Capsule: Despite its population increase, the White-tailed Eagle Haliaeetus albicilla has not become food-limited, and does not pose a serious threat to birds of conservation concern in the region east of the Baltic Sea.

Aims: We aimed to test variations in the main prey groups and dietary niche breadth of White-tailed Eagles through the years and along an environmental gradient as well as to evaluate the extent of predation on bird species of conservation concern.

Methods: Prey remains were collected during nestling ringing from successful nests located in Lithuania.

Results: The frequency of the prey groups varied along an environmental gradient, with a general pattern of increasing avian prey consumed by pairs breeding in areas with less abundant aquatic habitats. The frequency of alternative prey (i.e. terrestrial birds, mammals) and dietary niche breadth did not increase between 2005 and 2018 and during which time the White-tailed Eagle population nearly doubled. Instead, the occurrence of Northern Pike Esox lucius remains, which was the most frequent single prey species, increased throughout the study period. Bird species of conservation concern constituted only a small fraction of all the prey identified.

Conclusions: The White-tailed Eagle has not become more dependent on alternative prey despite its population increase.

胶囊：尽管白尾鹰Haliaeetus albicilla的种群数量有所增加，但它并没有受到食物的限制，也没有对波罗的海以东地区的保护鸟类造成严重威胁。

目的：我们旨在测试多年来和环境梯度下白尾鹰的主要猎物组和饮食生态位宽度的变化，并评估对保护鸟类的捕食程度。

方法：在立陶宛成功筑巢的过程中，从巢中收集猎物。

结果：猎物群的发生频率随环境梯度的变化而变化，在水生栖息地较少的地区，成对繁殖的鸟类捕食者的捕食总体模式是增加的。在2005年至2018年期间，替代猎物（即陆生鸟类，哺乳动物）和饮食生态位宽度的频率没有增加，在此期间，白尾鹰种群几乎翻了一番。取而代之的是，在整个研究期间，北派克梭鲈的数量一直是最常见的单一猎物，但仍在增加。具有保护意义的鸟类只占所查明所有猎物的一小部分。

结论：尽管白尾鹰种群增加，但并没有更多地依赖于替代猎物。