Summary 137 
calculate the frequency, over a period of years, with which nest- 
ings would occur in March, by a study of weather summaries for 
the month. The results showed one year when nesting was im- 
possible and sixteen years of possible nestings, at Evanston, III. 
(For. the years 1910 to 1927, inclusive, excepting 1924.) During 
ten of the sixteen years nestings could have been successful ; dur- 
ing two they would have been destroyed by snow; and duvie 
four, weather and snow would have made success problematical. 
At Ithaca (for the years 1916 to 1927 inclusive) the summaries 
showed one year when nests were impossible and eleven years of 
possible March nests. During five of the eleven years, nesting 
could have been successful; during four they would have been 
destroyed by snow; and during two their success would have 
been problematical. Summaries could not be obtained for years 
previous to the earliest here noted. On the basis of those obtained 
it is shown that northern Illinois has more favorable weather in 
March than Southern New York. New York, it is to be remem- 
bered, is a state recently occupied by the Lark. 
It is concluded that three or more inches of snow, lasting two 
or more days, would destroy a nest. 
4. On finding nests and the reaction of nest-building and egg- 
laying Lark. It is suggested that the discovery of nests during 
nest building is possible by locating first the calling or singing 
male. At this period the male will be attending the female 
closely and she will be discovered shortly. The status of nesting 
can always be determined by the actions of the female. During 
nest building she is very restless, runs here and there, flies up 
and away, but shortly returns. Eventually she may disclose the 
site of the nest excavation. These reactions are instinctive re- 
sponses to the desire for nest concealment. All nest building 
Seems to be done by the female. 
_ During egg laying the discovery of a nest is at best accidental. 
Neither male nor female has been noted to approach a nest 
during this period. They express no solicitude beyond that of 
nest concealment, which is a remarkable nonchalance, especially 
on the part of the female. This reaction is so marked that an 
observer can nearly always be assured of the status of nesting 
whenever it is noted. 
When incubation has begun the behavior is very different, as 
is also the behavior after the eggs have hatched. These reactions 
