THE THRUSH GENUS 367 



tchack ! heard during the winter. It is the cocks who behave thus ; 

 the hens remain in their nests until the hand of the spoiler is 

 nearly upon them. 1 



It is curious that the redwing, which we see during the autumn 

 and winter months flying about our fields in flocks just like the 

 fieldfare, should not resemble it in breeding gregariously, the more so 

 as the habits of the two species are so alike in other respects. Closer 

 observation may reveal the reason. A careful comparison of the 

 gregarious instinct in the genus Turdus would be of considerable 

 interest, for we have in it the various degrees of the social relation- 

 ship fairly well represented. 



Thrushes, blackbirds and ring-ouzels are gregarious only as 

 migrants, using the latter term to cover any definite movement from 

 one area to another, whether within or beyond our shores, except 

 local changes of level. When the bond created by the migratory 

 instinct has been broken they separate, each individual or pair 

 going its own way. It is true that, as already noted, these birds 

 may be seen seeking their food in close proximity, but this frequently 

 recurring fact does not make them gregarious. On such occasions 

 they are no more gregarious than the audience in a theatre. They 

 form simply a temporary aggregation of independent units. 



The mistle-thrush, like the three species mentioned in the 

 foregoing paragraph, is gregarious as a migrant, but also to a greater 

 or less extent it flocks in this country outside the breeding season. 

 All the evidence goes to show that from midsummer up to the end 

 of the year the various families tend to unite into flocks. Bands 

 of fifty and over have been frequently observed, but to what extent 

 these larger flocks are immigrant remains to be ascertained. At 

 the end of the berry season the species appears to become less 

 gregarious ; but on this point, again, more evidence is needed. In 

 any case, towards the end of January, the approach of the mating 



' Journal fiir Ornithologie, 1864. According to the late B. Bowdler Sharpe, "the 'chuck,' 

 or the harsh challenge so familiar to our ears in winter," can be heard at the breeding-place. 

 See Seebohm and Sharpe, Monograph of the Turdidce, i. p. 204. 



