The bald eagle community at Besnard Lake has been studied continuously for over 50 years following their discovery there by
Jon Gerrard. In that time eagle population dynamics, behaviour, growth, and migration have been studied, resulting in the publication of more than 50
scientific papers and the 1988 book
The Bald Eagle: Haunts and Habits of a Wilderness Monarch. Over 800 eagles have been
banded, and have been found to winter mainly between Iowa and Missouri, Wyoming and Montana, but some have been found as far south as Texas, Arizona, and Southern California. In the 1960s it was considered that bald eagles were rare in Canada away from the Atlantic and Pacific coasts. In 1966 Gerrard found 18 nests with 27 young in the area. A more extensive aerial survey of the region in 1974 found 14,000 eagles. Besnard Lake was found to be a perfect area to study bald eagles in these
boreal breeding grounds. The lake has provided habitat for a stable population of about 100 eagles since the 1970s. One discovery was that the sex of immature eagles could be accurately and efficiently determined by measuring the size of the foot and length of the
culmen on the beak. This led to the discovery that the sex of the young seems to be regulated by the quantity of food available, with more females (which are larger than the males) hatching when food is plentiful. On other lakes where food is less plentiful a higher ratio of males hatch. == Besnard Lake Recreation Site ==