Communal nesting – the rookery at Sandy Creek Park

great blue heron DK7A5496© Maria de BruynUnlike Eastern bluebirds (Sialia sialis) and other songbirds, great blue herons (Ardea herodias) like to build their nests near one another, forming what is called a rookery, or colony of nests. The nests are often seen in the tops of tall trees and comprise large twigs and branches that surround grass, leaves and moss. As many as 135 nests have been counted in a rookery, but the one at Sandy Creek Park that I visited this spring had three nests.

The herons return to the nests for several years running. Each year, the males re-furbish the nests in order to attract a mate.

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You can see the nests well with binoculars from a walking path, but as I have no binoculars and rely on my camera’s zoom lens, I slogged through forest and marshy terrain on numerous occasions to get close to the pond that had their rookery pine trees on the other side. They were still a bit out of range for my lens, but occasionally I managed to get a half-way decent shot, which encouraged me to return often to follow the nestlings’ progress.I followed them from 8 March through 26 June.

great blue heron DK7A5924© Maria de BruynGreat blue heron DK7A3689© Maria de BruynThe top nest in an open-to-the sky tree appeared to have four babies, while the nest below it had three.

A nest in a tree to the right, which had much more dense foliage, seemed to be occupied by only one or two babies.

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There were always 1-4 adults around, including both parents on the nest and “guards”, who took up posts atop nearby trees to watch the nearby skies. This is one reason for the rookeries; the herons want to ensure that there are adults around to protect the nestlings from predators, which include raccoons, crows and hawks, such as this red-shouldered hawk (Buteo lineatus) that was hanging around the nests one day.

red-shouldered hawk DK7A7354© Maria de Bruyn red-shouldered hawk DK7A7371© Maria de Bruyn

great blue heron DK7A6601© Maria de BruynGreat blue heron DK7A3495© Maria de Bruyngreat blue heron DK7A8238© Maria de Bruyn resThe parents feed their young by regurgitating food and the young birds get excited when a parent returns after being away for a time.

The nestlings make quite a lot of noise squawking loudly while they jostle to get first in line for the meal.

great blue heron DK7A3743© Maria de BruynThe young herons appear to “argue” with one another with loud calls and it seemed that they “jousted” with one another using their beaks.

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Weaker chicks may miss out on getting enough food and can die of starvation, but that didn’t happen at the Sandy Creek rookery. Some chicks were obviously larger and stronger than others, but even the smallest fledglings survived.As they grew, the babies began standing tall and walking around the nest.

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great blue heron DK7A9348© Maria de BruynWhen they were close to fledging, they stood near the edge of the nest and practiced spreading and flapping their wings. Sixty days after hatching (much longer than smaller birds!), the young herons were ready to fly and began taking short flights to nearby trees, before venturing out on farther trips. great blue heron DK7A8960©Maria de BruynThe young ones will not breed until they are two years old.

Watching events unfold at the rookery was a new past-time for me this year and likely one I’ll repeat in the future. If you have time and the opportunity, I’d recommend the experience!

Patient fishers of the bird world

great blue heron IMG_8830© Maria de Bruyn resIt’s not uncommon for visitors to our ponds, lakes and rivers to see what look like tall, statuesque bird sculptures on shorelines. The great blue herons (Ardea herodias) – North America’s largest heron species – can stand for long periods without moving or only slightly tilting their heads as they exercise extreme patience in their quest for a morning, midday or evening meal.

If they have a chance for easy pickings, these herons will certainly take advantage of it, as I discovered when the koi and goldfish in my pond were disappearing. But in their natural habitat they will scan the water intently to find their prey.

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If you have the time and inclination to watch them for a lengthier period of time, you will note how they hunch down and stretch up as they position themselves to get good views of the water around them.

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great blue heron IMG_8791© Maria de Bruyn resThey stare downwards and to the side, following the movements of fish, frogs and crayfish. When the wind blows, their plumed neck and tail feathers sway gently and beautifully in the breeze.

great blue heron IMG_4343©Maria de Bruyn resIf nothing seems nearby, they will move with quiet and slow deliberation to another spot, often quite nearby. Unlike the snowy egrets, they don’t stir up the mud with their feet or flap their wings to create movement in the water.

When a fish does swim by, they burst into very fast motion, plunging their long beaks and whole heads down to grab what they have spotted.

 

 

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They are not always successful, sometimes coming up empty beaked!

great blue heron IMG_8878© Maria de Bruyn resgreat blue heron IMG_8879© Maria de Bruyn resBut their patience obviously does pay off, too.

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Once caught, they need to work the fish or other prey around so that they can swallow it down smoothly. As they swallow their meal whole, this is important. (And they can eat a very large meal; there is a film on the Internet showing a heron swallowing a groundhog!!)

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If you look carefully, you can see the meal slide down their long necks.

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Great blue heron IMG_0554©Maria de Bruyn resThis fishing strategy works well for the great blues as they can continue to hunt even when injured. This bird had a very badly damaged wing and apparently couldn’t fly anymore but it could stalk slowly in the lake as it looked for food.

The bird below had had some kind of encounter – either with a man-made obstacle or some form of wildlife that left it with an injured wing and broken leg. Bald eagles are one of the few predators of adult herons and this great blue lives at Jordan Lake which has a group of such eagles in residence. Despite the handicap, the heron could fly from spot to spot and then stand in wait for meals to swim by.

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If disturbed, these birds emit a very loud and harsh squawk or croaking sound and then often take off. They certainly wouldn’t win any singing contests with their definitively non-melodious calls.

great blue heron IMG_8516© Maria de Bruyn resgreat blue heron IMG_8940© Maria de Bruyn resgreat blue heron and egret IMG_5083© Maria de BruynThey prefer to fish in solitude and don’t care for other birds invading their territory. This great blue and great egret wanted the same spot and the great blue made some efforts to chase off its white competitor. However, the egret refused to leave and eventually they shared the spot with some meters of space between them.

Watching the herons fish has not only given me an appreciation for their innate patience but has also enhanced my own patience as well as I stand and wait with them until it’s finally mealtime.

 

Turtles as stepping stones

Northern mockingbird IMG_3689©Maria de Bruyn resOne day when I was at a beautiful nature park in the neighboring city of Durham, I was – of course – looking for wildlife. For a while I watched a Northern mockingbird (Mimus polyglottos) pecking along the path in a quest for insects. It wasn’t until I got to the pond, however, that a scene unfolded which kept me occupied for a while.

 

great blue heron IMG_4099©Maria de Bruyn resgreat blue heron IMG_3905©Maria de Bruyn resThe resident great blue heron (Ardea herodias) had stationed him (or her) self at the end of a log on which several pond slider turtles (Trachemys scripta) were basking. He seemed to be staring in their direction, so I wondered if he was considering eating one. After seeing a video of a heron swallowing a groundhog whole, I knew that they can consume quite large meals. After a time, though, it seemed that the bird wasn’t interested in the turtles but in the fish swimming in front of them. After patiently waiting for a time, the heron stabbed and had success!

painted turtle IMG_3815© Maria de Bruyn resThe heron decided to move to a new spot, down near the other end of the log. The sun was bright and the pond was filled with many dozens of turtles enjoying the warmth. Whereas red-eared sliders and painted turtles at Mason Farm Biological Reserve will often plop into the water in haste when they sense people nearby, these turtles didn’t seem to care if they were watched from the pond’s edge. But I did think they would move as the heron neared them.

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How wrong I was! The turtles saw him coming but they just let the huge bird use their backs as stepping stones!

 

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The bird’s claws completely encircled some turtles as it moved along, occasionally balancing on one leg.

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I noticed a few turtles with scutes bent up into the air. (Scutes are sections of the carapace.) I began to wonder if this was the result of the heron’s claws snagging on their shells as the bird proceeded.

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If that was true, though, why didn’t the turtles skedaddle out of there when the heron came near? I only saw one turtle plunge into the pond.

great blue heron IMG_4304©Maria de Bruyn respainted turtle IMG_3815© Maria de BruynAt home, I did an Internet search and found out that turtles shed their scutes from time to time and that was apparently what I was seeing. So I learned that turtles shed! Turtles’ shells are extensions of their rib cage and attached to their spine; terrestrial turtles don’t shed but aquatic turtles do shed scutes, which are made of keratin (like the material of horns or fingernails).

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The heron kept moving along as he wasn’t having much success in the different spots he chose. He did get a couple fish but smaller than his first catch. Eventually, I found that I wasn’t quite as patient as the heron so I finally left after a very entertaining hour of observation. I do so love watching the natural world!

Big Blue – my avian nemesis!

Over the past few years, I’ve become an avid birder, at least from the standpoint of photographing the different species I see and trying to get interesting shots of their behavior. And while I’ve grown to love the beauty in each type of bird, there is one particular individual that I would rather not see in my yard.

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What has caused this aversion, you might ask? It’s related to my pond and fondness for the fish that have populated it. At one time, I had a lovely group of goldfish, butterfly koi, shubunkins, comets and one medium-sized koi, whom I named Big Guy (or Girl, depending on my perception that day). The first predator to get some of them was a turtle, who I admired near the pond one day, not realizing that it would go into the pond and then not be able to get out.

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Turtle unfortunately accounted for the disappearance of a few smaller fish, until I finally figured out that I needed to put in a larger log for it to climb out on. (This turtle would NOT let me catch it.)

But then my real nemesis appeared – Big Blue (a name given by my neighbor, Kevin), a great blue heron (Ardea Herodias). I had seen Big Blue at a large neighborhood pond and admired the grace of this large bird.

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Big Blue at the neighborhood pond

However, the first time Big Blue visited my yard – to my knowledge – I caught sight of him (or her) standing in my small pond with one of my biggest goldfish hanging from his beak. I ran out into the yard, uselessly yelling for him to drop the fish. He stared at me and didn’t move until I was about three feet away – impressing me with his large size. (He was only about 6 inches shorter than me!) Then he lifted off with his prize meal.

Great blue herons, the largest North American heron species, have a varied diet that includes small fish, as well as shrimp, crabs, rodents, other small mammals, frogs, salamanders, lizards, snakes, crayfish, dragonflies, grasshoppers, aquatic insects and even small birds. Their main hunting technique is to wade slowly in shallow water, sometimes diving headfirst into the water to quickly spear their prey with their sharp long bills.

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Covering my pond with netting was not an option. I had used netting to protect some plants and then had to rescue a small bird and an anole that had gotten tangled up. The owner of the store where I bought my fish (sadly closed now after many decades of running their family business) recommended I buy a life-like statue of a heron to position by the pond. He had done this at his own pond and said it kept the herons away as they are solitary hunters and don’t want others in their territory. He said Big Blue would see the statue and fly on. So I installed the statue, changing its position from time to time.

This seemed to work for many months but the past weeks I was very busy and didn’t change the stationary bird’s place. Then I noticed that my family of three bullfrogs were gone and Big Guy had gone missing (all the fish would come to the surface when I gave them pellet meals and Big Guy was gone. A gorgeous red, black and white goldfish with wavy fins was also gone. Inexplicably, the statue was also facing a different direction!

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Apparently, Big Blue must have had a tussle with the imposter and discovered he was not real, leaving him free to take up fishing in my pond again. I realized this about 2 weeks ago, when I saw Big Blue at the pond’s edge. I ran out to chase him off and he flew up to a neighbor’s tree. Now the pond is partly covered with some metal fencing laid over one end; it has tiny holes so no animals can get caught in it. The fish can hide under that and the smaller birds can still perch on sticks to get a drink. As it’s getting colder, the fish are also going into hibernation so – hopefully – they will make it through the winter!

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I have never seen Big Blue with a mate at the large neighborhood pond and sincerely hope that he will remain a bachelor. I admire his beauty but don’t want a family of herons using my pond as a restaurant!

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Next blog: Caterpillars with fuzzy hair-dos