The reading and listening discuss about thepossible explanations regarding to the bird’s behavior of anting, which is anactivity to have ants rub on the birds’ skin. The passage mentions threetheories to explain the behavior. Whereas, the professor totally refutes thethree presented in the passage.
Firstly, the professor rebuts the reading’s ideathat birds use anting to irrigate skin during the season of feather change insummer. The professor claims that timing is the only supporting point in thistheory. However, it is just coincidence between the time of feather change andanting. During summer, it is easier for birds to find ants for anting and it isjust the right time for birds to change their feather. There is no causalrelationship between the two behaviors.
Secondly, the professor contradicts reading’sstatement that birds use this method to resist growth of parasites due to theacid released by ants during anting. The professor mentions that if the theorywas right in that case, then birds having the habit of anting would experiencea reduce of parasites growth, compared with those not. However, no evidence canprove the hypothesis.
At last, the passage states that during anting,ants will release acid, which makes birds better feed on those ants. However, theprofessor explains that other than ants, birds will rub themselves with otherthings like cigarettes and soap. And those birds will not eat on such smallthings. Therefore, the explanation of food preparation is not reasonableeither.