222 Mr. R. Collett on Phylloscopus borealis. 
The indefatigable manner in which the male gives forth its 
monotonous, but nevertheless strongly sounding, song is 
almost incredible. The song consists, as I have previously 
remarked, of a single note, zi-zi-zi-zi ., repeated 
unusually quickly, fourteen to sixteen times in succession. 
After each song follows a short period of rest, which in the 
height of the singing-time scarcely exceeds half a minute, 
when it recommences its song again. The song of the different 
specimens was almost precisely alike, but in some it might 
sound a little more or less harsh than in others. Seebohm has 
compared the song to the trill of the Redpole; and this seems 
to be a suitable description, although it appeared to me to 
resemble more the first quick notes of the song of Sylvia 
curruca. 
In these latitudes, where the day is but little lighter than 
the night, the song might be heard at any hour and even at 
midnight. A little after the middle of July most of the 
males had ceased to sing, although at Matsjok once or twice 
I heard the song so late as the 28tli of that month. 
This species never occurs in great numbers; but as each 
male in a district does not conceal itself from notice, the 
males are consequently more easily secured than the females, 
which, as a rule, are somewhat difficult to obtain. After the 
singing-time is past, the males are also but seldom seen; 
their characteristic and sharp call-note is then the only thing 
to direct one's attention to them. This call-note can best be 
described by a short and whistling “ tseers/' and may be 
heard at a long distance. It does not closely resemble the 
cry of any other northern bird, but is most like the note 
which Cinclus aquations utters during its flight. This 
note is always heard when one approaches its nest or its 
young. 
The food of P. borealis consists chiefly of mosquitos, which 
at their breeding-time swarm in myriads in the birch-woods. 
On two occasions I have found the larvae of a Cidaria or 
other Geometrid larva in its stomach, as well as other soft 
insects. 
Amongst the numerous specimens I have shot in Pinmark 
