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Balearic shearwater research


Balearic shearwater to become an ACAP Priority population.

The Agreement on the Conservation of Albatrosses and Petrels (ACAP) promotes globally the conservation of one of the fastest declining groups of birds on earth, by bringing together collaborative information and mitigation efforts and action especially where threats are known (for example from introduced predators or fisheries’ by-catch). 13 countries are signatories of the agreement, including Spain where the Balearic shearwater breeds, and UK and France into whose waters the species migrates after breeding. Most of the 31 species listed by ACAP are at least vulnerable, and many are recognised as endangered or critically endangered according by the IUCN. Within this group of seabirds, ACAP also now recognises a small number of populations that according to scientific evidence on their rates of decline and interaction with fisheries, must be regarded as the highest priority for monitoring research and conservation action. At its most recent meetings in Chile, ACAP has now recognised the Balearic shearwater as a priority population, making it one of only 8 such populations and the only one in Europe or indeed the entire northern hemisphere. The hope must be that with this ever brightening spotlight on the significance of this species within Europe and globally, the relevant national authorities will now take action to reverse the species’ precipitate decline by introducing by-catch mitigation measures (such as night setting of demersal long-lines already shown to be effective).


Mallorca 2016 NEWS

2nd April
A spell of good weather at the end of last week and the beginning of this one allowed us access to the colony and so we finished deploying a total of 27 GPS and have begun retrievals, with 12 back so far. The wind has turned northerly again now and so access to the colony has again become impossible. We have almost finished the geolocator redeployments on Dragonera. Here is an example of the tracks we have been getting back.

23rd March
Access to the main colony is still not possible because of north winds and a big swell. We attended a very constructive meeting at the Institute of Mediterranean Advanced Studies with Dani Oro, members of the Balearic Ornithological Group (GOB), and Caterina Amengual, from the conservation department of the new Balearic government administration.

22nd March
Today the north wind howls and access to our main colony by RIB is not possible. But 4 good days have allowed us to deploy 12 GPS and 2 accelerometers and recover/redeploy 12 Geolocators. We have retrieved our first camera trap pictures of Balearic shearwaters mating in the cave! We spent the day retrieving and redeploying geolocators in the small caves on Dragonera.

2016 Project update

Recent demographic analysis using multievent capture-recapture modelling shows that the Balearic Shearwater (Puffinus mauritanicus), Europe’s most threatened seabird species, is heading rapidly towards extinction. Unsustainably low adult annual survival (0.809 +/- 0.013) is the principle concern, with bycatch in fishing gear identified as the major cause of mortality (Genovart et al., 2016). Reproductive rates are also relatively low, with the upcoming ban on fisheries discards likely to depress these further, at least in the short term.

Our own work on Balearic shearwaters focuses on unravelling the mysteries of its extraordinary life-style (it’s the only seabird to nest deep underground in caves, for example), and particularly its behaviour at sea. On Mallorca using miniature GPS loggers we have confirmed the importance of long distance foraging commutes to mainland Spanish coastal waters in the Mediterranean (Meier et al., 2015). Long- term geolocator (GLS) deployments show that breeding birds migrate out of the Mediterranean after breeding to feed in Atlantic coastal hotspots, mainly off Portugal and France (Guilford et al., 2012).
Hooks (from demersal longlines) are probably the biggest killers in the Mediterranean foraging areas, but other fishing gear (e.g trawlers and purse-seiners) can cause occasional large numbers of deaths in the Atlantic (Oliveira et al., 2015).

Balearic shearwaters are increasingly reported in UK waters in the southwest in late summer, but we still do not know whether these are breeding adults or immatures (something we are currently trying to resolve by tracking fledglings with GLS). The risk of bycatch in UK waters remains unknown.

Repeat tracking shows that birds are highly faithful to their individual destinations, with males and females preferring differing locations. Females, who spend longer in the Atlantic than males, migrate further north, and isotopic analysis of their feathers moulted at different times suggests that they may be more dependent on fisheries discards there, although this is of low certainty (Meier 2015).

Back in the Mediterranean, we now know that birds appear only to dive for fish during the day (Meier et al., 2015), so night-setting of demersal longlines should provide a technically simple method for reducing bycatch. Indeed research at Barcelona University by Jacob Gonzalez-Solis and Vero Cortez has shown experimentally that night-setting is the most effective mitigation measure available and causes little or no reduction in fish catches.

In 2016 we are co-ordinating our GPS tracking campaign on Mallorca with Spanish colleagues Pep Arcos and Maite Louzao in Ibiza to try to determine the degree of segregation in Mediterranean foraging areas between major colonies – an important piece in the demographic puzzle. We are also developing methods for quantifying individual dependence on different foraging modes (natural and different fisheries scavenging behaviours) using on-board video-loggers and accelerometry (with Emily Shepard).

The natural park of Dragonera provides us with great facilities for conducting this work, which is made possible by the generosity of volunteers, and donations from Natural England, RSPB and private individuals – in particular Mark Constantine and Steve Votier. If you feel motivated to help, please use our campaign page below.


Genovart, Meritxell, Jose Manuel Arcos, David Álvarez, Miguel McMinn, Rhiannon Meier, Russell Wynn, Tim Guilford, and Daniel Oro. "Demography of the critically endangered Balearic shearwater: the impact of fisheries and time to extinction." Journal of Applied Ecology (2016): n/a - n/a.

Meier, Rhiannon E., Russell B. Wynn, Stephen C. Votier, Miguel McMinn Grivé, Ana Rodríguez, Louise Maurice, Emiel E. van Loon, Alice R. Jones, Lavinia Suberg, José Manuel Arcos et al. "Consistent foraging areas and commuting corridors of the critically endangered Balearic shearwater Puffinus mauretanicus in the northwestern Mediterranean." Biological Conservation 190 (2015): 87-97.

Guilford, T., R. Wynn, M. McMinn, A. Rodríguez, A. Fayet, L. Maurice, A. Jones, and R. Meier. "Geolocators Reveal Migration and Pre-Breeding Behaviour of the Critically Endangered Balearic Shearwater Puffinus mauretanicus." PLoS ONE 7, no. 3 (2012): e33753.

Oliveira, Nuno, Ana Henriques, Joana Miodonski, Joana Pereira, Débora Marujo, Ana Almeida, Nuno Barros, Joana Andrade, Ana Marçalo, Jorge Santos et al. "Seabird bycatch in Portuguese mainland coastal fisheries: An assessment through on-board observations and fishermen interviews." Global Ecology and Conservation 3 (2015): 51-61.

Balearic shearwater campaign

Europe’s rarest seabird is the Balearic shearwater (Puffinus mauretanicus), which breeds in the Mediterranean and migrates north into the Atlantic in the summer. It is seen increasingly off Britain with perhaps ¼ of the world population visibly using our seas at times in late summer. But it is critically endangered, and faces as a species a deeply uncertain future. Despite this, still remarkably little is known about its behaviour and ecological needs: knowledge which must underpin conservation efforts to avert its extinction.

You can help

Balearic shearwater at sea

At OxNav we have been collaborating with scientisis at the National Oceanographic Centre in Southampton, with Spanish biologists in Palma and elsewhere, and with the RSPB, to try to fill important knowledge gaps and raise awareness of the species’ plight. We have been engaged in answering fundamental questions about where and how breeding birds feed (and how this relates to human fisheries), where they overwinter, and their patterns of colony use in the pre-breeding months. We are now trying to determine the provenance of birds using UK waters, which we think may be non- or pre-breeders becoming increasingly dependent on our waters as the changing climate drives important marine resources north. And we are setting up longer term monitoring efforts to help assess key changes in breeding success, overwinter survival, and patterns of breeding and migratory phenology.

Our research efforts have always depended on voluntary contributions of time, effort and funds, in addition to small awards from organisations. You can help us take the work on into the future by giving a donation, of any size, that we can use to help purchase essential tracking devices (a geolocator costs about £120 +VAT, and can be used to track an individual bird’s migration and pinpoint the timing of its key life-history events for several years), artifical nest boxes, or pay for boat fuel needed to visit the colonies. If you are interested in donating to our Balearic shearwater project you can do so by clicking here