Добірка наукової літератури з теми "Birds – Nests – Ireland"

Many ground-nesting bird species have been observed incubating foreign objects in their nests (Mellink 2002). Pine cones, golf balls, guano, hermit crabs, mammalian bones and many more objects have all been recorded in bird nests (Knight & Erickson 1977; Mellink 2002; Langlois et al. 2012). A study by Conover (1985) showed that 10% of Ring-billed Gull Larus delawarensis and 6% of California Gull L. californicus nests contained a foreign object. These foreign objects were more similar in size and shape to the gull eggs than to randomly selected pebbles. Little Terns Sterna albifrons have been observed incubating egg-like pebbles for several weeks on two separate occasions at a breeding colony in Kilcoole, Co. Wicklow, Ireland (Farrelly 1990). Several hypotheses have been put forward to explain this behaviour. Coulter (1980) suggested that foreign objects may act as an incubation stimulus. Many tern and gull species, unlike other birds, have three brood patches not one (Gochfeld 1976; Reid 1987). Coulter (1980) conducted incubation studies of several species of gulls suggesting that birds incubating three eggs sat for longer periods of time, resettled less frequently, have a shorter incubation period and a higher hatching success than birds on either fewer eggs or more. He speculated that gulls are highly adapted for three-egg clutches whereby the foreign objects provide an important stimulus for incubation behaviour when there are less than three eggs (Beer 1961; Beer 1965; Baerends et al. 1970; Coulter 1980). Alternatively, the mistaken-food hypothesis suggests that a predatory bird brings a foreign object back to the nest, regurgitates the object and then proceeds to incubate it, mistaking it for one of its own eggs (Sugden 1947; Twomey 1948). A third hypothesis is that the foreign object is mistaken by the bird for one of its own eggs and rolled into the nest, in this scenario the foreign object is likely to have originated from close to the nest (Conover 1985).

The common snipe (Gallinago gallinago) is a wader that breeds in subarctic regions from Iceland to Russia, and for which global populations are in decline. We studied snipe breeding in western Iceland between 1998 and 2020, locating nests and ringing birds annually. In 2019 and 2020, we deployed geolocators on nesting adults to estimate the timing of their annual migration and the location of overwintering areas. Birds moved principally between breeding locations in Iceland to wintering areas in Ireland, although some birds may winter farther north. We also found that apparent annual adult survival averaged 66%, but was higher in years with warmer, wetter winters. Given the similarity of our survival estimates to those from snipe elsewhere, we suggest that adult survival is unlikely a major contributor to declining populations, and other factors like habitat loss may be of more concern.

Abstract Of the three swan species that occur in Britain, the Bewick’s and Whooper Swans are migratory and the Mute Swan resident throughout the year. The Bewick’s Swan Cygnus columbianus bewickii (see drawing above) breeds on tundra in the Russian arctic, and birds from the western population fly some 4000 km each autumn to wintering sites located primarily in the Netherlands, Britain, and Ireland. British-wintering Whooper Swans Cygnus cygnus, on the other hand, are predominantly from the Icelandic breeding population, and have a comparatively short migratory journey of some 800 km between the breeding and wintering grounds. They nest in a variety of habitats ranging from lowland marshes, amidst areas of intensive farming, to upland sites, where pools and lakes in the glacial moraine support aquatic vegetation, thus providing a food supply for the birds. Differences between Bewick’s and Whooper Swans in the timing of their arrival and departure in Britain each season reflect the different migratory distances undertaken; Whooper Swans generally return to their wintering sites earlier than the Bewick’s Swans in autumn, and leave later in the spring. In Britain the Mute Swan Cygnus olor is very sedentary; only some 3 % of individuals move more than 100 km from their natal area (Birkhead and Perrins 1986). It occupies a wide range of waters including ponds, rivers, and gravel pits, and often frequents urban areas.