Male and female Black-tailed Gulls Larus crassirostris feed on the same prey species but use different feeding habitats

Kazama, Kentaro; Nishizawa, Bungo; Tsukamoto, Shota; Gonzalez, Jordi E.; Kazama, Mami T.; Watanuki, Yutaka

doi:10.1007/s10336-018-1565-9

Cited by 24 publications

(11 citation statements)

References 51 publications

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“…Black‐tailed gulls feed on various prey species including zooplankton (krill and amphipods), epipelagic fish including sand lance Ammodytes spp., sardine Sardinops melanostictus , anchovy Engraulis japonica and age‐0 Okhotsk atka mackerel Pleurogrammus azonus , insects and anthropogenic waste (Deguchi et al 2004). At Rishiri Island, black‐tailed gulls fed mainly on sand lance, crustaceans and some insects during their incubation period in our study years (Kazama 2018). In our study, the tracked birds performed hop plunging and surface plunging after flapping flights or gliding possibly to feed on fish or crustaceans under the water, and they also performed surface seizing or surface filtering while they were swimming possibly to collect surfacing zooplankton from the sea surface as described in Watanuki (1987).…”

Section: Discussionmentioning

confidence: 93%

“…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%

“…They are the second most abundant seabird species in Japan (Senzaki et al 2014), and therefore a suitable indicator species for determining mIBAs. Moreover, black‐tailed gulls can travel > 100 km in a single round trip during the breeding season (Kazama et al 2018), during which their at‐sea behavior can conveniently be classified as flying or not based on the typically cyclic acceleration signal from wing flapping. Further, this species uses a variety of feeding techniques including surface seizing, hop plunging and surface plunging (Watanuki 1987).…”

Section: Introductionmentioning

confidence: 99%

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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: 93%

Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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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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“…The southern part of the Okhotsk Sea off Hokkaido is known as one of the important fishing grounds in Japan due to abundant fishery resources, such as scallops and salmon (Kasai et al 2017;Sakurai 2011;Shiomoto et al 2018). At higher trophic levels (sea birds and marine mammals), this region is also an important foraging habitat (Kazama et al 2018). In summer, this area is characterized by three different water masses: the warm and saline Soya Warm Current (SWC) distributed in the coastal region, the less-saline Fresh Surface Okhotsk Sea Water (FSOSW) observed in the surface layer of the offshore region, and low-temperature Intermediate Cold Water (ICW) distributed in the lower layer (Takizawa 1982).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution of the protist community in the southern part of the Okhotsk Sea off Hokkaido during summer

et al. 2022

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The southern part of the Okhotsk Sea off Hokkaido has rich fishery resources supported by high primary production. The phytoplankton community has been described by several studies based on size-fractionated chlorophyll a concentration and primary production; however, the details of the species composition of nano- and micro-protist communities have not been well investigated. We evaluated the spatial distribution and relationship with hydrography of nano- and micro-protist communities in the southern region of the Okhotsk Sea off Hokkaido during the summer of 2019. Forty-two species of diatoms from 19 genera, dinoflagellates from 7 genera, tintinnid ciliates, oligotrich ciliates, and 1 genus of silicoflagellates were identified. Their spatial distribution showed distinct differences among the taxa. Cluster analysis based on the protist cell density identified six groups with geographically well-distinguished distributions. Diatom-dominant communities were distributed in the Cold Water Belt and Soya warm current along the coastal area of Hokkaido. Nanoflagellate-dominated communities were distributed in the offshore area. Some harmful species of diatoms (Pseudonitzschia pseudodelicatissima) and dinoflagellates (Alexandrium spp.) were dominant in the Cold Water Belt off Wakkanai. We suggest that the upwelling of cold water could increase the abundance of harmful species, with immanent negative impacts on marine ecosystems or fishery resources. In summary, the species composition and abundance of the summer protist community was strongly related to different water masses in the southern part of the Okhotsk Sea off Hokkaido.

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“…tens of kilometres; Egunez et al , ). In other words, even though gulls are efficient flyers and are able to cover long distances to find food (Isaksson et al , ; Kazama et al , ), there is evidence that the use of certain feeding sources can be very local. Consequently, potentially important food subsidies may have a relatively small area of influence, which would result in only a limited impact from the large geographic‐scale perspective.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the effect of distance to different food subsidies on the trophic ecology of an opportunistic seabird species

et al. 2020

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The availability of food subsidies of anthropogenic origin has strong consequences on the trophic ecology and population dynamics of several opportunistic species. However, evidence suggests that the use of certain feeding sources is very local, and hence, potentially important food subsidies may have a relatively small area of influence, resulting in only limited impact from the large geographic-scale perspective. In the south-eastern part of the Bay of Biscay, the Yellow-legged Gull Larus michahellis population is distributed across several colonies, which are located close to each other but have variable dependence on the landfills and fishing harbours in the area. This population is therefore a good model to test the influence of anthropogenic food subsidies on the trophic ecology of an opportunistic species at the local scale. Distance to the nearest fishing harbour showed a stronger effect on the diet of Yellow-legged Gull chicks than distance to the nearest landfill site. Gulls notably reduced their consumption of marine prey (mostly comprised of fishing discards) in relation to decreasing distance of their colony to the nearest fishing harbour. This result has direct implications from a management standpoint, since fish discards were also found to have only a limited effect on diet at regional scales, but a very high impact at the local scale. Moreover, those colonies that consumed a higher proportion of marine prey showed better population trends. In line with European Union policies, a reduction in the availability of fish discards, together with the closure of landfill sites, will occur in the coming years, probably leading to a change in the trophic ecology and dynamics of Yellow-legged Gull populations.

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Male and female Black-tailed Gulls Larus crassirostris feed on the same prey species but use different feeding habitats

Cited by 24 publications

References 51 publications

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

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

Spatial distribution of the protist community in the southern part of the Okhotsk Sea off Hokkaido during summer

Evaluating the effect of distance to different food subsidies on the trophic ecology of an opportunistic seabird species

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