Herons, Egrets & Bitterns - Habitats and Niches.

Family Ardeidae, Herons, Egrets and Bitterns, contains 65 different species. Very broadly the habitats in which they are found can be called Wetlands. They range from open wetlands with fresh or alkaline, inland or coastal waters, through pastures and areas of cultivation, lake fringes, reed-beds, marshes and swamps, to streams in dense wet forests.

In the following sections I focus on the habitats and behaviour which enable the various species to cope with competition from other birds and avoid possible predators. The birds range from large and confident, to medium sized and secretive. They have very similar body-forms with "dagger-like" beaks which they use to spear or catch fish or aquatic invertebrates. The Herons and Egrets especially can be seen in two different poses: a "hunched posture" with the neck retracted and an upright "ready for action" posture with the neck ready for a quick strike.

The images I have chosen to use here highlight in italics some of the key aspects of their habitats and their feeding behaviour.

Using common names they can be split into the following sub-groups:-

Common Name Species Comments
Heron 29 12 species can be found in Costa Rica
Night Heron 7 Nocturnal birds - widespread
Tiger Heron 4 Mainly found in Middle America
Reef Heron 2 Old World species - Gambia was good
Egret 9 White plumage birds
Bittern 14 Very secretive - widespread

In terms of distribution the Old World region (Australasia, Africa and Europe) has rather more species than the New World (Middle and North America with a few species in South America).

Herons.

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The most widely used common name, 65% of the species, is Heron. Egrets are often referred to as White Herons.

Tiger Herons.

Tiger-Herons are probably the most ancient lineage in family Ardeidae. They are secretive, possibly nocturnal birds which have established niches in wet forest regions. Three species are found in Middle America and one in Africa. Of the three Middle America species one likes fast flowing streams, another prefers quiet streams and a third likes mangrove marshes.

Fasciated Tiger-Heron - forages along rocky, fast flowing streams in forested areas.

Rufescent Tiger-Heron - forages at edges of quiet streams or swampy areas within mature wet forest.

Bare-throated Tiger-Heron (right) - secretive and possibly partially nocturnal. Found in more open habitats than the other Tiger-Herons. This one was photographed at the side of Tarcoles River in Costa Rica.

Nocturnal Herons.

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Some Herons are nocturnal feeders. Still in Middle America the Boat-billed Heron (left) nests and roosts by day in vegetation which overhangs ponds and streams. This one was also photographed on Tarcoles river in Costa Rica.

Two other Night Herons, which are found in Costa Rica, are also readily seen in Stone Habor, New Jersey in North America and have featured in Nelson's Page from which the next three photographs have been taken.

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The Back-crowned Night Heron (right) roosts by day in dense vegetation near water.

It is most common in fresh water habitats and has a worldwide distribution.

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The Yellow-crowned Night Heron (left) is more diurnal than the BCNH. This image shows an adult bird (left) with a Juvenile (right).

It is found on beaches and mudflats where it stands on river banks and mudflats in daylight. It is less common inland and is only found in North and Middle America.

The female lays three to five eggs on a nest of sticks placed in a tree or sometimes on the ground. Both the male and female build the nest and incubate the eggs. The eggs hatch in about three weeks. Both parents care for the chicks and feed them regurgitated food. The chicks fledge when they are about 25 days old.

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At the end of August, on the way to see the Ospreys, Nelson captured an image in which two Yellow-crowned Night Herons (right) seemed to be on sentry duty guarding the approach to nest 1.

Suddenly, as he approached, an Osprey took off from an adjacent piling and flew very close between the two Herons. The Night Herons stayed where they were.

The behaviour of standing confidently on the posts is at variance with the rather secretive crouching posture associated with these birds. Were they perhaps acting as lookouts for others - but if so, it was not for the Osprey.

Reef Herons.

Two species are called Reef Herons and are only found in the Old World region of the world.

Both of these species exist in two morphs - light and dark.

Pacific Reef Heron (Eastern Reef Egret) - favours the inter-tidal zone, rocks, coral, mangroves, mudflats in Australasia.

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TheWestern Reef Heron (left) - favours coastal areas and estuaries as well as brackish water near mangroves.

It can be found in Europe, Africa and Australasia.

This one, which thinks it is a tight-rope walker, was photographed in The Gambia.

Our birding guide led us to the roof of a pumping station, which was unfenced and required great care, but we were rewarded by fantastic views of this and other birds of the area.
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New World Herons.

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These birds are mainly found in North and Middle America. They favour open wetlands, pastures, lake fringes, cultivation and urban areas.

Two Blue Herons adopt different feeding techniques.

The Little Blue Heron can be found along the edge of marshes, ponds, lakes and lagoons. It hunts alone in shallow waters stalking its prey with slow, deliberate movements. The juvenile is initially all white but light blue patches then begin to appear as its plumage develops.

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The Great Blue Heron (left) can be found in almost any open, saline or freshwater, wetland area.

It can hunt in deeper waters than the Little Blue Heron but it chooses to stand motionless for long periods of time waiting for prey to come within reach.

The Tricoloured Heron (right) - which can be found at the edge of marshes, mangrove swamps, ponds and lakes adopts both techniques.

It stands and waits but, when that does not work, it stirs the sediments with its feet to catch small fish. The photograph illustrates the high level of concentration which the bird displays as it watches for prey.

The Green Heron (below, left) - can be found in the vegetation along almost any body of water. It perches low down close to the water surface where it can watch for prey.

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Old World Herons.

These are mainly birds of Africa and Australia.

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The Grey Heron (below, right) is found on coasts and open shores, soda and fresh water lakes, wetlands and grasslands. The image, taken in The Gambia, shows the confident and purposefulwalk which characterises this bird.

The Squacco Heron (below, right) - favours coastal mangroves and small highland, freshwater pools. This photograph was taken during a birding trip to Hungary.

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Black Heron - like open tidal flats and marshy lake fringes. Africa.

Goliath Heron - this largest Heron likes lakes, swamps, large coastal estuaries. Africa.

Black-headed Heron - found in coastal lagoons, lakes, inland rivers but has a preference for drier habitats, grassland/cultivation, often far from water. Africa.

Great-billed Heron - found in mangrove fringed, tidal channels, exposed mudflats, grassy river banks. Tropical Australasia.

White-necked Heron - favours moist pasture and shallows in freshwater wetlands. Australia.

The White-faced Heron (below, left) is associated with pasture, parkland, farm dams, urban areas. It was photographed in Whangamata, New Zealand.

Pied Heron - has become a scavenger found in near-coastal swamps, rubbish tips, sewage works. Australia.

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Egrets - Open wetland habitats, freshwater and alkaline, coastal waters.

Two (Great and Cattle) are found worldwide, two are New World birds and the remainder are Old World birds.

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This photograph of the Great Egret (right) was taken by Nelson in Stone Harbor, New Jersey. It usually alone in almost any open wetland habitat. Flavours edges of marshes, lakes and ponds. Watch, wait and spear feeder.

Little Egret - often in small groups in shallow waters. Fresh and alkaline wetlands including coastal areas. Found in temperate regions of Europe, Africa and Australasia.

The Snowy Egret (below, left) - some consider this species to be the American counterpart of the Little Egret. Found in both inland and coastal waters where they are known to shuffle their feet to disturb prey which they chase in shallow waters. Some suggestion that they also employ "dip fishing" where they fly with feet touching the surface of the water to disturb prey. Found in North And Middle America.

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Reddish Egret - favours brackish water. Coastal lagoons, tidal flats, estuaries, mangrove swamps. It stalks its prey visually in shallow water far more actively than other herons and egrets, frequently running energetically and using the shadow of its wings to reduce glare on the water once it is in position to spear a fish. Found only on North and Middle America.

Yellow-billed Egret (Intermediate Egret) - favours shallow coastal or fresh water, even flooded fields. Found in Africa and Australasia.

Cattle Egret - Fields and pastures with livestock, damp grassland, cultivated areas. Worldwide distribution.

Dense vegetation of reed-beds, marshes and swamps - Bitterns and Herons.

Most of these birds are extremely secretive. Various species are found in all the main regions of the world as indicated below.

Eurasian Bittern - very secretive, stalks prey through reed-beds. Europe.

Pinnated Bittern - hides in wet fields of tall grass and in marshy areas. Lowlands. MA.

Least Bittern - freshwater marshes, skulks in dense vegetation. NA, MA.

Little Bittern - reed-beds, dense vegetation of freshwater swamps. Europe, Africa, Australasia.

The Dwarf Bittern (below, right) - is widespread but uncommon in well vegetated pools. This one was photographed in Kenya.

Black Bittern - mangroves, stream-side vegetation in forests. Australasia.

Australasian Bittern - reed-beds, swamps, streams. Australia.

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American Bittern - shallow freshwater wetlands, nests in bull-rushes. NA.

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The Agami Heron (below) - stalks in shallow streams and swamps in forested areas. This one was photographed on the Tortuguero Lagoon in Costa Rica.
Purple Heron - well vegetated swamps and lake edges, feed in cover. Europe, Africa, Asia.

Rufous-bellied Heron - areas of abundant cover in freshwater swamps. Africa.

Straited Heron - crouches low , Bittern-likewhen disturbed, inter-tidal flats, mangroves. Inland and coastal waters. Europe, Africa, Australia, South America.

Concluding Remarks.

This review shows how a knowledge and understanding of bird behaviour can reveal how a variety of species have been able to establish niches in various habitats and sub-habitats in many parts of the world. All use their "dagger beaks" to spear or catch prey but it is their other skills and abilities which enable them to make use of their habitats to cope with competition and avoid predators.

Although the range of habitats which these birds require are clearly available in many parts of the world it is perhaps surprising that only three species have a world-wide distribution.