BirdLife International, David Attenborough Building, Pembroke Street, Cambridge, CB2 3QZ, U.K.
Centre for Biodiversity and Conservation Science, University of Queensland, St Lucia, QLD 4072, Australia.
Conserv Biol. 2020 Oct;34(5):1252-1261. doi: 10.1111/cobi.13486. Epub 2020 May 6.
Birds have been comprehensively assessed on the International Union for Conservation of Nature (IUCN) Red List more times than any other taxonomic group. However, to date, generation lengths have not been systematically estimated to scale population trends when undertaking assessments, as required by the criteria of the IUCN Red List. We compiled information from major databases of published life-history and trait data for all birds and imputed missing life-history data as a function of species traits with generalized linear mixed models. Generation lengths were derived for all species, based on our modeled values of age at first breeding, maximum longevity, and annual adult survival. The resulting generation lengths varied from 1.42 to 27.87 years (median 2.99). Most species (61%) had generation lengths <3.33 years, meaning that the period of 3 generations-over which population declines are assessed under criterion A-was <10 years, which is the value used for IUCN Red List assessments of species with short generation times. For these species, our trait-informed estimates of generation length suggested that 10 years is a robust precautionary value for threat assessment. In other cases, however, for whole families, genera, or individual species, generation length had a substantial impact on their estimated extinction risk, resulting in higher extinction risk in long-lived species than in short-lived species. Although our approach effectively addressed data gaps, generation lengths for some species may have been underestimated due to a paucity of life-history data. Overall, our results will strengthen future extinction-risk assessments and augment key databases of avian life-history and trait data.
鸟类在国际自然保护联盟（IUCN）红色名录上的评估次数比任何其他分类群都多。然而，迄今为止，在进行评估时，尚未按照 IUCN 红色名录标准的要求系统地估计世代长度以衡量种群趋势。我们从主要的已发表的生活史和特征数据数据库中为所有鸟类编制了信息，并使用广义线性混合模型将物种特征作为功能来推断缺失的生活史数据。根据我们首次繁殖年龄、最大寿命和成年期每年存活率的模型值，为所有物种推导出了世代长度。由此产生的世代长度从 1.42 年到 27.87 年不等（中位数为 2.99 年）。大多数物种（61%）的世代长度<3.33 年，这意味着在 A 标准下评估种群减少的 3 个世代期<10 年，这是 IUCN 红色名录对世代时间较短的物种进行评估所使用的值。对于这些物种，我们基于特征的世代长度估计表明，10 年是威胁评估的一个稳健的预防值。然而，在其他情况下，对于整个科、属或个别物种，世代长度对其估计的灭绝风险有重大影响，导致长寿命物种的灭绝风险高于短寿命物种。尽管我们的方法有效地解决了数据空白，但由于生活史数据的匮乏，某些物种的世代长度可能被低估了。总的来说，我们的研究结果将加强未来的灭绝风险评估，并补充鸟类生活史和特征数据的关键数据库。
