Herons

It is bird migration season, and there are a great many birds returning from their wintering grounds farther south.  Two of my favorites are the Great Blue Heron, Ardea herodias and the Great Egret, Ardea alba.  These tall birds, 36″-48″ in height, can be seen in ponds, lakes and rivers where they are searching for their favorite foods: fish, crustaceans and small amphibians.  At this time of year, before the growing season has started, they can also be found in dry agricultural fields hunting for small mammals such as field mice.

Th​​e long curved neck​ is a modification of one vertebrae ​that ​allows the neck to easily flex. In addition, muscles can pull the neck into a tight coil and spring the head and beak forward at incredible speed allowing the bird to quickly snatch a meal from the water.  Both of these species are stealthy hunters, moving slowly on long, slender legs through shallow water.  They may be seen moving their heads from side to side, crouching or standing upright, or pointing their bills straight down at the water.  All of these behaviors are thought to be used to reduce glare on the water surface and allow the birds to ​better ​see their prey.

Over the summer, these birds will find a mate and raise a family in our area.  Nesting usually takes place in colonies, large gatherings of birds that can number between a couple dozen to a few hundred birds.  Nests are usually built at the tops of tall trees standing in water.  This may be a defensive strategy against ground and climbing predators.  You can easily spot these nests sites in the early spring before the trees have leafed out.  Colonies of nests are called a rookeries, and there are many to be observed in our area.  A rookery that you may want to visit to learn more is at Lake Renwick Preserve in Plainfield.  Hours are limited, so please see their website at: https://www.reconnectwithnature.org/preserves-trails/visitor-centers/lake-renwick-heron-rookery-visitor-center

Other herons that are found in our area include the Black-crowned Night Heron, Nycticorax nycticorax and the Green Heron, Butorides virescens.  These smaller birds, typically 16″-24″ in height, can also be found foraging near open water, but are ​often seen in the early morning or early evening. ​Both species ​use bait such as insects, seeds, leaves or feathers as well as bread put out by people for ducks and other waterfowl, to attract fish to swim within their reach.

You should be able to observe these birds as you visit any area that includes shallow water containing fish or other small aquatic species.  They will be here until late autumn when ponds start to freeze over.  Heron and egret migration routes depend on continually finding open water for hunting, so winter feeding grounds may include much of Illinois​,​ depending upon our winter temperatures.