Abstract
AbstractUnmanned aerial vehicles (UAVs) are increasingly being recognized as potentially useful for detection of marine mammals in their natural habitats, but an important consideration is the associated uncertainties in animal detection. We present a study based on field trials using UAVs to carry out image‐based monitoring of cetaceans in two fjords in northern Norway. We conducted 12 missions to assess the effects of both environmental‐ and aircraft‐related variables on detection certainty. Images were inspected for animal presence and its associated detection certainty. Images were also assessed for potentially important covariates such as wave turbulence (sea state), luminance, and glare. Aircraft variables such as altitude, pitch, and roll were combined into a single variable—pixel size. We recorded a total of 50 humpback whales, 63 killer whales (KW), and 118 unidentified sightings. We also recorded 57 harbor porpoise sightings. None of the environmental conditions (sea state, glare, and luminance) affected the detection certainty of harbor porpoises. In contrast, increasing sea state and luminance had negative and positive effects, respectively, on the detection certainty of humpback and KW. The detection certainty was not significantly affected by pixel size for both harbor porpoises, and humpback and KW. Our results indicate that at lower altitudes, variations in aircraft position (pitch and roll) do not have a variable effect on detection certainty. Overall, this study shows the importance of measuring variability in both environmental and flight‐related variables, in order to attain unbiased estimates of detectability for UAV‐based marine mammal surveys, particularly in Arctic and sub‐Arctic regions.
Highlights
A major challenge for society is the management of Earth’s biodiversity with the aim of protecting the integrity and health of species, their habitats, and ecosystems
We suggest an approach for including modeled detection certainty in future abundance estimates from Unmanned aerial vehicles (UAVs)-based surveys
In Kaldfjord, we recorded with certainty 37 humpback whales (HW), 50 killer whales (KW), and six unidentified species
Summary
A major challenge for society is the management of Earth’s biodiversity with the aim of protecting the integrity and health of species, their habitats, and ecosystems Animals in their natural habitats have often proved challenging to study and manage due to their complex movement patterns and individual behaviors. This is challenging for those species occupying habitats in remote regions where the use of traditional monitoring methods can be difficult, timeconsuming, and expensive (Chabot and Bird 2015). The high velocity of aerial compared to ship-based surveys may affect detection probability, depending on the diving/surfacing intervals of the animals under study in relation to the speed at which the platform passes overhead
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