Reproduction 73 
the contrary. This cavity is most probably dug with the bill, 
though there is no positive evidence on that score. However 
Sutton (1927) after saying (page 136) that a ‘‘natural de- 
pression is sought,’’ adds (page 138) that the ‘‘female was 
working busily . . . the bird dug at the earth with her bill and 
kicked the loose material out with her feet.’’ Usually the exea- 
vation is made partly under a clod or a tuft of grass (Plate V, 
Fig. 2; Plate VI; Plate VII, Fig. 1). The bulk of the material 
placed in this cavity consists of grass stems and leaves and often 
heavier weed material with comparatively coarse roots and much 
dirt. The lining is usually of finer material, plant down, paper, 
feathers, fine rootlets. For a careful and extensive tabulation of 
nests, nest sizes, sites and materials see Tables 3, 4, 7 and 8. The 
photographs of numerous nests among the plates will give also 
the structure and location of nests at various seasons. 
The time required for nest building was not ascertained def- 
initely. Mouseley (1916) gives four days for this phase in a ease 
he carefully watched after removing the eggs of a previous set. 
The eggs were taken April 14, the new nest was begun the next 
day, completed April 18, the first egg was laid April 9. My 
observations showed, in the case of renestings in April after snow 
had destroyed previous nests and in one case where cultivation 
destroyed a nest, that the Lark works at times considerably 
faster than this. Thus on April 6, 1927, at Ithaca, one Lark 
dug three cavities, almost completed the lining of one on that 
date (eight or ten hours), but then abandoned all of them. The 
nest she finally occupied was not discovered until after incuba- 
tion had begun, but counting back from the hatching date, allow- 
ing the optimum incubation period (11 days), she must have 
completed this fourth nest-start between the 6th and the 8th, for 
the first egg was deposited on the latter date. It is probable 
that this nest was also begun on the 6th (for the female was 
repeatedly observed in the vicinity where the nest was finally 
found), and that she completed it in two days time or less. 
Seasonal Variation in nest structure—An often repeated 
Statement regarding Lark nests must be considered before the 
subject is dismissed. Thus Davie (1889), quoting Jones (1892), 
Bendire (1895), quoting Harris, Hess (1910), Sutton (1927) as 
well as other writers, say that later nests are more poorly built 
than early nests. This is attributed to a lessened ‘‘necessity’’ 
