Although both linguists and language community members recognize the potential utility of automatic speech recognition (ASR) for documentation, one of the obstacles to using these technologies is the scarcity of data necessary to train effective systems. Recent advances in ASR, particularly the ability to fine-tune large multilingual acoustic models to small amounts of data from a new language, have demonstrated the potential of ASR for transcription. However, many proof-of-concept demonstrations of ASR in low-resource settings rely on a single data collection project, which may yield models that are biased toward that particular data scenario, whether in content, recording quality, transcription conventions, or speaker population. In this paper, we investigate the performance of two state-of-the art ASR architectures for fine-tuning acoustic models to small speech datasets with the goal of transcribing recordings of Enenlhet, an endangered Indigenous language spoken in South America. Our results suggest that while ASR offers utility for generating first-pass transcriptions of speech collected in the course of linguistic fieldwork, individual vocabulary diversity and data quality have an outsized impact on ASR accuracy.