Egg viarkings and sunlight.



193



morning', I enjoyed a fine view of a great spotted woodpecker

engaged in working assiduously at the trunk of a silver birch tree,

of which one or two specimens in the vicinity showed unmistakable

indications of the bird’s handiwork. My attention was first attracted

by the woodpecker alighting on the tree, and through my glass I

was able to put its identity beyond doubt, the brilliant crimson of

the under tail-coverts being plainly seen.


Since that date I have not been fortunate enough to observe

this interesting bird again, and, so far, its smaller relative, noticed

by Mr. Stone, has not come across my path.



EGG MARKINGS AND SUNLIGHT.


By Dr. A. G. Butler.


Very little seems to be known respecting the production of

the markings on birds’ eggs. In some cases, of course, the colouring

and ornamentation are admitted to be protective and consequently

are to a great extent hereditary ; but, in many cases, the ground¬

colouring and striking character of ornamentation render them

extremely conspicuous and therefore are valueless for protective

purposes.


During the time when J was an industrious collector of our

British nests and eggs I paid particular attention to the greater or

lesser intensity of the markings on the specimens which I found, in

conjunction with the character of the nests and nesting-sites in

which they were obtained : in a few cases also I noted peculiarities

in the colour-scheme of eggs laid in my aviaries : these observations

all tended to convince me that sunlight and heat during the period

of oviposition have a marked effect in intensifying the colouring of

eggs.


With a few notable exceptions, birds which lay in comparative

darkness produce unmarked, and more often than not white eggs :

as examples one may cite the spotted pardalote or panther-bird of

Australia which builds in a hole, the waxbills, grassfinches and

mannikins which lay in spherical nests often with a tubular entrance,

some of the typical weavers whose retort-shaped nests are closely



