218 Mr. R. Collett on Phylloscopus borealis. 
seas. Its northern boundary in our land may be said to be 
70° 20', while, in Siberia, Mr. Seebohm did not meet with it 
north of 69°. 
It was especially in the months of June and July 1885 
that I had good opportunities of observing this species 
during its summer residence in our latitudes. That year I 
visited the wide Tana valley *; and here I found P. borealis 
everywhere about the lower course of the river (Matsjok, 
Seiaa, Oldernses, Polmak), where the birch-woods were 
tolerably luxuriant, and where the ground was not too dry, 
but well overgrown with plants and grasses. In South 
Varanger, where I have met it on several previous occasions 
(in Langfjord and on the Pasvig river), I found it last 
summer again in the old localities at Elvenses and Salmi- 
Javre, and met with it also in Jarfjord. 
At several of these places, especially at Polmak, in Tana, 
and at Salmi-Javre on the Pasvig, these birds were com¬ 
paratively numerous, and during a few hours' walk I have 
met with a dozen singing males. 
As the luxuriant birch-woods are only to be found in the 
larger valleys, these are the chief places of resort of this 
species; but they do not live on the plateaus or open places, 
even when these are partially wooded, as the woods there are 
generally more or less thin and the trees stunted. They 
frequent both the birch trees and willow-thickets, and often 
sit singing from the top of the tall fir trees which are to be 
found singly or in small numbers in the birch-woods. In 
its habits P. borealis resembles the other Phylloscopi , but is 
wilder, flies with greater strength, and appears reluctant to 
show itself so openly between the leaves as, for instance, 
P. trochilus. They are often seen fluttering about the end 
of the branches like the last-mentioned species in order to 
look for insects. 
Concerning the breeding of P. borealis but little, so far as 
I know, has yet been published. 
Near Lake Baikal, in 1866-71, Dybowski found it breeding 
* Lately described by Mr. Alfred Chapman in ‘ The Ibis ’ for 1885, 
p. 158, in his “ Birds’-nesting Ramble in Lapland.” 
