Great Cormorant Phalacrocorax Carbo Research Articles

Intraspecific kleptoparasitism in flock-fishing Great Crested Grebes (Podiceps cristatus) and Great Cormorants (Phalacrocorax carbo) – a cost to participants?

Abstract Intraspecific kleptoparasitism was studied in flock-fishing Great Crested Grebes Podiceps cristatus during May and June 2011 and in Great Cormorants Phalacrocorax carbo during September 2011 and August 2012 at Lake Krankesjön, South Sweden, for a total of c.11 h for grebes and c.6 h for cormorants. Only attempts to steal large fish (relative to a bird’s gape) were recorded, because small fish mostly did not elicit kleptoparasitic attempts and those seen appeared never to be successful. Attempts to steal large fish were rare, 0.14 h-1 grebe-1 (N = 96) and 0.39 h-1 cormorant-1 (N = 163). In both species, the host lost its fish in about 20% of cases. Based on the observed low parasitism and success rates, it is concluded that kleptoparasitism was a minor cost of participating in flock-fishing

Effects of a large northern European no‐take zone on flatfish populationsa

In March 2006, a 360 km² no-take zone (NTZ) was established north of Gotland in the central Baltic Sea, with the purpose to scientifically evaluate the effects of a fishing ban on flatfish populations. A monitoring programme was set up to study the populations in the NTZ and in a reference area east of Gotland where the fishing pressure was high. The programme included fishing with multimesh survey nets, modelling of potential larval export and estimation of fish consumption by large marine predators. Overall, the results showed a clear positive effect of the NTZ on turbot Scophthalmus maximus, with higher densities in the closed area compared with the fished area and also higher densities after closure compared with before. The NTZ also had older individuals and a more even sex ratio. This, in combination with a high potential for larval export from the NTZ to Gotland, shows that the marine reserve may be important for maintaining a viable S. maximus stock at Gotland. Also, for flounder Platichthys flesus, the densities were higher in the NTZ compared to the reference area and there was a net larval export to the fished area. For both species, density-dependent growth was evident, with a lower length at age in the closed area. Potential predation by grey seal Halichoerus grypus and great cormorant Phalacrocorax carbo sinesis on flatfishes, that could hamper the evaluation of the marine reserve, was also addressed. Taken together, the results show that there are clear benefits of the fishing ban for both flatfish species within the NTZ, while the net effects on fisheries are difficult to quantify.

Discussing implications of fast depleting rural ponds on the globally threatened wetland winter migratory bird in Haryana: a Case Study of Nigdu village pond in Karnal District

The Nigdu-Sarovar is located in Nilokheri block in Karnal district in Haryana (29°50°N, 76°55°E). The duration of observations span over seven years (September, 2005 to March, 2012). The recording of wetland winter visitor birds during 2005-08 in winter season included atleast 58 species of birds belonging to 10 orders and 18 families. It is important to mention that 29 species of wetland birds were winter migratory, 17 residents, 9 local migratory and three species of wetland birds like Lesser-whistling Duck Dendrocygna javanica, Pheasant-tailed Jacana Hydrophasianus chirurgus and Blue-cheeked Bee-eater Merops persicus were summer migratory. The special features of 2005-06 winter was the huge populations of birds like Northern Shoveller Anas clypeata, Northern Pintail Anas acuta, Common Teal Anas crecca, Spot-billed Duck Anas poecilorhynchus, Common Pochard Aythya ferina, Bar-headed Goose Anser indicus, Greylag Goose Anser anser, Gadwall Anas strepera, Great Cormorant Phalacrocorax carbo, Mallard Anas platyrhynchos and Common Redshank Tringa totanus etc.In successive years, the scenario was more or less a substantial one depicting stability with respect to diversity of birds, number of birds upto the year of 2008. The popular birds included Painted Stork Mycteria leucocephala, Openbill Stork Anastomus oscitans, White-necked Stork Ciconia episcopus, Black-necked Stork Ephippiorhynchus asiaticus, Eurasian Spoonbill Platalea leucorodia, Spotted Greenshank Tringa guttifer and Kentish Plover Charadrius alexandrines. The sharp decline in winter migratory birds at Nigdu-Sarovar started in the year of 2008 when the pond was leased out for FISH-FARMING as per the policies of Govt. of Haryana. Fish Farming based deepening of the pond by excavation of bottom resulting in total decimation of rooted, floating, submerged and ejecting plants along with its subsidiary fauna, Zooplanktons, phytoplankton etc. The age old structural regime of the pond was obliterated to turn it in a scientifically managed fish pond. The year of 2009-10, 2010-11 and 2011-12 (March, 2012) showed the total absence of migratory birds like Mallards, several Geese, Dabbling Ducks, Pochards and Teals etc. As of today (2012), the sarovar is a clean sheet of water with bird repelling devices installed in places.

DIET AND GROWTH OF GREAT CORMORANT (PHALACROCORAX CARBO) NESTLINGS IN A MEDITERRANEAN ESTUARINE ENVIRONMENT (AXIOS DELTA, GREECE)

ABSTRACT The diet and growth of great cormorant (Phalacrocorax carbo) nestlings were studied in the Axios Delta, Greece in 1993 and 1994. The diet, based on analyses of regurgitations, consisted of fish from 12 families. In both years, the dominant prey were the goby Gobius jozo and mullets (Mugilidae). There were changes in number and wet-biomass prey composition during the study, probably due to the opportunistic foraging behavior of the birds. Most prey occurred in aquatic environments at all salinity levels, consisted mainly of benthic fish, and had no particular economic value. The growth of great cormorant nestlings was analyzed using a modification of the method proposed by Ricklefs and White (1975). Sets of estimated values for all variables studied (tarsus, bill, bill+head, and weight) plotted against age yielded sigmoidal curves. The increase in all growth variables over time was best described by the logistic equation. Body weight and tarsus increased at similar rates, and were faster than thos...

Is it always beneficial to breed in the centre? Trade-offs in nest site selection within the colony of a tree-nesting waterbird

In most of colonial avian species, central parts of the colonies offer higher safety in terms of predatory pressure. However, in heterogeneous habitats, nest sites of high physical quality are likely to offer effective protection against predators or adverse weather conditions regardless of their location within the colony. The aim of this paper was to investigate whether nest site selection in a tree-nesting waterbird, the Great Cormorant Phalacrocorax carbo sinensis, depends on the within-colony location of sites, their physical quality or a combination of these components. The study was conducted during 2010–2011 in a cormorant colony in central Poland. We found that early-breeding individuals preferred nest sites in the central parts of the colony and located high off the ground. The high quality of pairs nesting in these locations was confirmed with good body condition of nestlings, measured by their body masses and plasma concentrations of glucose and urea. A similar spatial pattern was found for the daily nest survival rate and reproductive success. It was found that the central nesting sites associated with high nesting densities were better protected against predators, while the physical quality of nesting sites determined the probability of nest collapse before the conclusion of breeding activities. The two-way process of assessing nest site attractiveness (nest site location vs. physical quality) suggests that, under the limitation of the most attractive nesting sites (good-quality central sites), tree-nesting waterbirds may trade central nesting locations for the high-quality sites at the peripheries of the colony.

Further studies on Contracaecum spasskii Mozgovoi, 1950 and C. rudolphii Hartwich, 1964 (sensu lato) (Ascaridida: Anisakidae) from piscivorous birds in China

Contracaecum spasskii Mozgovoi, 1950, collected from the great crested grebe Podiceps cristatus (Linnaeus) (Podicipediformes: Podicipedidae), is redescribed using both light and, for the first time, scanning electron microscopy. Contracaecum spasskii differs from its congeners by having marked transverse cuticular annulations, the length of the oesophagus and spicules, the ratio between the intestinal caecum and the ventricular appendix, the number and arrangement of male caudal papillae, and especially by the particular morphology of the lips and interlabia. Some previously unreported morphological features of C. spasskii are also revealed and others corrected. Contracaecum rudolphii Hartwich, 1964 (sensu lato) is also redescribed based on the specimens collected from the great cormorant Phalacrocorax carbo sinensis (Blumenbach) (Pelecaniformes: Phalacrocoracidae) from China. Based on the geographical perspective, the present Chinese material may represent the species C. rudolphii B.

Energetic constraints may limit the capacity of visually guided predators to respond to Arctic warming

AbstractFor many polar species, climate change is likely to result in range contractions and negative population trends. For those species whose distribution is limited by sea ice and cold water, however, polar warming could result in population increases and range expansion. Population increases of great cormorants Phalacrocorax carbo in Greenland are associated with warmer sea surface temperatures, but the actual impact of environmental change on cormorant spatial ecology remains unclear. In the present study, we investigate how Arctic warming is likely to influence the distribution of cormorants in Greenland. Using geolocation data, we show that many individuals that breed above the Arctic Circle migrate south and winter at lower latitude. We then couple estimates of migratory flight costs with a model that predicts daily energy expenditure during winter on the basis of water temperature, ambient illumination during diving, dive depth and day length. This model shows that the most energy efficient strategy predicted for any breeding location is to migrate as far south as possible, and that, for a given wintering location, it is more energetically expensive to breed at high latitude. We argue that cormorants currently undertake a winter migration to escape the polar night and reduce winter energy costs and that their wintering grounds in Greenland will remain largely unchanged under Arctic warming. This is because low levels of ambient illumination during the polar night will continue to restrict foraging opportunities at high latitude during winter. Northward expansion of the breeding range will result in increased energy expenditure associated with long migratory flights, and the cost of such flights may ultimately limit the breeding range of cormorants. Such limitations are likely to represent a general constraint on the capacity of visually guided predators to respond to climate warming, and may limit the predicted poleward range shifts of these species.

Diet of Phalacrocorax carbo sinensis (Aves, Phalacrocoracidae) and impact on fish stocks: a study case in Cabras and Mistras lagoons (Sardinia, Italy).

1 - The work aims to study the feeding habits of Phalacrocorax carbo sinensis wintering in the Cabras and Mistras lagoons and to assess the impact of the cormorants colony on fish stocks. 2 - 438 bird flocks of Great Cormorant (Phalacrocorax carbo sinensis) wintering in the Cabras and Mistras lagoons (central-western Sardinia) (SPA ITB034008 and ITB034006 respectively) were analysed. 3 - Through the morphological analysis of undigested hard body parts, such as otoliths, it was possible to trace to the preyed species and their biomass and, then, to the average daily consumption of cormorants. 4 - The trophic spectrum was dominated almost exclusively by euryhaline, gregarious fish species. Mugilidae, and particularly Liza ramada with a percentage index of relative importance (%IRI) of 75.28 and L. saliens (%IRI = 17.78) were the most important preys, while Dicentrarchus labrax (%IRI = 3.53) was of secondary importance. Other species, as Diplodus vulgaris (%IRI = 0.06), Sparus aurata (%IRI = 0.01), Solea solea (%IRI = 0.04) and Anguilla anguilla (%IRI = 0.01), completed the diet. 5 - The Daily Food Intake (DFI) was estimated in 478.4 ± 18 g/day. The overall amount of biomass preyed by the cormorants during the entire wintering season was calculated in about 422 tons. Considering the Cabras lagoon area, it was possible to estimate an amount of fish taken equal to 189.4 Kg/ha during the same period.

Input of seabird-derived nitrogen into rice-paddy fields near a breeding/roosting colony of the Great Cormorant (Phalacrocorax carbo), and its effects on wild grass

Terrestrial ecosystems near breeding/roosting colonies of piscivorous seabirds can receive a large amount of marine-derived N in the form of bird feces. It has been well demonstrated that N input from seabirds strongly affects plant communities in forests or coastal grasslands. The effects of nutrient input on plant communities in agricultural ecosystems near seabird colonies, however, have rarely been evaluated. This relationship was examined in rice-paddy fields irrigated by a pond system located near a colony of the Great Cormorant Phalacrocorax carbo in Aichi, central Japan. In the present study, spatial variations in N content (N %) and N stable isotope composition (δ15N) of soils and wild grass species together with the growth height of plants in paddy fields in early spring (fallow period) were examined. Soils had a higher N % and δ15N values in fields associated with an irrigation pond that had N input from cormorants. The δ15N values tended to be higher around the inlet of irrigation waters, relative to the outlet. These results indicate that cormorant-derived N was input into the paddy fields via the irrigation systems. Plants growing in soil with higher δ15N had higher δ15N in the above-ground part of the plants and had luxurious growth. A positive correlation in plant height and δ15N of NO3–N was observed in soil plough horizons.

Postnatal growth of the great cormorant Phalacrocorax carbo sinensis (Aves: Phalacrocoracidae) in northeastern Mediterranean wetlands

Postnatal growth of nestling great cormorants Phalacrocorax carbo sinensis was studied at two northeastern Mediterranean wetlands, the Lakes Kerkini and Mikri Prespa, northern Greece. A method for constructing growth curves from only two visits to bird colonies was used. Logistic growth parameters re-calculated from the logarithmic equation fitted well to the actual growth data of initial-final measurements of body mass, bill length, bill + head length, and tarsus length. Growth rates (K) did not significantly differ between colonies for all variables: body mass (0.205 and 0.206 day−1 at Lakes Kerkini and Mikri Prespa respectively), bill length (0.131 and 0.147 day−1), bill + head length (0.109 and 0.121 day−1) and tarsus length (0.201 and 0.215 day−1). Asymptotic values (A) did not significantly differ between colonies for body mass (2126.7 g and 2128.95 g) and bill length (70.57 and 68.83 mm) but did so for bill + head (147.89 and 151.51 mm) and tarsus length (75.42 and 71.31 mm). The inflection point (T) was similar for body mass (16.6 and 16.4 days) and tarsus length (7.9 and 7.1 days) but significantly different for bill (13 and 11.2 days) and bill + head length (12.2 and 11.1 days). Climatic conditions and food availability were not considered as factors greatly affecting the observed intercolony variation, and therefore other proximate and ultimate factors should be further examined. The proposed method is very helpful because growth curves can be constructed with the allocation of the smallest amount of time and effort, while at the same time keeping the disturbance of vulnerable breeding avian populations to the minimum level. Furthermore, and provided that other factors are controlled, this method could be used for the monitoring of the influence of spatial and temporal variation of ecological conditions on nestling growth.

Natural born indicators: Great cormorant Phalacrocorax carbo (Aves: Phalacrocoracidae) as monitors of river discharge influence on estuarine ichthyofauna

The ecological traits of piscivorous marine birds have been acknowledged to reflect ecosystem changes. We used the great cormorant as our indicator species in the Minho estuary (NW-Iberian Peninsula, Europe) to assess the temporal variation of their diet and the factors that could influence that variation. Pellets were collected in a night roost, located centrally in the estuary, during two consecutive wintering periods (2005–2006 and 2006–2007). The great cormorant population showed a high degree of feeding plasticity and most of the variation in cormorants' diet was attributed to river discharge fluctuations. Overall, during periods of increased river discharge, marine and marine opportunistic species disappeared from diet, whereas freshwater species increased. The cormorants in this study were using a roost in the middle of the estuary, so they were facing a changing food base over time, in accordance to variation in river discharges. The birds did not keep their diet constant but rather took what became locally available, notwithstanding their broad foraging range. Therefore, we suggest that great cormorants may be considered good samplers of local ichthyofauna and thus, temporal variation in the local prey can be followed by analyzing cormorants' diet.

Distribution of pair quality in a tree-nesting waterbird colony: central-periphery model vs. satellite model

The spatial distribution of pair quality within waterbird colonies has been suggested to follow one of three theoretical models: central-periphery, satellite, or random. The central-periphery pattern occurs in homogeneous habitats, where good-quality pairs occupy better protected, central nesting sites. In contrast, the satellite and random patterns are associated with heterogeneous habitats and they assume that good-quality pairs occupy the most attractive nesting sites irrespectively of their location within the colony. Spatial patterns of laying date, clutch size, and fledging success were analysed with geostatistical tools in the colony of tree-nesting subspecies of Great Cormorant ( Phalacrocorax carbo sinensis (Blumenbach, 1798)) in central Poland. There was support for the random or satellite model in the distribution of clutch size, which was considered a reliable proxy of pair quality. We also found a positive correlation of clutch size with nest height. These results implicate that the habitat of tree-nesting colonial waterbirds may produce sufficient variation in the nesting-site quality to disrupt the central-periphery gradients of pair-quality distribution. In contrast, distribution of fledging success within the colony followed a clear central-periphery pattern, which was suggested to reflect an increased predation rate at the edges of the colony, rather than the intrinsic quality of breeding birds.

Breeding Biology of the Great Cormorant Phalacrocorax carbo sinensis in Southern Coasts of The Caspian Sea, Iran

Breeding biology of the Great Cormorants Phalacrocorax carbo sinensis is assessed in thesouthern coasts of the Caspian Sea, Iran during the years 2008-2010. About 84 nests located on 63 trees wereexamined. Nests were built on large trees located in Abbas abad marsh, Gilan Province. Initially, eggs werefound on first week of April and egg laying continued until the last week of May. Clutch size varied from 2 to5 eggs, with a mean clutch size of 2.8±0.69. Mean shape index for all eggs were 1.68±0.035 and 1.706±0.048,respectively. The length of the incubation period was estimated at 26.6±2.2 days. in 2010 of the 84 eggs laid,26.6% were lost. In 2009 of 92 eggs laid, 62% were lost. Number of eggs hatched per nest averaged at1.57±0.57 in small ones and 1.8±1.6 in large nest. Mean weight of eggs was estimated at 46.8±1.28g (N=10,mean =48.9, min=45.2).

О НОВОЙ КРУПНОЙ СМЕШАННОЙ КОЛОНИИ БОЛЬШОГО БАКЛАНА PHALACROCORAX CARBO (LINNAEUS, 1758) И СЕРОЙ ЦАПЛИ ARDEA CINEREA LINNAEUS, 1758 В ОКРЕСТНОСТЯХ ГОРОДА ХАБАРОВСКА

The data on a new big mixed colony of the Great Cormorant Phalacrocorax carbo (Linnaeus, 1758) and the Grey Heron Ardea cinerea Linnaeus, 1758 in the Amur River Basin near the City of Khabarovsk are presented.

Establishment of a stable local population of Great Cormorants Phalacrocorax carbo in Hyogo Prefecture

Establishment of a stable local population of Great Cormorants Phalacrocorax carbo in Hyogo Prefecture

Long-term attachment of GPS loggers with tape on Great Cormorant Phalacrocorax carbo sinensis proved unsuitable from tests on a captive bird

In preparation for a field study on wild birds, we conducted an experiment on captive Great Cormorants Phalacrocorax carbo sinensis to evaluate methods of attaching GPS loggers. Loggers (65 g) were attached to two injured cormorants in a bird rehabilitation centre. One logger was attached to the first bird with TESA tape and another logger to the second bird with a teflon harness. The taped logger was attached on the lower back, and subsequently on the upper back and the tail. This logger was removed within 10 (lower back), 4 (upper back) and 15 (tail) days by the cormorant biting off and pulling out the feathers to which it was attached. The logger deployed with the teflon harness on the second bird stayed on for 21 days, after which we removed it undamaged.

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

The stable isotopes of nitrogen (δ15N) and carbon (δ13C) were analysed in the feathers of the Great Cormorant (Phalacrocorax carbo), Grey Heron (Ardea cinerea) and Long-tailed Duck (Clangula hyemalis) staying in the different seasons at the Lithuanian Baltic Sea coast. Stable isotope ratios in bird feathers represented dietary variations and foraging habitats during the feather growth period. Adult Great Cormorants fed juveniles by smaller fish at the beginning of fledging, switching later to larger prey. The stable isotope analysis indicated that the Grey Heron diet did not change significantly during the fledging period of their juveniles. The calculated trophic levels of Great Cormorants and Grey Herons were similar (3.55 ± 0.12 and 3.57 ± 0.41, respectively). The isotopic values in Grey Herons and Great Cormorants were 14.6–16.0‰ for δ15N and –27.3–(–24.9)‰ for δ13C. These values are typical of piscivorous bird species mostly feeding in freshwater bodies, i. e. in the Curonian Lagoon. The δ15N values found in the feathers of Long-tailed Ducks ranged from 7.7 to 13.9‰ and the δ13C values ranged from –33.6 to –24.9‰ showing high variation of feeding habitats during the moulting period: from freshwater to marine environment.

Seasonal Decline of Investment in Egg Production with Increasing Food Abundance on the Great Cormorant in a Riverfront Colony

Abstract To understand seasonal declines of investment in egg production, we studied the relationships among laying date, clutch, and egg sizes in a Great Cormorant Phalacrocorax carbo population. Seasonal changes in the amount and number of fish caught per casting net were used as an index of food abundance for Great Cormorants. Clutch size and egg volume were positively correlated and decreased as the breeding season progressed. Clutch volume (i.e. total egg volume within clutches) was explained by clutch size and laying date. However, the amount and number of fish caught per casting net increased through the season. We conclude that the observed seasonal decline in egg production investment was not a result of declining food abundance during the breeding season in Great Cormorant. The amount of egg investment appeared to depend on the fishing ability of the individual rather than fish availability during the breeding season. Early in the breeding season, only those individuals with strong fishing abili...

Scoring of the extent and intensity of carp (Cyprinus carpio) skin changes made by cormorants (Phalacrocorax carbo sinensis): relationship between morphometric and histological indices

Cormorants cause damage to fish in aquaculture not only by consuming large number of fish but also by wounding them. Quantification of the actual damage in fish induced by wounding is important for reliable estimations of the overall loss in aquaculture caused by cormorants. In this study, specimens of mirror and scaly carp (Cyprinus carpio L.) injured by attacks of great cormorant (Phalacrocorax carbo L.) were collected from the “Ecka” fish farm in Serbia. Surfaces of superficial and open subepithelial wounds (expressed as a percent of the total body surface), estimated by computer-assisted image analysis, had mean values 10.66 ± 1.86 and 0.85 ± 0.90, respectively. Histological evaluation of wounds was performed by two scoring systems: system proposed by Bernet et al. (J Fish Dis 22:25–34, 1999) and modified system described by Wahli et al. (Aquaculture 225:371–386, 2003). The most frequent histopathological changes were disturbed epidermal structure and surface cell morphology and increased number of club cells (on more than 75% of specimens); increased number of melanocytes and their distribution in different layers in dermis; and enlarged hypodermis (more than 80% of samples) and myolysis (50% of samples). Comparison of wounds’ surfaces (surface of superficial injures) and histopathological changes, estimated by two scoring systems, revealed significant positive correlation. Bernet’s scoring system showed higher correlation coefficients, when compared with the modified Wahli’s scoring system.

Seasonal Shifts in Diet Composition of Great CormorantsPhalacrocorax carbo sinensisforaging at a Shallow Eutrophic Inland Lake

The diet of Great Cormorants Phalacrocorax carbo sinensis at Lake Dummer, a shallow eutrophic lake of 1240 ha in Lower Saxony (Germany) was analysed by collecting 562 regurgitated pellets over a period of one year. Pellets contained structures of 10,645 fishes belonging to 15 species. Substantial differences were found in frequency, composition and size of prey fish species. Pikeperch, Ruffe, Roach and Perch accounted for the largest seasonal differences in the diet. During late autumn and winter the diet was dominated by small-sized cyprinids and Ruffe. In spring Great Cormorants primarily foraged on larger-sized cyprinids. Young-of-the-year percids, dominated by Pikeperch, were the primary prey during summer. We estimated that at least 32.6 tons (26.3 kg/ha) of total fish biomass was removed by Cormorants, of which one third (10.8 tons) consisted of Pikeperch. 81% of the Pikeperch biomass was removed in August—September, indicating that the Great Cormorant is an important predator of juvenile Pikeperch ...