If you are not familiar with the great blue heron rookery at the Coon Rapids Dam and you are a birder, or you are just interested in nature, then you definitely should take a look at it. There are over 65 nests there with over one hundred great blue heron currently residing there. It is visible on the Coon Rapids side of the dam and the Brooklyn Park side. The rookery is located on an island in the middle of the river directly west and across the river from Cenaiko Lake. The best view of the rookery is a bit south of Cenaiko Lake.
This rookery has been at this sight for many years now. I first noticed it over 20 years ago. On May 22, 2011 a tornado hit the Camden Heron Rookery in Minneapolis, destroying over 100 nests and many birds died as a result. Nine heron chicks were taken in by the Wildlife Rehabilitation Center in Roseville where they were cared for until they were released at Cenaiko Lake at the Coon Rapids Dam on July 18, 2011. I was there on that day and took photos of the release. The hope was that since we had a good sized rookery at the dam that some of the adult herons would look out for the just fledged chicks. At that time the rookery at the dam had only about 35 active nests and has since nearly doubled, so many of us think that some adults who survived the tornado built nests at the dam.
The herons at the dam will soon be on eggs. The great blue heron is the largest heron in North America and is roughly twice the weight of the great egret. It has head-to-tail length of 36–54 inches a wingspan of 66–79 inches and a height of 45–54 inches. It weighs 4.6–7.9 pounds. The great blue eats mostly fish but can eat shrimp, crabs, rodents, small amphibians, reptiles and small birds. The female lays three to six pale blue eggs in roughly two-day intervals. The male incubates the eggs about 10 hours a day and the female incubates the rest of the time. Both adults feed the young by regurgitating food. The adults typically eat four times as much during this period as usual. After about 27 days the chicks begin to hatch and after 70-80 days in the nest they begin to fly.
This year, as in the many past years that I’ve been observing the herons at the dam, other birds have used these nests at roughly the same times as the great blue heron. On at least three occasions I’ve seen great horned owls successfully nest on the heron nests and three times I’ve seen red tailed hawks nest there. Several weeks ago I saw a pair of red tails in one of the nests, but when I checked the other day there was no sign of them.
If you walk the trails around the dam regularly you will see many great blue herons overhead and along the sides of the Mississippi River and Cenaiko Lake. On occasion I have seen great egrets amongst the herons in the rookery and at Cenaiko Lake. You will likely see them at the dam all summer. I hope that you get a chance to see this great bird.