The British Warblers. 13 



We now come to the subject of winter aviaries and we 

 shall have a choice of three courses which we may briefly 

 describe as (i) no heat, (2) heat or (3) some heat. So far as my 

 experience goes all the Warblers, except the hardy little Black- 

 cap, and I may add the majority of the smaller insectivorous 

 species are better for a little heat in the winter. Only the other 

 day I found a very fine Yellow Wagtail in a cold aviary in a badly 

 collapsed condition after a night of hard frost. It was so weak 

 that it was only with the greatest difficulty it could swallow a 

 mealworm and it would undoubtedly not have survived another 

 night in the open. I caught it and placed it in a heated aviary 

 and in two days time it hati perfectly recovered. 



If we decide to heat our winter aviary we still have to 

 consider whether our Warblers shall be confined solely in the 

 heated portion, or whether they shall be allowed access to the 

 outer flight. Some years since I determined to give the former 

 system a good trial and I accordingly built a small house 

 measuring 12ft. long by 8ft. wide by 7ft. high, the sides being 

 entirely of glass and the roof having two glazed lights, each 3oins. 

 by 24ins. of double glass with an air space between to avoid loss 

 of heat. One side is planted with large clumps of Bamboo and 

 Eucalyptus; on the other side is a large quarantine cage, a small 

 division for invalids and an apparatus for rearing Quails. The 

 foundations are of brick and are mouse-proof and the large 

 ventilating windows (each 4feet long) are screened with mouse- 

 proof netting. The pipe-area is large and the temperature 

 averages 65^. Last winter I quartered all my Warblers here and 

 the result was most promising. Every sunny morning there was 

 a continuous chorus of song, the Lesser Whitethroats contribu- 

 ting the tenor parts, the Greater Whitethroats the baritone and 

 the Garden Warblers, whose song closely resembles the Black- 

 birds', tlie bass. To enter this little aviary on a bleak, chilly 

 morning was to pass in a single moment from mid-winter to 

 mid-summer. All the Warblers moulted successfully and, when 

 I turned them out in Ma}', they were in the pink of condition. 

 Then came the disappointment! The weather was cold, espec- 

 ially at night. The first day or so all went well. After that 

 there was no more singing and I saw clearly that something was 



