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NOTES ON THE ECOLOGY OF THE ROBIN
Author(s) -
Lack David
Publication year - 1948
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.1948.tb01690.x
Subject(s) - census , geography , mile , breed , ecology , archaeology , demography , biology , population , sociology , geodesy
Summary.1 In winter, in England, the Robin chiefly frequents cultivated land and the wood‐edge, but a few occur in the interior of woods. In summer, proportionately more frequent the interior of woods. 2 The Robin associates with man to a much greater extent in England than on the Continent of Europe. It seems first to have appeared round human habitations in winter, breeding being a later development. 3 The Robin suffers severely in hard winters, census figures being given in Table 2. During a cold spell, the woods may temporarily become empty of Robins, but it is not known whether most of these birds have died or moved out. 4 The Robin is “dimorphic”, some individuals migrating and others residing for the winter, the proportion in each class differing in different parts of Europe according to the severity of the winter. The activities of man have probably changed the proportion of residents to migrants in England. 5 Young Robins commonly disperse to breed between 1 and 4 miles from their place of birth, but only 5 per cent, have been found more than 8 miles from their birth‐place. Once a Robin has taken up a territory, it rarely moves more than a mile, only 3 per cent, being found 1–3 miles away and another 3 per cent, over 10 miles away. 6 The expectation of life for a Robin is about one year, and there is a suggestion that this figure is lower for north European migrants than for British birds. 7 The Robin eats a great variety of small invertebrates, which are chiefly detected from a perch as they move on the ground or litter below the bird. Seeds and fruits are also taken. 8 Particularly in hard weather, the Robin follows mammals or large birds which break up the ground, thereby rendering insects available to it. 9 In winter the Robin probably has no serious food competitors. In summer it takes many geometrid larvae, as do titmice and warblers, but this food is probably superabundant. 10 The Sparrowhawk is the only serious predator of the Robin. 11 The external parasites are listed. 12 More than 60 per cent, of adult Robins die each year. Winter food shortage is thought likely to be the chief mortality factor. Population control is briefly discussed. 13 There is no real evidence that territorial behaviour controls population density or that it is important in ensuring a food supply for the young.