Written by Mark Kramer

The season is changing. As water temperatures cool, a great migration is underway. Unseen by human eyes, small fish, shrimp, and crabs are leaving the bayou, headed for Galveston Bay and the Gulf of Mexico. They’ve spent the first summer of their life in the lush marshes and warm water of Armand Bayou.

This abundant fishery, especially the presence of juvenile Blue Crab attracts a member of the heron family which specializes in targeting these small crabs. Night Herons have several key adaptations which other herons don’t, that allow for their special feeding behavior.

Large, red, light-gathering eyes enable Night Herons to hunt diurnally at dawn, dusk, and into the darkness. The shallow margins of the bayou’s water cool quickly as the sun sets. The cooling water and abundant food draws young crabs into the shallows to forage. Into the shallows where night herons hunt.

Careful dining is a must when dinner has claws | Photo by Gary Seloff

The second adaptation is a short, stout bill structure. Most herons and egrets have long, slender bills evolved for catching fish. Night Herons have a bill made for crushing. This is an important feature when your primary prey is covered with spiny armor. Can you imagine swallowing a whole crab?

Even better, remove claws and tenderize shell first | Photo by Gary Seloff

The bill allows Night Herons to crunch the exoskeleton of dinner before swallowing. Often, larger crabs are disarmed immediately. Crab claws can produce a painful pinch.

Yellow-crowned Night-Herons are the most common of the two species seen on Armand Bayou. They may be identified by the black and white horizontal stripe running through their eye.

They are crustacean feeding specialists, but don’t limit themselves to crabs | Photo by Gary Seloff

When available, a red crustacean is a tasty addition to the menu.

After a good gully washer last summer, I spotted a Yellow-crown Night-Heron foraging in the flooded field. I approached for a picture, but the bird flew, dropping this prize catch. Happy to have escaped with his life, I returned the crawfish back to his burrow.

Yellow Crowns are commonly seen when the fields and ditches are filled with water after a good rain. They come to hunt crawfish. They can be so abundant that a friend of mine calls them Ditch Pigeons (not suggested when you’re with Birders).

There are 350 species of crawfish in North America. Forty-three species live in Texas. Local crawfish spend the majority of their life burrowed in the moist soil and underground aquifers below our feet. When the fields flood after a rain, crawfish come to the surface, foraging on whatever they can find.

As the water recedes, they create a characteristic “crawfish chimney”. This chimney closes the entrance to the burrow minimizing evaporation to their moist underground habitat. Some of my fondest childhood memories are of collecting crawfish after a summer rain to put in my red wagon from the flooded fields around my house. It’s also a bonanza for the Yellow Crowned Night Heron.

Herons grow special breeding plumes during the nesting season which are held upright during courtship displays. The plumes may also be raised to warn another bird that it’s getting too close to their fishing hole.

Yellow-crowned Night-Herons nest in our area. In fact, they commonly nest in residential neighborhoods. They prefer to nest in colonies with their own kind. I have a friend who had one of these nesting colonies in his backyard which contained over 30 nests. While fascinating to watch them in such close proximity, it also has some drawbacks. The birds aren’t capable of digesting crab or crawfish shell which means a bolus of shell is regurgitated. Also, a massive amount of fishy smelling poop is delivered into your backyard—free of charge.

Most colonial nesting waterbird rookeries are composed of an assortment of species. The colonies are typically on islands in treetops located over nesting alligators. Nesting female alligators possess a strong maternal instinct, protecting their own eggs and inadvertently protecting any egret eggs in the trees overhead from scavenging raccoons. It’s theorized that Yellow-crowned Night-Herons may seek out backyards with multiple dogs. The dogs are substituted for alligators as the protective guardian to minimize raccoon raids.

The Black-crowned Night-Heron is less commonly seen on the bayou. This is true in part because they are most active after dark when human activity on the water is low. Most sightings occur during the day while the birds roost in the surrounding trees waiting for nightfall.

Their large red eyes are striking and enable them to see well with very limited light.

Black Crowns are more strictly nocturnal and seldom seen feeding during the light of day. However, they share the same passion for eating crab. Their nesting habits differ from Yellow Crowns in that Black-crowned Night-Herons nest in large Rookeries with other species of colonial nesting birds. They are one of the few herons that eat other bird nestlings as a regular part of their diet.

Their distribution is impressive. Black-crown Night-Herons are the most widely distributed heron in the world. They occur on every continent except Australia and Antarctica.

The first cool fronts mark the end of the season that Night Herons are seen on the bayou. As crabs migrate out of the bayou, so do the Night Herons. They travel with the food and are commonly seen in winter along the edges of Galveston Bay or further down the Texas coast into Mexico. I always welcome the first sightings of them as the true return of summer.

Night Heron Departures