( Hv ) 



wharf -staging from which we dispatched our flies. When the 

 second lot was loosed the swallows at once proceeded to 

 retrieve the flies while the latter were crossing the river 

 in various directions ; — the swallows never seeming to pause, 

 but retrieving the flies unerringly while themselves in full 

 flight." 



These interesting experiments showed the danger of a 

 conspicuous colour when associated with palatability. 



2. The far-reaching distance of birds' vision was indicated 

 in an article to which his attention had been called by Dr. 

 F. G. Penrose : — " Hawk-catching in Holland, I." in "Country 

 Life" for August 7, 1909 (p. 185). The article described the 

 ancient methods which are still practised at the Dutch village 

 of Valkenswaard (Falcon's Heath). One important element 

 was the use of a tethered great grey shrike to act as a sentinel. 

 "Now as soon as any bird of prey appears — even far beyond the 

 ken of any hnvian observer — this sentinel shows evident signs of 

 terror, which increase if the enemy should come nearer. Old 

 Adrian Mollen, father of the great master of the art, used to 

 say, that, by the gestures and sounds of alarm of the shrike, 

 he could sometimes form a pretty correct guess as to the size 

 and species of the hawk . . ." (p. 187). The Avords here 

 printed in italics were good evidence of the great distance at 

 which birds could recognise the details of form and movement. 



3. The following observation was recorded by Professor 

 Poulton:— "On July 29, 1910, at Wykeham House, Oxford, 

 my daughter and I saw a flycatcher, sitting on the branch of 

 an elm, rather over 30 ft. distant, make a dash after a 

 specimen of Tryphaena proouiba that was flying inside a room 

 towards and on to the inside of the window. We were stand- 

 ing inside the room and saw the bird dash itself against the 

 glass within a few feet of us. The pair of small windows, the 

 only ones in the room, are somewhat deeply recessed in the 

 side of the house, and the observation offers convincing 

 evidence of the power of a bird's sight in penetrating shadow 

 at a distance." 



4. The following observation, also made by Professor Poulton, 

 shows that small birds will attack insects of great relative 



