Kookaburras, Snakes and the Balance of Nature in Sydney

The sound of a Laughing Kookaburra is such a familiar part of life along Australia’s east coast that it is easy to take these remarkable birds for granted. From suburban backyards to national parks, kookaburras have lived alongside snakes, lizards, frogs, insects and small mammals for thousands of years.

They are all part of the same ecological fabric.

Kookaburras are well known for catching snakes. It is an impressive sight, but snakes make up only a small part of their varied diet. Kookaburras also eat insects, worms, rodents, frogs, lizards, crustaceans and occasionally small birds.

Nevertheless, by taking small snakes and juveniles when the opportunity arises, kookaburras contribute to the network of natural predators that helps keep wildlife populations in balance.

Kookaburras are native snake predators

Laughing Kookaburras are powerful, patient hunters. They often sit quietly on a branch, fence or powerline, watching the ground before dropping suddenly onto their prey.

When a kookaburra catches a snake, it generally grips it in its strong bill and repeatedly strikes it against a branch or the ground. This helps subdue the snake before it is swallowed.

Kookaburras are capable of killing venomous snakes, but they are not immune to snake venom. They rely on speed, precision and the strength of their bill while attempting to keep the snake away from their body.

Small snakes are most vulnerable. A large adult Eastern Brown Snake or Red-bellied Black Snake would present a very different challenge and would rarely be suitable prey for a kookaburra.

It is about balance, not eliminating snakes

People sometimes describe kookaburras as a natural form of snake control. There is some truth in this, but it is important not to exaggerate their influence.

Kookaburras do not prevent snakes from living in an area, and snakes are not dependent upon kookaburras. Both have broad diets and interact with many other animals.

The real story is the balance created by all these relationships.

Kookaburras prey on insects, rodents, lizards, frogs and some snakes. Snakes prey on rodents, frogs, lizards, birds and other snakes. Birds of prey, monitors and other animals also prey upon snakes. At the same time, snakes themselves help control animals that might otherwise become overly abundant.

Remove one species and the effects can spread through the ecosystem in ways that are difficult to predict.

Without kookaburras, one important native predator would be missing. Without snakes, rodents and other prey animals could increase, while animals that naturally prey upon snakes would lose part of their food supply.

Neither kookaburras nor snakes are unnecessary. Both belong here.

What happened when kookaburras were moved west?

The relationship is very different in south-western Western Australia, where Laughing Kookaburras did not naturally occur.

Beginning in 1897, hundreds of kookaburras from eastern Australia were released in Western Australia, partly because people believed they would control snakes. The birds established themselves and spread across much of the south-west.

However, kookaburras are generalist predators. They did not restrict themselves to eating snakes. They also preyed on native frogs, lizards, insects, nestlings and small birds that had evolved without Laughing Kookaburras.

The same bird that forms a natural part of eastern Australia’s ecosystems became an introduced predator in another part of the country.

It is a valuable reminder that the labels “native” and “introduced” depend on location. An animal may belong naturally in one part of Australia while causing ecological problems somewhere else.

Sydney’s wildlife has evolved together

Here in Sydney and along the east coast, kookaburras and snakes have shared the landscape for an extraordinarily long time.

They are not enemies locked in a simple battle. They are participants in a complex ecological system involving predators, prey, competition, habitat, weather and seasonal food availability.

Even within suburban Sydney, these relationships continue. Kookaburras hunt from fences and clotheslines. Snakes follow the cover provided by gardens, waterways and bushland corridors. Rodents are drawn to food, rubbish and shelter around buildings. Frogs gather around ponds and drainage areas.

Each animal influences the others.

This is the fabric of life: thousands of relationships operating at the same time, often unnoticed, but collectively keeping the natural world functioning.

Snakes still belong in the Sydney environment

Finding a snake around your home can be confronting, but its presence does not mean the local ecosystem has failed. In many cases, it means suitable habitat and prey are nearby.

Snakes play an important role by consuming rodents, frogs and other animals. They also provide food for kookaburras, birds of prey, monitors and other predators.

The aim should not be to eliminate snakes from the environment. It should be to manage encounters safely while allowing native wildlife to continue performing its ecological role.

If you see a snake around your home, keep a safe distance and watch where it goes. Do not attempt to catch or kill it. Contact Urban Reptile Removal and arrange for a licensed Sydney snake catcher to safely remove and relocate it.

Kookaburras and snakes have shared the east coast for thousands of years. With sensible management and respect for both species, there is no reason they cannot continue sharing it with us.

How an Australian Snake Changed an Entire Island

The Brown Tree Snake is a familiar native species across much of northern and eastern Australia. In its natural environment, it forms part of a functioning ecosystem.

But when several Brown Tree Snakes were accidentally transported to Guam after the Second World War, the consequences were extraordinary. Within decades, this adaptable nocturnal predator had driven most of Guam’s native forest birds to extinction, disrupted the island’s forests, caused an explosion in spider numbers and created an ongoing problem that authorities are still struggling to control.

Guam is a tropical island in the western Pacific covering approximately 540 square kilometres. That makes it only slightly smaller than Chicago and about one and a half times the size of Tasmania’s Bruny Island.

Despite its modest size, Guam once supported a distinctive community of birds, lizards, bats and other animals. Many had evolved in isolation without an efficient climbing snake as a predator. That changed during the late 1940s.

Brown Tree Snakes are native to Australia, Papua New Guinea and several neighbouring islands. The Guam population is believed to have originated around Manus Island in the Admiralty Islands, north of Papua New Guinea. The snakes were most likely concealed in cargo containing American military equipment transported to Guam shortly after the Second World War. As nocturnal animals that readily shelter inside vehicles, containers, buildings and stored materials, Brown Tree Snakes were particularly well suited to becoming accidental stowaways. Urban reptile removal regularly remove them from homes in Sydney, particularly on Sydney’s Northern Beaches, like this particular animal that was loose in a home for almost two weeks! https://au.news.yahoo.com/180cm-discovery-in-childs-bedroom-in-aussie-suburbs-after-almighty-thump-sparks-excitement-040012125.html

Only a small number may have made the journey. Unfortunately, that was enough. Guam provided abundant prey, warm conditions and few effective predators. The snakes spread across the island and eventually reached densities that have historically been estimated at up to 11,600 snakes per square kilometre in some locations.

The consequences for Guam’s wildlife were catastrophic. Brown Tree Snakes are agile climbers that feed on birds, eggs, nestlings, lizards and small mammals. Guam’s native birds had not evolved alongside a predator capable of reaching nests high in the forest canopy. The snakes contributed to the disappearance of nine of Guam’s 11 native forest bird species. Some were eliminated from Guam but survived on neighbouring islands or in captivity. Others, including the Guam Flycatcher, became globally extinct. Researchers even discovered Brown Tree Snakes using a previously unknown form of movement called “lasso locomotion”. The snake loops its body around a smooth trunk or pole and slowly works its way upwards. This allows it to overcome some barriers designed to protect nesting birds. The result is that forests once filled with birdsong are now remarkably quiet.

Removing birds from an ecosystem affects far more than the birds themselves. Many of Guam’s forest birds ate spiders and other invertebrates. Once the birds disappeared, that predation pressure was removed. Researchers comparing Guam with nearby snake-free islands found that spider-web densities were up to 40 times higher on Guam during the wet season. Even during the dry season, web densities were approximately 2.3 times higher. The snakes were not directly causing spiders to reproduce. Instead, they removed one of the spiders’ principal predators. This is known as a trophic cascade: changing one part of a food web produces a series of effects throughout the ecosystem. Bird losses have also reduced seed dispersal. Many native trees rely on birds to carry seeds away from parent plants. Without them, seeds frequently fall directly beneath the trees, where seedlings face greater competition and are less likely to survive. The long-term structure of Guam’s forests may therefore continue to change.

Brown Tree Snakes have also had a significant effect on Guam’s residents and infrastructure. The snakes regularly climb power poles and electrical equipment, causing short circuits and blackouts. These outages have cost Guam millions of dollars through repairs, lost productivity and damage to electrical systems. Snakes also enter homes, sheds and other buildings in search of prey.

Brown Tree Snakes are rear-fanged and mildly venomous. Although they are not generally considered highly dangerous to healthy adults, bites can be more serious for babies and small children. Authorities now use traps, night searches, detector dogs and cargo inspections to prevent snakes from leaving Guam and establishing populations on other Pacific islands.

The Guam invasion presented scientists with an interesting genetic puzzle. A population founded by only a handful of snakes should experience a severe genetic bottleneck. Limited genetic diversity generally increases inbreeding and reduces a population’s ability to respond to disease and environmental change. New research has revealed that Guam’s Brown Tree Snakes possess more hidden genetic variation than earlier methods could detect. Researchers identified more than 19,000 structural variations in their DNA, including duplicated, deleted and rearranged sections. Many of these variations occur in genes associated with immunity, stress responses and the sense of smell. This hidden diversity may help explain how such a small founding population survived, adapted and expanded so dramatically. The discovery may also have implications for endangered species. Some threatened animals could possess forms of genetic variation that standard measurements have previously overlooked.

The Brown Tree Snake’s impact on Guam does not make it a destructive species everywhere. In Australia, it is a native predator living alongside animals that have evolved with snakes. Its prey species, competitors and predators are all part of the same ecological system. Guam demonstrates what can happen when a native animal is transported beyond its natural range and introduced to an ecosystem that is unprepared for it. Brown Tree Snakes occur across northern and eastern Australia, from the Kimberley and Top End through Queensland and south along the NSW coast to approximately the Sydney region. Urban Reptile Removal regularly encounters and relocates Brown Tree Snakes, particularly around Sydney’s Northern Beaches in suburbs like Bayview, Davidson, Terrey Hills and Killarney Heights. They become progressively more common farther north along the east coast and are widespread across tropical northern Australia. They are mainly nocturnal and are excellent climbers. During the day they may shelter in roof spaces, sheds, thick vegetation, tree hollows and stored materials. Their colour varies considerably, meaning they are not always immediately recognisable.

If you find a Brown Tree Snake around your home, keep a safe distance, watch where it goes and contact a licensed snake catcher. Do not attempt to catch or kill it yourself. The story of Guam is not evidence that Brown Tree Snakes are inherently harmful. It is a powerful demonstration of why wildlife belongs within its natural range—and how the accidental movement of even a few animals can transform an entire ecosystem

Chris Williams with a brown tree snake on Sydney’s Northern Beaches