280 
MIGRATION OF BIRDS 
with the European bird. One specimen, collected at Ankoli 
in Uganda, was very close, but it was not quite mature. 
18. The Woodchat Shrike ( Lanius senator senator) breeds 
in the central countries of Europe, east to south Russia and 
Asia Minor. Most birds of the European form migrate to 
North Africa and West Africa, but a few come this way. 
There are local north-east African forms which also migrate 
to a certain extent, so one has to be careful when reporting 
the occurrence of this bird not to confuse it with these. 
Odd birds are to be met with here from October to March. 
14. The Red-backed Shrike ( Lanius collurio ) as a breeding 
species is found over Europe generally ; they arrive in April 
and leave in August and September. They are quite a common 
migrant to this country, passing through Egypt in September 
and arriving here in October ; they are present up to the end 
of March in fair numbers, but last spring they were here till 
late in April. 
Layard reports that they breed in Namaqualand, but this 
is doubtful. 
15. The Isabelline Shrike (Lanius isabellinus) breeds in 
Persia and Turkestan, north to southern Siberia. 
I can find no records of dates of arrival and departure at 
and from these countries. They were plentiful in this country 
last winter and spring from October to February. 
16. The Spotted Fly- catcher ( Muscicajpa griseola ) generally 
distributed over Europe during summer from April to Sep- 
tember. They arrive in Nairobi district about the second 
week of October and remain till third week of March, though 
some remain on till April. 
17. The Willow Warbler (Phylosco'pus trochilus) breeds 
in England and Europe generally ; arriving in April, leaving 
in September. This is the smallest migrant to these shores, 
and is also one of the most common. They arrive here in 
great numbers in October, leaving again in March and April. 
Whilst here they frequent practically all types of country, 
even grass lands, where there are a few odd shrubs. Two 
other species of this group are reported from this country, 
but I have not collected them. 
18. The Great Reed Warbler (Acroce'phalus turdoides) 
