Some Habits and Hosts of Bird Ceratophylli. 75 



Within 10 days a pair of Tawny Owls {Symium aluco) had taken possession 

 and laid two eggs. 



From the entirely artificial nature of the nesting site, it was clear that 

 any parasites found later would be derived either from the Owls or from their 

 prey. Accordingly, from time to time throughout the summer, bagfuls of 

 nesting material were carefully examined and the results noted. This 

 material consisted mainly of woody detritus mixed with feathers, fur, and 

 castings. 



On 8th April there were numerous castings in the nest, while feathers 

 of the Sparrow {Passer domesticus) were plentiful. Very minute Siphon- 

 apterous larvae were present in swarms. These being kept damp in a 

 warm corner grew rapidly and had spun up in a few days. On 28th April 

 imagines began to emerge. These included two species of Ceratophyllus, 

 viz., gallince — in crowds, and sciurorum — a few. 



By 5th May there were two young birds in the nest, one showing 

 incipient quill feathers, the other being in down. The prey was more varied 

 than a month before, for, in addition to mouse and vole casts, there were un- 

 doubted remains of Pied Wagtail {Motacilla lugubris) ; Wren {Troglodytes 

 pauvulus) ; Greenfinch {Ligurinus chloris); and Thrush {Turdus musicus). 

 Other feathers pointed almost certainly to Garden Warbler {Sylvia hortensis) 

 and Chaffinch {Fringilla ccelebs). 



Siphonapterous larvae were less numerous now, but an additional species, 

 C. fringillce, was sparingly bred from material collected on this visit. 

 Larvae of a Dipteron, Blepharoptera serrata, occurring in swarms, yielded 

 imagines by 31st May. 



Several visits were paid to the nest in the first ten days of June. On 

 the second a striking sight was to be seen — Oeratopihylli leaving the nest 

 in a regular 1 army. They jumped towards one when approached within 

 2 to 3 inches and bit viciously at the exposed hands. Sciurorum only was 

 detected in the act on this occasion, but gallinai was far the commoner 

 species. 



Owing to the accumulation of faeces, largely composed of lumps of 

 pink chalky urates, the nesting hole had a strong alkaline smell. Under 

 these conditions the dipterous maggots throve well, but latterly not a single 

 flea larva could be detected. The environment was possibly too acrid. 



In June the bill of fare included Blackbird {T. merula), and Starling 

 {S. vulgaris), in addition to others already mentioned. Latterly heavy toll 

 was exacted from young Passerines — especially Thrushes. 



1 Very large swarms of fleas have been noted on five occasions. In three cases the 

 species was gallince, in the other two, farreni. 



