VARYING FECUNDITY IN BIRDS 191 



thological authorities informed me, for them to nest, they disappear else- 

 for instance, that a hedge - sparrow where. Some agency in the bird world 

 laid from four to six eggs in a clutch, brings them news of lovely nesting 

 Yet near my northern home I never weather in Cheshire and Derbyshire, 

 found a larger clutch than two ; and or else they migrate in sheer despair, 

 so scant was the insect life of the At any rate March's promise of an 

 neighbourhood that a year would occa- increased avi-fauna too often brings 

 sionally pass without my discovering but regrets in May. And even when a 

 a single nest of the species. My note- few insectivorous birds had the hardi- 

 books record many clutches of two hood to remain, their clutches were 

 eggs, and a friend's voluminous diary invariably very small, clearly evidenc- 

 can only furnish three nests in excess ing the poor condition of the parents 

 of that number during a continuous and the sparseness of the food supply, 

 residence of twelve years in the same Contrast the Bristol district, for in- 

 district. In Gloucestershire, on the stance, in which I have often found 

 contrary, I have no recorded clutch of six hedge-sparrows' nests each contain- 

 less than five, and six was so common ing five or more eggs, within the con- 

 that it excited no wonder. In Lanca- fines of a single meadow, the hedges 

 shire the lingering winter of a northern of which also sheltered robins and 

 latitude, combined with a foul and chiff-chaffs and whitethroats, all cater- 

 smoke-polluted atmosphere and the ing for hungry families on very similar 

 absence of plant-life, rendered insects lines, and each with a full complement, 

 nowhere abundant. In most English Again, the standard authorities assert 

 localities, if a pair of resident birds are that a sand-martin is accustomed to 

 seen frequenting the hedgerows late lay from four to six eggs in its solitary 

 in March, they will stay to breed, but clutch year by year. In the south and 

 often in Lancashire a pair of birds west this rule seems justified, five being 

 that have wandered thither in the the commonest number, and four being 

 winter grow weary of awaiting a tardy distinctly exceptional. I found a colony 

 spring, and realize that the supply of of martins in Lancashire. It was a 

 food on which they have contrived to miniature amphitheatre of oozing clay, 

 support themselves will be quite inade- its lofty sides dotted by Irishmen 

 quate for the demands of the nesting wielding spades and daily encroaching 

 season ; and so just when you look further on the plateau of meadow-land 



