Clark et al. Sign surveys can accurately reflect river otter distribution when conducted during periods of presumed high river otter activity, and not within three days following high water levels or heavy rainfall. Results of this study agree with this assessment. Sign surveys were a highly variable yet an economical and rapid means of broadly assessing river otter distribution and relative abundance in southeastern Oklahoma. It is possible that detection rates during 1994 were low because of an absence of trackable substrate.
Tracks are obviously more easily identified on a muddy substrate than on dry soil substrates.
Because precipitation was lower during the 1994 surveys, otter tracks may not have been identified because of harder, drier substrates. Sign survey reliability and success depend on the researcher's ability to observe and identify sign. Substrate type can also influence sign survey results. For instance, otter tracks were the most common form of sign observed during this study. Tracks were more easily observed and identified on stream banks that had exposed soft soils.