PRAIRIE HORNED LARK 347 



month. The results showed one year when nesting was impossible 

 and 16 years ,of possible nestings, at Evanston, 111., for tlie years 

 1910 to 1927, inclusive, except 1924. During 10 of the 16 years 

 nestings could have been successful; during 2 they would have been 

 destroyed by snow; and during 4 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 11 years of possible March nests. During 5 of the 11 years, 

 nestings could have been successful; during 4 they 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 will be noted, is a State recently 

 occupied by the lark. It is concluded that 3 or more inches of snow, 

 lasting two or more days, would destroy a nest. 



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 deter- 

 mined 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 responses 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 conceal- 

 ment, thus displaying 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 will be 

 noted later. During these periods nests may be located by a syste- 

 matic search that involves driving the male about until the female 

 is noted. She will flush from the nest and the male will go to her. 

 Then a patient watch of the female will, after a variable length of 

 time, disclose the nest. When young are being fed the male will, 

 at times, disclose the nest much more quickly than the female, for he 

 assists in feeding and has nest-concealing instincts that are very 

 poorly developed. Though the nest of the prairie horned lark is 

 never concealed from above, it fits its semibarren environment so 

 closely that a promiscuous search over a breeding territory is nearly 

 always tiresome and unavailing. An incubating or brooding lark, as 

 will be discussed later, often remains close to her nest on a chilly 



