Readers’ wildlife photos

Once again I present the last photos I have in the queue. If you got ’em, and they’re good, please send them in.

Today’s wildlife pictures come from reader Jan Malik, and concentrate on one act of predation. Jan’s captions are indented, and you can enlarge the pictures by clicking on them.

In early April, I visited the Edwin B. Forsythe National Wildlife Refuge in New Jersey, which encompasses both brackish coastal marshes and lowland mixed forest. The refuge, previously known by the more graceful name Brigantine, features a wildlife drive where a car serves as the ultimate “blind,” allowing for the close observation of birds.In one section, a group of herons assembled, intently staring at a culvert outlet—a sort of fast-food restaurant for wading birds. The Great Blue Heron (GBH, Ardea herodias) in the center has already caught a small fish, though this is not a meal an adult heron finds satisfying:

The same was true for this Great Egret (Ardea alba) with a small fry. All the birds were patiently waiting for a main course:

Finally, one heron caught a fish worthy of the hunting effort. Visible in this picture are the nuptial plumes of this GBH—wispy feathers on the lower neck, similar plumes on the wing coverts, and a long, elegant black plume on the head. These grow only during the breeding season:

The fish, likely a White Perch (Morone americana)—a predator of mollusks, arthropods, and small fish—displays a defense reflex here. It has two dorsal fins: the posterior fin is soft, while the spiny anterior fin is raised when the fish is in danger. This reflex is intended to make the fish harder for a predator to swallow:

The heron has speared the fish through its posterior region, but the prey is still alive, writhing to get free. The heron, now knee-deep in water, must finish the fish off and reposition it to be swallowed head-first:

To do that, the bird first walks to shallower water where it can momentarily drop the fish without risk of escape. Additionally, moving away from the group decreases the chances of the catch being stolen by a competitor:

Catch and release (but not for long): In the shallow, muddy water, the GBH releases the fish; it cannot swim away and is visible as a dark blob below the bird. Whether this GBH is male or female cannot be determined from these pictures, as the sexes are monomorphic. This suggests that both sexes are “choosy” in mate selection, as both provide significant parental care and investment:

The GBH delivers the coup de grâce—the perch is now speared through the head. For me, looking at these pictures raises the question: how many bird species are sexually dimorphic versus monomorphic and why? Some are strongly dimorphic—ducks, songbirds, turkeys, and grouse—while others, like herons, gulls, parrots, corvids, and raptors, are not. Others fall somewhere in between, like the American Robin. While males have darker heads and more vibrant breasts, they do not incubate the eggs, though they do guard the nest and feed the chicks.  Are these differences exclusively the result of parental care roles?  Or is it an adaptation to the environment?  For instance, a GBH cannot be too flashy, or the fish would easily spot its silhouette against the grey sky:

In one smooth move, the heron tosses the fish into the air and catches it head-first. The fish is now incapacitated, no longer resisting, and bleeding heavily. With its defensive fins down, it can finally be swallowed:

Only once have I seen a GBH unable to swallow a large eel—mostly due to its length rather than its girth. Otherwise, once prey is caught—be it a fish, a duck, or a rodent—it is swallowed whole, sometimes after a brief struggle:

The fish is now in the esophagus; the heron’s flexible neck tissue expands to accommodate the meal until it can be digested:

Here is a picture of a Great Egret also in breeding plumage, sporting its long, wispy feathers (aigrettes). These will be lost through molting or wear shortly after the breeding season ends:

A Great Egret in flight, with its head retracted—a trait that makes them easy to distinguish from cranes. While they occupy similar ecological niches to the Great Blue Heron, they are not identical.Egrets often hunt “on the move,” flying or hopping, while GBHs prefer ambush hunting or slow, deliberate wading. Egrets typically target smaller prey, while GBHs: