No relationship between clutch size and the embryonic heart rate of Eastern Blue birds

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Northern Kentucky University
Natural selection will favor birds that maximize their fitness with a clutch size that will produce the most viable offspring while not being too stressful to take care of. We predicted that nests with a larger clutch would have a slower development, and therefore a lower heart rate, since it would be more difficult for the mother to incubate all the eggs evenly. For this study we used the Buddy digital egg monitor, which uses infrared light absorption in order to noninvasively measure the embryonic heart rate, on Eastern bluebird (Sialia sialis) eggs to determine if the clutch size had any effect on the heart rate of the individual eggs. We collected 237 readings from individual Eastern Bluebird eggs which came from 28 different nests. Contrary to our prediction, our results showed that the clutch size had no effect on the heart rate of the eggs. However, we did find a positive relationship between embryonic heart rate and both age of the eggs and external temperature. This study provides new information on the embryonic heart rate of wild birds and more insight on the different factors that may impact the rate.
2021 Celebration of Student Research and Creativity presentation
Eastern bluebird, Animal clutches, Heart rate monitoring