Monitoring the life status of a developing embryo is very useful, especially during last days of incubation when hatching could potentially be assisted if deemed necessary. A commercially available digital egg monitor (Buddy, Vetronic Services, Devon, UK) uses noninvasive methodology to monitor the heart rate of an embryo by measuring the amount of infrared light absorbed by embryonic blood. Thirty specific pathogen-free (SPF) chicken eggs (29 fertile) were incubated at 37.8 ± 0.1°C and the heart rate of each embryo was measured. Heart rates were first detectable in 13 eggs at day 6 of incubation. At day 7, an average heart rate of 170 ± 20 beats/min was detected in all 29 fertile eggs, which is comparable to reported values. Ten additional SPF chicken eggs were evaluated at day 13 of incubation to test the effects of ambient temperature changes on embryonic heart rate. Embryonic heart rates dropped from 262 to 106 beats/min in eggs kept at room temperature (25°C) for 90 minutes and to <60 beats/min after 70 minutes at 5°C. Heart rates increased to 215 beats/min after 75 minutes at the original incubator temperature. Thirty (26 fertile) incubated turkey eggs were also evaluated with the digital egg monitor. Heart rates in 10 embryos were first detected at day 9 of incubation. At day 12, embryos had an average heart rate of 234 ± 10 beats/min. The digital egg monitor was also used to measure the heart rate of peregrine falcon (Falco peregrinus) and Northern goshawk (Accipiter gentilis) embryos.