The curse of observer experience: Error in noninvasive genetic sampling

Area of Science:

• Wildlife ecology
• Conservation genetics
• Field research methods

Background:

• Noninvasive genetic sampling (NGS) is vital for studying elusive species.
• Potential observer bias in NGS data collection is understudied.
• Gray wolf (Canis lupus) populations are often monitored using NGS.

Purpose of the Study:

• To investigate the impact of observer experience on NGS data quality for gray wolves.
• To determine if observer bias affects sample detection, amplification, and species identification.
• To assess the reliability of experienced versus new observers in field genetic sampling.

Main Methods:

• Analyzed 4,836 gray wolf fecal samples collected over 7 years (2008-2014).
• Compared sample collection success rates between new (n=33) and experienced (n=25) observers.
• Evaluated detection, amplification, and species identification accuracy across observer groups.

Main Results:

• New observers outperformed experienced observers in detecting and collecting wolf scats.
• New observers demonstrated higher accuracy in identifying wolf scats from other carnivore species.
• Contrary to hypothesis, observer experience did not improve, and potentially decreased, NGS data quality.

Conclusions:

• Observer experience can negatively influence noninvasive genetic sampling (NGS) data quality.
• Adequate training for new observers is essential, but experienced observers require attention regarding potential biases.
• Field savvy and local knowledge are important, but investigators must consider experience-related fatigue or boredom effects on sampling.