Date: 11/15/20 1:15 pm From: Jim Moore <epiphenomenon9...> Subject: Re: [MDBirding] Black-capped Chickadee?
That passage means that each species has an equivalent call that serves
a similar function. It doesn't mean they call the same. As it states
later in the same paragraph "The differences between the two species are
in the details of these shared calls." The article does later suggest
differences among individuals might make it difficult to differentiate
the species, but it also lists at the top of the article the speed of
the "chickadee" call as the third most important means of distinguishing
the two species.