Size Selectivity in Summer and Winter Diets of Great Cormorant (Phalacrocorax carbo ): Does it Reflect Season-Dependent Difference in Foraging Efficiency?

@inproceedings{ech2008SizeSI,
  title={Size Selectivity in Summer and Winter Diets of Great Cormorant (Phalacrocorax carbo ): Does it Reflect Season-Dependent Difference in Foraging Efficiency?},
  author={Martin {\vC}ech and Pavel {\vC}ech and Jan Kube{\vc}ka and Marie Prchalov{\'a} and Vladislav Dra{\vs}t{\'i}k},
  year={2008}
}
Abstract Diet of the Great Cormorant (Phalacrocorax carbo) was studied using regurgitated pellets, individual fish bones and fish remains collected from below roosting trees at Želivka and Slapy Reservoirs, Czech Republic, during summer, a warm winter and a cold winter. Both reservoirs have the same trophic status and similar fish assemblages. Using diagnostic bones (os pharyngeum, dentale, praeoperculare) and our own linear regression equations relating dimensions of the diagnostic bone and… 

Seasonal Shifts in Diet Composition of Great Cormorants Phalacrocorax carbo sinensis foraging at a Shallow Eutrophic Inland Lake

The diet of Great Cormorants Phalacrocorax carbo sinensis at Lake Dümmer was analysed by collecting 562 regurgitated pellets over a period of one year, finding substantial differences in frequency, composition and size of prey fish species.

Winter diet of great cormorant (Phalacrocorax carbo) on the River Vltava: estimate of size and species composition and potential for fish stock losses

Most probably, both great cormorants and anglers are responsible for the decrease in catches of brown trout and grayling from the River Vltava in Vyšší Brod.

The great Cormorant (Phalacrocorax carbo) at lower lake Constance/Germany: dietary composition and impact on commercial fisheries

The dietary composition significantly differed between autumn and winter, and fish of high commercial value played a considerable part in the cormorants’ diet.

TOWARDS THE OPTIMAL FORAGING STRATEGY: IS SEASONAL SHIFT IN THE DIET OF CORMORANTS PHALACROCORAX CARBO (L.) IN A DAM RESERVOIR THE EFFECT OF WATER TEMPERATURE OR SIZE PATTERN IN FISH ASSEMBLAGES?

The study on Cormorant diet and the species composition of prey fish as- semblages in the Dobczyce Reservoir in spring and in autumn showed differences in the food composition and the prey size affected by seasonal changes in fish availability.

Change of foraging behavior of cormorants and the effect on river fish

Results from studies using radio-telemetry, PIT-tagging, and traditional fish surveys to estimate the impact of predation in Danish lowland rivers suggest predation from cormorants appears to be at a level that explains the observed collapse of grayling and brown trout populations in many Danish streams.

Change of foraging behavior of cormorants and the effect on river fish

Since the European population of great cormorants (Phalacrocorax carbo sinensis) rapidly increased 30 years ago, Denmark has been one of the core breeding areas for this colonial water bird.

Great Cormorants Phalacrocorax carbo feed on larger fish in late winter

Fisheries management should reflect on the fact that competition for larger-sized fish is the highest in late winter and in early spring, and stocking of potentially vulnerable fish could be delayed to the time when overwintering birds leave the area and recreational fishing could be restricted in latewinter.

Selective predators or choosy fishermen? Relation between fish harvest, prey availability and great cormorant (Phalacrocorax carbo sinensis) diet

It is concluded that potential effects of cormorants on commercially important fish will mainly depend on habitat type (fish ponds, natural deep lakes, others), and that in the natural lakes in Lombardy c Cormorants mainly concentrate on species which are of limited value for commercial fishing.

Trophic peculiarities of the Great Cormorant, Grey Heron and Long-tailed Duck on the Baltic Sea Lithuanian coast: a stable isotope approach

The stable isotope analysis indicated that the Grey Heron diet did not change significantly during the fledging period of their juveniles, and the calculated trophic levels of Great Cormorants and Grey Herons were similar.

Differences in the diet of breeding Cormorants Phalacrocorax carbo sinensis in an inland colony: the effect of years, breeding stages and locations within the colony

The impact of Great Cormorants on native fish assemblages may be dependent on the location within the colony, development state of the chicks and season, not just fish availability.

References

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The decrease in Cod in the diet of the Great Cormorant most probably reflected the decrease in the Norwegian coastal Cod population, and the increase in Saithe in the diets is related to the relative increase in the abundance of this fish prey asThe abundance of Cod decreased.

Roach rules: shoaling fish are a constant factor in the diet of Cormorants Phalacrocorax carbo in Switzerland

The spatial and temporal variation in the diet of Cormorants Phalacrocorax carbo visiting Switzerland in the non-breeding season was studied, by means of regurgitated pellets and stomach contents, to find a preference for eutrophic lakes that support high densities of Roach and Perch.

Spatial Patterns of Winter Diet of the Great Cormorant in Coastal Wetlands of Greece

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This study describes how 30 Great Cormorants Phalacrocorax carbo carbo managed to catch sufficient food for their daily energetic needs under conditions of reduced daylight and cold while wintering

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Parents responded to increasing food requirements of the brood by increasing the number of foraging trips per day, but maintained constant foraging effort, load size and catch per unit effort, showing that birds do not tend to visit distant foraging areas to compensate for prey stock depletion around the breeding site.

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The effect of cormorant predation on one trout and two grayling populations was examined in two rivers in north-eastern Switzerland, the only sites in the country at present where both bird and fish data are sufficient for such an analysis, and no evidence was found to support predictions of a negative effect on fish population dynamics by c Cormorants.

Long term effects of cormorant predation on fish communities and fishery in a freshwater lake

Monitoring of fish community composition/abundance before and after a cormorant colony was established in a high productive lake, Ymsen, of south-central Sweden indicates that c Cormorant impact upon fish populations in Lake YMSen was small and probably in no case has led to declines of neither commercial nor of non-commercial fish species.

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It is postulate that similar behavioural patterns allowed early diving birds (Cretaceous) to colonize cold coastal areas before they evolved efficient insulation, and this concept is challenged by comparing the bioenergetics of cormorants living in temperate and arctic conditions.

Distribution and diel vertical migration of Eurasian perch (Perca fluviatilis L.) during winter

The distribution and migration patterns of overwintering perch were studied by hydroacoustics and gill netting in Lake Constance, central Europe. In autumn, perch left the littoral and moved to