52 MR. J. C. MOTTRAM ON THE 



these birds the angler knows when to begin fishing ; nevertheless, they 

 occasionally become satiated with these insects. During the close of the 

 "May-fly" (Ephemera danica) season it is by no means uncommon to see 

 the swallows hunting over the fields whilst May-flies are hatching-out. 



Obs. — "June. 5, 1913, E. Kennet, Thatcham, whilst a good hatch of E. danica 

 was on, swallows were hunting over the meadows to the windward of the river aud 

 were therefore not feeding on the ' May fly,' which for several days they have been 

 eagerly devouring." 



In contrast to their liking for the Ephemeridae, they have only on a very 

 few occasions been observed to take the " Black Gnat" (B. joliannis) : there 

 evidently appears to be a distinct difference in palatability between 

 these insects. A difference in the ease with which they may be captured 

 cannot account for the selection, because the birds take other insects whose 

 flight is quite as erratic as that of the " Black Gnat," and also the " Black 

 Gnat" is often over the water in such dense swarms that the birds would 

 have but to fly through them in order to obtain a mouthful, a method of 

 feeding which they often employ for the capture of many small insects 

 which swarm in the air. 



Emberiza sclmniclus, Linn, (the Reed-Bunting), is very adept at picking 

 the sub-imago of the Ephemeridas off the water; it in the same way r feeds 

 upon Brachycentrus subnubilus (the Grannoin), and has never been seen 

 taking B. joliannis (Black Gnat). 



Motacilla lugubris, Linn., M. boarula, Linn., and M. rayi, Bouap. (Wagtails), 

 are commonly seen taking Ephemeridae : on two occasions, during [a double 

 hatch of "Grannoin" and "Olive Dun/' it was noticed that the birds took 

 the Ephemeridse by preference, allowing " Grannom," close at hand, to pass 

 untouched whilst flying several yards for a " Dun." 



Obs. — "April 16, 1910, R, Latubourne, a mixed hatch of ' Grannoin ' and ' Olive 

 Dun,' 11.0 a.m. to 1.0 P.M., a pair of M. lugubris feeding on both flies; when a dun 

 was available it was always taken though 'Grannoin' were often closer on the 

 water." 



A second observation with JI. rayi, on the same river, was precisely 

 similar. 



A large number of different species of birds collect at the river-side 

 during the " May-fly" season: Fringillidoe (Sparrow, Chaffinch, Greenfinch), 

 Sturnus vulgaris, Naum. (Starling), Laridae (Black-headed Gull and Common 

 Tern), Anatidae (Ducks), Muscicapa grisola, Linn. (Flycatcher), Anthus pra- 

 tensis, Beohst. (Meadow-Pipit), Sylviidse (Warblers), and other birds which 

 are not, as a rule, observed feeding upon the smaller species of the 

 Ephemeridse. These observations indicate that the several British species of 



