Golden and sea eagle populations have been declining in the British Isles for 1,500 years because of human activity, a report released Friday said.

The report in the journal Bird Study blamed habitat loss and killing by humans for the decline, The Scotsman reported. Researchers believe there were between 1,000 and 1,500 pairs of golden eagles, and between 800 and 1,400 pairs of sea eagles, also known as white-tailed eagles, in the British Isles in A.D. 500.

The team identified 556 place names that suggest eagles were once in the area.

The BBC reported that 440 golden eagles and 31 pairs of sea eagles were counted in 2003.

"The results of this study are striking as they provide compelling evidence that eagles were widespread throughout most of Britain and Ireland in the Dark Ages," said Richard Evans of the Royal Society for the Protection of Birds and the lead author of the study. "Between 500 and 1800 we see massive loss of eagle range in the south, which is consistent with the effects of habitat loss and killing by humans, rather than the influence of climate change on habitat, or competitive exclusion, as some have suggested."

By the end of World War I, a small number of golden eagles remained in remote areas, Evans said. While golden eagles have recovered somewhat, Evans said the recovery "has stalled."