Grey-headed Albatross by Annie Shoemaker-Magdaleno‎, from a photograph by Dimas Gianuca

Lily Bentley (Department of Zoology, University of Cambridge, UK) and colleagues have published in the journal Marine Biology on diving by three species of albatrosses breeding on Bird Island in the South Atlantic.

The paper’s abstract follows:

“Diving is an ecologically important behaviour that provides air-breathing predators with opportunities to capture prey, but that also increases their exposure to incidental mortality (bycatch) in commercial fisheries. In this study, we characterised the diving behaviour of 26 individuals of three species, the black-browed albatross Thalassarche melanophris, grey-headed albatross T. chrysostoma and light-mantled albatross Phoebetria palpebrata, breeding at Bird Island, South Georgia. Individuals were tracked using Global Location Sensor (GLS)-immersion loggers and time-depth recorders (TDRs) and, for two species, Global Positioning System (GPS) loggers. Although the TDRs recorded 589 dives (defined in this paper as submersion > 1 m), average dive depths and durations were just 1.30–1.49 m and 2.5–3.3 s, respectively, for the three species. In addition, many individuals (22% of black-browed, 20% of grey-headed, and 57% of light-mantled albatrosses; total n = 9, 10 and 7 individuals, respectively) did not dive at all. Most dives occurred at the distal end of foraging trips and were rare during the commuting phase. No dives took place in darkness, despite long periods spent on water at night. The limited and shallow dive activity contrasts with impressions from a previous study using capillary-tube depth gauges (which are less accurate than TDRs) and has implications for the susceptibility of albatrosses to bycatch on longlines. This study provides further support for regulations requiring night setting and increased sink rates of baited hooks to help mitigate albatross bycatch.”

With thanks to Richard Phillips.

Reference:

Bentley, L.K., Kato, A., Ropert-Coudert, Y., Manica, A. & Phillips, R.A. 2021  Diving behaviour of albatrosses: implications for foraging ecology and bycatch susceptibility.  Marine Biology 168.  doi.org/10.1007/s00227-021-03841-y.

John Cooper, ACAP Information Officer, 27 February 2021

 A scavenging Southern Giant Petrel; photograph by Liezl Pretorius

William Mills (British Antarctic Survey, Cambridge, UK) and colleagues have published in the journal Marine Biology on diets of non-threatened (Least Concern) Northern Macronectes halli and Southern M. giganteus Giant Petrels in the South Atlantic.

The paper’s abstract follows:

“Northern Macronectes halli and southern giant petrels M. giganteus are opportunistic predators and the dominant avian scavengers in sub-Antarctic and Antarctic ecosystems. At South Georgia, there are globally important breeding populations of both species; however, no detailed diet study has been carried out at this site for > 35 years. Here, we analysed stomach contents of northern (n = 81) and southern giant petrel (n = 73) chicks at Bird Island, South Georgia (2014/15–2016/17). Specifically, we investigated: (1) interspecific and sexual dietary segregation; (2) diet changes within and among recent years; and (3) long-term diet changes since 1979/80–1980/81. Overall diet composition was similar between species, with penguins comprising approximately half the diet by mass. In both species (but more pronounced in southern giant petrels), prey delivered by female parents included higher proportions (by mass) of penguins and Antarctic krill Euphausia superba, and by male parents included more Antarctic fur seal Arctocephalus gazella carrion and seabirds other than penguins. Consumption of penguins increased, and of seal carrion declined, as chick-rearing progressed, mirroring the decreasing availability of the latter after the peak pupping period in December at South Georgia. Comparisons with data from 1979/80–1980/81 suggest some changes in giant petrel diets; however, these differences were no greater than the typical annual variation, and there were no clear links between diet and breeding allochrony or the differing population trends (more rapid increase in northern than southern giant petrels). The high diet diversity and ability of giant petrels to exploit both carrion and marine prey facilitates coexistence with other sympatric Procellariiformes and explains their favourable population status.’

Southern Giant Petrel by Marion Schön entitled "Bloody Beauty" - Pastels on Pastelmat, from a photograph by Jaimie Cleeland

With thanks to Richard Phillips.

Reference:

Mills, W.F., Morley, T.I., Votier, S.C. & Phillips, R.A. Long‑term inter‑ and intraspecific dietary variation in sibling seabird species.  Marine Biology doi.org/10.1007/s00227-021-03839-6.

John Cooper, ACAP Information Officer, 26 February 2021

Amsterdam Albatross painted by Birgit Bührlé (left) from a photograph taken at sea by Kirk Zufelt (right)

Alexandre Corbeau (Centre d’Études Biologiques de Chizé, Villiers en Bois, France) and colleagues have published in the journal Animal Conservation on at-sea tracking of Amsterdam Diomedea amsterdamensis and Wandering D. exulans Albatrosses in relation to the presence of fishing vessels in the southern Indian Ocean.

The paper’s abstract follows:

“Many seabirds are attracted to fishing boats where they exploit foraging opportunities, often involving bycatch‐related mortality. Bycatch risk is generally estimated by overlapping seabirds foraging ranges with coarse‐scale monthly maps of fishing efforts, but a more direct estimation would be the time birds actually spend attending fishing boats. Here we matched data from Automatic Identification Systems from all declared boats in the Southern Ocean, with 143 simultaneous foraging trips from all populations of large albatrosses (Diomedea amsterdamensis and Diomedea exulans) breeding in the Indian Ocean (Marion, Crozet, Kerguelen, Amsterdam islands). We quantified and compared real‐time co‐occurrence between boats and albatrosses, at different scales (100, 30 and 5 km). We also examined to what extent co‐occurrence at a large‐scale (5×5° grid cell) predicted fine‐scale attendance (5 km). Albatrosses on average spent about 3 h per trip attending fishing boats (<5 km) at both Amsterdam and Marion and about 30 h per trip at Kerguelen. In all populations, >90% of declared fishing boat attendances occurred within Economic Exclusive Zones (EEZ) where bycatch mitigation measures are enforced. Outside EEZs, birds from all populations to a large extent also attended non‐fishing boats. Fishing boat density at a large scale (5 × 5°, 100 km) was a poor predictor of time spent attending fishing boats (<5 km) across populations. Our results indicate a large variation in fishing boat densities within the foraging ranges of different populations and in the time birds spent attending boats. We discuss the pros and cons of considering bycatch risk at a large geographical scale and methods that can be implemented to improve the estimation of seabird vulnerability to fishing activities when fine‐scale data are available, particularly for the conservation of those highly threatened species.”

Reference:

Corbeau, A., Collet, J., Orgeret, F., Pistorius, P. & Weimerskirch, H. 2021.  Fine‐scale interactions between boats and large albatrosses indicate variable susceptibility to bycatch risk according to species and populations.  Animal Conservation doi.org/10.1111/acv.12676.

John Cooper, ACAP Information Officer, 25 February 2021

 Albatross translocation site in Hawaii with shaded chicks and adult decoys, photograph from Pacific Rim Conservation

Carmen Antaky (Department of Natural Resources and Environmental Management, University of Hawai'i at Mānoa, Honolulu, USA) and colleagues have published open access in the journal Marine Ornithology on a review of seabird site fidelity and dispersal, informing whether translocated chicks are likely to return to their translocation sites.  It seems albatrosses and petrels (tubenose procellariiforms) make good candidates, at least within the Hawaiian Archipelago.

The paper’s abstract follows:

“Management of avian species threatened by land use and climate change requires a thorough understanding of their site fidelity and dispersive behaviors. Among long-lived colonial seabird species, the behavior of returning to the natal colony to breed, i.e., natal philopatry, may increase the likelihood that adequate resources and mates are available, but it may also increase the potential for inbreeding, competition, and ecological traps. Successful management of seabird populations—using chick translocation to encourage colony establishment to locations having minimal threats—must also be informed by the likelihood that birds will return to the new sites. However, the extent of philopatry and the traits that dictate variation across seabirds have yet to be fully summarized. We evaluated whether seabirds returned to their natal colony at rates greater than those predicted by colony size and various dispersal variables, based on data gathered for 36 seabird species nesting in the British Isles and the Hawaiian Archipelago. We compiled long-term banding and census data across 663 colonies. A linear mixed-effects model was employed to determine the relationship between philopatry and colony demographics, wingspan (mobility), and spatial variables. Our results indicate that philopatric rates are higher in the Hawaiian Archipelago than in the British Isles. Additionally, our research suggests that seabird management using chick translocation will have the greatest success with Procellariiformes species.”

Reference:

Antaky, C.C., Young, L., Ringma, J. & Price, M.R. 2021.  Dispersal under the seabird paradox: probability, life history, or spatial attributes?  Marine Ornithology 49: 1-8.

John Cooper, ACAP Information Officer, 24 February 2021