176 THE SWANS 



is found in the true wild state in Denmark and Southern Sweden, and migrates 

 thence in winter, it is probable that a few genuine wild birds occur as winter visitors 

 in our islands (cf. Saunders, III. Man. B. B., 2nd ed., 1899, p. 417). [A. L. T.] 



4. Nest and Eggs. As a rule the nest is placed on an islet in a lake or 

 stream, not far from the water's edge. It is a large heap of aquatic vegetation of 

 some sort, five or six feet across and eighteen inches to two feet high, composed of 

 dead reeds, flags, rushes, grass tufts, etc., with a hollow on the top in which the eggs 

 are laid. Both sexes take part in the construction of the nest, the male providing 

 most of the material and the female arranging it, while the male bird frequently sits 

 in the nest before the eggs are laid and shapes it by movements of the breast and 

 tail. The eggs are large and somewhat elliptical in shape, and when freshly laid 

 are generally dull greenish white in colour, occasionally showing patches of a deeper 

 greenish tint under a white incrustation. This tends to wear off during incubation, 

 and when near hatching the eggs are often a polished dirty green in colour. Young 

 females will sometimes only lay three to five eggs in the first year, but the normal 

 clutch ranges from five to twelve, although seventeen have been recorded from one 

 nest (probably the produce of two females). (PL T. ) Average size of 71 eggs 4*44 x 

 2-89 in. [112-8x73-5 mm.]. Incubation is performed chiefly by the female, the 

 male remaining on guard close at hand, but he takes a short turn at incubation 

 when she is away feeding. The estimates as to the period differ considerably, and 

 there is probably some variation due to temperature. Oswin Lee says 34-38 days, 

 Heinroth about 35, Saunders about 36, but a pair of Polish swan hatched out in 

 39-40 days (J. H. Gurney), and Heinroth says it extends exceptionally to as much 

 as 43 days ! Possibly the longer estimates include the period of sitting by the male 

 before the eggs are laid. The usual laying time is from early April onward, but 

 eggs have been recorded in March, and in some cases are not laid till May. Later 

 dates are due to second layings, but only a single brood is reared during the season. 

 [F. c. B. J.] 



5. Food. A good account of the food of this species is quoted by Stevenson 

 from Dixon, who states that they prefer the lower forms of vegetation, Confervce 

 and Cheracice ; then Callitriche aquatica (water starwort), and the Potamogetons or 

 pond weeds. Rhizomata of all sorts of reeds, rushes, arrowheads, etc., are greedily 

 devoured, but water-lily roots are scarcely ever touched. Soft, starchy parts of 

 aquatic plants are eaten, and garden produce is preferred when it has been at least 

 twenty-four hours in the water. To this list Mr. Stevenson adds the American 

 weed, Anacharis alsinastrum. There seems to be no clear evidence of its devouring 



