Urban landscapes present substantial opportunities for biodiversity conservation with residential gardens offering some of the greatest potential conservation gains given that they represent a significant proportion of the total greenspace in urbanised landscapes. However, knowledge of wildlife ecology within gardens remains scarce, likely due to the difficulties associated with field ecologists accessing privately owned areas. Citizen-sourced data presents an alternative approach to typical field-based investigations and could be used to develop an extensive understanding of biodiversity within privately owned green spaces, providing concerns of data unreliability could be overcome. Here we i) examine the potential for urban householders to identify a threatened nocturnal mammal, in the presence of a similar non-threatened species, ii) examine which attributes can predict the level of accuracy in householders’ species identifications and iii) investigate how their self-reported level of certainty affects identification reliability. We found up to 80% agreement between householders and experienced ecologists when we assessed presence and absence of nocturnal mammals on urban properties. The amount of time a householder had lived at their residence was a significant predictor of accuracy for mammal species identification, suggesting that familiarity with a site enhances the accuracy of citizen science data. Those people with a high level of certainty in their ability to correctly identify nocturnal mammals were no more likely to show higher species identification accuracy than those with low certainty. In urban areas, where ecological surveys for nocturnal taxa are especially challenging, our results inspire optimism that householders can add to the body of knowledge about biodiversity persisting in these landscapes, especially on properties where they have resided for at least one year.

城市景观为生物多样性的保护提供了巨大的机会，住宅花园提供了一些最大的潜在保护收益，因为它们占城市化景观总绿地的很大比例。然而，由于野外生态学家进入私有区域所带来的困难，对花园内野生动植物生态学的了解仍然很少。公民来源的数据为典型的基于实地的调查提供了一种替代方法，可用于发展对私有绿色空间内生物多样性的广泛了解，但前提是可以克服对数据可靠性的担忧。在这里，我（i）研究了在存在类似的非威胁物种的情况下，城市居民识别夜行性濒危哺乳动物的可能性，ii）检查哪些属性可以预测住户物种识别的准确性水平，并且iii）研究其自我报告的确定性水平如何影响识别可靠性。在评估城市属性中夜间哺乳动物的存在与否时，我们发现住户与经验丰富的生态学家之间达成了高达80％的共识。住户在其住所中居住的时间是预测哺乳动物物种识别准确性的重要指标，这表明对地点的熟悉可以提高公民科学数据的准确性。那些能够正确识别夜间哺乳动物的高度确定性的人，比那些具有低确定性的人，更不可能表现出更高的物种识别准确度。在城市地区