Thermodynamics and Upper Lethal Temperature of California Valley Quail Eggs


Erin Moser

Document Type


Degree Name

Master of Science (MS)


Ag Science and Natural Resources

Date of Award

Summer 2021


The objectives of this project were to determine the upper lethal temperature (ULT) of California valley quail (Callipepla californica) embryos in ovo and the thermal equalization times of their eggs. The temperatures influencing development are unknown for valley quail. Historically, data from animal models like the chicken (Gallus domesticus) have been used for quail species; however, recent studies have shown that key temperatures influencing development vary among galliformes. The ULT for bobwhites occurs at 51, 50, and 47° C for 1, 3, and 6 hr of exposure, respectively. Chicken embryo ULT is reported at 43° C. Mean time (±SE) to equalization temperature for fertilized northern bobwhite eggs was 38 ±1 min, less than the ~2 hr for chickens. To investigate ULT for valley quail eggs, eggs were assigned a pre-incubation temperature ranging from 40–51° C, in increments of 1° C, with exposure times of 1, 3, or 6 h. An additional 3 fertilized valley quail eggs were placed into the pre-incubation chamber to record thermal equalization times. The ULT for valley quail occurs at 46, 45, and 45° C for 1, 3, and 6 hr of exposure, respectively. Mean time (±SE) for thermal equalization for valley quail eggs was 43.92 ±4.11 min. Thermal tolerance of valley quail is below that of bobwhites, but above that of chickens. Valley quail embryos exhibit a high tolerance to brief hyperthermic exposure, surviving temperatures up to 45° C for 1 h, and 44° C for 3 and 6 h. In their native range in California, valley quail can experience temperatures up to 43.33° C, during drought years, resulting in the mean proportion of juveniles in a population of 35%. The results of this study contribute new knowledge on the thermal tolerance of valley quail and could partially explain the observed reduction in juvenile production in drought years.


Kelly Reyna

Subject Categories

Agriculture | Animal Sciences | Life Sciences