THE CALLS OF Poecile atricapillus (Black-capped Chickadee) ARE CHANGING

This paper is intended to supplement present knowledge of the vocal array of Poecile atricapillus (Black-capped Chickadee) with three calls presently known only from Poecile carolinensis (Carolina Chickadee) and evidence that morphing is occurring. Originally conceived as a simple list of all calls that adult Blackcapped Chickadees make during the winter months in northern Michigan, the inclusion of calls already described for P. carolinensis and the surprising paucity of the complete Chick-a-dee call suggested consideration of anthropogenic factors affecting their communication. In addition, calls made by wild birds before, during, and after copulation are described for the first time, as well as a novel element that is sometimes associated with a Gargle call. Some possible language systems have been considered for the chickadees since before 2000, with their complicated combinatorial Chick-a-dee and Gargle calls. In 2016 lexical syntax in another parid was demonstrated. The repetitive dee alarm given by P. atricapillus in response to a high-risk predator suggests phonological components in their semantics. Here is presented spectrographic evidence for one call type integrating into another and frequent use of polyphonic sounds, providing a new window for viewing communication in these very social birds. Understanding the meaning of P. atricapillus' vocalizations is incomplete, but progress is being made, chiefly on the basis of spectrograms revealing far more detail than the average human ear can discern.