Final answer:
An egregious error refers to a significant mistake, and in biological studies, underestimating population size because animals learn to avoid traps would constitute such an error.
Step-by-step explanation:
The statement: An egregious error is one seldom detected, is false. In the context of biological studies, such as those involving animal populations, an egregious error refers to a significant or blatant mistake. When considering studies involving animals that learn to seek out bait, an underestimate of population size may indeed be an egregious error if the animals are intentionally avoiding the researchers or becoming trap-savvy, thus not being counted accurately. This could significantly affect the results of the study, leading to poor conservation decisions.