Egg markings and sunlight.



195



more exposed nests containing the more heavily spotted and blotched

eggs; moreover I noticed that in these, as in other species, the eggs

first deposited before the hen begins to incubate, are less distinctly

marked than those laid subsequently, I imagine because greater

warmth is generated when the mother is snug than when she is out

in the open. In the case of one of a clutch of white blackbird’s

eggs given to me by a lady friend I regret that I failed to ascertain

the position in which she discovered the nest.


Eggs of the robin laid in holes in fruit trees, where the sun

did not reach them, were noticeably whiter and more sparingly

speckled than those taken from sloping banks on the borders of

woods or from openings in ivy covering walls, where they were

exposed to the light. In most of my wren’s nests the spots are

reduced to points, as might be expected from the small entrance to

these cave-like nests. In a case where a blue-tit which had pro¬

bably been deprived of its own nest, had deposited three eggs in

that of a sand-martin the markings were few and reduced to mere

dots, thus again favouring th6 view that sunlight modifies the

character of the eggs.


Of the British Hirundinida, as is well known, the only species

which lays spotted eggs is the swallow, the nest of which is open at

the top, and the most heavily marked eggs of that species which I

obtained were laid in a nest built under a portico of a mansion in a

position exposed to bright light : I figured one of these eggs in my

“ Handbook of British Oology ” pi. XXXVII., fig. 6. When the

nest is built, as it sometimes is even in England, close below the

overhanging eaves of an outhouse and therefore in shadow, the

markings are small and inconspicuous, at any rate that is my

experience.


The spotted flycatcher usually builds in a fairly exposed

position, often on the branch of a fruit-tree trained against a wall,

or in a slight depression at the junction of a branch with the trunk

of a fruit-tree ; but sometimes in a hedge or the forking branches of

a large shrub ; the largest, palest and least marked eggs which I ever

found were in a nest built in a Hawthorn hedge and which did not

greatB differ from some eggs of our greenfinch ; this nest w r as, of

course, less conspicuous than if it had been situated on an open



