THE MARSH-WARBLERS 71 



characteristic babbling song, which, day and night from April to August, 

 forms the chief part of the concert of bird voices in fen and by river- 

 side. From August to the time when they leave us for the winter 

 they are silent, and it then requires very close observation to discover 

 their whereabouts. 



Three species, the sedge-, reed-, and marsh-warbler are regular 

 summer migrants to this country. The sedge-warbler is the commonest 

 and most widely distributed, being less specialised in its nesting opera- 

 tions than the reed-warbler, to which reeds are almost a necessity. 

 The marsh-warbler is rare, and was not known to nest in this country 

 until comparatively recent years, but now in favoured localities where 

 the conditions are sufficiently varied all three species may be found 

 nesting together. 



On the strength of occasional visits two other species have a 

 claim to inclusion in the British list, the aquatic-warbler, somewhat 

 smaller and more brightly coloured than the sedge-warbler and very 

 similar to it in general habit, and the great reed-warbler, which except 

 for its superior size resembles its commoner congener in habits and 

 appearance. There is in fact a strong family resemblance in general 

 habit throughout the whole group, and although each species is 

 characterised by traits providing ample means of identification, yet 

 the generic characters are so strong, and often show themselves 

 in so unexpected a manner, that preconceived ideas of specific habits 

 are constantly being dispelled. 



As with most other warblers, the two sexes do not appear to 

 migrate together, the males arriving in their nesting quarters from one 

 to two weeks before the females. Migration is singly or in small com- 

 panies, which are probably interspersed with mixed flocks of other 

 migrants. The first to come is the sedge-warbler. A few may 

 occasionally arrive in the middle of April, but there is no serious 

 influx until the 20th to the 25th of the month. The first reed-warblers 

 follow a few days later, and there is a gradual increase in number of 

 these two species throughout May. The marsh-warbler is a very late 



