Abstract Within certain limitations of timing, embryos of one of the two species, Bobwhite quail (Colinus virginianus) and Japanese quail (Coturnix coturnix japonica), influenced the hatching time of embryos of the other species when embryonating eggs of the two species were in contact during the latter stages of incubation. When the expected hatching time of Bobwhite quail was approximately three days later than that of Japanese quail, neither species exerted a significant influence over the hatching time of the other. Virtual synchronization of hatching time was achieved when Japanese quail were expected to hatch approximately two days ahead of Bobwhite quail and was accomplished by a significant speeding-up of hatching time of the Bobwhite quail coupled with a significant retarding of hatching time of the Japanese quail. Synchronization occurred where Japanese quail were expected to hatch approximately one day ahead of Bobwhite quail; however, in this case, the synchronization was achieved solely by a significant retarding of hatching time of the Japanese quail. When eggs of the two species were set at such a time that they were expected to hatch at approximately the same time, synchronization of hatching time was easily achieved. Where Bobwhite quail were expected to hatch approximately one day ahead of Japanese quail, sycnhronization of hatching time was not achieved even though hatching time of the Japanese quail was significantly speeded-up. Where Bobwhite quail were expected to hatch two days ahead of Japanese quail, neither species exerted a significant influence over the hatching time of the other.