HERONS, EGRETS AND BITTERNS Their biology and conservation in Australia docx

[...]... an interminable length of time before striking with lightening speed as some 18 Herons, egrets and bitterns unsuspecting frog or fish comes within range; in contrast, the Little Egret dashes through the shallows in active pursuit of fishes Then, there are the more dry-footed herons, who search out their prey by walking and peering in potential hiding places among sedges and grasses Herons as bioindicators... throat Other self-maintenance behaviours are fluffing out their feathers and loosening their wings while vigorously shaking their bodies, and simultaneously stretching the wing and leg on one side of the body and then on the other Brightly coloured bare parts Unfeathered body surfaces in herons are the bill, the lore (skin between the bill and the eyes) and the skin of the lower leg and foot (from the... dieldrin have been found in the brains of herons in the USA and DDE in herons of Europe These contaminants are implicated in the deaths of adult birds but at lower concentrations they may affect heron eggs and chicks in ways that are more subtle and less easily detected DDE was first associated with eggshell thinning in Britain in 1967 in the Grey Heron, Ardea cinerea, whose eggs were up to 16% thinner... cm long and 2600 g in weight) and the smallest, found in Australia and the Old World (Europe, Asia and Africa), is the Little Bittern, Ixobrychus minutus (minimum length 25 cm, weight 85 g) The large day herons are particularly elegant birds, with their slim body and long neck and legs; whereas some of the smaller day herons, and the night herons and bitterns have a more compact build Male and female... diversity in the USA coincided with resource diversity and that species feeding in the same What makes herons different? 15 Great Egrets and Royal Spoonbills feed in the shallow margins of a water storage habitats partitioned the available food resources, thus increasing their foraging efficiency and reducing the scope for inter-species competition The Recher’s thesis is that there are different kinds of... are considerably fewer herons in the south-west of Western Australia than in the Top End Furthermore the vast, difficult to 24 Herons, egrets and bitterns 3 2 4 5 1 6 7 9 8 Figure 4.1 Important heron areas in Australia: (1) South-western Australia drainage basin (2) Western Australia/ Northern Territory wetlands (3) Darwin/Kakadu floodplain (4) Gulf of Carpentaria tidal wetlands (5) Cooper Creek system... Nycticoracinae, are more heavily built birds that typically feed at low light intensities The tiger herons, subfamily Tigrisomatinae, so called because of their striped plumage, have not been recorded in Australia They tend to be secretive and solitary and may be the most primitive members of the Ardeidae The bitterns, subfamily Botaurinae, 4 Herons, egrets and bitterns also tend to be nocturnal and generally... Delta and Suez Canal Zone The Egyptian study showed that Cattle Egret numbers reduced after farmers started using DDT on cotton but have recovered since DDT use has been discontinued The alarming reductions in the number of raptors such as the Peregrine Falcon, Falco peregrinus, in several countries have, however, been convincingly attributed to DDE-induced eggshell thinning In some parts of Australia, ... suffered local breeding failure and population disruption due to DDE contamination but Peregrine Falcon eggshell thickness has returned to normal here and overseas since the ban on DDT Similarly dieldrin is now banned in this country, as it has been for many years in the USA and Britain Poisons coming from industrial sources, such as PCBs and dioxins, have been associated with abnormalities in heron embryos... habitats and in the bodies of herons include organochlorine compounds, organophosphorus insecticides, trace elements and petroleum (For details on the significance of contaminants to heron populations see Custer in Kushlan and Hafner (2000).) DDT and dieldrin are organochlorine insecticides that at one time were used widely in agriculture DDT breaks down to the compound DDE and high concentrations of DDE and . understanding of their feeding ecology. Herons also need safe places to roost and nest and most often use vegeta- tion occurring on or adjoining wetlands. for the speed and helpfulness of their replies. The Australian Bird and Bat Banding Scheme provided heron recovery data that gives banding and recovery