Fish are not safe from great cormorants in turbid water

Grémillet, David; Nazirides, T.; Nikolaou, Harris; Crivellì, Alain J.

doi:10.3354/ab00430

Cited by 17 publications

(8 citation statements)

References 24 publications

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“…Luminosity levels would be even lower than the ones reported here from a 57 m depth dive if we consider that male Imperial cormorants dive up to 100 m depth [ 60 ]. Thus, even though we found no evidence of Imperial cormorants locating prey by touch, in agreement with previous studies [ 25 , 58 , 59 ] we believe these animals would locate prey with other sensory systems in addition to sight, especially on their deepest dives.…”

Section: Discussionsupporting

confidence: 92%

“…Cormorants´poor visual acuity is further reduced under low light conditions [ 46 ]. Several authors have proposed that in turbid and dark water environments, cormorants must employ tactile and/or acoustic foraging strategies [ 26 , 58 , 59 ]. Although we did not measure light, our data revealed that while foraging along the seafloor cormorants frequently visit low luminosity environments.…”

Section: Discussionmentioning

confidence: 99%

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Selfies of Imperial Cormorants (Phalacrocorax atriceps): What Is Happening Underwater?

et al. 2015

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During the last few years, the development of animal-borne still cameras and video recorders has enabled researchers to observe what a wild animal sees in the field. In the present study, we deployed miniaturized video recorders to investigate the underwater foraging behavior of Imperial cormorants (Phalacrocorax atriceps). Video footage was obtained from 12 animals and 49 dives comprising a total of 8.1 h of foraging data. Video information revealed that Imperial cormorants are almost exclusively benthic feeders. While foraging along the seafloor, animals did not necessarily keep their body horizontal but inclined it downwards. The head of the instrumented animal was always visible in the videos and in the majority of the dives it was moved constantly forward and backward by extending and contracting the neck while travelling on the seafloor. Animals detected prey at very short distances, performed quick capture attempts and spent the majority of their time on the seafloor searching for prey. Cormorants foraged at three different sea bottom habitats and the way in which they searched for food differed between habitats. Dives were frequently performed under low luminosity levels suggesting that cormorants would locate prey with other sensory systems in addition to sight. Our video data support the idea that Imperial cormorants’ efficient hunting involves the use of specialized foraging techniques to compensate for their poor underwater vision.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Selfies of Imperial Cormorants (Phalacrocorax atriceps): What Is Happening Underwater?

et al. 2015

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“…Where grayling are common, they comprise a substantial portion of the cormorant's diet but grayling larger than 40 cm are rarely taken (Keller, ; Suter, ; Marquiss et al ., ). Cormorants remain efficient predators even during turbid water conditions (Grémillet et al ., ). In this study, water turbidity in winter and spring were significantly higher than in summer.…”

Section: Discussionmentioning

confidence: 97%

Fish in space: local variations of home range and habitat use of a stream‐dwelling fish in relation to predator density

Lucas

Bubb

2014

Journal of Zoology

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A key response of animals to local environmental variation is altered use of space, but studies simultaneously examining local variation in habitat use and space use are uncommon. We predicted that elevated abundance of avian predators would result in grayling Thymallus thymallus, a stream‐dwelling fish, using mesohabitats containing more cover, superimposed on seasonal changes in use of key resources (and hence space use) for functions such as reproduction. Using radio‐telemetry, the pattern of space and habitat use by 40 wild grayling was determined in neighbouring stream sections in relation to season and predator density. Grayling used different habitats between seasons, but displayed similar patterns of habitat use in adjacent sections. Although patterns of habitat use were stable between stream sections, space use was not. In two winter periods, grayling ranged significantly more widely where there were significantly greater densities of avian predators, especially cormorant, Phalacrocorax carbo. No such differences were apparent in summer when cormorants were absent, but experimental manipulation of predator densities was not possible, so results are correlative. Support for a predator effect is provided from significantly greater rates of injury, associated with avian beak scar marks, present on grayling from the section with highest avian predator densities, compared with adjacent sections with lower levels of avian predators. Unlike many studies of fish behaviour to elevated predation risk, in which fish make greater use of ‘refuge’ habitat, grayling exhibited wide‐ranging behaviour and high activity, possibly reflecting avoidance behaviour.

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“…Cormorants, Phalacrocorax spp., and their mode of visual predation present an example of sensory pathways interrupted by degradation of cue/signal transmission ( Figure 1A). Highly efficient piscivores, cormorants use vision to find their underwater prey (Gremillet et al, 2012). Increased precipitation, an aspect of global change (IPCC, 2013), will lead to increased freshwater runoff as well as nutrient and sediment loads in the nearshore environment.…”

Section: Changes In the Environment Can Affect Properties Of The Cue/mentioning

confidence: 99%

“…Indeed, under increasingly turbid water, the distance at which a great cormorant, Phalacrocorax carbo sinensis, reacts to the presence of its prey declines exponentially (Strod et al, 2008). Although it is possible that P. carbo sinensis will switch to a tactile-based foraging method as visual cues/signals are degraded by environmental conditions (White et al, 2007;Gremillet et al, 2012), deterioration of visual cues will likely have significant implications for predator-prey interactions.…”

Section: Changes In the Environment Can Affect Properties Of The Cue/mentioning

confidence: 99%

Mechanisms Involving Sensory Pathway Steps Inform Impacts of Global Climate Change on Ecological Processes

Rivest

Jellison

et al. 2019

Front. Mar. Sci.

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Fish are not safe from great cormorants in turbid water

Cited by 17 publications

References 24 publications

Selfies of Imperial Cormorants (Phalacrocorax atriceps): What Is Happening Underwater?

Selfies of Imperial Cormorants (Phalacrocorax atriceps): What Is Happening Underwater?

Fish in space: local variations of home range and habitat use of a stream‐dwelling fish in relation to predator density

Mechanisms Involving Sensory Pathway Steps Inform Impacts of Global Climate Change on Ecological Processes

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