2.2.10 Aerial at-sea surveys

Probably not relevant for Palau at this point.

Scientific investigations in offshore areas are logistically challenging and expensive; therefore, the available knowledge on seabird at-sea distribution and abundance, as well as their seasonal variations, remains limited. While tracking studies have provided valuable information on seabird ecology and distribution, that technology still excludes a large proportion of seabird populations (such as nonbreeding or non-accessible birds, small or shy species) that cannot easily be equipped with data loggers.

At-sea visual surveys allow whole seabird populations to be considered and offer valuable information on their distribution at various scales and different times. Boat-based surveys can be more frequent and allow for closer views of birds thus increasing chances of identification and study of behaviours, but aerial surveys have advantages for broad-scale investigation of seabirds’ ecological preferences or distribution, covering greater areas at a faster speed. They are thus comparatively more economical, and the high speed of the aircraft allows the selection of the best weather conditions for observation, while ensuring a faster coverage of the sampled region than a boat would achieve. Aerial surveys generally aim to assess the distribution of all seabird taxa present in the area (particularly familial groupings, as smaller or similar species can be hard to identify to species level from airplane surveys). They can also investigate their seasonal variations, estimate their densities and abundances, and finally highlight areas of importance for seabird conservation at sea, especially offshore. The next case study highlights how these surveys are undertaken, how the results are used, and what the strengths and limitations of this methodology are.

Drones can provide a useful tool for surveying seabirds nesting and roosting along coastlines and on islands, especially where access is difficult, or birds would be greatly disturbed by ground parties. This is essentially the same method as flying a drone survey from land, just that the platform for operating is from a boat deck (see Section 2.2.7).

UAV (or drones) are also used to survey marine megafauna behaviours including seabirds, cetaceans, and fish schools, as well as covering more localised marine areas. As always, make sure you are fully aware of the legal requirements for undertaking surveys with drones in your area, and ensure you operate in an ethical way that does not cause stress to the species you are studying.