Immigration of the common cormorant Phalacrocorax carbo hanedae into inland areas of the northern part of Nagano Prefecture, eastern Japan, inferred from stable isotopes of carbon, nitrogen and sulphur

Natsumeda, Takaharu; Sakano, Hiroyuki; Tsuruta, Tetsuya; Kameda, Kayoko; Iguchi, Kei’ichiro

doi:10.1007/s12562-014-0823-x

Cited by 9 publications

(2 citation statements)

References 35 publications

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“…Interpretation of consumers d 15 N relative to the d 15 N of the primary producer provides a measure of their trophic position that is indicative of ''average'' trophic function (Levine 1980). The combined use of d 13 C and d 15 N has clarified the feeding records of the cormorants in various regions of the world (Bearhop et al 1999;Doucette et al 2011;Natsumeda et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The seasonal trophic link between Great Cormorant Phalacrocorax carbo and ayu Plecoglossus altivelis altivelis reared for mass release

Takai

Kawabe

Togura

et al. 2018

Ecological Research

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The feeding ecology of Great Cormorants (Phalacrocorax carbo) during the breeding season in the Kano River basin, central Japan, was examined to clarify the trophic relationship between the cormorants and ayu (Plecoglossus altivelis altivelis) reared for mass release in the river. The ayu was most frequently found in stomachs of cormorants culled during the breeding season, despite relatively poor catch in the year-round fish fauna research in the watershed. Carbon and nitrogen stable isotope ratios of some ayu individuals extracted from the stomachs of the culled cormorants were similar to the isotopic values of ayu caught in the watershed, whereas the other stomach-content ayu showed peculiarly high nitrogen isotopic values, clearly distinct from the values of the ayu caught in the watershed, and overlapped with the values of mass-release ayu. Furthermore, isotopic values of past diets inferred by the isotope analysis of livers of the culled cormorants were closer to the values of the mass-release ayu, relative to the past diet values inferred by the analysis of the cormorant muscles. This suggests that the food supply from the mass-release ayu had increased in the breeding season, since the isotopic turnover rate is faster in livers than in muscles. The huge number of formula-fed ayu released in the watershed create an anthropogenic food chain which is assumed to significantly support the breeding of the cormorants.

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Section: Introductionmentioning

confidence: 99%

The seasonal trophic link between Great Cormorant Phalacrocorax carbo and ayu Plecoglossus altivelis altivelis reared for mass release

Takai

Kawabe

Togura

et al. 2018

Ecological Research

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“…An experimental study using repellent visual stimuli demonstrated that contemporary cormorants retained their sensitivity to a human figure (Yamamoto et al, 2012), suggesting that contact with humans is still perceived as a threat by cormorants. Nonetheless, a large number of cormorants have established their novel habitats in the midst of cities, where encounters with humans are common (Fukuda et al, 2002;Natsumeda et al, 2015). The basis on which cormorants choose their habitat remains unexplained.…”

Section: Introductionmentioning

confidence: 99%

Differing Wariness for Approaching Humans among Cormorant Migrants Advancing into Rural or Urban Habitats

Iguchi

Tanaka²,

Shinagawa³

et al. 2015

JAS

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The great cormorant (Phalacrocorax carbo hanedae) is one of the largest piscivorous water birds in Japan. It is in the phase of recovery from a long-term decline in the numbers, with its population drastically increasing throughout Japan. This potentially impacts cormorant's predation conflicts with inland fisheries. Recent cormorant migrants often appear to inhabit more urbanized areas although the species once preferred habitats remote from human activities. This novel dwelling preference remains unexplained. The present study aimed to understand the processes promoting their expansion, especially focusing on those that help acquire foraging success in urban habitats. Measurements on primary production in aquatic ecosystem did not detect superiority of urban habitats over rural ones. This indicates that exploitation of a habitat by cormorants is less explicable by the potential food richness. Our field survey revealed that more urbanized habitats provided more frequent contacts with pedestrians who were indifferent to wildlife, potentially allowing cormorants' habituation to humans. The degree of tolerance to human-associated disturbances in cormorants was measured using flight-initiation distance (FID) defined as a distance at which an individual animal moves away from an approaching human. Urban cormorants showed shorter FID than those in the rural habitats suggesting that reduced threshold of risk-avoidance against approaching humans could be implicated in the increase in foraging opportunities. Our results suggest that recent urban environments are selectively advantageous for cormorants as new habitats.

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A Stochastic Impulse Control Model for Population Management of Fish-Eating Bird Phalacrocorax Carbo and Its Numerical Computation

Yaegashi

Yoshioka

Unami

et al. 2018

Communications in Computer and Information Science

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Immigration of the common cormorant Phalacrocorax carbo hanedae into inland areas of the northern part of Nagano Prefecture, eastern Japan, inferred from stable isotopes of carbon, nitrogen and sulphur

Cited by 9 publications

References 35 publications

The seasonal trophic link between Great Cormorant Phalacrocorax carbo and ayu Plecoglossus altivelis altivelis reared for mass release

The seasonal trophic link between Great Cormorant Phalacrocorax carbo and ayu Plecoglossus altivelis altivelis reared for mass release

Differing Wariness for Approaching Humans among Cormorant Migrants Advancing into Rural or Urban Habitats

A Stochastic Impulse Control Model for Population Management of Fish-Eating Bird Phalacrocorax Carbo and Its Numerical Computation

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