Concentrations of trace elements vary naturally between geological environments and as a result of emissions from anthropogenic activities. Habitat use strategy is an important determinant of trace element concentrations in tissues and eggs of wild birds. However, a scarcity of studies have documented the relationships between individual bird movements related to foraging activities and exposure to contaminants including trace elements. The objective of the present study was to investigate the influence of habitat use strategy, determined using GPS-based telemetry, on the liver concentrations of selected trace elements including rare earth elements (REEs) as well as lead (Pb) isotope ratios in an urban-adapted omnivorous bird, the ring-billed gull (Larus delawarensis). Male (n = 20) and female (n = 18) ring-billed gulls breeding near Montreal (QC, Canada) in one of the largest colony in North America were tracked using miniature GPS devices to characterize their movements over a 10-days period. The time spent foraging by both male and female gulls in landfills and wastewater basins positively correlated with liver Pb concentrations. A positive correlation was also found between the time spent foraging in agricultural fields and liver concentrations of yttrium (Y) in male and female ring-billed gulls. Heavy REE concentrations were significantly greater in female gull liver relative to those of males, although this was not associated with the time spent in any foraging habitats. Pb isotope ratios (²⁰⁸Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁷Pb) in the liver of male ring-billed gulls tended to be lower in individuals that foraged in landfills, thus indicating that they may have been exposed to different Pb sources relative to birds that visited other sites. This study provided valuable information on the potential sources of trace elements at the landscape level in free-ranging birds spanning urbanized environments.

微量元素的浓度在地质环境之间是自然变化的，而且是人为活动产生的排放的结果。栖息地使用策略是决定野生鸟类组织和卵中微量元素浓度的重要决定因素。但是，缺乏研究记录了与觅食活动有关的个体鸟类运动与暴露于包括微量元素在内的污染物之间的关系。本研究的目的是调查通过基于GPS的遥测技术确定的栖息地使用策略对城市中选定的痕量元素（包括稀土元素（REE）和铅（Pb）同位素比）的肝脏浓度的影响适应性杂食鸟，环嘴鸥（Larus delawarensis）。男性（n = 20）和雌性（n =  18）在北卡罗来纳州最大的殖民地之一的蒙特利尔（加拿大QC）附近繁殖的雌性环嘴海鸥，使用微型GPS设备追踪其在10天内的运动特征。雌性海鸥在垃圾填埋场和废水池中觅食的时间与肝铅浓度呈正相关。在农田中觅食的时间与雄性和雌性环嘴鸥的肝脏中钇（Y）的浓度之间也存在正相关关系。尽管与在觅食生境中所花费的时间无关，雌性鸥肝中的重稀土元素浓度明显高于雄性。铅同位素比（²⁰⁸ Pb / ²⁰⁶ Pb和²⁰⁶在垃圾掩埋场觅食的雄性环嘴海鸥的肝脏中的Pb / ²⁰⁷ Pb）趋向于较低，因此表明它们相对于探访其他地点的鸟类可能已暴露于不同的Pb来源。这项研究为跨越城市化环境的自由放养鸟类在景观水平上微量元素的潜在来源提供了有价值的信息。