Development of a Thermocouple Device to Measure Zebra Finch Nest Temperature During Incubation

Abstract

Determination of avian nesting behavior is challenging for a number of reasons: accessing the nest can be difficult, electronic recording devices are costly and may be damaged by the parents, and presence of the device may disrupt normal parental behavior. External devices such as video cameras can be used to record nesting activity, but these are expensive and labor intensive (i.e., every minute recorded requires an equal amount of viewing time and encoding by the researcher) and so are not feasible for long-term observations. Because the goal of avian incubation is to maintain the eggs at the temperature suitable for optimal embryonic development, we investigated whether the use of thermocouples placed in the nest could as a surrogate for nest attentiveness. We tested three types of thermocouples for this purpose. Because zebra finches are prolific nest builders and will use any material available for nest-building, an exposed thermocouple wire is vulnerable and could easily become damaged. Therefore, we chose to disguise two of the thermocouples by embedding them in dummy eggs and placing the eggs in the nest at the end of egg-laying. We emptied nonfertile zebra finch eggs and experimented with filling them with different substances including agarose and a silicone adhesive compound that, when cured, would secure the thermocouple in the egg and remain thermally responsive. Testing with breeding zebra finches established that this device was well tolerated and provided a good measure of incubation behavior.