Odor thresholds in passerines

1. 1. Eight species of passerines were evaluated for their ability to form conditioned responses to odor stimuli. Only 5 species met training criteria and were tested for odor detection thresholds. 2. 2. Detection thresholds were comparable to other passerines tested. Detection values were also similar to mammalian macrosmatic species, such as rats and rabbits. Thus, despite the poorly elaborated olfactory anatomy of passerines, these birds possess an adequate sense of smell. 3. 3. Within the Passeriformes there is no correlation between olfactory acuity and relative size of the olfactory bulb. However, there is a correlation between acuity and olfactory bulb size across orders of birds. These latter observations are consistent with hypotheses correlating form and function.