Diet and breeding habitat preferences of White-tailed Eagles in a northern inland environment

Abstract

Many apex predator populations are recolonizing old areas and dispersing to new ones, with potential consequences for their prey species and for livestock. An increasing population of the White-tailed Eagle (Haliaeetus albicilla) has settled north of the Arctic Circle in northern Finland, mainly at two big water reservoirs but also in areas with mainly terrestrial habitat. We examined nesting habitat preferences and prey use of White-tailed Eagles in this environment, where reindeer husbandry is a traditional livelihood and concerns are rising that the growing White-tailed Eagle population poses a threat to reindeer calves. Lakes, peat bogs, and marshlands were preferred habitats in the nesting territories. Fish constituted 64.3% of the identified prey items, with birds accounting for 28.5% and mammals 7.2%. The nesting territory habitat within a 10 km radius and the latitude influenced the prey composition at both the group and species level. The occurrence of reindeer calves as prey increased with latitude but was not associated with any habitat. Knowledge of the diet and territory preferences can be used to predict future dispersal and local prey use of this species. Nesting White-tailed Eagles do not seem to pose a threat to traditional reindeer herding, but further research is needed regarding non-breeding sub-adults and whether the White-tailed Eagles actually kill reindeer calves or simply exploit their carcasses.

Per- and polyfluoroalkyl substances (PFAS) in white-tailed sea eagle eggs from Sweden: temporal trends (1969–2021), spatial variations, fluorine mass balance, and suspect screening

“…30 The home range can vary in size due to the environment but typically has a radius of <15 km in the Baltic region. 31 These factors make them ideal sentinel species for studying changes in contaminant exposure within a local/regional environment over time. Eggs analyzed in the present work were collected during late spring/early summer, 1-2 months aer failure to hatch.…”

Lead, cadmium, and other trace elements in the liver of golden eagles and white-tailed eagles: recent data from Poland and a systematic review of previous studies

“…We hypothesize that this difference may be due to the different dietary preferences of both species. White-tailed eagles generally prey on fish and waterfowl, and mammals comprise only a few percent of their diet (Zawadzka 1999 ; Ekblad et al 2020 ). A study on the feeding habits of raptors from Wigry National Park in NE Poland showed that the biomass of prey of white-tailed eagles consisted mainly of birds (70%), including different species of the Anatidae family (19.1%) and Eurasian coot ( Fulica atra ), and several small to medium-sized fish (26.8%), with common bream ( Abramis brama ) as the dominant species (10.4%) (Zawadzka 1999 ).…”

White-Tailed Eagles’ (Haliaeetus albicilla) Exposure to Anticoagulant Rodenticides and Causes of Poisoning in Poland (2018–2020)

“…The difference in results may also be due to the disparate ways samples were collected. Considering that the diet of white-tailed eagles consists mainly of fish and birds, and only occasionally mammals [30,33], dead or weakened rodents seem an unlikely source of AR for white-tailed eagles. Potential sources of AR for white-tailed eagles in Poland could be the red fox (Vulpes vulpes), especially during the winter period when the availability of fish is limited.…”

“…It is most likely to nest in older forests on large trees, near feeding grounds that are rich in fish and waterbirds [30,32]. The diet of the white-tailed eagle is mainly fish, but also includes animals such as birds, mammals (including red fox Vulpes vulpes), and occasionally carrion [30,33]. This is the first report about white-tailed eagles' (Haliaeetus albicilla) exposure to AR in Poland.…”