Featured Creature: Black-crowned Night Heron

Photo by Tania Roa

What dapper creature enjoys formal wear, is most active in the evenings, and is an indicator for wetland ecosystem health?

Black-crowned Night Herons!

Photo by Tania Roa

During quarantine, I decided to take up photography as a new hobby. I wanted to know more about the creatures I encountered on my hikes and snorkel sessions. Photography allows me to view nature through a new lens, literally and figuratively, and it provides the perfect opportunity to zoom in on details I would otherwise miss.

One day while walking my dog at our local park, I noticed that a night heron was really focused on one section near the edge of the lake. I had a feeling that a hunt was taking place, so I crouched down with my camera to get at eye-level with the heron, and sure enough within a minute the bird was pulling a fish out of the lake! I quickly took as many pictures as possible. To this day, this experience is one of my favorite wildlife encounters.

Photo by Tania Roa

A Skilled Hunter Indeed

Night herons are ambush hunters. To lure in their prey, these clever creatures will vibrate their bills in their water, creating an alluring sound that prey will inevitably investigate, although they will likely regret their curiosity. The birds patiently wait along the edges of lakes and other bodies of water for their prey to make a false move. As soon as the moment is right, they strike. Once their prey is firmly inside their beaks, night herons shake their prey to induce a daze, then gulp it down in a few swift motions. Thanks to their serrated beaks, their mouths are built for this method. 

Black-crowned night herons mostly eat fish, but they also feast on squid, crustaceans, aquatic insects, frogs, mussels, clams, rodents, and snakes. They have quite the appetite. When young night herons notice an intruder at their nest, their previous meals are used as a defense mechanism. Their stomach acid is extremely potent, to the point where bones can be dissolved in it, and this is regurgitated to frighten potential predators. Any attackers hoping to get an easy meal walk away hungry and smothered in digested material. 

(Almost) Worldwide

Like their diets, Black-crowned night herons have a variety of breeding preferences. As long as the habitat has enough tree cover for nesting and hiding from predators, and a body of water for hunting grounds, night herons will move right in. They occupy streams, salt marshes, swamps, man-made ditches and wet agricultural fields. Night herons are the most widespread herons in the world, on every continent except Antarctica and Australia.

The Black-crowned night heron’s non-picky lifestyle is demonstrated in their behavior, too. During the day, night herons will socialize with other birds, even those of other species. The birds they interact with tend to hunt during the day, but night herons will take to the edges of lakes usually at night, unless they need extra energy during breeding season. It is theorized that night herons are more active at nighttime to avoid confrontations with their neighbors. 

Time For the Runway

If you saw a young night heron, you might not recognize it. Before adulthood, these birds have brown feathers to blend in with the natural environment. Even at this age, night herons have a distinct hunched over posture – one that would send me right to the chiropractor!

Photo from Public Domain Pictures

Once they’re older, night herons put on their royal black crown and elegant tuxedo-looking black and gray feathers. During mating season, their yellow legs and feet turn a reddish color, and their black crowns take on a blue-green glossy appearance. To top off this dapper outfit, two thin, white plumes extend from the back of the heron’s head, growing to around 10 inches long. These social birds are ready for the upcoming ball!

You can see these famous plumes and some night heron behaviors here:  

How are human activities impacting Black-crowned night herons?

Due to their broad range and variable diets, night herons are of least conservation concern according to the International Union for Conservation of Nature (IUCN). However, this doesn’t take into consideration the well-being of Black-crowned night heron populations within any one area. Conservation efforts tend to evaluate overall populations, but analyzing subsets of populations can bring forth important and overlooked information. 

Habitat loss, especially the removal of trees, impacts the ability for night herons to nest and find shelter from predators. Water pollution threatens prey populations and wetland ecosystems. Pesticides such as DDT have harmful and lingering effects, therefore threatening the health of night heron habitats.

The wide distribution and feeding habits of night herons are valuable to the places they inhabit. Since these creatures rely on intact bodies of water, and are vulnerable to changes in water quality, they are crucial indicators of ecosystem health. Where there are night herons, there are happy wetlands.