The Skyrail Lake

Skyrail Nature Diary: April 2014


Immediately after departing the Smithfield station, Skyrail guests will notice a small lake on their right. This lake, coffee-coloured, its edges decked with water lilies, was created 18 years ago during the construction of Skyrail. It supports numerous fish, turtles, aquatic plants, insects and micro-organisms. These in turn form the diet of a large variety of water birds. Just how so many varied birds succeed in sharing the resources of this small lake will be the focus of this month’s Nature Diary.

The 26 species of water birds that have so far been recorded on Skyrail’s lake are able to share the lake due to each species having specialised diets, different feeding techniques and patterns. The lake supports resident birds, seasonal visitors and opportunistic nomads that use the lake from a few hours to several weeks.

Little Pied Cormorants, Australian Darters and Pelicans

Darters and the related Little Pied Cormorant may be observed on the lake’s floating orange buoy that houses a solar pump as they dry their plumage. Their easily saturated feathers allow both species to hunt underwater, targeting fish of small size and cylindrical proportions. Larger fish such as barramundi and tilapia are too big for these birds to swallow. Due to the modest size and depth of the lake and its limited stock of suitably-sized fish, these pursuit predators are short term visitors.

Another fish lover is the Australian Pelican. Groups of pelicans visit the lake during the dry season when water levels are low. Such conditions aid the pelican as it uses its voluminous bill pouch to net fish. Groups may work together to shepherd a shoal of fish and drive them into shallow water. Individuals will then take turns in capturing their share, which, stored in the bill pouch, may  be gobbled down at their leisure. Pelicans eat fish of all shapes and sizes.

Jabirus, Night Herons, Bitterns, Herons and Egrets

Standing at one and a half metres, the extraordinarily long-legged Jabiru  (Black-headed Stork) hunts in deeper water than birds such as herons and egrets. Jabirus will take larger fish such as eels however, they do not directly compete with pelicans, cormorants or darters. Jabirus are opportunists that devour anything from fish through to turtles, amphibians, small mammals and reptiles. In contrast to the next group of birds to be discussed, the Jabiru is rapidly mobile. It moves through water probing with its bill.

Herons, egrets and bitterns operate in a similar yet with subtly different fashion. Like the Jabiru they are opportunistic wading birds with richly varied diets. Due to their smaller size these birds seek foods such as juvenile fish, frogs, tadpoles, insects and invertebrates.

Nomadic within the local area, the White-faced and White-necked herons visit the lake periodically. These herons slowly wade through the shallows in search of tasty morsels. They do not cramp the style of resident Intermediate Egrets, which prefer to remain stationary in the shallows of a particular “beat” catching their prey with a devastatingly swift thrust of their bill.

The resident Nankeen Night Heron does not compete with any of these birds as it is a strictly nocturnal hunter. The secretive Black Bittern uses the lake-side trees for roosting. It hunts along the margin of the lake during dusk, night and early morning. Black Bitterns also work dimly lit flooded areas and nearby creek beds with a thick covering of reeds.

Spoonbills and Ibises   

Ibises and spoonbills resemble herons in build and size, the most notable difference being their unique bills. Royal Spoonbills use their long and spoon-shaped bills in shallow muddy water in a sweeping motion, relying upon the remarkable sensitivity of the bill to locate tadpoles, insects and crustaceans by touch. They occupy a niche that excludes egrets and herons which rely upon sight to capture their food. Spoonbills frequent the lake during the late dry season when water levels are low and the water is turbid.

The sickle-shaped bills of the White Ibis, Straw-necked Ibis and the Glossy Ibis allow these birds to feed by probing in damp earth and mud or by shifting through grass or aquatic vegetation.           

Whistling Ducks, Hardhead Ducks, Teals, Pygmy Geese and Magpie Geese

These related birds co-exist harmoniously, often forming communal roosts. Due to their differing feeding habits, the lake has something for everyone.

The Plumed Whistling Ducks use the lake purely for roosting. At dusk they depart to graze on selected grassland vegetation. The Wandering Whistling Duck does not clash with its plumed cousin as it feeds upon aquatic plants by dabbling and diving in the shallows.  

The resident Hardhead feeds on the surface plants and minute creatures but also has the ability to dive and remain submerged for about half a minute in search of food. 

The Pacific Black Duck, another resident bird, is versatile in its feeding habits. They target plants and insects on or just below the surface either in shallows or in deeper water. Pacific Black Ducks also graze and forage insects on grasslands.

The Grey Teal goes about its affairs differently, taking insects and seeds in slightly deeper waters than the Pacific Black Duck by upending itself and scouring the bed of the lake for its target food.

Resembling some exquisite Faberge creation, the Green Pygmy Goose feeds on aquatic plants and seeds on the surface or by upending and diving. These birds do not encroach upon the domain of their larger cousins as they typically confine their operations to the belt of water lilies near the lake’s edge.        

The ancient and primitive Magpie Goose, the sole member of its family, visits the lake during the driest time of year (typically October). Receding water levels assist this bird as it probes in the muddy shallows for plant bulbs. This bird may often be observed in distinct groups of three, as males will often mate with and share parenting duties with two females, who are often siblings!

Australasian Grebes and Coots

Like cormorants and darters, grebes dive and swim underwater to secure their prey of fish fry, tadpoles, insects and small crustaceans. Due to their small size and different diet, these occasional visitors to the lake do not compete with the larger diving birds. 

Coots occupy a unique feeding niche by grazing at or near the shoreline or diving in search of aquatic plants and small insects.                

Masked Lapwings and Red-kneed Dotterels

Masked Lapwings (also known as Spur-winged Plovers) prefer to hunt along the shore of the lake and the surrounding lawns and in temporary pools of water. Their varied diet includes insects and small frogs.

Diminutive darting dotterels forage along the shores of the lake, especially in muddy margins or receding pools. Their diet of small aquatic and terrestrial insects and invertebrates is mostly too small to be of interest to the Masked Lapwing.             

Jacanas

Also known as Lotus-birds, Comb-crested Jacanas with their extraordinarily long legs and toes are able to disperse their weight so as to walk on the pads of water lilies. This ability offers them unique access to the insects and molluscs that cling to the pads of water lilies and other water plants.