76 Trans. Acad. Sci. of St. Louis 
for good nests, since ‘‘the season is warmer.” Jones (1892) 
takes it as a matter of course and writes that nests in February 
or March ‘‘would very naturally be more elaborate and warmer 
while those in July would be very slight.’’ I hesitate to at- 
tribute any such prescience to the Larks. I thought by weighing 
the nests to prove or disprove this, but the weighings show 
nothing (see tables 7 and 8) for the dirtier material of later 
nests overbalances any lessened bulk of material. It is true, in 
general, and in some cases conspicuously so, that later nests 
have less bulk, less material than earlier, even for the same in- 
dividual (see Table 8.) The explanation for this lies, I firmly 
believe, merely in the fact that there is far less desirable ma- 
terial later in the season than earlier, for vegetation has grown 
up to conceal and to make inaccessible the dead grasses, or rains 
of May and June have rotted them down. To confirm this take 
the case of nests B1, Bz, Bs (Table 8). Bu, in March, was bulky, 
well made, of fine rootlets and weed stems; Bz, in April, was 
a flimsy affair of dirty stems and leaves; but Bs, in June, was 
well made, about as bulky as Bi. The explanation is simple. 
Just prior to the construction of this third nest a field of fall 
rye was turned under. On this overturned ground Bs was 
placed and great quantities of fresh, fine rootlets and dead leaves 
of the rye were near at hand. Sutton (1927, p. 136) also at- 
tributes variations in nest structure to variations in availability 
of material and adds that first nests are better because there is 
more time before the ‘‘onerous duties of brood-rearing have 
been assumed.’ 
One thing more is to be mentioned concerning the nests of 
the Prairie Horned Lark. This seems to have more than 4 
little of prescience in it. By a reference to Tables 3 and 4 it 
will be seen that nearly all nests were, in spite of their open lo- 
cation, placed beside some protecting object, usually a tuft of 
dead grass. There is something more than mere chance ope!- 
ating here, that of more than thirty nests nearly all should have 
this protection on the west or northwest. 
“Pavings.”—About a portion of the rim of the nests of 
O. a. praticola, usually on the side away from the protecting 
elod or grass clump, there was nearly always a definable layer 
of material (clods or pebbles), which the Lark had laid down 
during nest building. Peabody (1906) has, very appropriately, 
