58 MR. J. C. MOTTRAM ON THE 



swallowed. The following are details of some of the observations, given to 

 show that the above statement is not open to doubt. 



Obs. — " 3. 6. 1913, watched a spotted flycatcher feeding upon small flying insects, 

 chiefly gnats, observations extending over half an hour, bird seen to set out after 

 small pieces of feather, chaff, <fcc. on three occasions, and a fourth time the object 

 was taken in the bill. 



" 13. 5. 1914, swallows feeding upon ' olive duns,' bird took small piece of feather 

 which was not seen to he discarded. 



"18. 4. 1910, wagtails feeding upon ' Grannom,' on several occasions bird made for 

 small floating objects resembling the insect, and twice picked these off the surface 

 of the water, then dropped them." 



Whilst making such observations, it was noted that the birds often flew 

 long distances after passing insects, as much as twenty yards, and that many 

 of the mistakes were then made. 



The dry-fly fisherman's evidence that birds are easily deluded, is very 

 clear. Swallows, martins, and swifts very commonly pick the artificial 

 insect off the water, when an imitation of one of the Ephemera is being used. 

 Two typical experiences are given : — 



Obs .— " 5. 7. 1909, E. Lambourne, Great Shelford, 3.0 to 4.0 p.m., hatch of 

 'Blue-winged Olives' (Ephemerella ignita), swallows picking insects off the water as 

 well as taking them in the air, my artificial ' Blue-winged Olive ' was repeatedly 

 picked off the water and carried for a yard or two in the air, by both swallows and 

 martins : so persistent were the birds that they interfered with the fishing. 



"20.4.1913, hatch of 'Grannom,' 11.0 to 12.30, black-headed bunting picking 

 insects off the water, on two occasions bird mistook my artificial insect." 



Similar mistakes have been personally witnessed in the case of the following 

 birds : Motacilla rayi, M. boarula, Sterna (a tern in New Zealand), Antlms 

 pratensis, Acrocephalus schcenobamus, Newton, Caprimulgus europceus, Linn., 

 Anser (domestic duck), Podiceps Jluviatilis, Degl. & Gerbe, and species of Bat 

 (undetermined). 



It is clear therefore that birds, like trout, frequently mistake crude 

 imitations for living insects. 



The Importance of these Observations with respect to certain Aspects 



of Mimicry. 



It has been shown that a crude resemblance suffices to delude both birds 

 and trout. It would appear therefore highly probable that if one insect only 

 slightly resembled another, which the bird was avoiding, then the mimicking 

 insect would, to some extent, be also avoided. The fact that birds have been 

 observed to begin their attack from considerable distances would help to give 

 value to a crude resemblance ; because at such distance all details of pattern 

 and coloration (especially during motion) cannot be seen. 



