Bird feathers are one of the most widely used animal tissue in mercury biomonitoring, owing to the ease of collection and storage. They are also the principal excretory pathway of mercury in birds. However, limitations in our understanding of the physiology of mercury deposition in feathers has placed doubt on the interpretation of feather mercury concentratoins. Throughout the literature, moult sequence and the depletion of the body mercury pool have been taken to explain patterns such as the decrease in feather mercury from the innermost (P1) to the outermost primary feather (P10) of the wing. However, it has been suggested that this pattern is rather a measurement artefact as a result of the increased feather mass to length ratio along the primaries, resulting in a dilution effect in heavier feathers. Here, we attempt to untangle the causes of variation in feather mercury concentrations by quantifying the mercury concentration as μg of mercury (i) per gram of feather, (ii) per millimetre of feather, and (iii) per day of feather growth in the primary feathers of Bulwer’s Petrel Bulweria bulwerii chicks, effectively controlling for some of the axes of variation that may be acting in adults, and monitoring the growth rate of primary feathers in chicks. The mercury concentration in Bulwer’s Petrel chicks’ primaries increased from the innermost to the outermost primary for all three concentration measures, following the order of feather emergence. These observations confirm that the pattern of mercury concentration across primary feathers is not an artefact of the measure of concentration, but is likely an effect of the order of feather growth, whereby the earlier grown feathers are exposed to higher blood mercury concentrations than are later moulted feathers as a result of blood mercury depletion.

由于易于收集和存储，鸟羽是汞生物监测中使用最广泛的动物组织之一。它们也是汞在鸟类中的主要排泄途径。但是，由于我们对羽毛中汞沉积的生理学的理解受到限制，使得人们对羽毛中汞含量的解释产生了疑问。在整个文献中，已经采用换羽顺序和体内汞池的消耗来解释各种模式，例如从机翼的最内层（P1）到最外层主要羽毛（P10）内的羽毛汞减少。然而，已经提出，由于沿着原基的羽毛质量与长度之比增加，该图案实际上是测量伪像，导致较重的羽毛具有稀释作用。这里，Bulweria bulwerii雏鸡，有效控制可能在成年中起作用的某些变异轴，并监控雏鸡中主要羽毛的生长速度。对于三种浓度测量，Bulwer的海燕雏鸡的原色中的汞浓度从最内层到最外层都是按羽毛出现的顺序增加。这些观察结果证实，主要羽毛上的汞浓度模式不是浓度测量的假象，而是可能是羽毛生长顺序的影响，因此，较早生长的羽毛比后来换羽的血液所含的汞浓度更高羽毛由于血液中的汞消耗而减少。