134 Trans. Acad. Sci. of St. Louts 
C. Nesting territories. 
1. At Evanston, Illinois. A breeding territory was delimited 
by a male Lark on February 7, 1926, at Evanston, Illinois. From 
his selected territory he could not be driven. This territory was 
about 100 yards square. Late March snows disrupted all terri- 
tories and it was not learned here whether the original sites were 
ultimately resumed or whether the same territory was main- 
tained through more than one nesting. The pressure of vege- 
tation in late May and June greatly modified the territories at 
Evanston and caused, eventually, the abandonment of most of 
those on the erstwhile golf course. 
2. At Ithaca, New York. A male Lark was forced to mark 
territory for the first time on March 13, 1927, though it had 
undoubtedly been established some time before this. Territories 
voluntarily marked were somewhat larger than those indicated 
when the birds were forcibly driven out. The regions of a breed- 
ing territory most frequently occupied were those boundaries 
which joined the territories of a neighboring Lark. 
The territories at Ithaca were much larger than those at 
Evanston. (Possibly due to fewer Larks attempting to occupy 
them.) At Evanston they were seldom over 100 yards square, 
at Ithaca they ran out to lengths of 300 yards, and widths of 
200 yards, in March and April. 
In general all suitable territory was occupied at Ithaca and 
most boundaries were established by the margins of unsuitable 
areas (see Figures 2, 3 and 4), though a large amount of suit- 
able territory, extending north of territory ‘‘C’’, was used only 
in part by this bird. 
Boundaries between males were often definitely established on 
ground that had no natural marker whatsoever. 
3. History of territories in subsequent nestings. The territory 
history of three pairs of Larks was followed from March to June 
at Ithaca. One influence only modified the territories, viz., the 
growth of vegetation. Territory ‘‘A’’, entirely on fall wheat, 
was abandoned completely by the close of the second nesting in 
May. Territory ‘‘B’’, in part on fall wheat and in part on the 
gardens, was gradually reduced to the gardens, from an area 
once 300 by 200 yards to an ultimate area about 100 by 50 yards. 
Territory ‘‘C’’, almost entirely on the gardens, suffered no major 
