Western Ecological Research Center, U.S. Geological Survey, Dixon Field Station, Dixon, California, 95620, USA.
Western Ecological Research Center, U.S. Geological Survey, Santa Cruz Field Station, Santa Cruz, California, 95060, USA.
Ecol Appl. 2021 Apr;31(3):e2267. doi: 10.1002/eap.2267. Epub 2021 Jan 27.
Occupancy methods propelled the quantitative study of species distributions forward by separating the observation process, or the imperfect detectability of species, from the ecological processes of interest governing species distributions. Occupancy studies come at a cost, however: the collection of additional data to account for nondetections at sites where the species is present. The most common occupancy designs (repeated-measures designs) require repeat visits to sites or the use of multiple observers or detection methods. Time-to-detection methods have been identified as a potentially efficient alternative, requiring only one visit to each site by a single observer. A comparison of time-to-detection methods to repeated-measures designs for visual encounter surveys would allow researchers to evaluate whether time-to-detection methods might be appropriate for their study system and can inform optimal survey design. We collected time-to-detection data during two different repeated-measures design occupancy surveys for four amphibians and compared the performance of time-to-detection methods to the other designs using the location (potential bias) and precision of posterior distributions for occurrence parameters. We further used results of time-to-detection surveys to optimize survey design. Time-to-detection methods performed best for species that are widespread and have high detection probabilities and rates, but performed less well for cryptic species with lower probability of occurrence or whose detection was strongly affected by survey conditions. In all cases, single surveys were most efficient in terms of person-hours expended, but under some conditions the survey duration required to achieve high detection probabilities would be prohibitively long for a single survey. Regardless of occupancy survey design, time-to-detection methods provide important information that can be used to optimize surveys, allowing researchers and resource managers to efficiently achieve monitoring and conservation goals. Collecting time-to-detection data while conducting repeated-measures occupancy surveys requires only small modifications to field methods but could have large benefits in terms of time spent surveying in the long term.
占据方法通过将观测过程（即物种的不完全可检测性）与控制物种分布的生态过程分开，推动了物种分布的定量研究。然而，占据研究需要付出代价：需要收集额外的数据来解释在存在物种的地点的未检测到的情况。最常见的占据设计（重复测量设计）需要重复访问地点或使用多个观察者或检测方法。检测时间方法已被确定为一种潜在有效的替代方法，仅需要单个观察者对每个地点进行一次访问。将检测时间方法与视觉遭遇调查的重复测量设计进行比较，可以让研究人员评估检测时间方法是否适合他们的研究系统，并可以为最佳调查设计提供信息。我们在两个不同的两栖动物重复测量设计占据调查中收集了检测时间数据，并使用位置（潜在偏差）和出现参数后验分布的精度，比较了检测时间方法与其他设计的性能。我们进一步使用检测时间调查的结果来优化调查设计。检测时间方法在广泛分布且具有高检测概率和速率的物种中表现最佳，但在发生概率较低或检测受调查条件强烈影响的隐蔽物种中表现较差。在所有情况下，单次调查在人力消耗方面效率最高，但在某些条件下，为了达到高检测概率所需的调查持续时间可能会对单次调查造成严重影响。无论采用哪种占据调查设计，检测时间方法都提供了重要的信息，可以用于优化调查，使研究人员和资源管理人员能够高效地实现监测和保护目标。在进行重复测量占据调查时收集检测时间数据只需要对野外方法进行微小的修改，但从长远来看，在调查时间方面可能会带来很大的好处。
