Unusual pattern of skipped or shortened moulting of flight feathers in late-breeding Common Shelducks

Experimental studies have shown that individual wildfowl can shorten or skip moulting if the time between breeding and wintering is short; however, studies in wild birds are scarce. We tracked nine Common Shelducks Tadorna tadorna during the breeding and moulting seasons and determined the flightless time during moulting based on typical movement patterns. We found different movement patterns for two late-breeding females, suggesting that they skipped or shortened the moult of their flight feathers. These results provide a link between previous experimental studies and the situation in wild birds, likely reflecting an individual trade-off between the times allocated to moulting and breeding, respectively

Marked changes in megafauna composition of the North Sea require multidisciplinary collabrations: an historical overview

Checklist of works in the exhibition "Robert Rauschenberg Prints: Selections from Dallas and Fort Worth Collections," December 21, 1986-March 15, 1987 held at the Dallas Museum of Art

How does a generalist seabird species use its marine habitat? The case of the kelp gull in a coastal upwelling area of the Humboldt Current

Indexación:Scopus.The distribution of kelp gulls (Larus dominicanus) was studied by ship-based transect counts in the SE Pacific Ocean off Chile, South America. Some 96-98% of the kelp gulls were in a band less than 20 km from the coast, mainly near the breeding colony on Pájaros Island and the City of Coquimbo. Abundance did not change significantly among years, but was influenced significantly by distance to land. Principal component analysis yielded two components that jointly explain 53% of the standardized variance. The first (explaining 36% of the variance) includes distance to the nearest coast and water depth, the second (17%) associates with the presence of fishing vessels. The results suggest that the stability of the summer distribution of kelp gulls is generated by the large and semi-permanent offer of food at fish markets and city sewage works, as well as the location of the breeding colonies. Further analysis on other temporal scales (seasonal, decadal) associated with reproductive or non-reproductive changes within the population and/or ENSO cycles will be necessary to confirm the multiscale stability of the pattern described. © 2007 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved.https://academic-oup-com.recursosbiblioteca.unab.cl/icesjms/article/64/7/1348/72823

Risks to different populations and age classes of gannets from impacts of offshore wind farms in the southern North Sea

The southern North Sea holds the world's highest concentration of offshore wind farms (OWFs). Northern gannets (Morus bassanus), a species considered at high risk from OWF impacts, show a strong seasonal peak there in November, but it is unclear which populations and age classes are most at risk of collision with wind turbines. We tagged adult and juvenile gannets at the world's largest colony (Bass Rock) and reviewed two sources of survey data for different age classes to study their movements through southern North Sea waters. Tracked birds showed peak numbers in the southern North Sea in mid-October, with much smaller numbers there during November. Adults were distributed throughout the area, including waters close to OWFs, whereas juveniles were confined to the coast. Survey data indicated high proportions of immature gannets in southern North Sea waters, suggesting higher collision risk than for adults. Gannets present in November may be predominantly from colonies further north than Bass Rock

The impact of fishing of marine birds

Birds are the most conspicuous, wide-ranging, and easily studied organisms in the marine environment. They can be both predators and scavengers, and they can be harmed by and can benefit from fishing activities. The effects of fishing on birds may be direct or indirect. Most direct effects involve killing by fishing gear, although on a lesser scale some fishing activities also disturb birds. Net fisheries and hook fisheries have both had serious negative effects at the population level. Currently, a major negative impact comes from the by-catch of albatrosses and petrels in long-lines in the North Pacific and in the Southern Ocean. High seas drift nets have had, prior to the banning of their use, a considerable impact on seabirds in the northern Pacific, as have gillnets in south-west Greenland, eastern Canada, and elsewhere. Indirect effects mostly work through the alteration in food supplies. Many activities increase the food supply by providing large quantities of discarded fish and wastes, particularly those from large, demersal species that are inaccessible to seabirds, from fishing vessels to scavengers. Also, fishing has changed the structure of marine communities. Fishing activities have led to depletion of some fish species fed upon by seabirds, but may also lead to an increase in small fish prey by reducing numbers of larger fish that may compete with birds. Both direct and indirect effects are likely to have operated at the global population level on some species. Proving the scale of fisheries effects can be difficult because of confounding and interacting combinations with other anthropogenic effects (pollution, hunting, disturbance) and oceanographic factors. Effects of aquaculture have not been included in the revie