After two years of relatively few bald eagles wintering in the Quad-City region, the population for this year is back up to normal, with a "good, strong percentage of young birds," according to bird-counter Kelly McKay.
McKay, a wildlife biologist from Hampton, Illinois, has for decades conducted an 81.5 mile mid-winter count of eagles along the Mississippi River from Clinton, Iowa, to New Boston, Illinois.
His counts are part the National Midwinter Bald Eagle Count administered by the U.S. Army Corps of Engineers. The goal of the survey is to collect, analyze and maintain long-term population data on the once endangered eagle.
McKay's total count this year along the Mississippi, plus a one-mile stretch at the confluence of the Mississippi and Rock rivers, was 2,199 eagles, compared with just 957 eagles in 2017 and 728 eagles in 2016, McKay said.
The reason for the healthy uptick is that cold temperatures farther north caused the river to ice over, sending a concentration of eagles to the Quad-City region in search of food because there is open water under the locks and dams, McKay said.
The past two years were mild, with little to no icing over of the river, so the birds stayed farther north.
McKay's all-time record count was 4,958 in 2014. McKay believes the reason for the exceptionally high number that year was related to the amount of ice on the river. A cover of 40 to 60 percent seems to be optimal because it concentrates the fish and the eagles don't have to expend as much energy to find food, he said.
During the count this year, McKay estimated the ice cover at about 56 percent overall, right in the optimal range.
Of the birds McKay counted this year, 1,447 were in Iowa and 752 were in Illinois. Those numbers figure out to an average of 27 eagles per river mile.
Also, 1,450, or 65.9 percent, of the birds McKay counted were adults; 706, or 32.1 percent, were immature; and 43, or 2 percent, were undetermined, he said.
"Any time you're above 30 percent (of immature eagles) is good," McKay said, explaining that it speaks well for the overall health of the species.
McKay conducted his accounts on Jan. 12-13 and Jan. 16, when temperatures ranged from a low of 2 degrees to a high of 18.