Which of the following statements is true regarding ectoparasites associated with bats?

Fleas, ticks, and mites are indeed commonly found among bat colonies, making the assertion that they are rare inaccurate. Ectoparasites thrive in the communal living conditions of bat colonies, where they can easily access food sources due to the close proximity of their hosts.

Regarding their impact on bat health, ectoparasites can have significant effects, including blood loss, irritation, and potential transmission of pathogens. This means that they do affect bat health, contradicting any statements suggesting that they do not.

The statement that ectoparasites tend to be highly populated is a further reflection of their typical presence within bat colonies. Due to the social nature of many bat species, ectoparasites can flourish, leading to substantial populations, but this characteristic does not support the choice identified as the answer.

In summary, the true nature of ectoparasite density and commonality among bats makes the other options less valid, highlighting that ectoparasites are prevalent and can impact both bat health and their population dynamics.