Introduction 9 



climates, and are frequently again in evidence for 

 similar periods in spring. The term resident is applied 

 not only to species which never or very exceptionally 

 leave us, but also to those which are for the greater 

 part non-migratory or only share in limited movements 

 within the kingdom. The word "resident" in fact is 

 often used in a comparative sense, and many birds of 

 this description are really partial migrants ; this must 

 necessarily be the case as long as we cannot safely 

 assert that the individuals met with in winter are the 

 same as those breeding with us in summer. 



Many attempts have been made to ascertain the 

 distances travelled on migration and the direction 

 followed by the flocks, as well as their numbers, the 

 altitude of flight, the pace in the several cases, the most 

 favourable weather, and so forth. Much has been dis- 

 covered with regard to the four last points by continued 

 observations at Lighthouses and Observatories, coupled 

 with those made on the rate of flight of individual birds ; 

 but much less success has attended the constant efforts 

 to determine the two first points. Mr Eagle Clarke in 

 particular has spent an immense amount of time at the 

 seasons of migration at Lighthouses, or on Lightships ; 

 the keepers of the Lighthouses have aided by trans- 

 mitting specimens that have been killed at the Lights 

 from many quarters, while Mr Clarke has prepared an 

 abstract of such reports ; marked rings have been 

 fastened to birds' legs at the nesting places by ornitho- 

 logists in different countries with a view to ascertaining 

 where they occur at later periods ; and finally watchers 

 have noted the arrival and departure of the different 

 species and filled lengthy lists with their observations. 

 Yet all this good w^ork has but resulted in confirming 



