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SUMMARY CUTHBERT, R.J. & SOMMER, E.S. 2004. Population size and trends of four globally threatened seabirds at Gough Island, South Atlantic Ocean. Marine Ornithology 32: 97-103. Gough Island in the South Atlantic Ocean is a site of international significance for breeding seabirds, yet for most species population estimates have not been quantified a...
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... Island (40°21′S, 9°53′W), part of the United Kingdom Overseas Territory of Tristan da Cunha, is located approximately 3000 km from South Africa and South America, and 350 km south- east of Tristan da Cunha (Fig. 1). There is a permanent weather station, run under lease by the South African Department of Environmental Affairs & Tourism, but no other habitation . It is a volcanic island, c. 65 km in area, with steep mountainous terrain. Four main vegetation types are found on Gough Island: coastal tussock (mainly comprising of the grasses Spartina ...
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Seabirds are known to be important indicators of marine ecosystems health. Procellariiformes are one of the most abundant seabird species distributed from warm tropical to cold temperate regions including Antarctica. With few long-term studies on breeding seabirds at the Antarctic continent, crucial biological parameters such as genetic variation,...
Seabirds are important indicators of marine ecosystem health. Species within the order Procellariiformes are the most abundant seabird species group distributed from warm tropical to cold temperate regions including Antarctica. There is a paucity of information on basic biology of the pelagic seabird species nesting on the Antarctic continents, and...
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... Conversely, the sooty albatross ( Phoebetria fusca , SA) is much more rarely observed flying towards fishing vessels (Griffiths, 1982 ), and anecdotal onboard observations suggest it may not be strongly attracted to boats. Nonetheless, several breeding population declines have been at least partly attributed to fisheries bycatch mortality Cuthbert and Sommer, 2004 ;Delord et al ., 2005 ;Rolland et al ., 2010 ;Schoombie et al ., 2016 ) and the species is in danger of extinction ( Endangered ; BirdLife International, 2018b ). This means their total world population is low compared to WCP. ...
Bycatch risk assessments typically rely on spatial o v erlaps betw een seabirds and fishing vessels but should also consider seabirds' position in the attraction spectrum. In v estigating seabird-fishery interactions in relation to habitat use is vital for species-specific risk assessments. To address this, we studied interactions bet ween soot y albatrosses (SA) and white-chinned petrels (WCP) with fisheries. GPS data from 20 SA and 18 WCP individuals from Marion Island were analysed alongside Automatic Identification Sy stem-deriv ed boat locations o v er tw o breeding seasons. We calculated encounter and attraction rates and correlated them with marine habitat characteristics. SA interactions occurred in deeper, warmer waters compared to their foraging habitat when vessels were absent, with 20% of individuals encountering and only 5% being attracted to boats. In contrast, WCP interactions occurred in shallo w, w arm South African shelf waters, consistent with their typical foraging habitats, with 72% encountering and 56% attracted to boats. These results highlight the need for continued reinforcement of mitigation measures for WCP. Despite the low attraction rates for SA, ongoing vigilance is required due to their smaller population size, which heightens the potential impact of illegal fisheries. The comparison of species along an attraction spectrum contributes to refining risk assessments and informs species-specific conservation strategies.
... Seabirds are long-lived avian top predators that include many species at risk of extinction (Butchart et al., 2004;Velando et al., 2015), with 19% of the globally monitored seabird population in severe decline (Cuthbert & Sommer, 2003;McCauley et al., 2015;Paleczny et al., 2015). Seabirds spend most of their lives hunting on the open ocean, where they face various threats, including fisheries bycatch (Anderson et al., 2011;Barbraud et al., 2011), contamination from oil spills (e.g., Tran et al., 2014), heavy metal bioaccumulation through the marine food web (Burger & Gochfeld, 2000;García-Tarrasón et al., 2013), and plastic pollution (Wilcox et al., 2015) leading to entanglement (Votier et al., 2011) or starvation (Pierce et al., 2004). ...
Seabirds are among the most endangered avian groups, with populations declining worldwide because of various threats, including invasive nest predators. Similar decreasing trends are occurring in the Southern Grenadines; however, the causes of decline remain uncertain, although non‐native rats have been suspected. Therefore, our objective was to determine whether non‐native rats are present on five Southern Grenadine islands that harbor seabird colonies, during May–July 2014–2017, using four methods (chew cards, tunnels, cameras, and questionnaires). Les Tantes East and Lee Rocks were the only two islands where cameras detected black rats (Rattus rattus). Although rat occupancy was low (0.125 ± 0.061) and the number of individuals and nesting attempts increased (except in 2017) for most species, the low detection probability and small number of nests prevented any inference about rat impact on seabirds. Rats might have affected seabird colonies, but other factors, such as seabird harvest, prey availability, or climatic fluctuations, could have also driven previous seabird population declines in the Southern Grenadines. However, non‐native rats are present and future research should focus on estimating their density and distribution on these and other islands of the region before an appropriate rat eradication program can be implemented.
... Seabirds, a threatened avian group for which extinctions are probable within the next century (Butchart et al. 2004, Cuthbert and Sommer 2004, Paleczny et al. 2015, are declining globally. These declines can be attributed to a variety of threats, including climate change, introduced terrestrial predators (Spatz et al. 2014), human disturbance in nesting colonies, marine plastic pollution, habitat loss and degradation, and overexploitation (Dias et al. 2019). ...
Despite their sociocultural and economic value, seabird populations have dramatically declined, in part due to overexploitation. Although seabird harvest is not as common worldwide as it was historically, partly because of protective laws, illegal harvest still occurs, particularly in tropical developing nations. In Grenada, seabird harvest could partly explain the decline of seabird colonies. Our objective was to determine if fishers and recreationists engage in seabird harvest in the Grenada Grenadines and, if so, which sociodemographic factors may be associated with harvesting seabirds. We designed a 64-question survey that we made available at the Fisheries Division office of Sauteurs, Grenada, for 6 weeks each year (15 June to 30 July) from 2015 to 2017. Although respondents claimed that harvesting is a tradition that infrequently occurs today, survey responses and anecdotal evidence suggest seabird harvest still occurs. Continued seabird harvest, combined with other threats (e.g., livestock grazing), could prove detrimental to existing Grenadine seabird colonies. Interestingly, respondents who have collected or eaten seabirds seem unaware of laws that protect seabirds from hunting, which are especially restrictive during the breeding season. Therefore, we recommend establishing a community-based monitoring program that 1) empowers fishers and recreationists through education and awareness of seabird harvest, 2) provides a patrolling presence on islands previously neglected, and 3) ensures continuity of seabird data collection in the Grenada Grenadines. Keywords egg collection, fishers, Grenada Grenadines, local knowledge, poaching, seabirds, sociodemographic factors Resumen Encuesta a los granadinos sobre la captura de aves marinas en las Granadinas de Granada • Las poblaciones de aves marinas han disminuido drásticamente, a pesar de su valor económico y sociocultural, y es debido en parte a la sobreexplotación. Aunque su captura no es tan común a nivel global como lo era históricamente, en gran medida por las leyes de protección, todavía ocurre de manera ilegal y sobretodo en las naciones tropicales en desarrollo. En Granada, la captura de aves marinas podría explicar en parte el declive de las colonias de estas especies. Nuestro objetivo fue determinar si los pescadores y aquellos que realizan actividades al aire libre en las Granadinas de Granada participan en la captura de aves marinas y de ser así, qué factores sociodemográficos pueden estar asociados con las mismas. Diseñamos una encuesta de 64 preguntas que estuvo disponible en la oficina de la División de Pesquerías de Sauteurs, Granada, durante 6 semanas cada año (del 15 de junio al 30 de julio) de 2015 a 2017. Aunque los encuestados afirmaron que la captura es una tradición que ocurre hoy en día con poca frecuencia, las respuestas de las encuestas y la evidencia anecdótica sugieren que todavía se produce. La captura continua de aves marinas, en conjunto con otras amenazas (por ejemplo, el pastoreo de ganado), podría ser perjudicial para las colonias de estas especies que existen en las Granadinas. Curiosamente, los encuestados que han recolectado o comido aves marinas parecen desconocer las leyes que protegen a estas especies de la caza y que son especialmente restrictivas durante la temporada reproductiva. Por lo tanto, recomendamos establecer un programa de monitoreo comunitario que 1) capacite a los pescadores y a aquellos que realizan actividades al aire libre en la zona a través de la educación y la concientización sobre la captura de aves marinas, 2) proporcione patrullaje en las islas que han sido descuidadas previamente, y 3) garantice la continuidad de la recopilación de datos de aves marinas en las Granadinas de Granada. Palabras clave aves marinas, caza furtiva, conocimiento local, factores sociodemográficos, Granadinas de Granada, pescadores, recolección de huevos Résumé Enquête auprès des Grenadiens sur la chasse aux oiseaux marins dans les Grenadines de la Grenade • Malgré leur valeur socioculturelle et économique, les populations d’oiseaux marins ont subi des déclins importants, en partie dus à leur surexploitation. Bien que la chasse aux oiseaux marins ne soit pas aussi répandue dans le monde qu’autrefois, notamment grâce aux lois de protection, la chasse illégale existe toujours, particulièrement dans les pays tropicaux en développement. À la Grenade, ces pratiques pourraient partiellement expliquer le déclin des colonies d’oiseaux marins. Notre objectif était de déterminer si les pêcheurs et les plaisanciers participent à la chasse aux oiseaux marins sur les îles des Grenadines de la Grenade et, si c’était le cas, quels facteurs sociodémographiques pourraient être associés à ces pratiques. Nous avons conçu un questionnaire de 64 questions que nous avons mis à disposition au bureau des pêches de Sauteurs, à la Grenade, chaque année pendant 6 semaines (du 15 juin au 30 juillet) de 2015 à 2017. Bien que les répondants aient affirmé que la chasse aux oiseaux marins constituait une tradition ancienne et était devenue rare de nos jours, certaines de nos observations (p. ex. un seau d’œufs) suggèrent que cette pratique a toujours lieu. La poursuite de la chasse aux oiseaux marins, combinée à d’autres menaces (p. ex. le pâturage du bétail), pourrait s’avérer préjudiciable aux colonies d’oiseaux marins des Grenadines. Il est intéressant de noter que les répondants ayant prélevé ou mangé des oiseaux marins ne semblaient pas connaître les lois qui protègent ces espèces de la chasse et qui sont particulièrement restrictives pendant leur saison de reproduction. Par conséquent, nous recommandons d’établir un programme communautaire de suivi des colonies qui 1) responsabilise les pêcheurs et les plaisanciers à travers l’éducation et la sensibilisation sur la chasse aux oiseaux marins; 2) assure une présence de patrouille sur des îles jusque-là non surveillées; et 3) permette la continuité de la collecte de données sur les oiseaux marins des îles des Grenadines de la Grenade. Mots clés braconnage, collecte d’œufs, connaissances locales, facteurs sociodémographiques, Grenadines de la Grenade, oiseaux marins, pêcheurs
... Esta especie presenta una población reproductora relativamente pequeña (con respecto a otras especies del género), endémica del archipiélago de Tristan da Cunha e isla Gough en el Atlántico sur central (Cuthbert et al. 2003b, Cuthbert y Sommer 2004, de donde provienen las aves que llegan a Uruguay. La población de Gough ha sido estimada en 5300 parejas anuales (Cuthbert y Sommer 2004). ...
... Esta especie presenta una población reproductora relativamente pequeña (con respecto a otras especies del género), endémica del archipiélago de Tristan da Cunha e isla Gough en el Atlántico sur central (Cuthbert et al. 2003b, Cuthbert y Sommer 2004, de donde provienen las aves que llegan a Uruguay. La población de Gough ha sido estimada en 5300 parejas anuales (Cuthbert y Sommer 2004). Existe menor precisión en las estimaciones del número de parejas para el grupo Tristan da Cunha, especialmente en la isla de Tristan donde las estimaciones son basadas en datos de 1974. ...
... Estimates of the annual numbers of breeding pairs for 10 seabird species breeding on Gough Island were taken from the literature (Cuthbert & Sommer 2004, Rexer-Huber et al. 2014 or from the authors' unpublished data ( Table 1). Six of those 10 species nest in burrows, caves or crevices below-ground: Atlantic Petrel, Grey Petrel, Softplumaged Petrel, Great Shearwater, Broad-billed Prion and MacGillivray's Prion. ...
Invasive species are the main threat to island biodiversity; seabirds are particularly vulnerable and are one of the most threatened groups of birds. Gough Island, a UNESCO World Heritage Site in the South Atlantic Ocean, is an Important Bird and Biodiversity Area, and one of the most important seabird colonies globally. Invasive House Mice Mus musculus depredate eggs and chicks of most seabird species on the island, but the extent of their impact has not been quantified. We used field data and bootstrapped normal distributions to estimate breeding success and the number of surviving chicks for 10 seabird species on Gough Island, and compared estimates with those of analogous species from predator‐free islands. We examined the effects of season and nest‐site location on the breeding success of populations on Gough Island, predicting that the breeding success of Gough birds would be lower than that of analogues, particularly among small burrow‐nesting species. We also predicted that winter‐breeding species would exhibit lower breeding success than summer‐breeding species, because mice have fewer alternative food sources in winter; and below‐ground nesters would have lower breeding success than surface nesters, as below‐ground species are smaller so their chicks are easier prey for mice. We did indeed find that seabirds on Gough Island had low breeding success compared with analogues, losing an estimated 1 739 000 (1 467 000–2 116 000) eggs/chicks annually. Seven of the 10 focal species on Gough Island had particularly high chick mortality and may have been subject to intense mouse predation. Below‐ground and winter breeders had lower breeding success than surface‐ and summer‐breeders. MacGillivray's Prion Pachyptila macgillivrayi, Atlantic Petrel Pterodroma incerta and Tristan Albatross Diomedea dabbenena are endemic or near‐endemic to Gough Island and are likely to be driven to extinction if invasive mice are not removed.
... Each nesting habitat was treated as a separate subcolony, and random sampling was followed for the selection of locations for the sampling units. This sampling method over different nesting habitats has been used to increase the accuracy of estimates regarding seabird abundance in a colony (Cuthbert & Sommer 2004). A rope was used to designate sampling units so as to count the number of occupied burrows within the area covered. ...
The Strofades Island complex in the Ionian Sea comprises two small islands, i.e. Stamfani and
Arpyia, and several rocks. The islands host a significant Scopoli’s Shearwater (Calonectris diomedea) colony,
which is regarded as the largest one in Greece, although no complete national population census has ever
been carried out. Here we present data of the first complete survey of the species population in the area,
evaluated via coastal counts of rafting birds at sea and nest surveys of occupied burrows. Both methodologies
provided similar estimates. The maximum number of Scopoli’s Shearwaters visiting the Strofades archipelago
during the pre-laying period was estimated at 17,000-18,000 individuals, based on the maximum counts of
3,068 and 2,723 rafting individuals/km of suitable nesting coastline of Stamfani and Arpyia islands,
respectively. The breeding population was censused by inspecting apparently occupied sites in 30 100 m2
sampling units, randomly located along the coastal habitats of each island. Sampling was made over two
habitat types of different quality for nesting. We estimated that a total of ca. 5,550 pairs breed on the two
main islands, of which 64% were located on the larger Stamfani Island. The study reveals that the Strofades
archipelago harbors the largest known Scopoli’s Shearwater colony in the eastern Mediterranean.
... Esta especie presenta una población reproductora relativamente pequeña (con respecto a otras especies del género), endémica del archipiélago de Tristán da Cunha y Gough Island en el Atlántico Sur central (Cuthbert et al. 2003b, Cuthbert y Sommer 2004, de donde provienen las aves que llegan a Uruguay. La población de Gough ha sido estimada en 5300 parejas anuales (Cuthbert y Sommer 2004). ...
... Esta especie presenta una población reproductora relativamente pequeña (con respecto a otras especies del género), endémica del archipiélago de Tristán da Cunha y Gough Island en el Atlántico Sur central (Cuthbert et al. 2003b, Cuthbert y Sommer 2004, de donde provienen las aves que llegan a Uruguay. La población de Gough ha sido estimada en 5300 parejas anuales (Cuthbert y Sommer 2004). Existe menor precisión en las estimaciones del número de parejas para el grupo Tristán da Cunha, especialmente en la isla de Tristán donde las estimaciones son basadas en datos de 1974. ...
... It is a nature reserve and a UNESCO World Heritage Site of international importance for breeding seabirds. It holds many endemic plants, invertebrates and a rich avifauna including 22 species of seabirds with a total population probably in the order of 4e6 million pairs (Richardson, 1984;Muirhead and Furness, 1988;Cuthbert and Sommer, 2004;Ryan, 2007;Ryan et al., 2014Ryan et al., , 2015Robertson et al., 2016). ...
... Populations of southern giant petrels have shown large fluctuations in recent decades at broader scales (ACAP Polar Biol 2014a), with increases on the Falkland Islands (Reid and Huin 2008), Gough Island (Cuthbert and Sommer 2004), some sites in the South Shetland Islands (Lynch et al. 2008), and the northern part of the Danco Coast, Antarctica (Gonzalez-Zevallos et al. 2013), and stable numbers at the Frazier Islands (Creuwels et al. 2005), and decreases at Pointe Géologie, East Antarctica (Micol and Jouventin 2001), Heard, Macquarie, Marion and King George islands (Patterson et al. 2008). Although many time series are from different periods and counts from many islands are unavailable, the most recent synthesis concluded that globally, southern giant petrels were increasing (ACAP 2014a). ...
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.
... This makes it difficult to infer long-term changes in lightmantled albatross populations on Marion Island. In recent years, sooty albatross population sizes have not been observed to decline significantly on either Marion or Gough Island (Cuthbert and Sommer 2004;Ryan et al. 2009;Cuthbert et al. 2014). However, the trend at Gough Island has to be interpreted with caution as it is based on only a small proportion of the total population (Cuthbert et al. 2014). ...
Sub-Antarctic Marion Island is one of the few islands where both species of Phoebetria albatrosses breed sympatrically. The last published assessment of their population trends, which reported counts up to 2008, concluded that the numbers of breeding pairs of sooty albatross P. fusca (Endangered) were decreasing, whereas numbers of light-mantled albatross P. palpebrata (Near Threatened) were increasing. Extending the counts to 2014 reversed these trends, with numbers of sooty albatrosses increasing from 2006 to 2014, and numbers of light-mantled albatrosses decreasing from 2007 to 2014. Confidence in island-wide counts is low due to the cryptic nature of the albatrosses on their largely inaccessible cliff-side nest sites, as well as counts for sooty albatrosses taking place late in the incubation period when 10−20% of nests have already failed. Given the greater conservation concern for the sooty albatross, we recommend that dedicated annual counts be conducted during the early incubation period, and be repeated shortly after the chicks hatch (late December), mid-way through the nestling period (late February) and prior to fledging (late April), to give a better idea of breeding success. Count zones also should be revised to facilitate more accurate counts, ensuring more reliable estimates of sooty albatross population trends at Marion Island.
