LIFE Artina (LIFE17 NAT/HR/000594) - Sea transect data 2019-2021 - Lastovo Archipelago, Croatia

Study Extent

A series of systematic at-sea surveys was conducted, following the standardized protocol of the ‘European Seabirds at Sea’ (ESAS) database (Tasker et al. 1984; Camphuysen et al. 2004). These transects were carried out monthly between March and October during a two year timespan (May 2019 – May 2021), following a petal shape within a nine nautical mile radius around the SPA Lastovsko otočje. A total of 12 transects, varying in length from 35 to 50 km, were surveyed by two observers on a semi-inflatable boat with a skipper, going at a speed of 15 km/h.

Sampling

Only birds flying on the port side of the boat (left side) were counted. Birds were identified to species level where possible, otherwise using larger overarching species groups. For each observation, the number of birds and their age (if possible) was noted, as well as notes on their behaviour (e.g. foraging, feeding, resting, flying by) and their distance to the boat (see code below), as well as direction of flight. Besides birds, sightings of Dolphins and turtles, and some large species of fish were also recorded. To mitigate the possible effects of weather on species identification, sea transects were only conducted 1) either in the early morning or late afternoon (when the sun is less strong), 2) during days with favourable weather forecast (little to no wind, no large waves, no rain or fog), and 3) by choosing the starting point of the transect based on the location of the sun (to avoid being blinded). Changes in sea state (see code below), visibility and cloud cover were also recorded during the transects. Codes used for distance from boat: A = swims, 0 - 50m B = swims, 50 - 100m C = swims, 100 - 200m D = swims, 200 - 300m E = swims, ≥ 300m F = flying inside transect F+ = flying outside transect Sea state codes: Sea like a mirror -> no wave; wind less than 1kt Small ripples -> wave 0,1m; wind 1 - 3kt Small wavelets -> wave 0,2 - 0,3m; wind 4 - 6kt Crests break -> wave 0,6 - 1,0m; wind 7 - 10kt Numerous white caps -> wave 1,0 - 1,5m; wind 11 - 16kt

Method steps

1. The field data, initially digitized in Excel, was subsequently imported into R for further processing. In the original dataset, some species were identified more broadly, such as "Larus/Ichthyaetus spec." or "Apus spec." In these instances, the original values were retained in the "verbatimIdentification" column. To provide further taxonomic context, the first general taxonomic rank for each case was identified and included in the database. Additionally, supplementary details—such as distance from the ship, flight direction, cloud cover, sea state, and visibility—were added as measurementOrFact entries.

1. Testudines
   rank: order
2. Suliformes
   rank: order
3. Laridae
   rank: family
4. Carcharhinidae
   rank: family
5. Corvidae
   rank: family
6. Upupidae
   rank: family
7. Anseriformes
   rank: order
8. Apodidae
   rank: order
9. Columbidae
   rank: family
10. Artiodactyla
    rank: order
11. Istiophoriformes
    rank: order
12. Procellariidae
    rank: family
13. Motacillidae
    rank: family
14. Animalia
    rank: kingdom
15. Phalacrocoracidae
    rank: family
16. Xiphiidae
    rank: family
17. Podicipedidae
    rank: family
18. Delphinidae
    rank: family
19. Passeriformes
    rank: order
20. Pelecaniformes
    rank: order
21. Falconiformes
    rank: order
22. Hydrobatidae
    rank: family
23. Actinopterygii
    rank: class
24. Chondrichthyes
    rank: class
25. Accipitriformes
    rank: order
26. Columbiformes
    rank: order
27. Scolopacidae
    rank: family
28. Aves
    rank: class
29. Apodiformes
    rank: order
30. Reptilia
    rank: class
31. Charadriiformes
    rank: order
32. Bucerotiformes
    rank: order
33. Accipitridae
    rank: family
34. Podicipediformes
    rank: order
35. Hirundinidae
    rank: family
36. Strigidae
    rank: family
37. Mammalia
    rank: class
38. Alaudidae
    rank: family
39. Caprimulgiformes
    rank: order
40. Carcharhiniformes
    rank: order
41. Falconidae
    rank: family
42. Apodidae
    rank: family
43. Turdidae
    rank: family
44. Procellariiformes
    rank: order
45. Caprimulgidae
    rank: family
46. Strigiformes
    rank: order
47. Cheloniidae
    rank: family
48. Ardeidae
    rank: family
49. Anatidae
    rank: family

The sea transects were carried out within a nine nautical mile radius starting from the border of the Nature Park Lastovo Islands. This border is identical with the one of the Natura 2000 site 'SPA Lastovsko otočje'.