SUMMER LIVERIES 319 



protective colourings. Their livery has no obvious purpose ; 

 and generally the theory is extended too far. From time 

 to time any observer must come across examples of adapta- 

 tion to environment which resemble a parody on the theory 

 of protective mimicry. We have quoted several elsewhere ; 

 but the writer has always felt a certain scepticism since 

 he saw one summer day a barn owl roosting on an apple- 

 bough up into where had grown a bush spiraea. The 

 owl's body was a most perfect match to the blurred white 

 flowers, of which, till you looked close, the bird seemed a 

 floral extension. However, birds' feathers are very often 

 consonant with their surroundings, especially when they 

 are young, and the mother's livery is less conspicuous 

 than males for protective purpose or with protective effect. 



BLACK-HEADED GULL 



