"Seabird Sunset", acrylics by Kitty Harvill, after a photograph by Dimas Gianuca

Caitlin Frankish (British Antarctic Survey, Cambridge, UK) and colleagues have published open access in the journal Aquatic Conservation: Marine and Freshwater Ecosystems on diving behaviour of White‐chinned Petrel Procellaria aequinoctialis (Vulnerable).

The paper’s abstract follows:

Many seabirds dive to forage, and the ability to use this hunting technique varies according to such factors as morphology, physiology, prey availability, and ambient light levels. Proficient divers are more able to seize sinking baits deployed by longline fishing vessels and may return them to the surface, increasing exposure of other species. Hence, diving ability has major implications for mitigating incidental mortality (bycatch) in fisheries.

Here, the diving behaviour and activity patterns of the most bycaught seabird species worldwide, the white‐chinned petrel (Procellaria aequinoctialis), tracked from Bird Island (South Georgia), are analysed. Three data sources (dives, spatial movements, and immersion events) are combined to examine diverse aspects of at‐sea foraging behaviour, and their implications for alternative approaches to bycatch mitigation are considered.

The tracked white‐chinned petrels (n = 14) mostly performed shallow dives (<3 m deep) of very short duration (<5 s), predominantly during darkness, but only 7 and 10% of landings in daylight and darkness, respectively, involved diving, suggesting that surface‐seizing is the preferred foraging technique. Nonetheless, individuals were able to dive to considerable depth (max = 14.5 m) and at speed (max = 2.0 m·s−1), underlining the importance of using heavy line‐weighting to maximize hook sink rates, and bird‐scaring lines (Tori lines) that extend for long distances behind vessels to protect hooks until beyond diving depths.

With thanks to Richard Phillips.

Reference:

Frankish, C.K., Manica, A., Navarro, J. & Phillips, R.A. 2021.  Movements and diving behaviour of white‐chinned petrels: diurnal variation and implications for bycatch mitigation.  Aquatic Conservation: Marine and Freshwater Ecosystems https://doi.org/10.1002/aqc.3573.

John Cooper, ACAP Information Officer, 15 April 2021

(a), (b) Broad-billed Prion eggshells with teeth marks from Black Rats in Hillpiece Cave, Tristan da Cunha, (c) incubating prions, with an abandoned whole egg in the background, (d) Black Rat harassing a small prion chick (from the publication)

Ben Dilley (FitzPatrick Institute of African Ornithology, University of Cape Town, South Africa) and colleagues have published in the journal Ostrich Journal of African Ornithology on the suspected role played by rats in low breeding success of Broad-billed Prions Pachyptila vittata on Tristan da Cunha.

The paper’s abstract follows in English and French:

Tristan da Cunha is a 96 km² volcanic island in the South Atlantic Ocean. Black Rats Rattus rattus reached the island from a shipwreck in 1882 and their depredation of seabirds’ eggs and chicks are likely partly responsible for the much lower densities of burrow-nesting petrels, compared with adjacent rodent-free islands in the archipelago. We monitored a colony of Broad-billed Prions Pachyptila vittata breeding in a coastal cliff cave in 2015/2016, where a maximum of 6% of chicks survived from 310 nests. We suspect rats frequently depredated eggs (36% of eggs were found broken with rat bite marks) and infrared trail cameras recorded how rats repeatedly hassled chicks, although no direct chick depredations were recorded.

Tristan da Cunha est une île volcanique de 96 km² localisée en océan Atlantique sud. Le rat noir Rattus rattus colonisa l’île en 1882 après le naufrage d’un navire. La predation du rat sur les oeufs et oisillons d’oiseaux marins est très probablement responsable de la très faible densité de Procellariidées nichant en terrier comparé à d’autres îles dépouvues du rongeur au sein de l’archipel. Nous avons suivi une colonie de Prion de Forster Pachyptila vittata nichant sur une falaise cotière au sein d’une grotte en 2015/2016. Seulement 6% des oisillons survécurent sur les 310 nids suivis. Nous suspectons que les rats prédatent fréquemment les oeufs (36% des oeufs ont été retrouvés cassés avec des traces de morsures de rats). Aussi, les cameras infrarouge sur les sentiers ont enregistré une incessante aggression des rats sur les oisillons, bien qu’aucune predation directe ne fut enregistrée.”

Although a draft operational plan to eradicate Tristan’s rodents was produced in 2007, there are apparently no current plans to eradicate them.  However, local control of rodents utilizing bait stations occurs in inhabited and cultivated areas.  In contrast, an attempt to eradicate introduced House Mice on Gough Island, part of the Tristan da Cunha group of islands, is set to occur this austral winter (click here).

With thanks to Ben Dilley.

References:

Brown, D. 2007.  Preliminary Operational Plan for Rodent Eradication from Tristan da Cunha.  Unpublished Report to the Royal Society for the Protection of Birds.  Sandy: Royal Society for the Protection of Birds.  115 pp.

Dilley, B.J., Davies, D., Repetto, J., Swain, G. & Ryan, P.G. 2020.  Rats and prions at Tristan da Cunha Island.  Ostrich  91(3). 

John Cooper, ACAP Information Officer, 14 April 2021

Balearic Shearwater at sea, photograph by Pep Arcos

Isabel Afán (Remote Sensing and GIS Laboratory, Estación Biológica de Doñana, Seville, Spain) and colleagues have published in the journal Marine Biology on tracking chick-rearing Balearic Shearwater Puffinus mauretanicus (Critically Endangered) at sea in relation to environmental factors.

The paper’s abstract follows:

“Foraging distribution of flying seabirds is constrained by environmental factors influencing individual decision-making. This must be particularly true during the breeding period, when individuals face additional limitations imposed by their central-place foraging behaviour. We used GPS data loggers and Argos PTTs to track the foraging flights of Balearic shearwaters (Puffinus mauretanicus) during the chick-rearing period of 2011–2014 in the Balearic Islands (Western Mediterranean).  We identified main areas used by tracked birds and characterised their productivity patterns. Based on a spatial seascape approach of flight costs varying with time, shaped by environmental processes as winds, we also estimated flight costs to reach foraging grounds in outward and return trips from the colony. Individuals repeatedly used the closest areas on the Iberian continental shelf. However, sporadic and favourable wind conditions facilitated low-cost flight to more distant and equally productive areas of the western North African shelf.”

With thanks to Pep Arcos.

Reference:

Afán, I., Arcos, J.M., Ramírez, F., García, D., Rodríguez, B. Delord, K., Boué, A.,·Micol, T., Weimerskirch, H. & Louzao, M. 2021.  Where to head: environmental conditions shape foraging destinations in a critically endangered seabird.  Marine Biology 168. doi.org/10.1007/s00227-021-03830-1.

John Cooper, ACAP Information Officer, 13 April 2021

Vulnerable Wandering Albatrosses Diomedea exulans display on Marion Island, photograph by Otto Whitehead

The Mouse-Free Marion Project is gaining increasing momentum, as we work towards an eradication operation in the austral winter of 2023.  There remains a lot to do between now and then, and the project is seeking to recruit some key positions for the project.  These provide an exciting opportunity to be part of the project team working towards restoring Marion Island and reclaiming it for its globally important seabirds.

Operations Manager

We are calling for expressions of interest for the position of Operations Manager for the project. The primary responsibility of the Operations Manager will be to develop, update and implement the Operational Plan for the eradication of mice at Marion Island.  The Operations Manager will work closely with the Project Manager and the Management Committee to lead the operational aspects of the project, including the actual eradication work on the island.

Eradication operation underway at South Georgia (Islas Georgias del Sur)*, where both rats and mice were successfully eradicated by the South Georgia Heritage Trust.

Communications Manager

We are also calling for expressions of interest for the position of Communications Manager. The Communications Manager will assist the Project Manager and Management Committee in developing and delivering the communication aspects of the project. These include the creation and management of content for social media pages, the drafting of newsletters for donor and project stakeholders, the provision of website content updates, and public awareness campaign content and planning. The ideal candidate will have strong communications skills and experience, especially in the ecological and nature conservation fields, and be passionate about using their skills to help support the project's goal of eradicating mice from Marion Island.

Endangered Grey-headed Albatross Thalassarche chrysostoma on Marion Island, photograph by Otto Whitehead

Fund Raiser

Lastly, we are seeking the services of a highly experienced fund-raising consultant or consultancy to help develop an effective fund-raising strategy for the project. We anticipate that this will involve a number of steps and components, which are set out in the specification document.

If you are interested, and meet the specifications for the roles, we look forward to hearing from you.  Should you have any enquiries, please direct them to the contact person listed in the relevant document for the specific position. Click here to access details of each position, including how to apply, deadlines for submissions or proposal (7 May) and preferred assumption of contract date for the first two posts (1 July).

Anton Wolfaardt, Mouse-Free Marion Project Manager, 12 April 2021

*A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands (Islas Georgias del Sur y Islas Sandwich del Sur) and the surrounding maritime areas.