Final answer:
The question cannot be answered without additional data from a study or observation context that specifies the count of harpy eagles at the given height.
Step-by-step explanation:
To determine how many harpy eagles were spotted 10 to 39 meters high in a tree, additional information is required that is not provided in the question. The answer would typically be found in the results section of a field study or an observational experiment that was conducted. Without this specific data or context from a study, text, or a given set of data, it is not possible to answer this question accurately.