^5 



Accordingly, the usual month of niditication throughout the country is 

 the month of April. From North Carolina, north through the Atlantic 

 states, there is a gradual increase in the dates to New England, and west 

 from the Middle states to the boundary of the Humid Province, with the 

 exception of Illinois, southern Wisconsin, and Iowa. The latter av- 

 eraging earlier than Pennsylvania, which may be accounted for by the 

 absence of notes on large series from any one locality, the numerous but 

 short reports from this section of the country containing records of the 

 earliest sets only. In the Arid Province, California averages later than 

 North Carolina, with Oregon and Washington but two days later than 

 New England. The given average in the Arid Province, with the excep- 

 tion of California, can hardly be relied upon, by reason of the small 

 amount of material collected. 



Incubation. — It has been seen that the nesting period extends from 

 early March to late June, and that climatic and seasonal conditions 

 greatly influence the birds. Hence, it is evident that to ascertain the 

 correct period of incubation would require considerable self-denial or an 

 unusual talent for original investigation on the part of the amateur. 

 Therefore it is not at all surprising that nothing of value has been re- 

 ceived bearing on this subject. I have found the period of incubation to 

 be about fourteen days ; but the difficulty of making observations, coupled 

 with the lack of sufficient time to visit the nest whilst the parent bird 

 was off in search of food, and the consequent meagerness of data, com- 

 pels me to state that I am by no means sure that this is the average period. 



Many ornithologists lack the opportunity and others the inclination to 

 penetrate the mysteries of this neglected branch of the science. While 

 we might have fewer eggs to hoard in our cabinets, or proudly exhibit to 

 our oft-times overcurious friends and neighbors, we might secure notes 

 of far greater value from a scientific stand point, and at the same time 

 show our love for the science, if we would pay more attention to this point. 

 That this subject is not open to all is evident. It requires a thorough 

 knowledge of the habits of the species under observation, unlimited time, 

 much patience and often considerable wood craft, with too often disap- 

 pointment and defeat the only reward. 



Me.\surements. — "The majority of widely distributed species are 

 more or less affected by geographical variations, from varying influences 

 of climate and other surroundings." — Robei't Ridf{zi.-}ix. If this be true 

 in relation to the birds, and the researches by our most eminent scientists 

 have proven it to be so, it must almost necessarily hold good in respect to 

 their nests and eggs. While the nest must vary indefinitely in accord- 



