Today’s readers’ wildlife feature will be presented by our own Greg Mayer, who visited a heron rookery. All the following text is Greg’s.
by Greg Mayer
Last weekend, my friend Andy Buchanan had reported to me seeing large birds in trees at the Mt. Pleasant, Racine County, WI, village compost site. He thought they resembled the storks he knew from Florida, but which don’t occur in Wisconsin, so we went this past week to take a look and see what they were. We found an active Great Blue Heron (Ardea herodias) rookery in big, dead trees, in a flooded wetland (about 6 acres of open water in a Google Earth image from this past April) to the NE of the compost site.
Careful, repeated, counts gave 10 active nests; each nest was a set of sticks a few feet wide and deep. There were 2-3 inactive nests/piles of sticks, the latter smaller; adults would alight on these unused piles, so it was necessary to see young in the nest to be sure a nest was active.
The nests were high in the dead trees, and could be fairly close to one another in the same tree. Adults are about 4 feet tall, to give you some idea of the spacing. There are 3 active nests in this photo (plus the inactive smaller pile of sticks to the left). How many herons can you find? How many are adult/how many young?
Nests held up to 3 young, which were fairly large and well-feathered, but unable to fly. The total number of herons was probably 20 adults and 20-30 young. The adult in this nest, with nape and chest plumes, is flanked by one standing young– notice how big it is– and two sitting behind.
Nests might have 0-2 adults in attendance at any instant. Here, both adults attend to their three young. In addition to having nape and chest plumes, adults can also be distinguished by their white crowns; in the young, the entire top of the head is dark.
When an adult arrived at a nest, the young ones would make a persistent duck-like clucking, evidently begging for food. In the following picture, the adult has just landed, and is being eagerly greeted by 3 young.
Adults were flying in and out, and might land on a nest, a pile of sticks, or a branch or stump of a tree; and, they might move within the stand (i.e. not just into the stand or out of the stand). In flying they of course flap up . . .
. . . and then flap down (these two images were taken .2 seconds apart):
One felled and another nearly-felled tree trunk (part of the same tree, it appeared) showed that Beavers (Castor canadensis) had created the wetland that drowned these trees. I was surprised to see in a Google Earth image that the trees were a flourishing green in July 2011, and at least mostly green in June 2015, so that the flooding and tree deaths must have occurred in the 2010’s, after 2011 or even 2015; there must be, or have been until quite recently, beavers present.
There was a Great Egret (Ardea alba) in the wetland, walking about in the water; look carefully and you’ll see it.
There were also three Sandhill Cranes (Grus canadensis) at the edge of the farm field next to the wetland; they moved back and forth between the open field and the brush at its N edge (which separated it from the wetland). All were warm-reddish-brownish, and one was very rusty– they’re usually grayer. They were probably parents and a young one, but we could not be sure which was which, since all had red foreheads (which they lack when first hatched).
Andy used a pair of German officer’s binoculars from WW II. They had belonged to his father, who served in the Royal Navy during the war, and probably got them as a souvenir. The binoculars were very well made, with leather cladding on the barrels, and still tight with good optics. (The outer surface of the lenses can always be cleaned; it’s when moisture or dirt gets inside that binoculars go bad.)
(All the pictures can be clicked on to enlarge.)