36 



MIGRATION. 



Eegular 

 migrants. 



Relation of 

 Summer to 

 Winter 

 range. 



Migration of 

 Barn-Swal- 

 lows. 



Moulting of 

 Barn-Swal- 

 lows. 



Sometimes, during a mild series of winters further north, they are absent for several years, 

 whilst an unusuallv severe winter in the north often causes unexpected migration, sometimes 

 in large numbers, of rare birds to our islands. 



The soft-billed insect-eating birds may be called Regular migrants ; their migrations 

 are remarkably constant, and their appearance in their breeding-grounds may be confidently 

 looked for almost to a day. Each species has its fixed time of migration, which appears to 

 be very slightly affected by the condition of the weather. Good weather does not seem to 

 hasten the arrival of these birds at their breeding-grounds, nor does bad weather retard 

 their movements. In their winter-quarters they are almost as punctual ; and though many 

 of these are reached by somewhat circuitous routes, it is remarkable how few birds lose 

 their way on migration. 



As a general rule, amongst regular migrants the further north a bird goes to breed, the 

 further south it goes to winter. As regards species this is very easy to prove, but as 

 regards individuals the statement has often been questioned. The Barn-Swallow is one of 

 those conspicuous birds which is easily identified, and which is so numerous that its 

 absence is quickly detected. Unfortunately we have no reliable records of the departure of 

 Swallows from Central Africa ; but when I was in Natal during the last week in March 

 Barn-Swallows were swarming in countless thousands on the coarse marine herbage on the 

 sand-hills between the sea and the lagoons at the mouth of the Umgeni River. Most of 

 the adults were in splendid glossy blue plumage, having just completed their moult ; but 

 most of the birds of the year had only moulted about half their quills, and would probably 

 not be in a condition to migrate for at least a fortnight. 



Barn-Swallows arrive in North Africa very early during the last half of February, in 

 Southern Europe during the first half of March, but in Central Europe not until the last 

 half of that month. It is perfectly certain that the Natal Swallows if they leave during the 

 first half of April, even allowing them only a few days in which to accomplish a journey of 

 five or six thousand miles, must go to some part of North Europe or to North-west Asia, 

 since the Swallows which breed further south have arrived at their breedina;-s;rounds before 

 the South-African birds have left their winter-quarters. So far as it goes, this evidence is 

 conclusive that, in the case of the Barn-Swallow, the individuals which go furthest north to 

 breed go furthest south to winter. 



The Barn-Swallow, and probably every other species of Hirundinae, only moults once in 

 the year. After having migrated six or seven thousand miles to their breeding-grounds, 

 spent nearly six months in the stormy summer of Northern Europe, again migrated six or 

 seven thousand miles back to their winter-quarters, and spent another six months during 

 the rainy season of Natal, it is a wonder that the poor birds have any feathers left. Some 

 of those which I shot had been in a lamentable condition ; the old feathers that still 

 remained had faded to a rusty brown and were worn to shreds. The plumage of the 

 yoimg birds, though they had only run the gauntlet of one journey and of one summer, is 



