Author: Dries Engelen
For the in-person replication & transferability visits of LIFE Artina we initially aimed to approach relevant public institiutions, other than the one on Lastovo, which are responsible for the management of areas with breeding Yelkouan and Scopoli’s shearwaters and Audouin’s gull in Croatia. These areas concern the SPAs Pučinski otoci (managed by More i Krs), Srednjedalmatinski otoci i Pelješac (managed by Dubrovačko-neretvanska županija) and the national park of Mljet. Coincidentally, while preparing for our south-Croatia replication spree, we got contacted by the much closer Public Institution of Maksimir, which manages protected areas in the city of Zagreb (see box 1).
Replication at Rakitje – 17.05.2023.
The island in Rakitje lake is home to the largest colony of Common tern in Croatia, with around 150 breeding pairs. This year, rats have been observed on the island via camera traps for the first time and no breeding attempts of Common tern were recorded. Public Institution Maksimir contacted Biom, and on the 17th of May we joined the PI to Rakitje island to educate them on different rat removal techniques. We installed several cage traps and one automatic A24 Goodnature Trap. During the first night three rats were caught and removed from the island. Afterwards, PI Maksimir continued to monitor and re-bait the traps for any potential remaining rats.
After a 7 hour travel we reached the first of our replication destinations, the National Park of Mljet. This park is situated on the west of the island and includes several small islands, mostly important for Mediterranean Shag and Audouin’s Gull. In the beginning of 2000s, 10-20 pairs of AG bred in NP Mljet, but in 2009 they stopped. After that, only occasional breeding was observed with 1 pair in 2013, 2018 and 2020. The 2023 census again did not find any breeding pair in the park.
After a night of sleep at the park’s accommodation, we met with a senior conservation staff member and got picked up to visit the nearby islets of Galicija and Maslinovac. On the islands we talked about the effects of rats and other introduced mammalian predators (Small Indian Mongoose in the case of Mljet) on island ecosystems and the different ways of detecting their presence and controlling their populations. Furthermore, we discussed the ecology of Audouin’s gull, their interaction with Yellow-legged gull and the dependence of the latter on waste management. While visiting Galicija there was one Audouin’s gull flying passed us and landing in the sea nearby, almost as if it was waiting for us to leave the island, so it could return to its nest… Perhaps it was overlooked during this year’s census…
After that we had some time to wander around the National Park, before heading to Goveđari in the evening. There, at Gallery Stara Skula we were welcomed with some myrtle liquor and held a presentation for the local community about different seabird species and their threats. The event was attended by 15 persons, young and old.
The next morning we got up early to catch the first ferry from Mljet back to the mainland. We drove through the scenic countryside of Pelješac to end up in the coastal town of Orebić where we would be meeting with three staff members from the Public Institution ‘Dubrovačko-neretvanska županija’ (DNZ). Together we would visit the small islets between the island of Korčula and the Pelješac peninsula, which are part of the SPA ‘Srednjedalmatinski otoci i Pelješac’.
These islands include the first location where Audouin’s gull was found breeding in Croatia, back in 1997. Currently the SPA is estimated to have 8 to 10 breeding pairs of the species, but as the islands are not monitored during most years, it is not sure whether this is still the case. Also, because Audouin’s gull changes its breeding sites annually, it is important that all historical breeding islets (e.g. all relevant islets around Lastovo, Mljet, Korčula and Pelješac) are checked yearly to have a complete overview of the species’ breeding status in Croatia.
The calm weather and flat sea were perfect to circle the islands by boat and look for Audouin’s gulls among the many pairs of nesting Yellow-legged gull. After checking the first 6 islands, we disembarked on the island of Velika Sestrica. Here we discussed the effects of rat eradication on seabird conservation and island restoration, and the actual technical feasibility of such an effort on the (north) easterly located islands in this archipelago. We introduced them to different tools for rat removal and also walked around the island looking for signs of rat presence. During our walk we noticed several remains of dead adult Yellow-legged gulls, most probably predated by a visiting Eagle Owl, and one dead Sandwich Tern, a wintering species of the SPA.
After an hour we got back on the boat and continued monitoring the remaining islands suitable for the nesting of Audouin’s gull. Although we had some nice sightings of Yellow-legged gull chicks, groups of resting Mediterranean Shags and two Little Egrets, we did not find and Audouin’s gull in the area. Nevertheless, it was an enjoyable meeting and already a success because it was the first time the staff of the Public Institution actually visited these islands that fall under their management. And who knows, the unpredictable Audouin’s gull may very well turn up again next year for a new breeding attempt…
25.05.2023 – For our last replication visit, we moved one county north (Splitsko-dalmatinksa županija) to meet with the Public Institution ‘More i Krs’. Together with a senior conservation staff member, and two rangers we set out for the island of Svetac. This island is part of the SPA Pučinksi otoci, and home to the largest colony of Scopoli’s shearwater in the Adriatic Sea. The estimated 240 – 560 breeding pairs are nesting in steep inaccessible cliffs, crevices and cave systems. The island also has a small population of Yelkouan shearwaters and the largest colony of Eleonora’s Falcon in Croatia. Estimating colony sizes of both shearwater species on Svetac is very difficult, however, because of the island’s difficult terrain. The idea was therefore to use this replication visit for installing a few sound recorders on the island, which can hopefully help in assessing and monitoring the populations of both species.
During the two-hour boat drive to the island, we already encountered the first Scopoli’s gliding over the flat sea surface. The time did not only allow us to have a decent Dalmatian lunch (with pršut, sir and panceta), but also provided a good opportunity to talk about rats and seabirds, island restoration and the possibility of removing rats from Svetac permanently (as the island’s remoteness will make it impossible for rats to return naturally). In fact, Biom Association and Public Institution More i Krs will join a larger partnership of Italian and Maltese organizations in a new LIFE project, called TETIDE, which will start in September this year and run until the end of 2028. In this project we aim to assess the feasibility of such a permanent rat removal from Svetac island, as well as two other important shearwater nesting sites in the Pučinski otoci SPA: Palagruža and Jabuka.
When we returned to Split, and later that day to Zagreb, we thought our replication and transferability spree had come to an end, but then two weeks later one more opportunity popped up to have an in-person meeting to once more talk about seabirds, their threats, and share some of our experiences from the LIFE Artina project (see Box 2).
Brijuni National Park – 13.06.2023.
The Brijuni National Park includes an archipelago of 14 islands in the northern Adriatic, situated to the southeast of Istria, and is one of the most important breeding sites for Mediterranean Shag in the Adriatic. Together with the park’s senior advisor to conservation and two rangers we circled the islands looking for breeding terns and visited several islands to search for signs of rat presence. Just after disembarking on the islet of Grunj, we observed a flock of 25 Yelkouan shearwaters come flying in and passing behind the parks’ boat (see video). Although GPS-tracking data gathered from Yelkouan shearwaters breeding around Lastovo, show that the species regularly visits the Northern Adriatic for foraging (even resulting in the recent designation of a BirdLife IBA), it is always exciting to see it confirmed in person. Somehow it felt like a fitting closure to the replication and transferability work carried out over the last weeks.