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

  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},
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.

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.

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.

Cormorant diet in relation to temporal changes in fish communities

The stomach contents of 229 great cormorants shot between March and October 2009 along the Swedish east coast were analysed for differences in diet between gender, age, and breeding phase, suggesting no major shift in diet over the breeding season.

Fish Predation by the Great Cormorant (Phalacrocorax carbo sinensis)

The diet of a piscivorus top predator, the Great Cormorant (Phalacrocorax carbo sinensis), in the Baltic Sea is examined at two coastal locations, in the Bothnian Sea and in theBaltic Proper, to enable evaluation of its uses and applications.

Natural Regulation of the Baltic Population of the Great Cormorant Phalacrocorax carbo sinensis: The Interplay between Winter Severity and Density Dependence

After a period of continuous increase and range expansion, the Baltic Great Cormorant population has stabilised in large parts of its range in recent years. Ringing recoveries reveal that

Do Cormorants and Recreational Anglers Take Fish of the Same Species and Sizes?

The Great Cormorant Phalacrocorax carbo is a widespread piscivorous waterbird. The competition for resources between recreational anglers and Cormorants has been causing serious conflicts between



Annual Variation in Diet of Breeding Great Cormorants: Does it Reflect Varying Recruitment of Gadoids?

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

Differences found in diet between areas are probably due to differences in prey species composition and abundance, and suggests minimal competition with fisheries.

Foraging strategies of Great Cormorants Phalacrocorax carbo carbo wintering north of the Arctic Circle

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

Catch per unit effort, foraging efficiency, and parental investment in breeding great cormorants (Phalacrocorax carbo carbo)

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.

The effect of predation by wintering cormorants Phalacrocorax carbo on grayling Thymallus thymallus and trout (Salmonidae) populations: two case studies from Swiss rivers. Comment

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.

Foraging energetics of arctic cormorants and the evolution of diving birds

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.

Long-term development of fish populations in the Římov Reservoir

The Shannon–Weaver index of diversity increased during the fish community succession, mainly because of greater evenness amongst the species.