A Protracted Incubation Period in the Mourning Dove
A Protracted Incubation Period in the Mourning Dave.-During the summer of 1942 the writer studied caged White-winged Doves (Melopelia asiatica) with the cooperation of Carlos Stannard, of Phoenix, Arizona. A large three-compartment outdoor cage was constructed. In addition to the White-wings under observation we also obtained two pairs of aviary doves to serve as incubators and foster parents for wild White-wing eggs and young. One pair was Ring-necked Doves (Streptopelia risoria) .
The pair of Ring-necks obtained from a Phoenix aviary immediately set to work and constructed an excellent nest in the space provided; they spent much of each day brooding on the empty nest, and it was soon apparent that both were males.
On June 4 Stannard flushed a female Mourning Dove (Zenaidztra macrolcra) from a nest in an orange tree containing one egg. Passing to and fro at work he noted that the Mourning Doves did not return to the nest, and on June 7, motivated by idle curiosity, be took the single egg from the nest of the Mourning Dove and placed it in the nest of the male Ring-necks. Both males immediately started to brood the egg, sitting side by side upon the nest all day but deserting the nest at night to roost upon an open perch in the cage.
This procedure continued day after day to our great amusement; we had little thought that anything would result. The egg had not been incubated before its removal to the Ring-neck nest, and night temperatures dropped to as low as 65” and were seldom over 70”.
It was therefore with great surprise that on the evening of June 29 Stannard noticed one of the Ring-necks on the nest at 7:30 p.m., Standard Time. He went out to the cage at 9:00 p.m. to investigate and found the egg hatched, the tiny squab in the nest, but both male doves perched upon the roost. One of the males was placed upon the nest by hand and remained there the rest of the night. Next morning, after feeding, both males clambered onto the nest and in their efforts to brood the tiny youngster they succeeded only in smothering it and killing it.
The normal hatching period for the Mourning Dove in Arizona seems to be 14 or 15 days. Here, however, an egg was unattended in the nest for four days, then for 21 days was incubated under the adverse conditions of brooding by day and exposure by night to temperatures ranging from 65’ to 70’; yet from it hatched an apparently normal squab. During field studies on the White-winged Dove in the Phoenix district, the writer had frequently been puzzled by nests in which incubation appeared to be erratic, uncertain, or intermittent, and in which healthy young White-winged Doves were finally found; in other instances incubation continued for several days more than the normal White-wing hatching period. It would seem that plausible explanation may be suggested by the incident herein described.-JHONSON A. NEFF, United States Fish and Wildlife Service, Denver, Colorado, May 4,1944.
