Bronwyn Maree (Albatross Task Force, BirdLife South Africa, Cape Town, South Africa) and colleagues have published in the journal Animal Conservation on reductions in seabird mortality that occurs when trawl trail bird-scaring lines.

The paper’s abstract follows:

Globally, many thousands of seabirds are killed accidentally in demersal trawl fisheries through cable interactions and net entanglements.  However, multi-year datasets for estimating seabird–trawl interactions robustly are scarce.  In 2004/2005, an estimated 15 500 (7000–26 000) seabirds were killed annually through cable strikes in the South African deep-water hake trawl fishery; the majority were albatrosses.  We reanalysed those data using fishing effort from vessel logbooks (previously unavailable).  The new estimates are ∼40% lower across all taxa: ∼9300 birds in 2004, of which ∼7200 were albatrosses.  We compare these figures to data from 2006 to 2010, when vessels used a single measure (bird-scaring lines) to reduce seabird mortality.  From 64 trips and 690 hours of observation, 41 seabirds were confirmed killed due to cable strikes, of which 22% were albatrosses.  Fatal cable interactions occurred overwhelmingly when vessels discarded offal, with the highest rates (birds killed per hour of observation) in winter and during setting.  Comparing rates shows that bird-scaring lines alone resulted in 73–95% lower mortality in the winter/discard strata (all seabirds: 0.56 birds per hour before, 0.15 birds per hour after, P < 0.001; albatrosses: 0.44 birds per hour before, 0.02 birds per hour after, P < 0.001).  Estimated total mortality [mean and 95% confidence intervals (CIs)] in this fishery in 2010 was 990 (556–1633) seabirds, including 83 (38–166) albatrosses, a reduction in mean albatross deaths of > 95%, reflecting both bird-scaring line effectiveness (accounting for > 90%) and annual fishing effort reduced by 50% from 2004–2005 to 2010.  Bird-scaring lines cost < US$200 each in South Africa, a trivial expense per vessel for a measure that reduces fatal interactions with threatened seabirds so effectively.  Our results provide a strong case for the mandatory adoption of bird-scaring lines in trawl fisheries with high densities of scavenging seabirds.”

Black-browed Albatrosses gather behind a South Atlantic trawler

Photograph by Graham Parker

Click here to find BLSA's press release on their recently published research on bird-scaring lines for trwalers.

With thanks to Bronwyn Maree for information.

Reference:

B.A. Maree, B.A., Wanless, R.M., Fairweather, T.P., Sullivan, B.J. & Yates, O. 2014.  Significant reductions in mortality of threatened seabirds in a South African trawl fishery.  Animal Conservation doi:10.1111/acv.12126.

John Cooper, ACAP Information Officer, 08 May 2014

Steffen Oppel (Royal Society for the Protection of Birds, Sandy, U.K.) and colleagues have published open-access in the journal Nature Conservation on estimating population size of the Cory’s Shearwater Calonectris borealis.

The paper’s abstract follows:

Population size assessments for nocturnal burrow-nesting seabirds are logistically challenging because these species are active in colonies only during darkness and often nest on remote islands where manual inspections of breeding burrows are not feasible.  Many seabird species are highly vocal, and recent technological innovations now make it possible to record and quantify vocal activity in seabird colonies.  Here we test the hypothesis that remotely recorded vocal activity in Cory’s shearwater (Calonectris borealis) breeding colonies in the North Atlantic increases with nest density, and combined this relationship with cliff habitat mapping to estimate the population size of Cory’s shearwaters on the island of Corvo (Azores).  We deployed acoustic recording devices in 9 Cory’s shearwater colonies of known size to establish a relationship between vocal activity and local nest density (slope = 1.07,R2 = 0.86,p < 0.001).  We used this relationship to predict the nest density in various cliff habitat types and produced a habitat map of breeding cliffs to extrapolate nest density around the island of Corvo.  The mean predicted nest density on Corvo ranged from 6.6 (2.1–16.2) to 27.8 (19.5–36.4) nests/ha.  Extrapolation of habitat-specific nest densities across the cliff area of Corvo resulted in an estimate of 6326 Cory’s shearwater nests (95% confidence interval: 3735–10,524). This population size estimate is similar to previous assessments, but is too imprecise to detect moderate changes in population size over time.  While estimating absolute population size from acoustic recordings may not be sufficiently precise, the strong positive relationship that we found between local nest density and recorded calling rate indicates that passive acoustic monitoring may be useful to document relative changes in seabird populations over time.

Cory's Shearwater, photograph by Paulo Catry

Reference:

Oppel, S., Hervías, S., Oliveira, N., Pipa, T., Silva, C., Geraldes, P., Goh, M., Immler, E. & McKown, M. 2014.  Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping.  Nature Conservation 7: 1-13.

John Cooper, ACAP Information Officer, 07 May 2014

South Africa’s research station at sub-Antarctic Marion Island in the southern Indian Ocean is relieved once a year in April-May.  Returning today on the S.A. Agulhas II are two young researchers who have spent the last 13 months studying albatrosses on the island.

2012 BSc Honours graduates Kim Stevens (University of Cape Town) and Stefan Schoombie (University of KwaZulu-Natal) have been studying Grey-headed Albatrosses Thalassarche chrysostoma and the two sooty albatrosses Phoebetria spp., respectively.

Their two studies have been designed to be comparable.  Utilizing colour-banded birds in long-term monitoring colonies, birds were tracked at sea with back-mounted GPS loggers during three stages in their breeding seasons: early and late incubation and while brooding small chicks.  Deployments were made on 45 Grey-headed, 30 Sooty P. fusca and 15 Light-mantled P. palpebrata Albatrosses.  Return rates with successful downloads were good at 69 out of the 90 devices deployed.  Only a few loggers were lost at sea and some birds had data for more than one foraging trip.

A Grey-headed Albatross flies over a snowy Marion landscape

A Grey-headed Albatross on its nest has been fitted with a back-mounted GPS logger

With albatross crook close by Kim Stevens sits above a study colony on Grey-headed Albatross Ridge

Stefan Schoombie holds a Sooty Albatross on Marion Island

Photographs by Kim Stevens and Stefan Schoombie

In addition, chick regurgitations and squid beak casts were collected on an ad hoc basis to compare with previous studies made on the island, as will be information gathered daily on incubation shifts.

Kim’s study required overnight stays of up to 15 days at a time in a field hut at aptly-named Grey-headed Albatross Ridge on Marion’s south coast – a good day’s walk from the research station on the islands’ eastern side.  Stefan had it a little easier, with some of his study animals being within an hour's walk of the base, although he needed to use fixed ropes as safety aids when working with the sooties that bred on coastal cliffs.

Both Kim and Stefan will now register for Master’s degrees in the Percy FitzPatrick Institute at the University of Cape Town to write up their research findings.  Albatross research at Marion Island is managed by the Institute’s Director, Peter Ryan, who was also on the 2014 relief – as was ACAP’s Information Officer.

Click here for an earlier ACAP news item on research placing "daily diary" loggers on Wandering Albatrosses Diomedea exulans during this year's Marion relief.

John Cooper, ACAP Information Officer, 06 May 2014

The Endangered Black-capped Petrel) Pterodroma hasitata or Diablotin (Little Devil) breeds in remote areas of Haiti and the Dominican Republic, with a population estimated to be 600 to 2000 pairs.

To learn about its at-sea movements in the North Atlantic solar-powered satellite transmitters were placed on three breeding birds last month in the Sierra de Bahoruco along the border between the Dominican Republic and Haiti.  Click here to follow the birds’ journeys.

A Black-capped Petrel is equipped with a solar-powered satellite transmitter

“Much of the habitat loss stems from the desperate situation faced by communities on the Haitian side of the border, which depend on land for farming and fuel wood for cooking.  As a result, the remaining nesting habitat for this species is rapidly becoming deforested and degraded.  This affects the security of nesting colonies in Haiti, but also in the Dominican Republic, since Haitians are often hired by Dominicans to farm and make charcoal for them in the Sierra de Bahoruco, despite its protected area status.  In addition, the species is believed to be threatened by losses from collisions with power lines and communication towers, the periodic outbreak of wildfires and fires associated with forest clearing for farmland, and non-native predators such as rats and cats.” (click here).

The tracking project is being led by Patrick Jodice and Rob Ronconi with institutional backing from the South Carolina Cooperative Fish and Wildlife Research Unit at Clemson University, Grupo Jaragua in the Dominican Republic and American Bird Conservancy through the International Black-capped Petrel Conservation Group.

With thanks to Rob Ronconi for information.

Selected Literature:

Goetz, J.E., Hardesty-Norris, J. & Wheeler, J.A. (Eds) 2012.  Conservation Action Plan for the Black-capped Petrel (Pterodroma hasitata).  International Black-capped Petrel Conservation Group.  26 pp.

Simons, T.R., Lee, D.S. & Haney, J.C. 2013. Diablotin Pterodroma hasitata: a biography of the endangered Black-capped Petrel.  Marine Ornithology 41 (Special Issue): S3-S43.

John Cooper, ACAP Information Officer, 05 May 2014