Thermal physiology contributes to limits on heat tolerance and species’ geographical distribution. Small birds living in the desert is particularly at risk of heat stress because of heat waves, diurnality, and limited access to food and water. Using zebra finches (Taeniopygia guttata) as a model system, we tested whether temperatures at the upper limit of the thermoneutral zone would elicit anti-damage regulators to minimize cellular damage caused by heat. To test this, blood samples from birds were collected both in the field and lab. Laboratory birds were placed in two treatments: 1) 30°C for 8 hours and 18°C for the rest of the day, and 2) 40°C for 8 hours and 28°C for the rest of the day. These treatments occurred for 2 weeks, then all birds went through a period of the cooler temperatures (18°C or 28°C) for 2 weeks. After that, they were exposed to the higher temperatures (30°C or 40°C) again for 8 hours. Whole blood was collected from these individuals after the last heat exposure. Blood samples from field birds were collected during Cool temperatures (three or more days of maximum T_a less than or equal to 36°C) or Hot temperatures (three or more days of maximum T_a greater than or equal to 39°C). Currently, we are quantifying differential gene expression of heat shock protein (HSP) 60, HSP70, HSP90, interleukin 1 beta (IL1B), and APTX (mitochondrial DNA repair gene) in field samples and HSP70, HSP90, and IL1B in lab samples with the prediction that these genes will be elevated in the zebra finches exposed to 40°C in the lab or Hot temperatures in the field.