Herons

Herons

In Europe and North America, herons steal fish from ornamental ponds in suburban back gardens and have learned to raid fish farms whenever they are left unprotected. In tropical rice-growing countries, they feed on insects and amphibians and greatly benefit the hard-pressed farmers. This highly diverse and adaptable family of birds can be either harmful or beneficial to man. Unfortunately, their fish-stealing habits have led to much persecution. Herons are long-billed and long-legged wading birds, with short tails and long broad wings. All are highly specialized pre: actors adapted for the capture of live (usually aquatic) prey, which is often large compare: to the heron. Prey is stalked with a variety of techniques, but always ending. With a rapid stab to catch the animal. They preen themselves using special feathers that crumble to a powder that is rubbed into the other feathers. The claw of the third toe flattened for combing out the powder.

The day herons show a tremendous range of form, coloration, and behavior patterns. From the huge Goliath heron to the smaller egrets and the Stucco heron. Some are black, others white, while some, such as the Chestnut-bellied heron, are very brightly colored. Some breed singly; while many come together in huge colonies, and on the feeding grounds, some species are highly territorial, while others feed together in flocks.

The best-known and most widespread heron in the Old World is the Gray heron. Most northerly populations of which migrate southward during the winter to find ice-free waters. Its equivalent in the New World is the Great blue heron, which breeds as far north in Canada as the Great Lakes and south to Honduras and the Carob-bean. In Trinidad and South America, this habitat lost much of its darker markings with age until the final plumage becomes all white, or nearly so. The day herons all nest colonially, mostly, but not always, in trees.

Sometimes they join huge colonies of mixed species of egrets, storks, ibises, spoonbills, and other water birds. When nesting is complete the young of the year fly off in all directions, although northern birds do not remain long in their summer breeding areas before moving further south in search of their very varied diet of fish, amphibians, small mammals, crustaceans and insects, as well as snakes and sometimes small birds. It is this ability to adapt to such a wide variety of diets, as well as to make use of reed beds, sandy beaches, and even stone walls for their nests, which has enabled them to survive in an increasingly hostile environment.

Tiger herons take their name from their strikingly barred or striped plumage. They have also been called tiger-bitterns as a result of their bittern-like postures and” booming” calls. Some live in dense tropical forests, where their solitary breeding habits and camouflaged plumage have kept many aspects of their biology a mystery. Few nests have been recorded of the six species in this group, but these have always been in trees, particularly by rivers. Dates of breeding strongly suggest that river height and rainfall may be important factors in determining the onset of breeding. All species are nocturnal feeders. Night herons are very stocky birds with relatively short, thick bills and short legs. They are principally nocturnal feeders with large eyes but, particularly during the breeding season, they also feed by day.

The Black-crowned night heron is the most cosmopolitan of all herons, occurring in a wide range of non-arid habitats throughout the world (in Australasia it is replaced by the Nankeen night heron). It is the best-known of the night herons, being both gregarious in the feeding areas and colonial breeder. Although an attractive bird to watch, it has the nasty habit of eating the eggs and young of other herons in the colony. The Boat-billed heron, with its curious slipper-shaped bill, may be most closely related to the Black-crowned night heron and occurs from Mexico south to Argentina. Recent evidence suggests that this largely nocturnal feeder captures its prey by touch rather than sight, the shrimps and small fish of its diet perhaps being sucked in by rapid bill movements.

Both groups of bitterns are solitary, mainly daytime feeders, stalking their prey with great stealth. Most have brown plumage, often very heavily streaked to camouflage them in their redbud habitats. Their bills are yellowish and they have green feet. The largest is a very stocky bird, while the least bittern is the smallest heron. When disturbed, they freeze motionless, their bill pointed toward the sky. The larger species can handle very large fish, while small fish, frogs, and insects retook by them all. The Eurasian bittern is famed for its “booming” call during the breeding season, which can be heard from distances up to 5km (3 mi) away. The eggs are laid in a nest of reeds which is usually suspended over open water. The chicks leave the nest sometime before fledging and clambering out in the reeds.

Many different styles of breeding can be seen among the heron family. Most species are monogamous, the pair-bond being of at least seasonal duration. The Eurasian bit-tern male, however, may mate with up to five females during a single breeding season, and in such cases probably takes no part in incubation or raising the young. Most bit-terns are solitary nesters, while egret’s handsome herons nest colonially, sometimes in huge numbers. On the feeding areas, they also show a wide range of habits, some such as the bitterns being solitary, while many of the other species are highly gregarious, congregating in enormous numbers in good feeding places.

Breeding is often timed to coincide with peaks in food abundance. Nests are simply constructed of twigs or reeds, often being no more than a simple platform on which to lay eggs. Most species start incubation immediately after the first egg has been laid, Resulting in the eggs hatching over a period of time. This gives the first chick a great advantage over the others and may be important in maximizing breeding success. The chicks are fed by their parents until they fledge, although many will leave their nests within a few days of hatching, to clamber around the vegetation near to the nest. Allure is fed by regurgitation.

Herons are very resilient no family of birds has suffered predation on a greater scale. The ruthless slaughter of egrets at their breeding colonies to obtain the plumes for the adornment of ladies’ hats caused the death of millions of adults and young and whole populations to be wiped out. The Royal Society for the Protection of Birds in Britain and the Audubon Society in America owe their existence to the outcry caused by this devastation. In spite of this, herons have survived and in many areas even prospered. But the wetland habitats that they require have been destroyed at a greater rate than any natural habitat other than forests.

There are some herons, however, which have not been able to adapt. Highly specialized feeders needing, as all such species do, a very special set of circumstances, have reached dangerously low numbers, but the species involved are fortunately few and are outnumbered by the species that have expanded. The most endangered, the Chinese orSwinhoe’s egret, has been found nesting in pitifully small numbers in Hong Kong, and this is the only known colony in the whole of China, although recent reports from North Korea indicate increasing numbers nesting on islands there. The plume hunters obviously massacred most of the birds of this species and its remnant population found difficulty in recovering. They can only feed saltwater estuaries and virtually all of these have been utilized to grow rice right down to the water’s edge. Mangrove vegetation has been eradicated to provide high-intensity cultivated paddy fields.

This trend is noticeable in other parts of Asia, although the peoples of southern Asia and India do not cultivate as intensively as the Chinese. Small herons can live almost next door to a man in villages and towns. Feeding at dusk and dawn and hiding indeed foliage, the small bitterns, the Green-hacked heron, and the often tamer, confiding pond herons (Areola species) have adapted easily to populated areas. Almost every zoo and park contains its resident, free-roaming population of these birds, and many cheekily steal the food from the troughs of captive animals.

As the forests of South America have been destroyed and cattle ranching expanded, shave the African emigrant Cattle egrets pro-spared. Originally arriving in South America probably in the first few years of this century, this species has spread rapidly. As their numbers have risen, they have moved northward into North America. And spread throughout the plains and ranches of the USA, which only 4o years ago had never seen this aggressive little heron.

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