Several studies have applied induced regurgitations to characterize the diet of cormorants, but none have presented quantitative information indicating complete stomach contents were obtained. Our ...goal was to test the value of induced regurgitations for the assessment and monitoring of Imperial Cormorant (Phalacrocorax atriceps) diet. Stomach samples were obtained from male and female breeding adults bringing food back to the colony during the chick rearing stage (n = 22) at Isla Arce, Argentina. Samples were obtained through induced regurgitation, and immediately afterward each individual was flushed with sea water. The diet of the Imperial Cormorant consisted of at least 23 prey taxa, mostly fish complemented by crustaceans, cephalopods and polychaetes. However, only Argentine anchovy (Engraulis anchoita) and rockcods (Patagonotothen spp.) showed a significant contribution by mass (70.7% and 25.3%, respectively). Analysis of similarity indicated that prey composition between samples obtained by induced regurgitation and those obtained by combining regurgitation followed by stomach flushing were similar in both the numerical frequency of all prey taxa recorded and the contribution by mass of the main prey. Our results show that induced regurgitation provides complete stomach contents, and thus validates the use of this technique for quantifying Imperial Cormorant diet composition.
Ground-nesting Great Cormorants were monitored in three neighbouring colonies at Lake IJsselmeer, The Netherlands. Using aerial photographs taken during peak breeding time, nest density and nearest ...neighbour distance were determined for four sequential years. In addition, species and number of predators were determined. In total, five mammalian and nine avian predatory species were associated with the Cormorant breeding colonies. Spatial distribution of nests mostly showed dispersed and random patterns rather than a contagious pattern. The latter distribution, with less distance between nests than expected both from a random and equal distribution pattern, was found in the colony of De Ven in 2013 during the last year of its existence. The predator Red Fox Vulpes vulpes arrived at the colony in 2010. In all three colonies, nest density was highest and nearest neighbour distance shortest in colonies with the highest number of predators. At low to moderate predatory pressure, ground-nesting Cormorants left free space between nests that was used by adult birds during take-off and landing. During the last years of its existence the shrinking colony of De Ven showed an almost circular shape, with an extreme nest density and the lowest edge-to-surface area ratio. But with Foxes present, breeding at the fringe still caused greater losses due to direct predation. Breeding success fluctuated synchronously between colonies but was lower in colonies where the number of predators was higher. The arrival of Red Foxes in De Ven caused extreme losses of young and over the years resulted in a strong decline in number of breeders, eventually leading to complete abandoning of the site in 2014. Large gulls formed another important group of predators but did not cause the Cormorants to abandon the breeding site. In the Vooroever colony, bush and tree cover supplied shelter and allowed birds to breed in greater density without causing nearest neighbour density to decrease, as was the case when no cover was available. Greater nest density and reduced nearest neighbour distances are considered to be a pro-active response by individual birds to the presence of predators. When predator numbers increased, the within-colony open spaces that normally exist under circumstances of moderate density were filled up with nests, leaving little or no room for landing and departure. This leads to reduced edge effects and a circular shape of the colony, thereby potentially limiting predation risk. As a consequence of extreme high nest densities, breeding success was lower due to interference by other Cormorants. This study is the first to show that colony structure in waterbirds is affected by forces of attraction and repulsion between founding birds that are predator driven.
We report fossils of the darter Anhinga pannonica Lambrecht, 1916 from two late Miocene (Tortonian, 11.62 and 11.44 Ma) avifaunas in Southern Germany. The material from the hominid locality ...Hammerschmiede near Pforzen represents the most comprehensive record of this species and includes most major postcranial elements except for the tarsometatarsus. We furthermore show that the putative cormorant Phalacrocorax brunhuberi (von Ammon, 1918) from the middle Miocene of Regensburg-Dechbetten is another, previously misclassified, record of A. pannonica, and this may also be true for early Miocene fossils described as P. intermedius Milne-Edwards, 1867. A. pannonica was distinctly larger than extant darters and reached the size of A. grandis from the late Miocene of North America. We detail that only fossils from the Miocene of Europe and Africa can be referred to A. pannonica, whereas putative records from Asia fall within the size range of extant darters. A. pannonica appears to have been a long-living species (16 to 6 Ma) with an extensive distribution from the equator to the northern mid-latitudes. The extinction of large-sized darters in Europe is likely to have been due to climatic cooling in the late Neogene, but the reasons for their disappearance in Africa and South America remain elusive.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
An ethogram is a catalogue of discrete behaviors typically employed by a species. Traditionally animal behavior has been recorded by observing study individuals directly. However, this approach is ...difficult, often impossible, in the case of behaviors which occur in remote areas and/or at great depth or altitude. The recent development of increasingly sophisticated, animal-borne data loggers, has started to overcome this problem. Accelerometers are particularly useful in this respect because they can record the dynamic motion of a body in e.g. flight, walking, or swimming. However, classifying behavior using body acceleration characteristics typically requires prior knowledge of the behavior of free-ranging animals. Here, we demonstrate an automated procedure to categorize behavior from body acceleration, together with the release of a user-friendly computer application, "Ethographer". We evaluated its performance using longitudinal acceleration data collected from a foot-propelled diving seabird, the European shag, Phalacrocorax aristotelis. The time series data were converted into a spectrum by continuous wavelet transformation. Then, each second of the spectrum was categorized into one of 20 behavior groups by unsupervised cluster analysis, using k-means methods. The typical behaviors extracted were characterized by the periodicities of body acceleration. Each categorized behavior was assumed to correspond to when the bird was on land, in flight, on the sea surface, diving and so on. The behaviors classified by the procedures accorded well with those independently defined from depth profiles. Because our approach is performed by unsupervised computation of the data, it has the potential to detect previously unknown types of behavior and unknown sequences of some behaviors.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Hansson et al. (2017) concluded that competition between fisheries and piscivorous mammals and birds exists in the Baltic Sea, based on the estimation of biomass of the fish species consumed ...in the ICES subdivisions. We compared their results to the data and scientific knowledge from the coastal waters of Finland and show that local differences in fisheries, fish assemblages and abundance of predators should be taken into account to reliably assess potential competition. Hansson et al. (2017) did not include the piscivorous fish in their analysis, but these may be the most important predators. In the Archipelago Sea, for instance, the consumption by fish predators is considerably larger than that of cormorants.
Since many years now it is rumoured that the inland European cormorant Phalacrocorax carbo sinensis was introduced by Dutchmen from China to Holland in the 16 century to perform cormorant fishing in ...Europe and thus has to be classified an Invasive Alien Species (IAS). Although this hypothesis is not based on scientific evidence it has already been referred to in scientific literature. To check its plausibility, this review confronts three essential aspects of the introduction hypothesis with German sources mainly from the Middle Ages and historical reports on European cormorant fishing. The analyses show that there is no evidence for the introduction of birds from China. Instead, a medieval breeding record as well as regular appearance of the cormorant in religious and secular literature from the Middle Ages show that the bird was at least temporarily well-known in deeper inland regions of the German-speaking area. The results raise strong doubts about the hypothesis of Phalacrocorax carbo sinensis being an introduced alien species. Merimetson sisamaamuodon (Phalacrocorax carbo sinensis) on viime vuosina vaitetty vierasperaiseksi Euroopassa, ja tuoduksi Eurooppaan kalastustarkoituksiin Kiinasta 1500-luvulla Hollantilaisten toimesta. Vaikka vaittama ei ole perustunut tieteelliseen nayttoon, on vierasperaisyys-hypoteesi esiintynyt myos tieteellisessa kirjallisuudessa. Tassa artikkelissa kasitellaan hypoteesin kannalta kolmea keskeista nakokohtaa, perustuen saksankielisiin keskiaikaisiin ja muihin historiallisiin kirjallisuuslahteisiin. Lahteet kasittelevat merimetson kayttoa kalastuksessa Lansi-Euroopassa, seka esiintymista sisamaassa saksankielisessa Keski-Euroopassa. Kirjallisuuskatsauksessa ei loytynyt viitteita sinensis-merimetsojen tuonnista Kiinasta Eurooppaan. Sen sijaan merimetso tunnettiin keskiajalla saksankielisen Keski-Euroopan sisaosissa seka pesimalintuna etta tavallisesti esiintyvana lajina, seka uskonnollisen etta sekularistisen kirjallisuuden perusteella. Tulosten perusteella sinensis-merimetson vierasperaisyys-hypoteesi on vahvasti kyseenalainen.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The coastal waters of southern British Columbia, Canada, encompass habitat of international conservation significance to coastal and marine birds, including sizeable areas designated in the early ...1900s as Migratory Bird Sanctuaries (MBS) to protect overwintering waterfowl from hunting near urban centres. Two of these, Shoal Harbour (SHMBS) and Victoria Harbour (VHMBS), have seen significant marine infrastructure development in recent decades and experience considerable vessel traffic. Vessel-related stressors are known to affect waterbirds, but traffic characteristics in coastal urban areas are poorly understood for the smaller vessels not tracked by Automatic Identification Systems (AIS). We conducted a pilot study using shore-based observers to develop small-vessel baselines for the winter months, when regional waterbird numbers are highest. During our surveys we recorded considerable inter-site variability in vessel traffic characteristics, with one site (SHMBS) a source of nearly twice as many vessel transits as the other (VHMBS). Most recorded vessels were small watercraft (mean length 26 ± 17', mode 18'), and vessels at the high-traffic site were both shorter and faster on average. One in six vessels were classified as 'noisy', of interest given that noise is an important component of vessel disturbance of waterbirds and other marine animals. Few vessels (7% of all recorded) were of the type required to carry AIS transponders, which highlights the monitoring gap created by using AIS-based approaches alone in nearshore waters, and allows for correction of AIS-derived vessel counts. Waterbird community composition also varied by locality, with one site dominated by gulls (Laridae), cormorants (Phalacrocoracidae), and seaducks (Tribe Mergini), and the other by gulls, cormorants, and alcids (Alcidae). Our results demonstrate that fine-scale local variability must be taken into account when managing for vessel traffic disturbance of waterbirds, particularly at sites of high human population density and increasing coastal development.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The anthropause during the recent COVID-19 pandemic provided a unique opportunity to examine the impact of human activity on seabirds. Lockdowns in Peru prevented people from visiting coastal areas, ...thereby reducing garbage disposal on beaches and the movement of microplastics into the ocean. This cessation of activities likely led to a temporary decrease in plastic pollution in coastal regions. We aimed to investigate this phenomenon in inshore-feeding neotropic cormorants (
) along the Circuito de Playas Costa Verde (CPCV), situated on the coastal strip of Lima, Peru (∼ 11 million people).
We collected and analyzed fresh pellets along the CPCV before (over 11 months) and during the pandemic lockdowns (over 8 months).
Our findings revealed a significant reduction in the occurrence of plastic in pellets during the pandemic period (% Oc = 2.47,
= 647 pellets) compared to pre-pandemic conditions (% Oc = 7.13,
= 800 pellets). The most common plastic debris item found in the pellets was threadlike microplastic. Additionally, our study highlights the direct correlation between human presence on beaches and the quantity of microplastics (mainly threadlike) found in cormorant pellets. We suggest that the reintroduction of these materials into the sea, previously accumulated on the coast, is likely facilitated by the movement and activity of beachgoers toward the ocean.
Plasma biochemistries provide a complementary method for assessing physiological and nutritional status of free-ranging wild birds. Triglycerides, total protein and alkaline phosphatase were ...determined in 110 free-living Imperial Cormorant (Phalacrocorax atriceps) chicks aged 16-35 days, at Punta León (Argentina) during 2010 and 2011. Body mass at 30 days of age (“pre-fledging body condition”, 2010 only) and body mass corrected by tarsus length at the time of blood sampling (“current body condition”, 2011 only) were also determined. Variability of parameters by sex, hatching order, survival, age and breeding season was assessed, and the relationship between biochemical and morphometric indices was also explored. Morphometric indices were higher in A-chicks (pre-fledging body condition also varied with sex), and explained 35-55% of B-chick survival. Biochemistries differed significantly between breeding seasons, being higher in 2011. Alkaline phosphatase increased with age, and total protein was higher in A-chicks. Triglycerides and total protein accounted for 26% and 30%, respectively, of variation in current body condition; however, they did not forecast pre-fledging body condition. Lastly, total protein levels predicted B-chick survival (higher levels in surviving B-chicks), but their prognostic value was relatively low. The results suggest that unlike morphometric indices, the biochemistries chosen are valuable to assess individual body condition at the time of sampling, yet their applicability for predicting chick survival requires further evaluation.
We describe species richness of birds, especially North American ardeids, from Crooked Tree Lagoon, northern Belize. We recorded 62 species, 27 families, and 33 species of migrants. The dominant ...species include limpkin (Aramus guarauna), Neotropic cormorant (Nannopterum brasilianum), great egret (Ardea alba), and snail kite (Rostrhamus sociabilis). By macrohabitat, 38 species (61%) are primarily aquatic, 17 (27%) primarily terrestrial, and 7 (11%) transitional. Ardeids are a species-rich family, with 13 of the 16 species of North American herons and egrets represented; the dominant species are great egret and great blue heron (A. herodias). We discuss explanations for the diversity observed, as well as reasons for the absence of three species. This reserve is important not only for ardeids and aquatic species but also many migrant land birds.
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