WILLOW WARBLER 



description, and therefore the prefix "Willow" which has been 

 applied to it, and which may seem somewhat trivial, is in 

 reality expressive of a characteristic, though but a small one, 

 of the species. 



In the order of migration the bird must be placed between 

 the Chiff-chaff and Wood Warbler, since it arrives considerably 

 later than the former species and somewhat earlier than the 

 latter. As in the case of the Chiff-chaff, the date of arrival 

 varies year by year — at least in the west Midlands where my 

 records have been kept — the earliest record I have being 

 March 30th, and the latest April 16th. On the average the 

 first males may be expected towards the latter end of the first 

 week in April, but all the males do not arrive on the same day 

 or during the same week, the migration extending over some 

 days. Neither do they all arrive before the females, but the 

 majority do so ; the first females, however, are usually later by 

 a week or more in reaching the breeding grounds than the first 

 males. Meteorological conditions no doubt influence the 

 migration and are a cause of erratic movement. Insect life 

 is scarce in cold springs, and in exceptional weather almost 

 entirely absent for a time, and upon insects these birds 

 entirely depend for sustenance at this season of the year. 

 When, therefore, we find the smaller and more delicate-looking 

 Chiff-chaff a fortnight earlier still at this critical period, we 

 naturally seek an explanation. What difference there can be 

 in the constitution of the Chiff-chaff that enables it to face 

 such inhospitable conditions so much earlier we do not know, 

 and yet there must be some reason, some advantage to be 

 gained by its doing so. Can it be that the restless activity, 

 so prominent a feature of its behaviour, enables it to find a 

 living even under the most adverse conditions ? It may be so, 

 for in studying the two species the Willow Warbler certainly 

 appears to be less active and rather more sluggish in its move- 

 ments. But although this may be a reasonable explanation 

 of the one being able to exist under more trying conditions 

 than the other, yet it leaves the main difficulty unsolved, 



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