Department of Biology, Institute for Integrative Bird Behavior Studies, College of William & Mary, Williamsburg, VA 23187, USA.
Ecotoxicology. 2011 Jan;20(1):39-46. doi: 10.1007/s10646-010-0554-4. Epub 2010 Oct 10.
Mercury has become a ubiquitous contaminant in food chains worldwide. A large body of literature detailing bioaccumulation and effects on birds has revealed the potential for mercury to adversely impact avian physiology and reproduction. However, the extent to which these effects impair survival remains poorly understood. The objective of this study was to determine whether mercury exposure was associated with reduced annual survivorship in tree swallows (Tachycineta bicolor) breeding at a site with legacy industrial contamination. From 2005 to 2008, we captured and marked 932 adult swallows. We used Cormack-Jolly-Seber models and an information-theoretic approach to test our hypotheses that adult survival varied by sex, breeding location, and cumulative individual mercury exposure. Blood mercury was significantly elevated on contaminated sites (2005-2007 combined mean ± SE: 2.84 ± 0.09 μg/g; reference: 0.17 ± 0.01 μg/g). Model-averaged estimates of female apparent survival ranged from 0.483 to 0.488 on reference sites and 0.473 to 0.477 on contaminated sites. For males, apparent survival ranged from 0.451 to 0.457 on reference sites and 0.444 to 0.448 on contaminated sites. Thus, we observed approximately a 1% difference in survival between mercury-contaminated and reference sites. Such a small difference is unlikely to impact population viability in this short-lived species; however, some songbirds accumulate mercury to a greater degree than tree swallows and do not possess the migratory behavior that removes swallows to less contaminated areas for the majority of the year. Identifying whether such species are at risk of suffering biologically significant reductions in survival should become a focus of future research.
汞已成为全球食物链中无处不在的污染物。大量详细描述鸟类生物积累和汞影响的文献表明，汞有可能对鸟类生理和繁殖产生不利影响。然而，这些影响对生存的损害程度仍知之甚少。本研究的目的是确定在一个具有遗留工业污染的地点繁殖的树燕（Tachycineta bicolor）中，汞暴露是否与年生存率降低有关。2005 年至 2008 年，我们捕获并标记了 932 只成年燕。我们使用 Cormack-Jolly-Seber 模型和信息理论方法来检验我们的假设，即成年燕的存活率因性别、繁殖地点和个体累积汞暴露量而有所不同。受污染地点的血液汞含量明显升高（2005-2007 年合并平均值±SE：2.84±0.09μg/g；参考值：0.17±0.01μg/g）。参考地点的雌性实际存活率估计值在 0.483 到 0.488 之间，而受污染地点的存活率在 0.473 到 0.477 之间。对于雄性，参考地点的实际存活率在 0.451 到 0.457 之间，而受污染地点的存活率在 0.444 到 0.448 之间。因此，我们观察到受汞污染和参考地点之间的生存率差异约为 1%。这种微小的差异不太可能影响这种短命物种的种群生存能力；然而，一些鸣禽积累的汞比树燕多，并且没有迁徙行为，在一年中的大部分时间里将鸣禽转移到污染较少的地区。确定这些物种是否面临生存生物意义上显著减少的风险，应成为未来研究的重点。
