On the Froductio7i of Colour in Birds Eggs. ;;9 



expected from their known keenness of vision), and tlio 

 influence upon the colouring of the eggs remarkable. The 

 nests of the eagles, falcons, and hawks are large, and exposed 

 on the tops of trees or on the ledges of lofty cliffs. The eggs 

 are generally more or less blotched with rusty red, presenting 

 a marked resemblance to old blood spots, such as the family 

 are so well acquainted with. The nankeen kestrel breeds 

 in spouts of trees, where, of course, the colour cannot 

 be protective, yet the eggs retain the family peculiarit}^ 

 Here we see natural selection apparently ruled out of court, 

 and mental receptivity as the sole cause of the variations in 

 the one specified direction. The eggs of the other members 

 of the family are, from their situation, inaccessible, and it 

 therefore seems very questionable whether the factor of 

 natural selection has operated at all in the case of the eggs 

 of this group. 



We find very different degrees of development of the 

 blotches. In one clutch of the sparrow-hawk (Accipiter 

 torquatus) one egg was white, a second smudged, and the 

 third well blotched. In a clutch of the goshawk (Astur 

 approxhnans), again, one egg was smudged, one smudged 

 and blotched, and the other blotched. Similar gTadations 

 are to be observed in the average colour of the species. The 

 eggs of the harriers (Circus), which lay on or near the 

 ground, and generally among thick scrub, and those of the 

 crested hawk (Baza suhcristata), which builds in the holes 

 of trees, are pure white ; and we have gTadually more and 

 more colour introduced, until the climax is reached by 

 the brown hawks (Jeracidea herigora) and kestrels 

 (Tinnunculus cenchroides). 



Great irregularity and much play of variation amongst 

 individuals, characterise eggs, which derive their colour 

 from changing and varjdng appearances. We obtain thus 

 a natural explanation of the infinite variety of colouring in 

 the eggs of the rapacious birds, and of such birds as the 

 magpies and the sparrows. 



Many birds continue to protect their eggs themselves, 

 consciously or unconsciously. Some, as the partridge, will 

 cover up the eggs when they leave the nest. The grebes 

 lay eggs which are at first white, but become stained by 

 mud from the body of the sitting mother bii^d, usually brown 

 and gradually browner, a tint well in keeping with the 

 colour of the nest, of the dead reeds and leaves. Many of 



