Throughout the years of observing wildlife through a lens or a pair of binoculars, we have had the pleasure of learning the habits of many different critters. It's absolutely amazing to watch them and to note the similarities in their habits but also the differences. Often as you watch them, you think to yourself, "well, that's logical behavior". Other times you just can't make sense of it and wonder how they ever come to adopt this universal behavior among their species. In this post I will be mainly talking about Great Blue Herons but will also briefly point out how they differ from other birds and mammals.
To get this discussion underway, lets talk about the term used in the title of this post, "rookery". Many of you may have never heard of the term and quite possibly saw one or more than one, but didn't realize that you just drove by a hotbed of wildlife activity. A rookery is colony of nesting animals but generally birds. Often you may have ridden by a group of trees sitting back from the road and while you did notice a number of nests or piles of sticks scattered among the branches, you just rode on by and gave it no more thought. Chances are you just passed by a "rookery" which we consider a wonder of nature or maternity ward of the animal kingdom.
In this particular post I will be talking about Heron rookeries but this term is by no means limited to just Great Blue Herons because there are other birds and animals that colonize in their nesting sites. One thing we have observed over the years is that typically Great Blue Herons will chose a site for their rookery that is difficult to access by humans and is often in a wet swampy area. One thing for certain, it is always located very close to a wildlife supermarket, which is a stream, river or lake. This is absolutely vital so that they have a steady source of fish and aquatic life to keep themselves nourished during this time of breeding, nesting and feeding the newborns up until the time of fledging. Fledging is the day that the young Great Blue Herons step to the edge of the nest and start their own life and adventures.
I had mentioned that there are similarities and differences in the behavior of animals but motherly love with the young is strong and universal and amazing to observe and photograph. In my eyes, a rookery is an amazing occurrence in nature. When you think about so many animals and think about how they have their young, it's so different from the Great Blue Heron. Think about a deer or bear or even an elk. In the bird world, look at the Bald Eagle for instance. All of these just mentioned will pick a secluded spot to have their young and certainly not at all like a colony of Herons. A Bald Eagle will nest in the trees often in the same spot for many years just as the Herons do but they are alone and not in a rookery environment. It does seem to be a common occurrence though, where a Bald Eagle will take over a Heron nesting area, and chase the Herons out. But even when they do this, it's a lone Eagle and not a colony like Herons. It's interesting to me how the Herons will nest in great numbers and often their nests are only a couple feet away from each other.
Most of the pictures in this post were taken at a rookery out in the Cuyahoga Valley in Ohio. What's cool about this particular rookery is the fact that it is quite close to a road and very easy to photograph which is quite unusual for a Heron nesting area. It is my understanding that this rookery has been re-used for a number of years. Each year the Herons return and either build or rebuild their nest. Building or rebuilding may take 3 days to a couple weeks. The Herons fly in with sticks and weave them into a strong nest where they can lay their eggs which can be as few as three or as many as seven or eight. As you can imagine, the nest can get quite crowded by fledging time.
As we photographed this nesting area we tried to count the nests but foliage made it difficult. This one giant Sycamore had at least 40 - 50 nests and each nest appeared to have at least 3 young Herons. Just this one tree will most likely produce 150 young Great Blue Herons. Just amazing isn't it! Now let's rewind to 2003 when there were approximately 176 nests. Back in 2013 there were 110 nests which produced about 251 young Herons. In this area this year there are easily 100 plus nests. It's absolutely amazing to see and to listen to all the vocalizations coming from the nests. It's equally amazing to photograph and observe the activity in the nests. Our last trip to this location was early June and the Herons are getting quite large and seemed to be getting tired of sharing the small nests with their brothers and sisters. This becomes quite evident by their actions as they bite at each other and push each other around in the nest. Because it is only a few weeks from fledging time they are constantly spreading their wings as they get the feel for the wind trying to give them lift in preparation for their first flight. Activity in a rookery begins as early as late February - early March and will continue into July. Depending on when you visit, the activity will continually change. Early on you will witness the nest construction or re-construction. Next will be the partnering up and breeding. After that it will be the laying of the eggs and sitting on them for about 28 days. After the eggs are hatched, the feeding becomes a steady ritual and will continue until late June to early July when the young Herons fledge the nest.
While I don't really know if it is true, I believe the male and female parent will be a couple for just this nesting period. It's also been said that the courtship forms in quite an unusual way. The male Heron will choose a stick for the nest building and present it to the female and this act strengthens the bond between the male and female for that season. Such is life in the outdoors, one amazing thing after another! See it for yourself and witness the dynamics of nature as you watch these prehistoric appearing raptors of North America. You may be surprised at what you see and get hooked on nature such as we are.