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Title: Inter-observer variation in identifying mammals from their tracks at enclosed track plate stations
Author: Zielinski, William J.; Schlexer, Fredrick V.
Source: Northwest Science 83(4): 299-307
Publication Series: Journal/Magazine Article (JRNL)
Description: Enclosed track plate stations are a common method to detect mammalian carnivores. Studies rely on these data to make inferences about geographic range, population status and detectability. Despite their popularity, there has been no effort to document inter-observer variation in identifying the species that leave their tracks. Four previous field crew leaders identified the tracks of carnivores and non-carnivores on 105 track sheets from enclosed track plate stations that were used in field studies in California. Because the identity of the species was unknown, we evaluated the consistency in identifications among the 4 observers. The observers were in agreement on the identity of tracks on 73.3% of the track sheets. Considering only the putative carnivore tracks, the agreement was higher (86.8%) and was higher still (95.4%) when the lowest quality carnivore tracks were excluded. American martens (Martes americana) and fishers (M. pennanti) are important species from a conservation perspective, and there was only one occasion of inter-observer disagreement. Observers were much less consistent in identifying non-carnivores, achieving consensus on only 37.1% of the opportunities. When observers have training and experience similar to those involved here, tracks should be considered a reliable method for verifying the identity of most of the species that visit track-plate stations. Our results indicate that inter-observer variation is unlikely to have affected conclusions from previously published reports about the distribution or abundance of carnivores. We caution, however, that observers refrain from identifying a track when the quality is poor and also to assign only the highest level of taxonomic resolution that is justified.
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Zielinski, William J.; Schlexer, Fredrick V. 2009. Inter-Observer Variation in Identifying Mammals from Their Tracks at Enclosed Track Plate Stations. Northwest Science 83(4):299-307.
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