Balearic Shearwater at sea, photograph by Beneharo Rodriguez

Johan Elmberg (Department of Environmental Science and Bioscience, Kristianstad University, Sweden) and colleagues have published in the open access journal Marine Ornithology on counts of Balearic Shearwaters Puffinus mauretanicus and other seabirds made from a headland in Portugal.

The paper’s abstract follows:

“Land-based counts at Cabo Carvoeiro (Peniche, Portugal), made between 15 August-15 November 2015 (effort 90 d, 517 h), tallied 302 469 birds, most of which (99.98%) were southbound. Although 65 species were observed, four species contributed to 91% of the total: 207 608 Northern Gannet Morus bassanus, 32 281 Cory's Shearwater Calonectris borealis, 16 086 Manx Shearwater Puffinus puffinus, and 15 222 Balearic Shearwater Puffinus mauretanicus. Passage as a whole increased throughout the period, mainly due to a gradual intensification of Northern Gannet migration. More than 67 000 southbound procellariforms [sic] of 12 species were recorded, as were 6183 Stercorariidae of four species. Daily passage rates of species recorded on more than 68 d were positively correlated in 22 of 36 cases. For Northern Gannet and Mediterranean Gull Ichthyaetus melanocephalus, the proportion of adult birds increased steadily, outnumbering younger birds. Extrapolation based on counted versus uncounted daylight hours suggests that at least 415 000 Northern Gannets, 65 000 Cory's Shearwaters, and 30 000 Balearic Shearwaters passed south at Cabo Carvoeiro in autumn 2015. Clearly, a very large share of the global population of the endangered Balearic Shearwater can be monitored at Cabo Carvoeiro. Based on generally unidirectional passage patterns, high species diversity, as well as high season totals and daily passage rates of several species, Cabo Carvoeiro is one of the most promising mainland sites in the eastern North Atlantic to monitor a wide range of seabirds.”

Reference:

Elmberg, J., Hirschfeld, E., Cardoso, H. & Hessel, R. 2020. Seabird migration at Cabo Carvoeiro (Peniche, Portugal) in autumn 2015. Marine Ornithology 48: 231-244.

John Cooper, ACAP Information Officer, 23 September 2020

A New Zealand fishing vessel

Laura Tremblay-Boyer & Edward Abraham (Dragonfly Data Science, Wellington, New Zealand) have produced a report that assesses the value of cameras aboard fishing vessels in addressing seabird bycatch.

The report’s Executive Summary follows:

“Seabirds are incidentally captured in New Zealand commercial fisheries, including bottom-longline fisheries targeting snapper and bluenose in northern North Island.  Incidental captures of protected species, such as seabirds, are recorded by fishers and also by government fisheries observers when they are onboard commercial vessels.  Nevertheless, the rates of these incidental captures are uncertain, as fisher reported records may be incomplete and observer coverage of these bottom-longline fisheries is variable.

For this reason, a pilot electronic monitoring programme was implemented in October 2016 (the 2016–17 fishing year) in bottom-longline fisheries targeting snapper and bluenose in north-eastern North Island (the Hauraki Gulf and Bay of Plenty areas, Fisheries Management Area FMA 1).  The fisheries in this area overlap with the spatial distribution of black petrel (Procellaria parkinsoni), which has been identified as the species most at risk from commercial fisheries in New Zealand.  Black petrel breed on Little Barrier and Great Barrier islands in Hauraki Gulf during summer, and use the outer Hauraki Gulf area and pelagic waters for foraging during that time.

During the electronic monitoring programme, the haul of the catch was recorded using cameras onboard participating vessels, and the footage was subsequently reviewed.  Here, we used a modelling approach to assess whether fisher-reported seabird captures were affected by the presence of onboard cameras.

We found that the rate of fisher-reported seabird captures increased from 0.0044 birds per thousand hooks before the trial to 0.0089 birds per thousand hooks during the trial for the vessels that participated in the camera trial for the snapper target fishery. this increase of around a factor of two was also supported by a statistical analysis.  Key candidate model structures showed a positive effect of onboard cameras on the reporting of seabird capture rates: the model estimated that fisher reporting of seabird captures in the pilot programme fleet was around twice as high when vessels had onboard cameras than when they were without cameras (the median effect was 1.6 times higher when the analysis was restricted to vessels in the pilot programme, and 2.2 times higher when the whole fleet was included in the analysis). There was a 99.9% probability that the fisher-reporting rate increased during the trial for the analysis extended to the whole fleet.

To date, fisher-reported captures have not been used in the estimation of the impact of fishing on seabirds, due to the low reporting rates and potential limitations with species identification. Further data, both from observers and from an ongoing camera trial, will help to improve our understanding of variations in fisher-reporting rates in the bottom-longline fishery.”

Read popular accounts here:

https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12302577

https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12364809

With thanks to Robert Vagg.

Reference:

Tremblay-Boyer, L. & Abraham, E.R. 2020.  Increased fisher-reporting of seabird captures during an electronic monitoring trial.  New Zealand Aquatic Environment and Biodiversity Report No. 238.  32 pp.

John Cooper, ACAP Information Officer, 18 September 2020

From time to time ACAP Latest News posts reviews of books that cover aspects of the biology of procellariiform seabirds, and of the conservation of their habitats (click here).  Such reviews have also covered books directed at children, noting that one of ACAP’s roles is to increase awareness of the threats facing albatrosses and petrels among the general public.

Ordinarily, ACAP’s Information Officer sends out for review new titles received (or reviews them himself).  But we are not living in ordinary times: one outcome of the COVID-19 pandemic has been disruptions to international mailing.  The Information Officer is domiciled in South Africa and currently there are problems with postage to that country from Australia.  So, failing to have the book to hand to review, Australia’s CSIRO Publishing’s blurb follows for a new(ish) children’s book, Windcatcher, that describes the trans-equatorial migration of the Short-tailed Shearwater Ardenna tenuirostris – considered to be Australia’s most abundant seabird.

“A short-tailed shearwater flies from the edge of the Southern Ocean to the rim of the Arctic Circle – and back – every year.  This remarkable 30,000 kilometre journey is driven by seabird law.  Instinct and community will guide her.  A wingspan the size of a child’s outstretched arms will support her.  But first, she must catch the wind … .  Based on birds that live on Griffiths Island, near Port Fairy, Victoria, Windcatcher is a tale of migration, conservation and survival that begins with one small bird called Hope.” An estimated 100 000 shearwater burrows exist on the island.

The book was written by award-winning children’s author Diane Jackson Hill and illustrated by Craig Smith, described as one of Australia’s most prolific and popular illustrators.  The Children's Book Council of Australia (CBCA) has named Windcatcher as a 2020 Notable Book, Picture Book of the Year.  Read the CBCA's review here.  Available as a hardback (AUD 24.99) or an eBook.

Read comments by the author and illustrator on their book.

The trans-equatorial migration route of the Short-tailed Shearwater, illustrated by Craig Smith

With thanks to Claire Mason for the alert.

Reference:

Jackson Hill, Diane & Smith, Craig 2019.  Windcatcher. Migration of the Short-tailed Shearwater.  CSIRO Publishing.  32 pp. ISBN 9781486309870.

John Cooper, ACAP Information Officer, 17 September 2020

A Northern Giant Petrel feeds on a Sooty Albatross chick on Marion Island, photograph by Marienne de Villiers

Ryan Reisinger (Marine Apex Predator Research Unit, Nelson Mandela University, Port Elizabeth, South Africa) and colleagues have published open access in the journal Royal Society Open Science on differences in the diets and at-sea distributions of sympatrically breeding Northern Macronectes halli and Southern M. giganteus at Marion Island.

The paper’s abstract follows:

“To mediate competition, similar sympatric species are assumed to use different resources, or the same but geographically separated resources.  The two giant petrels (Macronectes spp.) are intriguing in that they are morphologically similar seabirds with overlapping diets and distributions.  To better understand the mechanisms allowing their coexistence, we investigated intra- and interspecific niche segregation at Marion Island (Southern Indian Ocean), one of the few localities where they breed in sympatry.  We used GPS tracks from 94 individuals and remote-sensed environmental data to quantify habitat use, combined with blood carbon and nitrogen stable isotope ratios from 90 individuals to characterize their foraging habitat and trophic ecology.  Females of both species made distant at-sea foraging trips and fed at a similar trophic level.  However, they used distinct pelagic habitats.  By contrast, males of both species mainly foraged on or near land, resulting in significant sexual segregation, but high interspecific habitat and diet overlap.  However, some males showed flexible behavioural strategies, also making distant, pelagic foraging trips.  Using contemporaneous tracking, environmental and stable isotope data we provide a clear example of how sympatric sibling species can be segregated along different foraging behaviour dimensions.”

Reference:

Reisinger, R.R., Carpenter-Kling, T.,  Connan, M., Cherel, Y. & Pistorius, P.A. 2020  Foraging behaviour and habitat-use drives niche segregation in sibling seabird species. Royal Society Open Science  doi.org/10.1098/rsos.200649.

John Cooper, ACAP Information Officer, 16 September 2020