Seven Worlds, One Planet – Natural History Education or Climate Change Propaganda? (Part II)

This is a continuation of my blog entitled Seven Worlds, One Planet – Natural History Education or Climate Change Propaganda? (Introduction and Part I) published on Nov 22, 2019. Part II provides a more detailed account of the material I collected from reading the scientific literature.

Part II:

First a lesson in geography as you may be wondering where Bird Island and South Georgia are located.

South Georgia is part of a group of islands known as South Georgia and the South Sandwich Islands. These are two geographically distinct groups of islands in the Atlantic Ocean sector of the Southern Ocean, situated between 26 and 43 degrees west longitude and 53 and 60 degrees south latitude.

South Georgia and its associated smaller offshore islands, islets and stacks lie between the parallels of 53°00’S and 55°00’S, and between the meridians of 34°30’W and 42°00’W. These islands are very isolated, lying about 870 miles (1,400 km) east-southeast of the Falkland Islands, 963 miles (1,550 km) north-east of Cape Dubouzet (the nearest point on the Antarctic continent), 1,336 miles (2,150 km) east of Cabo Virgenes (South America’s nearest mainland point) and 2,983 miles (4,800 km) from Cape Town, South Africa. The nearest land is Zavodovski Island, the northernmost island in the South Sandwich Islands group, 342 miles (550 km) to the east-south-east.

The island group covers 1,450 square miles (3,755 square km) and ranks as the third-largest sub-Antarctic archipelago after the Falkland Islands and Iles Kerguelen. South Georgia itself is 106 miles (170 km) long and 1.2 to 25 miles (2 to 40 km) wide, and its long axis is orientated in a north-west to south-east direction. It is surrounded by over 70 islands, islets, stacks and rocks, including the outliers Shag Rocks, 155 miles (250 km) west of the north-west end of the island, and Clerke Rocks, 47 miles (75 km) east of the south-east end. The larger offshore islands support vascular plants and breeding seabirds, and include Willis Islands and Bird Island off the north-west extremity, Cooper Island off the south-east extremity, and Annenkov Island, 9 miles (15 km) off the central south-west coast.

The south-west coast of South Georgia is fully exposed to the prevailing westerly weather systems. It is colder and more heavily glaciated than the north-east with numerous glaciers debouching into the sea and permanent snow and ice starting at 300 m altitude. The coastline is predominantly rock and ice, and extensive Tussac-covered lowland areas are uncommon. In contrast, the north-east coast is more sheltered, with a permanent snow line starting at 400–600 m altitude, and extensive ice-free vegetated peninsulas bounded by glaciers, many of which terminate on land. The south-west coast of the island is exposed to heavy wave action under the influence of the prevailing westerly wind and ocean swell.

South Georgia lies in the Scotia Sea within the Antarctic Zone of the Antarctic Circumpolar Current, and about 217 miles (350 km) south of the Polar Front. It is surrounded by eastward-flowing Antarctic surface waters, with temperatures between 0°C and 4°C. South Georgia’s high-altitude glaciated interior, together with its position south of the Antarctic Polar Frontal Zone and surrounded by cold Antarctic waters, results in a cooler oceanic climate than that of most other sub-Antarctic islands, and a harsher climate than expected from its latitude.

The orographic effects of the island’s central mountain ranges greatly influence regional precipitation and weather. The south-west side and the extremities of the island, being exposed to the prevailing westerly weather systems, are typically cold, wet and cloudy with strong winds. The northeast coastal areas are more temperate, being sheltered by the mountain ranges and local topography. Here, the average annual precipitation is 1,600 mm, average annual wind speed is 4.4 m per second, and average annual temperature is +2°C with an absolute range of -19°C to +24°C. Winter and summer seasons are clearly defined, with temperatures averaging +4.8°C in the summer and -1.2°C in winter. Föhn winds produce localised rapid increases in temperature; katabatic winds associated with passing frontal systems may result in gusts of over 100 knots (115.2 mph).

The literature also reports that the speed of the surface westerly winds over the Southern Ocean has increased by approximately 3 m/s in summer months which may be responsible for causing more Föhn wind events on the North East side of South Georgia.

Observation: So what have I established? This: South Georgia lies in an area called the sub-Antarctic. It is a very cold, very wet and very windy place. It is exposed to prevailing westerly winds and weather fronts, but conditions vary across South Georgia, as one would expect. Under certain conditions, the mountains and weather fronts interact to create very strong gust of wind over 100mph.

What about Albatrosses?

Grey-headed Albatross are covered by a multilateral agreement that goes by the name The Agreement on the Conservation of Albatrosses and Petrels. The UK signed the agreement in 2001 and this was ratified in 2004. The agreement strives to conserve albatrosses and petrels by coordinating international activities to mitigate threats to their populations. In May 2019 the ACAP Advisory Committee declared that a conservation crisis continues to be faced by its 31 listed species, with thousands of albatrosses, petrels and shearwaters dying every year as a result of fisheries operations. 

The Grey-headed Albatross has a circumpolar distribution, breeding at six island groups or archipelagos in the sub-Antarctic: South Georgia (in the South Atlantic); Crozet, Kerguelen and the Prince Edward Islands (in the southern Indian Ocean); Macquarie and Campbell islands (in the South Pacific); and Diego Ramirez and Ildefonso (in southern Chile).

South Georgia is a globally important breeding site for Grey-headed Albatrosses. The archipelago hosts approximately 50% of the world population, considerably more than any other island group.

South Georgia is not just the breeding place for Grey-headed Albatrosses, but also for other species as well. A number of these species populations at South Georgia are also in decline.

The Grey-headed Albatross is listed on the International Union for Conservation of Nature’s (IUCN) Red-list of Threatened Species. The species is currently listed as Endangered. Previously it was listed as Vulnerable.

The IUCN’s latest assessment of the species is dated August 7^th 2018. In this assessment they provide their justification for the listing as an Endangered species. This is what they say: “This species is listed as Endangered as data from South Georgia, which holds around half the global population, indicate a very rapid rate of decline of the world population over three

generations (90 years), even if colonies lacking trend information are assumed to be stable. The major driver of declines is likely to be incidental mortality in long-line fisheries.”

The assessment estimates the number of breading pairs to be c 98,601. This figure as based on a number of surveys undertaken at several breeding sites across the bird’s range, over the period 1997-2016. It is thought that the figures imply a population size of mature individuals of at least 250,000.

The IUCN also state that the population trend is downwards. At South Georgia, the population is estimated to have declined by 25% between 1977 and 2004, and by 43% between 2004 and 2015 which equates to a projected decline of 85% or even higher if declines continued at this rate over three generations. On Campbell Island, data from 2004 suggest that the population declined by over 75% between 1940-2004 which equates to a 95% decline over three generations. However, this population underwent a major decline until 1997 but has since stabilised. Population trends are unknown for Chile, Iles Kerguelen and Iles Crozet (representing around one third of the global population). Also, in contrast to South Georgia and Campbell Island, on Marion Island there has been a 1.2% annual population increase from 1988-2011.

The British Antarctic Survey reported in 2017 that 15 of the 22 species of albatrosses are threatened with extinction. They also state that the Waved, Tristan and Amsterdam Albatrosses are Critically Endangered (as opposed to Grey-headed Albatross which is only classed as Endangered).

In 2018 the IUCN changed the classification for the Amsterdam Albatross to Endangered since the population was increasing, even though it was still small (92 mature individuals). They also reported that the population of the Critically Endangered Triston Albatross was still decreasing with between 3400 and 4800 mature individuals (as compared with at least 250,000 mature individual Grey-headed Albatross).

The British Antarctic Survey also mentioned that the populations of albatrosses that are declining most rapidly are those breeding on the UK Overseas Territories in the South Atlantic. On the sub-Antarctic island of South Georgia, they say that the three species of albatrosses that they monitor are declining at between 2% and 4% a year.

It is of course possible, given the monitoring that takes place and the lack of information from other breeding sites, that the issue is not South Georgia specific.

The British Antarctic Survey also provides an explanation why albatross populations are so vulnerable. This is because they are one of the longest lived species of bird, with some surviving for more than 60 years. They take many years to reach sexual maturity, not breeding until they are around 10 years old. Although most breed annually, nine species – including the Grey-headed Albatross – lay only one egg every two years, and it takes the best part of a year for a young albatross to leave the nest. Because chick production is so slow, even small increases in death rates among adults will cause populations to decline.

All the papers and reports examined point to fishing being the primary cause of the decline in albatrosses, in particular the use of long-line fishing. The Grey-headed Albatross being a case in point – they become bycatch because they scavenge the bait on the fishing lines. As a consequence of this many are drowned by being pulled under the surface. The IUCN 2018 assessment identifies large scale fishing as a threat to the majority of Grey-headed Albatrosses with a severity: ‘rapid decline’.

Mitigation measures have been developed to deal with this problem and have proven to be effective. Around South Georgia, there is a 200 nautical mile maritime zone in which commercial fishing is controlled and mitigation measures are mandatory. During the late 1990s, 6000 seabirds were killed each year by fishing vessels around South Georgia. The introduction of these measures has been so successful that bycatch has been reduced to negligible levels in this fishery since 2006.

So why, given that the mitigation measures have been so successful, have populations continued to decline?

In May 2019 the ACAP Advisory Committee stated that thousands of albatrosses and petrels are continuing to die every year as a result of fisheries operations, notably by long-line and trawl vessels.  Despite efforts that have been put into researching and recommending effective mitigation measures to address seabird bycatch in fisheries by ACAP and other bodies, in many instances these are not being implemented or are not being fully implemented.  A lack of compliance with measures adopted by those Regional Fisheries Management Organisations responsible for high-seas tuna fisheries (tuna RFMOs) was identified as a critical issue.

During the breeding season, Grey-headed Albatross breeders forage predominantly in and to the south of the Antarctic Polar Frontal Zone, where they exhibit little overlap with fisheries due to the time-area closure of the South Georgia Patagonian Toothfish fishery. Nevertheless, their foraging distribution during the breeding season does extend out of this area and into the area managed by the International Commission for the Conservation of Atlantic Tunas

(ICCAT), particularly during incubation, where they overlap with pelagic long-line vessels targeting tuna and tuna-like species. However, it is during the non-breeding period that birds are likely to face the greatest bycatch risk. During this period, birds are widely dispersed across the Southern Oceans. Their circumpolar distribution and propensity to forage at oceanic frontal zones, also targeted by fisheries, brings Grey-headed Albatrosses into potential conflict with a wide range of pelagic long-line fisheries.

The above is one explanation. There could be others. So what about climate change?

The IUCN 2018 mentions climate change as a threat. Specifically its sub-category (11.3) Temperature Extremes resulting in eco-system stresses. To explain: this refers to eco-system degradation (direct damage to an eco-system’s biotic and/or abiotic biological condition) and indirect damage to the eco-system (such as threats to food sources). The IUCN have not listed the category (11.4) Storms and Flooding as a threat to the Grey Headed Albatross (as of August 2018) nor the stress category (2.3.7) Reduced Reproductive Success (for example through chick mortality).

Other scientific literature also mentions climate change. It is though, rather generic and speculative. I did find mention of heat stress in relation to a breeding site in the Indian Ocean, but nothing more. Two sources did mention possible positive effects on albatrosses of changing wind speeds, but this is evidently dependent upon their location and the time of year.

And what is being done in South Georgia to stop the population decline of Grey-headed Albatrosses?

In order to bolster efforts to better understand the factors contributing to the long-term decline in numbers of Grey-headed Albatrosses at South Georgia, and to address these threats, the Government of South Georgia and the South Sandwich Islands (GSGSSI) in 2016 identified the need for a dedicated Conservation Action Plan for this species at South Georgia.

This Conservation Action Plan is intended to serve as a framework to guide, in an informed, prioritised and co-ordinated manner, actions required to improve the conservation status of Grey-headed Albatrosses at South Georgia, and globally. The scope of the Conservation Action Plan is limited to the South Georgia population of Grey-headed Albatrosses (i.e. the actions identified are targeted specifically at this population, for which GSGSSI have responsibility). However, given the global importance of the South Georgia population, improvements in the conservation status of this population will positively influence the overall conservation status of the species. Furthermore, given their wide-ranging nature, the ultimate responsibility for addressing threats to South Georgia Grey-headed Albatrosses varies. This Conservation Action Plan includes measures that are the direct responsibility of

GSGSSI, but importantly also includes ‘external’ actions that involve other nations and organisations. In these latter cases, GSGSSI aims through outreach, collaboration and diplomatic engagement to promote and assist where possible the management of these ‘external’ threats to Grey-headed Albatrosses that breed at South Georgia.

The goal is to ensure the recovery and long-term survival of Grey-headed Albatrosses at South Georgia by understanding the nature and extent of the threats they face, and importantly to reduce or eliminate these threats by implementing or promoting the required conservation research and management actions. The ultimate aim is, by 2020, to have stopped the decline of the population of Grey-headed Albatrosses breeding at South Georgia.

And on the matter of brood guarding: In pelagic seabirds, the dilemma of leaving or staying is particularly acute given that foraging trips can last up to several days, and an unattended, young and hence vulnerable chick is potentially exposed for long periods between visits. The duration of brood guarding in albatrosses and petrels is highly variable, even within the same climatic region, for example lasting just 2-3 days in Antarctic prions, but 3-6 weeks in albatrosses. Part of the variation can be accounted for by nest site characteristics; brood-guarding is shorter in burrow-nesters, than surface-nesters. However, there are large variations even within these two general groups.

So what about chicks being blown out of their nests? There is no mention of this in the scientific literature that I examined, although it should be self-evident that this might happen in such stormy environment like Bird Island. In fact what is implied in the narratives of the two films concerns issues around brood guarding, chick mortality, and breeding success. Not all Grey-headed Albatrosses breeding efforts lead to a fledged chick. Many factors intervene to prevent this: predation, condition of the adult birds, weather, adult quality (i.e. past breeding success), availability of food, disease. It is also the case that chick survival is dependent upon the condition of the chick.

A chick’s ability to thermoregulate and to fend off predation increases with age, as does its appetite. There comes a point therefore when chicks no longer need the parent to provide heat, and parents have no choice but to leave chicks alone in order to forage for food.

Some research has shown that chick mortality in Grey-headed Albatrosses is high just after the end of brood guarding, and this mortality is strongly dependent on calendar date and chick condition, but is largely independent of the duration of brood guarding itself. The research has also shown that there is a marked seasonal decline in the duration of brood guarding, and that parents’ decisions concerning the regulation of brooding seem to be largely independent of chick age and also of their own [adult] body condition. One factor at work here is believed to be that chicks are safer when there are more chicks in nests. This is called the predator swamping effect – safety in numbers. This reduces the probability of an individual chick being eaten as predators cannot keep eating.

Research into Black-browed Albatrosses involving comparisons between two study sites, one being in the Falklands which has a more favourable climate than at the second site which was Bird Island, have shown that bad weather can be a problem for albatross chicks with limited thermoregulatory abilities, something confirmed by the fact, observed at both sites, that there were young unattended Black-browed Albatrosses apparently dying of cold during spells of inclement weather.

This research also examined something the researchers called the cold-protection hypothesis. This includes a prediction that brood guarding should be longer in environments with harsher climatic conditions, which in fact was not observed. It also includes a prediction that adults should respond to short term variations in weather by prolonging brooding during spells of bad weather, and that adults should be more prone to terminate brooding under favourable (warm and dry) conditions. What was observed was that short-term weather fluctuations (measured by the wind chill index) had a demonstrable effect on the decision by the parent not to terminate brooding. It was noted that virtually no chicks were left on days with heavy rain. However, it is clear that adult birds, being pelagic seabirds, once engaged in a foraging trip, cannot quickly resume brooding behaviour as a response to possible deterioration of the weather.

I did not find any specific scientific evidence that increasing wind speed is resulting in greater chick mortality rates at Bird Island, or even if it were, that this is having a major influence causing rapid population decline. What I did discover is that breeding success is the result of complex interactions among multiple factors. So simple statements like those offered in the TV programme cannot be made.