'Magic mud' on tidal flats key to shorebird populations

The "magic" in the mud was first uncovered just south of Vancouver where up to half the world's western sandpipers touch down to refuel as they migrate north.

Now the gooey, paper-thin biofilm has also been found to be a key bird food on the other side of the Pacific, revealing what researchers say is a "missing link" in the avian world.

Biofilm can make up to 70 per cent of the diet of small shorebirds, which slurp up the stuff like energy drinks, says Environment Canada researcher Robert Elner, who led the international team that reports its study findings this week.

Lees meer: Canada.com

Cross-hemisphere migration of a 25 g songbird

Auteurs: Franz Bairlein, D. Ryan Norris, Rolf Nagel, Marc Bulte, Christian C. Voigt, James W. Fox, David J. T. Hussel, Heiko Schmaljohann
Bron: BIOLOGY LETTERS, doi 10.1098/rsbl.2011.1223
Abstract: The northern wheatear (Oenanthe oenanthe) is a small (approx. 25 g), insectivorous migrant with one of the largest ranges of any songbird in the world, breeding from the eastern Canadian Arctic across Greenland, Eurasia and into Alaska (AK). However, there is no evidence that breeding populations in the New World have established overwintering sites in the Western Hemisphere. Using light-level geolocators, we demonstrate that individuals from these New World regions overwinter in northern sub-Sahara Africa, with Alaskan birds travelling approximately 14 500 km each way and an eastern Canadian Arctic bird crossing a wide stretch of the North Atlantic (approx. 3500 km). These remarkable journeys, particularly for a bird of this size, last between one to three months depending on breeding location and season (autumn/spring) and result in mean overall migration speeds of up to 290 km d−1. Stable-hydrogen isotope analysis of winter-grown feathers sampled from breeding birds generally support the notion that Alaskan birds overwinter primarily in eastern Africa and eastern Canadian Arctic birds overwinter mainly in western Africa. Our results provide the first evidence of a migratory songbird capable of linking African ecosystems of the Old World with Arctic regions of the New World.

Lees ook: LiveScience

The fascinating love life of the Dunnock

I watched a Dunnock today, feeding under the garden table, with that characteristic half hopping half walking way Dunnocks have, pecking here and there things too small to be seen at a distance, maybe seeds or small invertebrates. Dunnocks, or Hedge Sparrows (Prunella modularis) are little birds, which live their lives mostly unnoticed amongst the undergrowth and are easily overlooked or taken for House Sparrows. They have a grey chest and head and chestnut backs with dark stripes, a thin beak and orange legs. Both males and females look similar, females just a bit smaller than males. In gardens they often feed on the ground, under bird tables when there is some cover, and they prefer to skulk than to sit out in the open. Only in the spring, where males sing their weak, warbling song from a prominent perch they are somewhat more likely to be noticed (above). Contrasting with their modest attire and retiring habits the Dunnock shows a variable mating system - including a common arrangement of two males and a female, a system called polyandry- , and a courtship behaviour that can only be described as peculiar. I was lucky enough to witness courting Dunnocks a few years back.

Lees meer: The Rattling Crow

Migration and wintering areas of adult Montagu's Harriers (Circus pygargus) breeding in Spain

Auteurs: Liminana Ruben, Soutullo ALvaro, Urios Vicente, Reig-Ferrer Abilio
Bron: JOURNAL OF ORNITHOLOGY Volume: 153 Issue: 1 Pages: 85-93 DOI: 10.1007/s10336-011-0698-x
Abstract: Between 2006 and 2008, 14 Montagu's Harriers (Circus pygargus) were tagged with satellite transmitters at their breeding grounds in NE Spain, recording a total of 18 autumn and 10 spring journeys. In both autumn and spring migrations, harriers migrated between Europe and West Africa along a relatively narrow corridor between the coast of Morocco and Western Sahara and the western border of Algeria. Birds tended to follow a slightly more westerly track during spring migration compared to autumn migration. Harriers started autumn migration in late August-early September, arriving at their wintering grounds in early-mid-September, after travelling between 8 and 25 days, and covering a mean of 187 km a day. Spring migration started in mid-March, with birds arriving at the breeding grounds in mid-April after covering a mean of 114 km a day. On average, spring migration lasted longer, with birds covering longer distances than during autumn migration, and distances travelled in a day tended to be shorter. Significant differences in the routes followed by harriers were observed among seasons and individuals, with the same individuals following different routes in different years. Wintering areas were located in northern Senegal and the southern border of Mauritania with Mali, with some birds breeding in the same colony in Europe separated more than 1,200 km during the wintering season. Birds showed a relatively high fidelity to their wintering areas. Several birds moved from one area to another during the wintering period, which resulted in larger wintering areas, whereas others remained in the same area during the whole wintering season.