Mortality of adult Black-tailed Gulls Larus crassirostris on Kabu Island, Aomori Prefecture

Tomita, Naoki; Mizutani, Yuichi; Fujii, Hidenori; Sugiura, Rina; Yanai, Tokuma; Asano, Makoto; Niizuma, Yasuaki

doi:10.3838/jjo.59.80

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…For example, many colonies of both gull species are exposed to increasing predation pressure from the native White-tailed Eagle due to its population expansion in northern Japan since the 1990s (Ministry of the Environment of Japan 2015). Predation by foxes and feral cats on adult Black-tailed Gulls has also been observed recently in several colonies (Tomita et al 2010, 2016).…”

Section: Discussionmentioning

confidence: 61%

“…Predation by foxes and feral cats on adult Black-tailed Gulls has also been observed recently in several colonies (Tomita et al 2010(Tomita et al , 2016.…”

Section: Species With Decreasing Population Sizementioning

confidence: 69%

“…and/or feral cats Felis catus (e.g. Teuri Island, Rishiri Island, and Kabushima Island) (Tomita et al 2010(Tomita et al , 2016, as well as native predators such as White-tailed Eagle Haliaeetus albicilla (e.g. Teuri Island and Daikoku-jima) (Ministry of the Environment of Japan 2015).…”

Section: Focal Species and Study Timeframementioning

confidence: 99%

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Long-term declines in common breeding seabirds in Japan

Senzaki

Terui

Tomita

et al. 2019

Bird Conservation International

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SummaryGlobal seabird populations are in decline, with nearly half of all seabird species currently in an extinction crisis. Understanding long-term seabird population trends is an essential first step to inform conservation actions. In this study, we assembled historical breeding records of seabirds throughout the Japanese archipelago and quantified the long-term population trends of 10 major breeding seabird species using a hierarchical Bayesian state-space model. The model revealed that six species had increasing or no detectable trends (Short-tailed Albatross Phoebastria albatrus, Leach’s Storm Petrel Oceanodroma leucorhoa, Pelagic Cormorant Phalacrocorax pelagicus, Japanese Cormorant Phalacrocorax capillatus, Spectacled Guillemot Cepphus carbo, and Rhinoceros Auklet Cerorhinca monocerata). However, decreasing trends were found not only in nationally threatened species (Common Murre Uria aalge, and Tufted Puffin Fratercula cirrhata) but also common species that are often described as abundant (Black-tailed Gull Larus crassirostris and Slaty-backed Gull Larus schistisagus). These declining species have declined to 3–35% of baseline levels over the past 30 years. This study provides the first evidence of long-term declines in common and widespread seabirds in Japan.

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Section: Discussionmentioning

confidence: 61%

“…Predation by foxes and feral cats on adult Black-tailed Gulls has also been observed recently in several colonies (Tomita et al 2010(Tomita et al , 2016.…”

Section: Species With Decreasing Population Sizementioning

confidence: 69%

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Long-term declines in common breeding seabirds in Japan

Senzaki

Terui

Tomita

et al. 2019

Bird Conservation International

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“…The carcasses were collected in Kabu Island during the breeding seasons of 2012 to 2018 and are stored in Yamashina Institute for Ornithology (Abiko City, Chiba Prefecture, Japan). Adult specimens examined here are individuals probably killed by cats or foxes that had invaded from the mainland of Japan (Tomita et al, 2010(Tomita et al, , 2018, whereas nestling specimens were probably killed by cold weather or attacks by adult gulls other than their parents. The specimens examined here did not include juveniles that have fledged because their carcasses are hardly available due to low mortality in this stage.…”

Section: Specimensmentioning

confidence: 99%

Postnatal cranial ontogeny and growth strategies in the black‐tailed gullLarus crassirostrisbreeding on Kabu Island, Aomori, Japan

et al. 2021

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Although cranial morphology of modern birds has been an important subject of evolutionary studies, detailed information on postnatal ontogeny of the avian skull remains very scarce. Herein, a wild population of the black-tailed gull (Larus crassirostris) breeding on Kabu Island was examined to explore relationships between their growth strategies and ontogenetic changes in the cranial shape. By examining growth series covering a major part of the postnatal ontogenetic period, it was clarified that the typical form of the adult larid skull was produced through dynamic proportional changes among cranial structures after hatching. Cranial structures related to the oral capacity and deglutition (e.g., some elements of hyoid bones) attained the adult sizes before fledging, whereas other structures apparently reached the adult sizes well after leaving the nest. The palatal width exhibited positively allometric growth against the skull volume in chicks in the early nestling stage, followed by a period of negative allometry in the later growth stage. A nestling gull has to acquire swallowing ability by the time of fledging at the latest because this ability is apparently essential for a food intake without parental aid. In addition, because nestlings mainly feed on foodstuffs supplied by their parents, previous studies suggested the possibility that siblings within a nest compete for food resources. Under this scenario, early acquisition of swallowing abilities, as indicated by the allometric patterns of relevant cranial structures, may be an adaptive trait that enhances survival of nestlings.

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