Even after several years of frequent wader-watching at Brazos Bend, these birds continue to reveal new tricks in their extensive repertoire of hunting strategies. Recently I observed a Green Heron resting on an American Lotus leaf. Green Herons are common at Brazos Bend, and they can often be seen hunting and fishing from aquatic vegetation and partly submerged logs. Birds usually stand on their toes. What was interesting in this case was that the bird was crouching low, resting on its toes and feet (digits and tarsometatarsi, respectively) near the edge of the plant. The bird peeked over the edge of the leaf, studied the surface of the water, and every so often shot out its long neck and snatched a small fish from near the surface of the water. Was the bird hiding from the fish below or studying the fish-produced ripples on the surface of the water, or both? In any case, it was fun to watch.

Waders are great preeners, constantly cleaning and fussing with their feathers. Usually preening means that the action is over for a while–so the photographer interested in capturing hunting and fishing scenes may just as well move on to another bird. However, this summer I caught a Green Heron using the brilliant sunlight to find snacks on its wings. The bird, shown above, held its wings up to the sun. The light streaming through the feathers presumably allowed the bird to spot parasites, pick them off, and eat them. Pretty neat: dining at home!

This summer at least one Snowy Egret spent a lot of time blowing bubbles (and making ripples). This bubbling clearly activity attracted a variety of prey, mostly small fish, that were quickly snapped up. Once, the bubbling attracted something that was too big to handle. I saw a disturbance in the water, and the bird ran away squawking–perhaps a big gar or bowfin came slithering up? I also caught a bubbling Snowy Egret resting on its toes and feet on a log (shown below).

Although wary and uncooperative photographic subjects, Cattle Egrets are common in the grassy areas–and occasionally at the waters’ edge–at Brazos Bend. One day I saw a group of half a dozen Cattle Egrets stalking through the brush like a gang of young toughs grabbing dragonflies and spiders and whatever else moved. They strolled along together, a few feet apart, though the understory vegetation. If one bird flushed or disturbed a prey item an adjacent bird got a crack at it. Grasshoppers, spiders, dragonflies, maybe the occasional frog–down the hatch! Co-operation: it works!

There’s a fine line between fishing and just standing  on the shore like an idiot.—Steven Wright

©2013 Christopher R. Cunningham. All rights reserved. No text or images may be duplicated or distributed without permission.

There has been a bumper crop of fishing spiders this year at Brazos Bend State Park, and I have seen Little Blue Herons and Green Herons eat them, sometimes one spider right after another. Some years it seems as though wader diets consist of a fairly uniform mix of aquatic vertebrates and invertebrates, especially crawfish. This year, rather than crawfish, waders seem to be relying more heavily on smaller invertebrate prey items than in recent years. Lots of aquatic insect larvae, dragonflies, adult aquatic bugs and beetles, and spiders are being consumed along with the occasional small fish, frog, or tadpole.

Invertebrates are highly sensitive to environmental conditions of temperature, humidity, and rainfall. This year’s unusually cool, dry spring may have led to a different mix of potential prey for waders. The Upper Texas Gulf Coast is already behind in rainfall for the summer and water levels already appear low, perhaps impacting aquatic vertebrate numbers as well.

Many of the invertebrates (spiders especially) I see waders take are living among the Water Hyacinth that is growing profusely in some areas of the park. Water Hyacinth is native to the Amazon Basin, but has been imported to many areas of the world where it has become a major nuisance by crowding out and shading native plants and choking waterways.

Besides keeping an eye (and a lens) out for interesting wader predator-prey relationships, I am always on the look-out for hunting techniques. For example, Snowy Egrets are known for shuffling their bright yellow feet in the shallows to flush out prey. Several times over the past weeks I have seen a Snowy Egret (I think it was the same bird) employing a bubble-blowing technique on Elm Lake. This bird was (presumably) blowing bubbles to attract prey. Perhaps the bubbling simulates a small struggling animal, attractive to fish and other aquatic predators. Between bouts of bubbling, this bird also opened and closed its beak, a fishing technique I have seen employed by Black-crowned Night-Herons and Great Egrets, and one that also sends ripples out into the water. One time during this process this Snowy Egret grabbed a small aquatic invertebrate–it was down the hatch too fast to tell for sure what it was, although it was about the right size and shape for a water tiger (larval predaceous diving beetle). On another occasion, the egret was clearly catching small fish with this technique. Time will tell if anything bigger can be attracted by blowing bubbles!

©2013 Christopher R. Cunningham. All rights reserved. No text or images may be duplicated or distributed without permission.

What a book a devil’s chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel work of nature! –Charles Darwin

Usually when one sees a wader grab a prey item, the prey is subdued, perhaps by a few pecks, then manipulated into position and swallowed. Today at Brazos Bend State Park, however, I observed a Green Heron grab a large American Bullfrog tadpole. The bird picked up and then dropped the tadpole a few times after intermittently pecking it. Finally the bird discarded the tadpole and walked away. I thought this strange given that waders of all species at Brazos Bend eagerly consume amphibians in all stages of development. Perhaps (although it seemed unlikely) the bird considered the tadpole to be too big to swallow?

I continued to watch the Green Heron fully expecting the bird to reconsider and return to the tadpole and eat it. Instead, it caught a juvenile frog and repeated the whole process! After pecking the poor frog a few times, the Green Heron just walked off without eating it. I have only seen this sort of thing once before when a Little Blue Heron captured and then discarded a crawfish. Do these waders hunt and kill (or at least maim) instinctively without being hungry, and without lardering the prey–just like well-fed house cats? If so, stone cold killers, these fellows!

©2012 Christopher R. Cunningham. All rights reserved. No text or images may be duplicated or distributed without permission.