Kaja Corvus monedula är en fågel i familjen kråkfåglar.
Förekomst i Sverige
En del kajor stannar kvar i Sverige på vintern, inte bara i Skåne, utan också i Uppland. Andra flyttar till sydligare länder. De kajor som flyttar brukar komma tillbaka redan i mars-april. Kajan är vanlig i södra och mellersta Sverige och dess utbredning har ökat under 1900-talet.
Honan och hanen är lika. På ovansidan av huvudet är den blåsvart. Dess rygg är svart, de undre kroppsdelarna mörkgråa, vingarna och stjärten är glänsande svarta. Kroppslängden är nära 34 cm och vingspannet 64-73 cm. Den väger ungefär 240 gram. Näbben är kort och kraftig. Den adulta fågeln har en ljusblå iris medan ungfågeln har en brun. Ungfåglar har också en brunare ton på vingarna.
Tack till Wikipidia!
The Jackdaw Corvus monedula, sometimes known as the Eurasian Jackdaw, European Jackdaw, Western Jackdaw, or formerly simply the daw, is a dark-plumaged passerine bird in the crow family. It is found across Europe, western Asia and North Africa, and four subspecies are recognised. At 34–39 cm in length, it is one of the smallest species in Corvus, the genus of crows and ravens. It is a black-plumaged bird with grey nape and distinctive white irises. It is an omnivorous and opportunistic feeder, and eats a wide variety of plant material and invertebrates, as well as food waste from urban areas. The Jackdaw has benefited from clearing of forested areas and is found in farmland and urban areas, as well as open wooded areas and coastal cliffs.
Thank you Wikipedia!
A small number of Jackdaws reached the northwest of North America in the 1980s, presumedly ship-assisted, and have been found from Atlantic Canada to Pennsylvania.
The jackdaw forages in open areas and on the ground, but does take some food in trees. Garbage tips, bins, urban streets and gardens are also visited, more often early in the morning when there are fewer people about. Jackdaws employ various feeding methods, such as jumping, pecking, clod-turning and scattering, probing the soil, and rarely digging. Flies around cow pats are caught by jumping from the ground or at times by dropping vertically from a few metres above onto the cow pat. Earthworms are not usually extracted from the ground by jackdaws but are eaten from freshly ploughed soil.
The jackdaw is a highly sociable species outside of the breeding season, occurring in flocks that can contain hundreds of birds.
Konrad Lorenz studied the complex social interactions that occur in groups of jackdaws and published his detailed observations of their social behaviour in his book King Solomon's Ring.
The book observations on jackdaws' strong male–female bonding; he noted that each bird of a pair both have about the same rank in the hierarchy, and that a low-ranked female jackdaw rocketed up the jackdaw social ladder when she became the mate of a high-ranking male.
Every barnyard has a pecking order, as every farmer knows.
Jackdaws, like chickens, establish a hierarchy, and the position of the individual jackdaw determines all pecking rights. Who may peck whom? No jackdaw may peck another who ranks higher in the order. A high-ranking jackdaw may peck those of lower rank, and there is always that lowly jackdaw who is pecked by all, and can peck no one in return.
Jackdaws mate for life, and like most birds who follow this custom become engaged early in life, long before sexual maturity.
Birdfreak nr 81