. In both sexes of both species moult is probably concluded at least by early winter.
The general pattern of moult in giant petrels at Bird Island is contrasted with that of other populations and species of Southern Ocean seabirds. It is suggested that the unusually extensive overlap between breeding and moult in giant petrels is a consequence of the very abundant and easily available summer food supplies (especially carrion) and the much diminished winter resources, favouring a completion of moult by the beginning of the winter.     

Cool,cold or colder? Spatial segregation of prions and blue petrels is explained by differences in preferred sea surface temperatures

The Southern Ocean provides one of the largest environmental gradients on Earth that lacks geographical barriers, and small but highly mobile petrels living there may offer fine models of evolution of diversity along environmental gradients. Using geolocation devices, we investigated the winter distribution of closely related petrel species breeding sympatrically in the southern Indian Ocean, and applied ecological niche models to compare environmental conditions in the habitat used. We show that thin-billed prions (Pachyptila belcheri), Antarctic prions (Pachyptila desolata) and blue petrels (Halobaena caerulea) from the Kerguelen archipelago in the southern Indian Ocean segregate latitudinally, sea surface temperature being the most important variable separating the distribution of the species. Antarctic prions spent the winter north of the Polar Front in temperate waters, whereas blue petrels were found south of the Polar Front in Antarctic waters. Thin-billed prions preferred intermediate latitudes and temperatures. Stable isotope values of feathers reflected this near complete niche separation across an ecological gradient that spans large scales, and suggest evolutionary isolation by environment. In pelagic seabirds that exploit large areas of ocean, spatial niche partitioning may not only facilitate coexistence among ecologically similar species, but may also have driven their evolution in the absence of geographical barriers.     

The breeding biology of the gadfly petrels Pterodroma spp. of the Pitcairn Islands: characteristics, population sizes and controls

This paper reports the breeding biology and nesting seasons of the gadfly petrels which nest on the four islands of the Pitcairn group, Pitcairn, Henderson, Oeno and Ducie. The species currently breeding are Murphy's petrel Pterodroma ultima , Kermadec petrel P. neglecta , Herald petrel P. heraldica and Henderson petrel P. atrata. Of these, Murphy's petrel is the most numerous; an estimated 250000 pairs bred on Ducie, which is probably the major breeding station of the species. Novel basic breeding data for Murphy's petrel are presented. Incubation spells, averaging 19.3 days, are exceptionally long for a petrel. Phoenix petrel P. alba appears to have ceased to breed on the Pitcairn Islands since the 1922 surveys of the Whitney Expedition. Nesting success was low on Henderson Island during the study. For all four breeding species, less than 20% of eggs laid yielded fledglings. Failure occurred at the early chick stage and observations indicated that it was due to predation by Pacific rats Rattus exulans. Although rats are present on Ducie, predation was apparently less severe there. The situation on Oeno may be intermediate. I consider how the populations of Henderson are maintained in the face of this intense predation. The Murphy's petrel population may be sustained by immigration from Ducie while the Herald and Henderson petrel populations could be undergoing a long-term decline on Henderson. It is not clear how the Kermadec petrel population is maintained. The conservation implications of these findings are discussed.     

Regulation of incubation shifts near hatching by giant petrels: a timed mechanism, embryonic signalling or food availability?

In most seabird species incubation shifts shorten when hatching approaches, a behavioural response allowing the chick to be fed soon after hatching. Three mechanisms have been proposed to explain these shortened absences: endogenous timing, a response to embryo signals or a seasonal increase in food availability. I tested these hypotheses by cross-fostering eggs between two sibling species: the northern Macronectes halli and the southern M. giganteus giant petrels; the former normally breeds 5-6 weeks earlier than the latter but both have an incubation period of 60 days. The length of the last trip before hatching was unaffected by the timing of hatching, suggesting that trip length was not related to the increase in food availability with the progress of the season. Furthermore, northern giant petrels reduced their last trip lengths regardless of whether they were incubating their own developed or the southern undeveloped egg (with embryos not developed enough to signal). Parents presumably, therefore, possess endogenous control allowing them to predict hatching date and to reduce trip duration accordingly, regardless of the communication with the embryo. Nevertheless, shorter last trips before hatching in southern giant petrels incubating northern giant petrel eggs suggest that parents use embryo signals for a fine-tuning synchronization of the internal timer to the natural variability in the length of the incubation period.     

Who’s the boss? Giant petrel arrival times and interspecific interactions at a seal carcass at sub-Antarctic Marion Island

Most northern giant petrels Macronectes halli arrived before southern giant petrels Macronectes giganteus at a seal carcass at sub-Antarctic Marion Island and left earlier. In interspecific interactions, southern giant petrels initiated and dominated encounters. Level of aggression may be related to the degree of satiation. Dominance by southern giant petrels at seal carcasses may help explain why northern giant petrels commence breeding earlier than southern giant petrels in sympatric situations.     

Population genetic and behavioural variation of the two remaining colonies of Providence petrel (<Emphasis Type="Italic">Pterodroma solandri</Emphasis>)

Knowledge of the dispersal capacity of species is crucial to assess their extinction risk, and to establish appropriate monitoring and management strategies. The Providence petrel (Pterodroma solandri) presently breeds only at Lord Howe Island (~32,000 breeding pairs) and Phillip Island-7 km south of Norfolk Island (~20 breeding pairs). A much larger colony previously existed on Norfolk Island (~1,000,000 breeding pairs) but was hunted to extinction in the 18th Century. Differences in time of return to nesting sites are presently observed between the two extant colonies. Information on whether the Phillip Island colony is a relict population from Norfolk Island, or a recent colonization from Lord Howe Island, is essential to assess long-term sustainability and conservation significance of this small colony. Here, we sequenced the mitochondrial cytochrome b gene and 14 nuclear introns, in addition to genotyping 10 microsatellite loci, to investigate connectivity of the two extant P. solandri populations. High gene flow between populations and recent colonization of Phillip Island (95 % HPD 56–200 ya) are inferred, which may delay or prevent the genetic differentiation of these insular populations. These results suggest high plasticity in behaviour in this species and imply limited genetic risks surrounding both the sustainability of the small Phillip Island colony, and a proposal for translocation of Lord Howe Island individuals to re-establish a colony on Norfolk Island.     

Influence of reproductive output on divorce rates in polar seabirds

The high occurrence of social monogamy in birds has led to questions about partner fidelity, or the perennial nature of monogamy from one breeding season to another. Despite the evolutionary advantages of partner fidelity, divorce occurs among 95% of bird species. We aimed to describe patterns of divorce and partner fidelity in five seabird species breeding in Arctic and Antarctic regions and investigated the influence of breeding status on pair bond maintenance. For four out of the five species considered, we observed low divorce rates (respectively 1.9%, 3.3%, 2.5%, and 0.0% for Brünnich''s guillemot, glaucous gull, Antarctic petrel, and south polar skua), while the divorce rate was much higher (19.1%) for the black‐legged kittiwake. For kittiwakes, the divorce rate was lower for pairs that managed to raise their chick to 15 days of age, while the effect of breeding success on divorce in the four other species could not be tested due to the rareness of divorce events. Our results emphasize the potentially large temporal (interannual) variations that should be taken into account in understanding divorce and partner fidelity in seabirds.     

Hybridization, species collapse, and species reemergence after disturbance to premating mechanisms of reproductive isolation

There are now a number of well-studied cases in which hybridization between closely related sympatric species has increased, sometimes resulting in the replacement of species pairs by hybrid swarms. Many of these cases have been linked to anthropogenic environmental change, but the mechanisms leading from environmental change to species collapse, and the long-term effects of hybridization on species pairs, remain poorly understood. We used an individual-based stochastic simulation model to explore the conditions under which disturbances that weaken premating barriers to reproduction patterns between sympatric species might lead to increased hybridization and to species collapse. Disturbances often resulted in bouts of hybridization, but in many cases strong reproductive isolation spontaneously reemerged. This was sometimes true even after hybrid swarms had replaced parental species. The reemergence of species pairs was most likely when disturbances were of short duration. Counterintuitively, incipient species pairs were more likely to reemerge after strong but temporary disturbances than after weaker disturbances of the same duration. Even temporary bouts of hybridization often led to substantial homogenization of species pairs. This suggests that ecosystem managers may be able to refill ecological niches, but in general will not be able to resurrect lost species after species collapse.     

An assessment of the breeding range,colony sizes and population of the Westland petrel (Procellaria westlandica)

Abstract

The Westland petrel (Procellaria westlandica) is an endemic New Zealand species and one of the very few burrowing seabird species still breeding on mainland New Zealand. It nests only on a series of coastal ridgelines near to Punakaiki on the West Coast of the South Island. Between 2002 and 2005, surveys were undertaken at 28 of the 29 known colonies. The area occupied by the colonies was 73 ha; most colonies had fewer than 50 burrows, but six colonies had 201–500 burrows and four colonies had more than 1000 burrows. We find that the current breeding range of Westland petrel and the location of individual colonies are similar to those reported in both the 1950s and 1970s. Based on total burrow counts at 28 colonies and burrow occupancy rates determined by annual monitoring, the annual breeding population is estimated to be between 2954 and 5137 breeding pairs.     

Hybridization of Two Major Termite Invaders as a Consequence of Human Activity

While hybridization of an invasive species with a native species is a common occurrence, hybridization between two invasive species is rare. Formosan subterranean termites (Coptotermes formosanus) and Asian subterranean termites (C. gestroi) are both ecologically successful and are the two most economically important termite pests in the world. Both species have spread throughout many areas of the world due to human activity; however, their distributions overlap in only three narrow areas because of distinct ecological requirements. In south Florida, where C. formosanus and C. gestroi are both invasive, the dispersal flight seasons of both species overlapped for the first time on record in 2013 and 2014. Pairings of heterospecific individuals were readily observed in the field and C. gestroi males preferentially engaged in mating behavior with C. formosanus females rather than females from their own species. In the laboratory, heterospecific and conspecific pairings had an equal colony establishment rate, but heterospecific incipient colonies had twice the growth rate of conspecific incipient colonies, suggesting a potential case of hybrid vigor. As all pre-zygotic barriers were lifted between the two species in the field, the apparent absence of post-zygotic barriers in the laboratory raises the possibility for introgressive hybridization in south Florida. While laboratory observations remain to be confirmed in the field, and the alate hybrid fertility is currently unknown, our results raise a tangible concern about the hybridization of two major destructive pest species. Such hybridization would likely be associated with a new economic impact.     

Natural and Anthropogenic Hybridization in Two Species of Eastern Brazilian Marmosets (Callithrix jacchus and C. penicillata)

Animal hybridization is well documented, but evolutionary outcomes and conservation priorities often differ for natural and anthropogenic hybrids. Among primates, an order with many endangered species, the two contexts can be hard to disentangle from one another, which carries important conservation implications. Callithrix marmosets give us a unique glimpse of genetic hybridization effects under distinct natural and human-induced contexts. Here, we use a 44 autosomal microsatellite marker panel to examine genome-wide admixture levels and introgression at a natural C. jacchus and C. penicillata species border along the São Francisco River in NE Brazil and in an area of Rio de Janeiro state where humans introduced these species exotically. Additionally, we describe for the first time autosomal genetic diversity in wild C. penicillata and expand previous C. jacchus genetic data. We characterize admixture within the natural zone as bimodal where hybrid ancestry is biased toward one parental species or the other. We also show evidence that São Francisco River islands are gateways for bidirectional gene flow across the species border. In the anthropogenic zone, marmosets essentially form a hybrid swarm with intermediate levels of admixture, likely from the absence of strong physical barriers to interspecific breeding. Our data show that while hybridization can occur naturally, the presence of physical, even if leaky, barriers to hybridization is important for maintaining species genetic integrity. Thus, we suggest further study of hybridization under different contexts to set well informed conservation guidelines for hybrid populations that often fit somewhere between “natural” and “man-made.”     

Avian cholera in a southern giant petrel (Macronectes giganteus) from Antarctica

A southern giant petrel (Macronectes giganteus) was found dead at Potter Peninsula, King George Island, South Shetland, Antarctica. The adult male was discovered approximately 48 hr after death. Macroscopic and microscopic lesions were compatible with avian cholera and the bacterium Pasteurella multocida subsp. gallicida, serotype A1 was isolated from lung, heart, liver, pericardial sac, and air sacs. In addition, Escherichia coli was isolated from pericardial sac and air sacs. This is the first known report of avian cholera in a southern giant petrel in Antarctica.     

Projected distributions of Southern Ocean albatrosses,petrels and fisheries as a consequence of climatic change

Given the major ongoing influence of environmental change on the oceans, there is a need to understand and predict the future distributions of marine species in order to plan appropriate mitigation to conserve vulnerable species and ecosystems. In this study we use tracking data from seven large seabird species of the Southern Ocean (black‐browed albatross Thalassarche melanophris, grey‐headed albatross T. chrysostoma, northern giant petrel Macronectes halli, southern giant petrel M. giganteus, Tristan albatross Diomedea dabbenena, wandering albatross D. exulans and white‐chinned petrel Procellaria aequinoctialis, and on fishing effort in two types of fisheries (characterised by low or high‐bycatch rates), to model the associations with environmental variables (bathymetry, chlorophyll‐a concentration, sea surface temperature and wind speed) through ensemble species distribution models. We then projected these distributions according to four climate change scenarios built by the Intergovernmental Panel for Climate Change for 2050 and 2100. The resulting projections were consistent across scenarios, indicating that there is a strong likelihood of poleward shifts in distribution of seabirds, and several range contractions (resulting from a shift in the northern, but no change in the southern limit of the range in four species). Current trends for southerly shifts in fisheries distributions are also set to continue under these climate change scenarios at least until 2100; some of these may reflect habitat loss for target species that are already over‐fished. It is of particular concern that a shift in the distribution of several highly threatened seabird species would increase their overlap with fisheries where there is a high‐bycatch risk. Under such scenarios, the associated shifts in distribution of seabirds and increases in bycatch risk will require much‐improved fisheries management in these sensitive areas to minimise impacts on populations in decline.     

Foods of the south polar skua at Hop Island,Rauer Group,East Antarctica

Summary Pellets regurgitated by south polar skuas at Hop Island, in the Rauer Group, East Antarctica, Princess Elizabeth Land were collected and analysed. Individual collections were grouped in relation to the nearest breeding colony of seabirds, but irrespective of their source the frequencies of occurrence of the food items identified in pellets indicated that Adélie penguins were of varying, but major (29%–72%), importance to skuas inhabiting the Island. Though the incidence of Antarctic petrel remains (from adult or chick) was generally low in pellets (<7%), the occurrence of remains of southern fulmars was high (>27%) at all sites near the fulmar breeding colonies. Fish remains, and beaks of cephalopods, were present in few pellets. Whilst indicating the range of foods eaten on Hop Island, and perhaps their relative importance, it is considered that the pellets by themselves do not reflect accurately the level of predation of eggs of Antarctic petrels and southern fulmars, nor do the pellets necessarily include the remains of young of these species.     

Burrow densities and nest site preferences of petrels (Procellariidae) at the Prince Edwards Islands

Summary The nest-site preferences of six burrowing petrel species, Salvin's prion Pachyptila vittata salvini, blue petrel Halobaena caerulea, great-winged petrel Pterodroma macroptera, Kerguelen petrel Pterodroma brevirostris, soft-plumaged petrel Pterodroma mollis and white-chinned petrel Procellaria aequinoctialis, in the northeastern part of Marion Island (Prince Edward Island group, southern Indian Ocean) were analyzed by step-wise multiple regression. The nest-site characteristics measured were slope angle, soil depth and moisture content, percentage cover by stones or boulders and percentage cover by each of seven major plant species. The major nest-site preferences were: exposed areas with shallow soil (Salvin's prion); steep coastal slopes (blue petrel); sheltered well-drained slopes with deep soil (great-winged petrels); wet areas along drainage lines (Kerguelen petrel); steep slopes (soft-plumaged petrel); and areas with deep soil (white-chinned petrel). Similar species showed no significant avoidance of nest sites where there were burrows of potential competitors but did tend to nest spread out over different habitats. Burrow densities were determined in six habitat and seven vegetation types. Salvin's prion was the most abundant species (81% of burrows, with a maximum density of 279 burrows ha^-1) and used both burrows and natural cavities for nesting. For all species combined, burrow densities at Marion Island were lower than in comparable habitats and vegetation types at neighbouring Prince Edward Island. Depredation by feral house cats Felis catus, absent from Prince Edward Island, is assumed to be largely responsible for this difference.