Prioritizing roads for mitigation can be a challenge in conservation. The comparison of fatality estimates is an important tool to assist in this process, but the sampling errors in these estimates should be considered. Spatial and temporal patterns of wildlife fatalities vary among different roads, and multispecies evaluations can be biased by the abundance of a dominant fatality species. We compared three roads in southern Brazil regarding their mammalian fatality estimates, assessed temporal and spatial patterns of these records, and evaluated the effect of a dominant fatality species on these observed patterns. We found a discrepancy in road prioritization when using the estimated rather than the observed number of fatalities to the extent that the road with the lowest priority became the one with the highest. Therefore, we demonstrated the importance of considering sampling errors in fatality estimates. Our data evidenced the influence of the dominant fatality species on the temporal patterns on the three roads, changing the distribution of fatalities. We also demonstrated the importance of considering the influence of the dominant fatality species on the spatial patterns due to changes in the location of hotspots, representing hotspots with more non-dominant species. The decision of where to mitigate, given a stated mitigation target, could be improved by a simple cost–benefit approach considering all records or only non-dominant species. Independently of road or mitigation target, mitigating a small fraction of the road extension with effective action can avoid a considerable fraction of the fatalities.

优先考虑缓解道路可能是保护中的一项挑战。死亡率估计的比较是协助这一过程的重要工具，但应考虑这些估计中的抽样误差。野生动物死亡的时空模式在不同的道路上有所不同，多物种评估可能会因主要死亡物种的丰度而产生偏差。我们比较了巴西南部三条道路的哺乳动物死亡率估计，评估了这些记录的时间和空间模式，并评估了主要死亡物种对这些观察到的模式的影响。当使用估计的而不是观察到的死亡人数时，我们发现道路优先级存在差异，以至于具有最低优先级的道路成为最高的道路。所以，我们证明了在死亡率估计中考虑抽样误差的重要性。我们的数据证明了主要死亡物种对三条道路的时间模式的影响，改变了死亡人数的分布。我们还证明了考虑主要致死物种对空间格局影响的重要性，因为热点位置的变化代表了具有更多非优势物种的热点。考虑到所有记录或仅考虑非优势物种，可以通过一个简单的成本效益方法来改进在何处缓解的决定，给定一个既定的缓解目标。独立于道路或缓解目标，通过有效行动缓解一小部分道路延伸可以避免相当一部分的死亡事故。