82 Mr. W. C. Tait on the Birds of Portugal. 



individuals of dififerent species. It appears to me probable 

 tbat it may occur with individuals of the same species. 

 This is a subject worthy of attention, and it is only by the 

 close study of the migrations of geographical varieties that 

 it can be settled. 



My notes on the migration of birds in Portugal began 

 systematically in 1878, and since that time I have made many 

 thousands of notes,, which are condensed in this list. They 

 have supplied an interest to my walks during my leisure 

 hours. Had I possessed more time at my disposal, they 

 might have been more complete ; but it is useless to expect 

 absolute accuracy, they must go for what they may be worth. 

 I believe it has been noticed by American ornithologists 

 that towards the southern limits of a species the reproductive 

 powers of birds become weakened; and, so far as I have been 

 able to ascertain, this seems to hold good in Portugal. The 

 Missel Thrush and the Hedge Sparrow, which breed in this 

 country, their southern summer limit in the west of Europe, 

 appear to me to lay fewer eggs in Portugal than they do in 

 England. I have mostly found only three eggs in their 

 nests in Portugal, and of the Hedge Sparrow I have only once 

 found a nest with five eggs. To be able to draw a reliable 

 conclusion on this point, it would be necessary to keep for 

 some years a record of the number of eggs in each nest 

 found and repeatedly visited, allowing the bird to sit, of 

 course, to ensure that the nest shall have its full comple- 

 ment of eggs, and to compare the record with a similar one 

 kept in a more northern country. 



During my rambles in the various provinces of Portugal, 

 it has been my constant care to obtain the correct local 

 names of the commoner birds of each locality. My long 

 residence in this country and intimate knowledge of the 

 language have, I believe, enabled me to overcome many diffi- 

 culties and to avoid errors arising from the country people 

 giving the same name to different species in different loca- 

 lities, and occasionally giving the wrong name to myself, 

 for some of the country people are not acquainted with 

 the names of the birds in their own district. In this they 



