morning at the marsh

It’s amazing how much you can see early in the morning before the cyclists and hikers have hit the trails around the local marsh.  And it always amazes me to find such a diversity of wildlife inhabiting a small wild oasis in the urban landscape! I’m sure if I had spent more time on this hot, humid morning, I would have seen even more.

floating island-

Dense mats of cattails float around the marsh propelled by the prevailing water flow.  They attract a wide variety of wildlife that may hunt from their edges, nest in their stalks, and hide within small crevices from the peeping eyes of photographers.

great blue heron-

Great Blue Herons are often found along the shoreline, usually obscured by the vegetation.

great blue heron-

Another heron was making its way down toward the shoreline — perhaps the mate of the other one?

great egret-

I can always count on seeing a Great Egret or two foraging near the edge of the marsh.

green heron-

What else is hiding here in this vegetation near the shore? A Green Heron pops up to see if I’m a dangerous predator.

green heron-

A less nervous juvenile Green Heron hunted in the shallows.

common loon-

Out in the water, a Common Loon swam by.

double crested cormorant-

Nearby, a double-crested Cormorant surfaced from its dive, and took a look around.

I spotted something white way out in the middle of the marsh, swimming quickly away from me, and grabbed a quick shot of a Trumpeter Swan family with their two, seemingly newly hatched, cygnets.

trumpeter swan family-

It’s a bit late to find these newly hatched chicks; perhaps the first nesting failed and these are result of a second nesting attempt. The chicks have a lot of growing to do before they reach the body size of the adults which can weigh more than 20 lb.

trumpeter swan family-

The patient hunter

Nothing exemplifies patience better (in the bird world) than herons and egrets fishing.  On a recent morning walk at the marsh at Wood Lake nature center, I spied these statues along the shore.

great white egret fishing

I love the mirror image of this statuesque bird.  Unfortunately, I disturbed its hunting and it flew off.

If they are undisturbed by a photographer’s presence, they will stand, unmoving in a fixed stance, for minutes on end, patiently waiting for the unwary fish or invertebrate to swim by.

great blue heron fishing

I was so far away from this bird that it continued its imitation of a bird statue for 10 minutes while I stood there.

great blue heron fishing

An imperceptible lowering of the bird’s head must mean there is something interesting there, but another 5 minutes went by with the bird in this position with no action. I moved on.

green heron fishing

Further along the marsh shore I spied a juvenile Green Heron repositioning itself on a branch. It assumed the statue stance… while I hid behind a tree to capture what I hope would be some fishing action.

green heron fishing

Sure enough, within a minute of landing, the heron started into its attack stance.

green heron fishing

Another lesson in patience — holding a pose while upside down clinging to a branch. Waiting…waiting…(me with my finger on the shutter, I mean).

green heron fishing

The strike and grab happened in a blink. To make up for my slow trigger finger, I just pressed down on the shutter and rapidly clicked off multiple shots.

green heron fishing

It’s a tiny little fish, but every calorie taken in counts when you’re trying to put on fat to migrate.

green heron fishing

Toss that baby back in the throat, just like you would a much bigger fish.

green heron fishing

And now back to pose number one — the statue impression.

The patient hunter reaps a reward!  Herons and Egrets have an astounding 70% average success rate (# of captures/# of strikes) in both natural and man-made aquatic environments in the southeastern U.S*.  I assume it’s roughly the same up here in the northland.  Great Blue Herons were by far the most successful hunters in estuary habitat, racking up a 93% success rate there.  Great Egrets enjoyed their greatest success along rivers (94%).  Snowy Egrets were almost equally successful in a variety of aquatic habitats (65-75% success) but were not able to match the prey catching efficiency of their larger cousins.

*data from H.D. Mincey, 2006.  MS Thesis, Georgia Southern University.

Learning to fish

A family of Green Herons has taken up residence in the pond in the backyard.  I think there were 5 juveniles hunting along the shore of the pond, which is shallow and almost completely covered with duckweed.

Adult Green Heron, Butorides virescens

One of the adults just happened to be hunting near where I was standing.  They hunt the sparse openings in the duckweed right where tree limbs and debris have fallen into the water.  Perhaps this is where fish congregate as well.

Adult Green Heron, Butorides virescens

Shooting birds through a tangle of tree branches means there is always something obstructing the view. So I removed some of the clutter with Photoshop.  Adult Green Herons are striking birds with their chestnut-colored breast feathers and dark green head and back.

At the other end of the pond four of the five juveniles congregated on a tree trunk that had fallen into the pond this spring.  Its leafy branches hid them well from view, and also provided perches close to the water for them to practice their hunting.

Juvenile Green Herons

This was as close as I could get to four of the juvenile herons, about 200 feet away across the pond. The fourth heron is behind a big limb, and three mallard ducks perched on the fallen tree trunk for their afternoon nap.

I saw one of the parents feed one juvenile only once in the three hours I stood by the pond; the rest of the time they were on their own to search for food.  Adult Green Herons usually wander away from their breeding area after the nesting season, eventually moving into Central and northern South America for the winter. However, young herons stay at least until early fall on this set of ponds, where I have found them hunting in previous years. (See my earlier post on Heron fishing.)

Juvenile Green Herons learning to fish

I couldn’t tell what this youngster on the left found, but it tossed it around, dropped it, picked it up, and finally lost it in the water. Perhaps they don’t know yet what is edible.

Juvenile Green Heron and male Wood Duck in eclipse plumage

A fifth juvenile skulked far back in the leafy branches overhanging the pond scum. A male Wood Duck in eclipse (molt) plumage floated by, opening up some of the water surface as he swam and ate the duckweed.

The typical clutch size for Green Herons is 3-5 eggs, so this pair of herons must have harvested enough food to raise a large brood of youngsters.  I wouldn’t have thought such a small pond could support this many birds, but the heavy rain and run-off from feeder ponds upstream may have added to the fish and invertebrate populations this summer.

Thick as pea soup

That’s a good description of the duckweed on one of the ponds in the backyard.  It is truly disgusting.  Is there no check on the density of algal growth?  Obviously, the local herbivores (whoever they are) can’t keep up with it.

So, imagine my surprise to find a juvenile Green Heron trying to fish there one afternoon.  Silly bird — you can’t see through that muck.  But it tried, using first one log perch and then another and peering into the green soup to see what might be swimming below.  I never saw the bird make even one attempt to snatch something.  It finally sat down on one end of the log and had a nap.

All he got for his trouble was slimy green feet.

And to illustrate just what a thick carpet of algae has accumulated here, feathers rest on the surface quite nicely.

Ponds in this condition are terrible environments for aquatic life.  The dense mat of algae blocks the incoming light that submerged aquatic plants require.  Dying algal cells sink to the bottom and get consumed by detritivores who use up available oxygen, making it near impossible to sustain other critters (like dragonfly larvae).  YUCK!

Heron fishing

I have often seen a juvenile Green Heron foraging along the edge of the large pond in the backyard right before sunset.  It’s usually too dark to take decent photos of the bird then, but yesterday the heron was out on the fallen logs looking for a meal or two in late afternoon.

Young birds have striped breast feathers instead of the chesnut brown of the adults; their feet and legs are not yet bright orange, and the blue-green feather cap is incomplete.  (Compare the plumage of this bird with the adult in the photo from Wikipedia)

The youngster was enjoying great success fishing at this end of the pond where low-lying branches of a fallen tree gave it access to shallow water.  Over the hour I watched the bird forage, it made five attempts and caught four fish/frog/invertebrates (I couldn’t always see what it caught).

One of the keys to success is their excellent eyesight.  Their eyes are placed so far forward where the skull narrows that they must have great binocular vision, which gives them good depth perception.

Another key to this bird’s successful foraging was its “fishing from a perch” strategy.  Instead of standing in the water to spear fish from above, like the egrets and great blue herons do, this bird perched on a limb, slowly lowering its head all the way to the water, and then grabbing what was coming near the surface.

Those long toes wrap around the branch, securing its perch while it extends its neck fully to the water’s surface.

Fish were manipulated in the bill several times, dipping them back into the water and then out again; some prey (maybe crayfish) were swallowed immediately.

After several gulps, the bird finally got the fish down.

Green Herons hunt frogs and aquatic invertebrates as well as fish, and are normally active at dawn and dusk, well past twilight hours.  Their nocturnal habits and their use of “lures” to bait fish toward them makes them unique among the herons and egrets.  I did not see this particular heron try this, but some Green Herons have been observed dropping food items below their perch to attract fish.

Although they are summer residents throughout the eastern half of the U.S., they will depart soon for their winter range in Florida or Mexico and Central America.  Some birds may over-winter as far south as Venezuela.

Caribbean Herons

They are common, tolerant of photographers, and found everywhere, even in busy urban areas.  I was amazed at how easy it is to creep right up to foraging herons or their rookeries and take not one but multiple photos of them.  Every island we visited in this last week presented at least one good photo op of these interesting birds.    For example, I usually see Green Herons as they fly away from me, but I found one foraging for some large bodied winged insect on the lawn at the botanic garden on Grenada.  I took photos as he stalked and then stabbed his long sharp bill into the lawn and extracted the “bug”.

Bird guides say this is a short-necked heron, but it sure looked like this one could stretch it out when necessary.

I watched this heron perform this feat successfully three times, but couldn’t figure out a) what it was eating or b) where it found them in the lawn.  I certainly didn’t see any such large insects crawling around in the grass, but every so often, the heron would run across the lawn, probe into the grass and bring up a bug to engulf.

By far the most entertaining group of herons were the cattle egrets we saw on St. Croix Island.  The trees were overflowing with heron nests in all stages of nestling development from incubating parents to those feeding young chicks as large as the adults themselves.

The bright yellow, rosy bill of the egret on the far right is typical of an active breeder.  The adult hunched down in the nest has an all-yellow bill in contrast (already mated, and doing boring incubation duty).

One poor parent was feeding two chicks who alternated between being fed and bashing the parent with their wings as they flapped around the tree top for better position.  Then, when the parent left, they bashed each other around instead.

I was so busy taking photos of the two youngsters beating up on each other that I didn’t even notice there was probably another heron species nesting in these same trees.  What is that darker-colored bird in the lower left of the photo above?  Its dark color and blue-tinged bill looks like the Little Blue Heron I saw on a couple of the islands.

On a St. Croix beach, I spied a Little Blue Heron foraging along the shore.  I took lots of photos from quite a distance away thinking it would fly away at any moment.

The bill looked like it was the same color as the water.  The bird eventually let me walk up to within about 20 feet, but was eyeing me quite closely at that point.

These herons are larger than the cattle egret, but much smaller than the American Egret or Great Blue Heron.  They eat fish, frogs, rodents, crustaceans, and insects, so they seem adept at feeding on or near shore.  There were a great abundance of these crabs on the shore, so perhaps that was on the menu for today.

Back in town, I walked along a small creek and found another heron foraging in the weeds.  The blue bill is not so obvious on this bird and the color of their plumage seems almost purple instead of blue in the shadier light conditions.