Identification of biophysical regions in the south-western part of the Okhotsk Sea by satellite imagery classification

Mustapha, Muzzneena Ahmad; Lihan, Tukimat; Tangang, Fredolin; Saitoh, Setsuo

doi:10.1016/j.csr.2014.12.014

Cited by 2 publications

(1 citation statement)

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“…Excluding Bird 825 that fed in Coastal area, individuals conducted all three types of foraging behavior at least in one of the Strait, Off Soya, and/or Rishiri East areas. Our birds fed at the oceanic front in the Off Soya area (Mustapha et al 2015) where the availability of sand lances seems predictably high (Kazama et al 2018). Productivity in the Rishiri East, Coastal and Strait is assumed to be particularly high because these areas are known spawning sites of sand lance during spring and summer (our study seasons) (Resource evaluation of sand lance in Okamoto et al 1989, Soya Strait 2020.…”

Section: Discussionmentioning

confidence: 98%

Dynamic body acceleration improves mapping of at‐sea foraging behavior in black‐tailed gulls Larus crassirostris

Kazama

Yasutake³

et al. 2022

Journal of Avian Biology

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Areas at which seabirds forage intensively can be discriminated by tracking the individuals' at-sea movements. However, such tracking data may not accurately reflect the birds' exact foraging locations. In addition to tracking data, gathering information on the dynamic body acceleration of individual birds may refine inferences on their foraging activity. Our aim was to classify the foraging behaviors of surface-feeding seabirds using data on their body acceleration and use this signal to discriminate areas where they forage intensively. Accordingly, we recorded the foraging movements and body acceleration data from seven and ten black-tailed gulls Larus crassirostris in 2017 and 2018, respectively, using GPS loggers and accelerometers. By referring to video footage of flying and foraging individuals, we were able to classify flying (flapping flight, gliding and hovering), foraging (surface plunging, hop plunging and swimming) and maintenance (drifting, preening, etc.) behaviors using the speed, body angle and cycle and amplitude of body acceleration of the birds. Foraging areas determined from acceleration data corresponded roughly with sections of low speed and area-restricted searching (ARS) identified from the GPS tracks. However, this study suggests that the occurrence of foraging behaviors may be overestimated based on low-speed trip sections, because birds may exhibit long periods of reduced movement devoted to maintenance. Opposite, the ARS-based approach may underestimate foraging behaviors since birds can forage without conducting an ARS. Therefore, our results show that the combined use of accelerometers and GPS tracking helps to adequately determine the important foraging areas of black-tailed gulls. Our approach may contribute to better discriminate ecologically or biologically significant areas in marine environments.

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Section: Discussionmentioning

confidence: 98%