Data from: Hide and seek in vegetation: time-to-detection is an efficient design for estimating detectability and occurrence

1. Ecology and conservation require reliable data on the occurrence of animals and plants. A major source of bias is imperfect detection, which, however, can be corrected for by estimation of detectability. In traditional occupancy models, this requires repeat or multi-observer surveys. Recently, time-to-detection models have been developed as a cost-effective alternative, which requires no repeat surveys and hence costs could be halved. 2. We compared the efficiency and reliability of time-to-detection and traditional occupancy models under varying survey effort. Two observers independently searched for 17 plant species in 44 100 m2 Swiss grassland quadrats and recorded the time-to-detection for each species, enabling detectability to be estimated with both time-to-detection and traditional occupancy models. In addition, we gauged the relative influence on detectability of species, observer, plant height and two measures of abundance (cover and frequency). 3.Estimates of detectability and occupancy under both models were very similar. Rare species were more likely to be overlooked; detectability was strongly affected by abundance. As a measure of abundance, frequency outperformed cover in its predictive power. The two observers differed significantly in their detection ability. 4. Time-to-detection models were as accurate as traditional occupancy models, but their data easier to obtain; thus they provide a cost-effective alternative to traditional occupancy models for detection-corrected estimation of occurrence.

1. 生态学与保护研究均需可靠的动植物出现数据。偏倚的主要来源之一为检测不完全（imperfect detection），但可通过估算可检测性（detectability）对其进行校正。在传统占有模型（occupancy models）中，此类校正需要开展重复调查或多观察者调查。近年来，检测耗时模型（time-to-detection models）被开发为一种兼具成本效益的替代方案，其无需重复调查，因此调查成本可降低一半。
2. 本研究在不同调查强度下，对比了检测耗时模型与传统占有模型的效率与可靠性。两名观察者独立对瑞士44个100平方米的草地样方（quadrats）内的17种植物进行搜寻，并记录各物种的检测耗时，由此可通过检测耗时模型与传统占有模型两种方法估算可检测性。此外，本研究还评估了物种、观察者、植物高度以及两种丰度衡量指标：盖度（cover）与频度（frequency）对可检测性的相对影响。
3. 两种模型得到的可检测性与占有估计结果极为相似。稀有物种更易被忽略；可检测性受丰度的影响显著。作为丰度衡量指标，频度的预测能力优于盖度。两名观察者的检测能力存在显著差异。
4. 检测耗时模型的精度与传统占有模型相当，但其数据采集更为简便；因此，在开展经检测校正的物种出现估计时，检测耗时模型可作为传统占有模型兼具成本效益的替代方案。