Did you know that North American red squirrels (Tamiasciurus hudsonicus) announce territorial ownership by making vocalizations called rattles? Recently, a study found that short-term stress from capturing and handling squirrels affected acoustic structure of these vocalizations. This research reveals that rattles may also carry important information about squirrel physiological condition.
Source: Sehrsweeney, M., Wilson, D. R., Bain, M., Boutin, S., Lane, J. E., McAdam, A. G., & Dantzer, B. (2019). The effects of stress and glucocorticoids on vocalizations: a test in North American red squirrels. Behavioral Ecology, arz044, https://doi.org/10.1093/beheco/arz044