THE WILLOW-WRENS OF A LOTHIAN WOOD. 403 



The facts of departure from nesting-haunts are always more 

 difficult to grasp than those of arrival. It seems, however, that 

 many of the adult Willow-Wrens leave their breeding-grounds in 

 the end of July, and perhaps the only birds remaining are those 

 with late broods. This departure, however, is largely concealed 

 by the leisurely through-passage of the birds from further north. 

 Young birds commence to wander as soon as they are in- 

 dependent of their parents, and by mid-July, in a normal 

 season, many show themselves in gardens and other spots 

 hitherto strange to the species. Through-passage of northern 

 birds continues throughout August, but rapidly thins out in 

 September, and usually all have passed on by the end of that 

 month. 



Distribution of Pairs and Nests. — In 1910 the wood, which, 

 as already stated, is 25*999 acres in extent, held twenty-two 

 pairs of Willow-Wrens, and, in addition, what appeared to be 

 two unmated males. (The " song-centres " of these two birds 

 are indicated in the map thus : XXIII, XXIV.) 



That mateless birds occur, even amongst our small Passerines, 

 can scarcely be doubted. The fact, when it exists in such an 

 abundant species as the Willow-Wren, is not very easy to appre- 

 ciate, but in one or two other warblers, notably the Blackcap, I 

 yearly meet with instances. In this county — unlike its relative 

 the Garden-Warbler, which is generally, though sparingly, dis- 

 tributed — the Blackcap is local and somewhat irregular in appear- 

 ance. The fact that males are more abundant than females has 

 been repeatedly indicated by the arrival of scattered birds of the 

 former sex in spring, which settle down in suitable haunts for 

 some weeks, and, failing to procure mates, wander away into 

 fresh ground in June or early July, whereas those few which are 

 mated remain until August. The same phenomenon is to a 

 lesser extent apparent in the Garden-Warbler. It is probably 

 these wandering, unpaired birds which so frequently show them- 

 selves at curious times of the year in localities where none of the 

 species breed. Thus, I have records of solitary male Blackcaps 

 appearing in non-breeding spots in June 27th, July 2nd, July 

 3rd; Garden-Warblers on July 1st, July 7th; and Wood-Wrens 

 on June 20th, June 22nd. 



Another local instance, somewhat similar to those of Black- 



2i2 



