Gambel’s quail survey variability and implications for survey design in the Mohave Desert

Cory T. Overton; Michael L. Casazza; Daniel Connelley; Scott C. Gardner

doi:10.1002/wsb.1105

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Gambel’s quail survey variability and implications for survey design in the Mohave Desert

Cory T. Overton·Michael L. Casazza·Daniel Connelley·Scott C. Gardner

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Abstract

Careful design of a wildlife population monitoring strategy is necessary to obtain accurate and precise results whether the purpose of the survey is development of habitat suitability models, to estimate abundance, or assess site occupancy. Important characteristics to consider in survey design are sources of elevated variability, particularly within‐subject variability, which increases the amount of data needed to achieve statistical certainty either in terms of population trend analysis, hypothesis testing, or statistical power. However, alternative objectives, such as associating counts with habitat characteristics, may benefit from increased variation among counts when differences covary with habitat measures. This difference can result in competing needs when developing survey protocols. We investigated the relative precision of differing gamebird monitoring protocols to identify methods with the greatest statistical efficiency. We assessed call‐count transects using standard Breeding Bird Survey protocols (Passive call‐counts) and modified by including longer survey periods and call playback (Active call‐counts), autonomous recording units with supervised call detection (ARU‐recorded calls), camera traps, and roadside covey‐counts for Gambel's quail ( Callipepla gambelii ) in the Mojave Desert (CA, USA) during the spring of 2016. Active call‐counts had the lowest within‐site variation relative to estimated population index values, but Passive call‐count transects may be more efficient for some purposes because more survey stations can be completed within a single survey timeframe. The ARU‐recorded calls may provide a suitable alternative despite larger sample size needs, especially for occupancy surveys because multiple units can be deployed concurrently. The ultimate sample size required will depend on specific study objectives and scope of interest, but camera traps and breeding‐season covey counts are not likely to meet objectives in desert environments.

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Source-reported bounding extent: 33.8247936182649° to 35.576916524038616° latitude; -116.597900390625° to -114.378662109375° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Cory T. Overton, Michael L. Casazza, Daniel Connelley, Scott C. Gardner. 2020. Gambel’s quail survey variability and implications for survey design in the Mohave Desert. https://doi.org/10.1002/wsb.1105

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