Ravens (Corvus corax) learn from video demonstrations

2011 ◽  
Author(s):  
Elizabeth Price ◽  
Andrew Whiten ◽  
Thomas Bugnyar
Keyword(s):  
2020 ◽  
Vol 47 (1) ◽  
pp. 1-15
Author(s):  
Robin M. Sellers ◽  
Stephen Hewitt

Carlisle Museum's Natural History Record Bureau, Britain's first local environmental records centre, collected and collated records, mainly of birds but including also mammals and fishes, from amateur naturalists. It initially covered an area of 80 kilometres around Carlisle, and later from Cumberland, Westmorland and the detached portion of Lancashire north of Morecambe Bay: in effect the modern-day county of Cumbria. At the end of each year, those records which had been accepted were logged in a special “Record Book”, and a summary published. For the first eight years of its ten-year existence (1902–1912), these were printed in the local newspaper, The Carlisle Journal, but from 1908 they also appeared in The Zoologist. Alongside the Record Bureau, the Museum undertook a number of other activities, including a short-lived attempt to establish a bird-ringing project, an investigation into the impact of black-headed gulls ( Chroicocephalus ridibundus) on farming and fisheries interests (an early example of economic ornithology), the setting up of Kingmoor Nature Reserve and the protection of nesting peregrines ( Falco peregrinus), buzzards ( Buteo buteo) and ravens ( Corvus corax). The effectiveness of the Natural History Record Bureau and the reasons for its demise are briefly discussed.


1999 ◽  
Author(s):  
William I. Boarman ◽  
Bernd Heinrich
Keyword(s):  

1974 ◽  
Vol 29 (5-6) ◽  
pp. 239-242 ◽  
Author(s):  
Jens Poltz ◽  
Jürgen Jacob

The uropygial gland fats from four species of the family Corvidae are found to be mainly mono­ ester waxes, which consist of mono-, di-, and trimethyl substituted fatty acids and n- and methyl-branched alcohols. The positions of all methyl brandlings are even-numbered, the 2-position is preferred. About 2 - 40% of the secretions consist of triester waxes: Alkyl-hydroxy-malonic acids esterified with n-fatty acids and n-alcohols. Waxes of this type are very common in the uropygial gland fats of birds and therefore, in opposite to the monoester waxes, they are not usable for a chemotaxo­ nomy of birds.


2002 ◽  
Vol 64 (6) ◽  
pp. 831-841 ◽  
Author(s):  
Peter Enggist-Dueblin ◽  
Ueli Pfister

Ring ◽  
2006 ◽  
Vol 28 (2) ◽  
pp. 119-125
Author(s):  
Michał Ciach ◽  
Dominik Wikar ◽  
Małgorzata Bylicka

Density and Flock Size of the Raven (Corvus corax) In the Orawa - Nowy Targ Basin During Non-Breeding Season During the 2002/2003-2004/2005 non-breeding seasons the density of the Raven in the open habitats of the Orawa - Nowy Targ Basin was studied by line transect method. The results were analysed in four periods (autumn, early winter, winter and early spring). The median density of Ravens did not differ significantly between individual periods and was respectively: 3.5, 3.8, 4.8 and 3.8 indiv. / 10 km. Number of birds during particular controls varied from 1.0 to 24.8 indiv. / 10 km. However, while excluding flocks, the median density of single individuals and pairs of the Raven was considerably lower and in subsequent periods reached respectively: 2.2, 2.4, 2.2 and 1.7 indiv. / 10 km. Flock size did not differ significantly between individual periods. Single individuals and, less often, groups of two birds were recorded mostly. Small (3-5 indiv.) and medium (6-15 indiv.) flocks were recorded rarely and large flocks (16 indiv. and above) - only exceptionally. The high density and strong fluctuations of abundance of Ravens were determined by flocks presence, which was probably linked to irregular occurrence of food resources.


2012 ◽  
Vol 16 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Felice Di Lascio ◽  
François Nyffeler ◽  
Redouan Bshary ◽  
Thomas Bugnyar
Keyword(s):  

2005 ◽  
Vol 119 (1) ◽  
pp. 101 ◽  
Author(s):  
Lynn L. Rogers

During 16 August to 21 September 1984, I determined how Gray Jays (Perisoreus canadensis) carried flight-loads of different weights. Three individually identifiable Gray Jays weighing 60, 68, and 80 grams, used their bills to carry flight-loads weighing up to 33 percent of bodyweight but transferred heavier flight-loads from their bills to their feet 1-2 meters after takeoff. They had difficulty carrying flight-loads over 57 percent of bodyweight, and none attempted to carry flight-loads over 66 percent of bodyweight. By using their feet to bring heavy flight-loads closer to the center of lift, Gray Jays can carry heavier loads of meat, relative to body weight, than can Common Ravens (Corvus corax) which compete with Gray Jays at carcasses in winter and which do not carry objects with their feet. During 1969-2003, year-round observations near the southern edge of the Gray Jay range in northeastern Minnesota showed that caching behavior begins in August, continues over-winter, and ends at the onset of insect activity and green-up in early May. Gray Jays’ propensity to approach larger animals, including people, may not indicate unwariness but rather a superior ability and willingness to assess risks and food benefits. In the boreal forest in winter, risk of starvation is greater and risk of predation is lower than in relatively food-rich ecoregions farther south.


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