The incubation period of birds varies from approximately two to four weeks with three rather well defined periods known; namely, two, three and four weeks. Some of the factors suggested by others responsible for this variation include size of egg, condition of young at the time of hatching, temperature, etc. An evaluation of these factors will be discussed. A study of the histology of the digestive tract of an English Sparrow at the time of hatching (14 days) was carefully compared with the digestive tract of a chick incubated for the same length of time. Likewise, the histology of the tract of an English Sparrow seven days after hatching was compared with that of a chick at the time of hatching (21 days). These comparisons reveal facts of importance to the length of the incubation period.
Proceedings of the Iowa Academy of Science
©1939 Iowa Academy of Science, Inc.
Keck, Warren N.
"Factors Controlling the Incubation Period of Birds,"
Proceedings of the Iowa Academy of Science, 46(1), 453-453.
Available at: https://scholarworks.uni.edu/pias/vol46/iss1/137