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TERRITORY IN THE THICK‐BILLED NUTCRACKER NUCIFRAGA CARYOCATACTES.
Author(s) -
Swanberg P. O.
Publication year - 1956
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/j.1474-919x.1956.tb01425.x
Subject(s) - overcrowding , geography , nest (protein structural motif) , population , habitat , crowding , predation , ecology , biology , demography , sociology , political science , law , biochemistry , neuroscience
Summary.1 The main features of the territory in the Thick‐billed Nutcracker are:‐ ( a ) the territory is kept for life and inhabited throughout the year; ( b ) the special food, nuts, is stored in the territory; ( c ) song, copulation, nest‐site selection and nest‐building take place only in the territory; ( d ) territories examined were 11.2–14.9 hectares, averaging 32.7 acres, believed to be the normal size in Sweden. 2 There is no clear evidence that the territory has the function of securing more than a certain amount of food other than stored. 3 The territory is respected by other Nutcrackers as to its main functions, while simple visits by other Nutcrackers and ceremonial gatherings in the territory are tolerated. 4 Both territory‐holders attack intruders that try to take nuts but as they do not chase them out the behaviour is not regarded as truly territorial behaviour. 5 The territory is proclaimed by the calls, the song being exclusively sexual. 6 Unmated birds have not been recorded with territorial behaviour. 7 When the special food is limited and the nesting habitat ample, the population is limited by the amount of the special food; but when the special food is abundant and the nesting habitat limited, over‐crowding seems to be prevented by territorial behaviour. 8 It is suggested that the function of territory in the Nutcracker is to give the holders a well‐known refuge from predators, to serve as a food storing place, and by spacing out to prevent these positive qualities from reduction by overcrowding.