500 Dr. A. L. Thomson : Results of a Study of [Ibis, 
Of the above, 22 reappeared during their first year, 
2 during their second, 1 in its third, and 1 in its fourth. 
The first column of the seasonal analysis indicates that 
the native birds decrease in numbers in winter in Scotland 
and the north of England, and there is indeed no evidence 
from this source that any remain throughout. The other 
columns show that the birds may reach Ireland and south¬ 
western France. 
There is also one isolated record (Case 229) of a bird 
marked otherwise than as a nestling ; one of four birds 
marked at night on the shore near Aberdeen on 3.10.10 was 
recovered near the same place on 20. 7.11. 
Witherby’s records (28) include a Black-headed Grull 
marked in Yorkshire and recovered from the Azores in its 
first winter, and another marked as a chick in Cumberland 
in 1910 and reported from Aberdeenshire, over 200 miles 
farther north, on 20. 2.11. The species has also been studied 
by Thienemann (16), birds marked as chicks at Rossitten, 
at the south-eastern corner of the Baltic, being reported in 
winter as far afield as the south of England, the Bay of 
Biscay, the Balearic Isles, the south of Italy, and Tunis. 
VI.—THE MALLARD (Anas bosohas Linn.) : 
ANALYSIS OF RECORDS. 
The Mallard is found all the year round in the British 
Isles, but it is known to be a winter visitor and a bird of 
passage as well as a resident, and, as in so many other 
cases, the first problem is accordingly the separation of 
the movements performed by the native and immigrant 
birds respectively. Birds of this species are frequently 
hand-reared, often from eggs imported from other districts, 
and it is to cases of this kind that most of the records 
refer. 
Many hand-reared ducklings were marked at Pitcaple 
Castle, Aberdeenshire, in 1910, but owing to the loss of 
some of the notes the total is uncertain. Of these, 13 were 
recovered, ten of them in the same district (seven on the 
