THE BIRDS OF COOKHAM AND THE NEIGHBOURHOOD, 83 
and it will be seen that all I have to add is in favour of their spe- 
cific separation.” 
For the loan of the Danish birds I am indebted to the Rev. 
H. B. Tristram, who has always most kindly lent me specimens 
to aid me in my studies; but as in the present instance the sexes 
of the specimens were not marked, I cannot rely on their correct 
determination. They are both young birds, in which stage of 
plumage the two species approach each other ; but Scandinavian 
examples always have the white on the head and throat much 
purer than in any British specimen I have yet seen. I possess, 
however, through the kindness of Mr. J. G. Keulemans, of Leyden, 
a pair of adult birds from Holland, concerning which he has sent 
me the following note:—‘‘ The two birds I have sent you are 
male and female. The old male has a pure white head, and is 
less rufous on the back. Very young ones resemble the female, 
but are browneron the head. You will thus see that I have sent 
you a pair of adult birds. Itis seldom that Parus caudatus is 
found breeding in the winter time. It breeds in Northern 
Europe and only comes to us in winter; and from October to 
March they are seen flying in flocks of from five to twenty in- 
dividuals. These flocks consist of the old birds and the family of 
young ones,” 
From the foregoing remarks it will be seen that the white- 
headed Titmouse only comes to Holland in the winter... In 
Denmark, Norway, and Sweden, however, it breeds, according 
to the ornithologists of those countries, and in the two last- 
mentioned as far north as lat. 63 degrees* Still in Norway it is 
probably a local species, for my friend Mr. F. W. Backhouse 
tried unsuccessfully during a three months’ trip last summer to 
procure me a specimen, and the bird was not known to the 
country people of whom he enquired. 
The white-headed Bottle-Titmouse would, however, seem to 
be common in Siberia. Middendorff obtained an example in 
January at Udskoj-Ostrog, between the Stanovoi Mountains and 
the Sea of Ochotsk, which agreed with European specimens, as 
* Wallengren, Naumannia, 1855, p. 136. 
