val INTRODUCTION. 
young annually in the British Islands, and are to be found 
in some part or other of the United Kingdom throughout 
the year. Of these many are partially migratory, as, for 
mstance, Falco esalon, F. tinnunculus, Otus brachyotus, Turdus 
musicus, T. gorquatus, Regulus cristatus, Motacilla yarrellii, 
Linota cannabina, L. flavirostris, L. rufescens, Columba palum- 
bus, C. enas, Charadrius pluviahs, Atgialitis hiaticula, Tringa 
alpina, Scolopax rusticola, Gallinago media, and others. 
Nevertheless, as specimens of all may be obtained in some 
locality or other during every month in the year, they may 
be regarded for all practical purposes as residents. 
PeriopicaAL Micrants are those which visit us annually 
and regularly at particular seasons, and whose advent and 
departure may be dated in advance with considerable preci- 
sion. Of these we have familiar examples in Luscinia philo- 
mela, Cuculus canorus, and the Hirundines, which come here 
for the summer, and Twrdus iliacus and T. pilaris, which 
spend the winter with us; while others, like most of the 
Tringide, perform a double migration and pass through the 
country twice a year, viz. in spring and autumn. 
The Annvaut Visrtants comprise those which occur in 
some part of the British Islands. annually, but compa- 
ratively in very limited numbers and at irregular and uncer- 
tain intervals. The month in which some or one of them 
may be expected may be named; but the uncertainty of their 
arrival im any particular county precludes their being placed 
with the Periodical Migrants. Amongst these may be men- 
tioned Oriolus galbula, Regulus ignicapillus, Ampelis garrulus,, 
Emberiza lapponica, Linota linaria, Pastor roseus, Upupa 
epops, Coracias garrula, Merops apiaster, Recurvirostra avo- 
cetta, Ciconia alba, Grus cinerea, Anas strepera, Cidemia 
fusca, Sterna dougallii, and Larus minutus. 
Of the Residents, which, as above mentioned, may be 
