We explore whistled vowel categorization by untrained listeners, focusing specifically on the impact of the different vocalic frequency ranges of two whistlers (for the vowels /i/, /e/, /a/, /o/) and the effect of training on performance. In the experiment, we included stimuli that show inter-individual and intra-individual variations of production. In the analyses we looked at the whistler identity effect and at the learning effect through the experiment for the studied vowels. The results showed an effect of the whistler, where the larger vocalic range led to improved categorization, and highlighted the robustness of the vowel recognition hierarchy. There was no general learning effect, albeit for one vowel and for the whistler with a narrower vocalic range. This study provides insight into one's representation of the vowel space in non-tonal languages.