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UPDATE:  After an eight-day voyage the Pelagic Australis arrived at Marion Island last week and safely landed the researchers and film crew via rubber dinghy on Boulder Beach.  It seems field observations commenced straight away (click here).

The Pelagic Australis in Transvaal Cove, Marion Island - watched by a Subantarctic Skua, photograph by Vrikkie van der Vyver

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The Pelagic Australis departs from Cape Town harbour for Marion Island, photograph by Kim Stevens

The world-wide COVID-19 pandemic has not stopped determined researchers heading south to spend the austral summer monitoring seabirds and marine mammals on South Africa’s sub-Antarctic Marion Island.  A governmental decision to halt all field work on the island this year due to the virus and not to replace the island’s researchers with a new team during the annual relief voyage in April/May caused concern that a break in long-term monitoring of individually marked animals would irreparably harm data analyses.  Good news then that a plan was hatched to get field researchers to the island by yacht this month, including four who will study seals and seabirds (click here).

Wandering Albatrosses on Marion Island will no longer have a break in their over 40-year study, photograph by Michelle Risi

The yacht Pelagic Australis (a high-latitude expedition sailing vessel with years of service in both Arctic and Antarctic waters) left Cape Town harbour for Marion last Thursday with seven experienced researchers and a five-person film crew aboard.  Plimsoll Productions will make nature documentaries on the island.  The voyage is expected to take six days.

Strict procedures and protocols have been enforced by the South African Department of Environment, Forestry and Fisheries (DEFF) to mitigate against the risks of taking the Corona virus south and to ensure no new alien species reach the island.  These include quarantining and testing all the participants in Cape Town prior to sailing and inspecting and de-contaminating the yacht (click here).

Read more about the yacht trip here.

With best wishes to biologists Thando Cebekhulu, Danielle Keys, Yinhla Shihlomule and Frikkie van der Vyver for their Marion Island sojourn and thanks to Nico de Bruyn, Michelle Risi and Kim Stevens for their help.

John Cooper, ACAP Information Officer, 21 September 2020, updated 30 September 2020

 A breeding Grey-headed Albatross on Marion Island carries a back-mounted GPS logger, photograph by Kim Stevens

Tegan Carpenter‐Kling (Marine Apex Predator Research Unit, Nelson Mandela University, Port Elizabeth, South Africa) and colleagues have published open access in the journal Ecology and Evolution on aspects the foraging behaviour of four sub‐Antarctic albatross species.

The paper’s abstract follows:

“Seasonal and annual climate variations are linked to fluctuations in the abundance and distribution of resources, posing a significant challenge to animals that need to adjust their foraging behavior accordingly.  Particularly during adverse conditions, and while energetically constrained when breeding, animals ideally need to be flexible in their foraging behavior.  Such behavioral plasticity may separate “winners” from “losers” in light of rapid environmental changes due to climate change.  Here, the foraging behavior of four sub‐Antarctic albatross species was investigated from 2015/16 to 2017/18, a period characterized by pronounced environmental variability.  Over three breeding seasons on Marion Island, Prince Edward Archipelago, incubating wandering (WA, Diomedea exulans; n = 45), grey‐headed (GHA, Thalassarche chrysostoma; n = 26), sooty (SA, Phoebetria fusca; n = 23), and light‐mantled (LMSA, P. palpebrata; n = 22) albatrosses were tracked with GPS loggers.  The response of birds to environmental variability was investigated by quantifying interannual changes in their foraging behavior along two axes: spatial distribution, using kernel density analysis, and foraging habitat preference, using generalized additive mixed models and Bayesian mixed models. All four species were shown to respond behaviorally to environmental variability, but with substantial differences in their foraging strategies. WA was most general in its habitat use defined by sea surface height, eddy kinetic energy, wind speed, ocean floor slope, and sea‐level anomaly, with individuals foraging in a range of habitats. In contrast, the three smaller albatrosses exploited two main foraging habitats, with habitat use varying between years. Generalist habitat use by WA and interannually variable use of habitats by GHA, SA, and LMSA would likely offer these species some resilience to predicted changes in climate such as warming seas and strengthening of westerly winds. However, future investigations need to consider other life‐history stages coupled with demographic studies, to better understand the link between behavioral plasticity and population responses.”

Reference:

Carpenter‐Kling, T., Reisinger, R.R., Orgeret, F., Connan, M., Stevens, K.L., Ryan, P.G., Makhado, A. & Pistorius, P.A. 2020.  Foraging in a dynamic environment: response of four sympatric sub‐Antarctic albatross species to interannual environmental variability.  Ecology and Evolution doi.org/10.1002/ece3.6766.

John Cooper, ACAP Information Officer, 30 September 2020

  The bird-scaring kite deployed, photograph by Emanuel Constantino

Nuno Oliveira (Sociedade Portuguesa para o Estudo das Aves – SPEA, Lisbon, Portugal) and colleagues have published in the journal Bird Conservation International showing that a "raptor-like" bird-scaring kite reduced the chances of seabird bycatch by purse seiners.

The paper’s abstract follows:

“Bycatch is one of the main threats to marine biodiversity, affecting ocean ecosystems at a worldwide scale.  The main focus of bycatch studies has been on the impact of larger vessels, with few studies assessing the impact of artisanal fisheries.  Moreover, bycatch studies are often limited to a small number of marine regions, and significant gaps still exist in our knowledge of the spatial and temporal patterns of seabird bycatch.  Here we present a multi-approach method to accurately quantify seabird bycatch driven by small- and medium-sized fishing fleets operating in a high priority area for seabird conservation on the Portuguese mainland.  Results of three mitigation measures to reduce seabird bycatch on fishing gear where seabird bycatch is most likely to occur were also tested: high contrast panels in bottom gillnets, black hooks in demersal longlines and a bird scaring device in purse seines.  The efficacy, acceptance, and economic viability were tested for each mitigation measure.  Sixty-seven individuals of seven seabird species were bycaught during 295 monitored fishing trips between 2015 and 2018.  Bycatch occurred mainly in demersal longlines (0.07 birds fishing event-1), followed by purse seines (0.02 birds fishing event-1) and bottom gillnets (0.01 birds fishing event-1).  Nevertheless, the bird scaring device caused birds to interact less with the vessel (the presence of gulls was reduced by 11%), thus decreasing the likelihood of bycatch.  This device has proved to be low-cost (representing less than 5% income of a single day’s landings) and easy to implement, being also well accepted by purse seine fishermen.  It was not possible to evaluate the efficacy of high contrast panels and black hooks, as no bycatch events were recorded during trials.”

A drowned Cory's Shearwater Calonectris borealis comes aboard on a Portuguese longline, photograph by Iván Gutiérrez

Read a related post here.

With thanks to Nuno Oliveira.

Reference:

Oliveira, N., Almeida, A., Alonso, H., Constantino, E., Ferreira, A., Gutiérrez, I., Santos, A., Silva, E. & Andrade, J. 2020.  A contribution to reducing bycatch in a high priority area for seabird conservation in Portugal. Bird Conservation International, 1-20. doi:10.1017/S0959270920000489.

John Cooper, ACAP Information Officer, 29 September 2020

Great Shearwater at sea

Paloma Carvalho (Department of Biological Sciences, University of Manitoba, Winnipeg, Canada) and colleagues have published open access in the journal Marine Ornithology on foraging behaviour of Great Shearwaters gravis and Sooty A. grisea Shearwaters off Newfoundland.

The paper’s abstract follows:

“Species tend to concentrate in areas with high prey availability, which could lead to competitive interactions within a feeding assemblage as resources become depleted. In coastal Newfoundland, Canada, capelin Mallotus villosus is the focal forage fish species that many top predators feed on during the summer; however, inshore availability varies throughout the boreal summer when abundant aggregations migrate inshore to spawn. We investigated the interactions and responses of Great Shearwaters Ardenna gravis and Sooty Shearwaters A. grisea during their non-breeding season to supplemental food supply under changing natural prey availability (higher and lower capelin availability) by conducting an at-sea experiment during July-August (2015/2016) in coastal Newfoundland. Supplemental food was offered every 30 s over 10 min (‘experimental period'), which was preceded and followed by 10-min control periods (i.e., no food provided). The number of both species increased during the experimental periods, indicating that both species were attracted to the food supplementation experiment. Great Shearwaters were 7.6-13.8 times more likely than Sooty Shearwaters to land near the experimental platform and 95.2 times more likely than Sooty Shearwaters to fight over supplemental food items with individuals of the same or different species. These species-specific tendencies remained consistent as prey availability varied within years, but both species increased in their abundance and interactions with other species (including Herring Gulls Larus argentatus and Northern Fulmars Fulmarus glacialis) during prey capture at lower relative to higher prey availability, as evidenced by lower proportions of flying birds and a greater likelihood of landing on the water. Overall, we suggest that when Great and Sooty shearwaters feed in close association, Great Shearwaters are the more competitively dominant species, which may lead to higher risks of by-catch mortality, especially when the availability of natural prey decreases.”

Reference:

Carvalho, P.C., Maynard, L.D. & Davoren, G.K. 2020. Responses of sympatric shearwaters to supplemental food under varying natural prey availability on the wintering grounds of coastal Newfoundland, Canada. Marine Ornithology 48: 255-262.

John Cooper, ACAP Information Officer, 28 September 2020