Subsequent Nestings. — I was much interested in reading of Mr 
J. K. Jensen’s experience (Auk, January, 1918, pp. 83-84) with the White- 
rumped Shrike (Lanins ludovicianus excubitorides ) at Wahpeton, North 
Dakota, in 1917, as they are very similar to mine at Hatley, Quebec, in 
the same year with the Migrant Shrike (Lanius ludovicianus migrans) an 
account of which it had been proposed to add as a postscript to my “A 
Study of Subsequent Nestings after the Loss of the First,” Auk, Vol. 
XXXI\ , 1917, pp. 381-393, but which had to be omitted at the last 
moment owing to unforeseen circumstances. My pair of birds laid four 
sets of eggs in succession, the first set being taken on May 30, and the last 
on July 4, thus again giving practically eleven days interval between each 
set. The first two consisted of six eggs each, the third of five, and the 
fourth of four, the first nest being in an apple tree twelve feet up, the 
second m a fir eighteen feet up, and seventy-one yards from the first, the 
t nrd in the same apple tree as the first only seventeen feet up, whilst the 
fourth and last was again in an apple tree twelve feet up, and eighty-three 
yards from the fir tree, the site of the second, and one hundred anil fifty- 
four yards from the apple tree, the site of the first nest. Now the most 
interesting fact to me was the pigment in these eggs, for whereas with each 
successive set the size, beauty and construction of the nests fell off, as well 
as the number of the eggs, the pigment or coloring increased if anything, 
the last set being equally or more highly pigmented than any of the others. 
At a Meeting of the Nuttall Ornithological Club held at'Cambridge on 
ovember 19, 191/, at which 1 was present, I mentioned the above case. 
It was suggested by one of the members present (I believe it was Mr. 
Bangs) that the apparent higher coloring of this last set might be due to 
an increased thinness of the inner membrane or lining of the shell or to 
the thinness of the shell itself, or both. The latter (thickness of shell) I 
have examined with a microscope through the blow hole as well as I was 
able but can detect no apparent difference, but this is no easy matter to 
ecide elf hand, and will require much more careful consideration. It 
seems to me that we have here an interesting field for further investigation, 
as there really does not appear to be much known or at all events published 
on the causes and effects governing the pigment of eggs. The English 
Sparrow (Passer domeslicus hoslilis 1 ) amongst its many other sins, has 
been responsible to a large extent for the generally prevailing idea that as 
sets increase pigment decreases (which seems to be the rule in its case for 
some unexplained reason), but my ‘A Study of Subsequent Nestings’ 
already referred to, goes a long way I think to demonstrate that the oppo- 
site is the more general rule in the case of other birds. What we really 
want is a special work dealing with the subject, such as Dr. Bergtold’s 
‘The Incubation Periods of Birds’ and Dr. Casey Wood’s ‘The Fundus 
Oculi of Birds,’ wherein the subjects are fully dealt with and discussed 
in all their bearings.— H. Mousley, Hatley, Que. 
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