THE BACKYARD NATURALIST - Spring 1996

RATBAGS OF THE RAFTERS

High as kites on anything from crunched-up superphosphate to old car tyres, they gormandise, run, fight, build nests and grind their teeth all night.

SOME THINGS LIKE HAIRCUTS and rodents are introduced so early in life that it is almost impossible to remember your first.
On the way home from school on Sydney’s Central and Wynyard railway platforms we used to fire stones from slingshots at the rats that were thick in the black eerie tunnels. In between train arrivals they would run out of the darkness, through the cigarette butts and along the tracks, grabbing spilled Twisties and unspeak- able lumps of gristle spat from meat pies, screeching and fighting with each other, before charging back into the gloom when the rumble of the next train was almost upon them.

Those big, greasy brutes were every thing a rat was supposed to be, and a memorable introduction to something you’d never want living on your doorstep. I could be forgiven then, after moving with my parents up to Brisbane, for wondering what sort of black hole we’d come to, when among the first of our visitors were two big grunting men from the Council with funny metal buck ets, spades and vicious fox-terriers on one of their regular patrols - looking for...rats...around people's houses!
I couldn’t sleep at night knowing that those doberman-sized Wynyard rodents had hopped a train to Brisbane. It would surely be only a matter of time before they recognised me and the smell of my slingshot!

But the Brisbane ‘roof rats’ or ‘climb ing rats’, as the Council ‘ratters’ called them, were as different from the Sydney tunnel variety (Brown or Sewer Rats, Rattus norvegicus) as the gauge of the tracks between them. The ‘roof rats’ were really Black Rats (Rattus rattus).

Black Rats are sleeker, less vicious, more timid and arboreal than Brown Rats and, with a constitution evolved for mischief-making, it is probably just as well the, natural life span of a Black Rat only amounts to about 12 months. So just when it has parented 60 to 100 off spring, and perfected the technique of chewing electrical wiring down to the copper, its life is suddenly snuffed out along with its first birthday candle.

The very nature of that awesome reproductive potential - five to ten pups born after a 21-day gestation period and weaned after three weeks, five to six lit ters per year and the young sexually mature at three months - means one sure thing: that where there is one Black Rat, there will be a ceiling-full.

In 1758 Linnaeus chose the short, crisp scientific name Rattus rattus to christen the medium-sized, blackish rat that was common in Europe (and, according to recent Australian biochem- ical research, that probably had its ori- gins in South-East Asia).
This species, now more common in Australia than it is in Europe, embodies most of everything we have come to regard (and detest) as rat-like’.
It was responsible for piggy- backing the flea that carried the bubonic plague. bacillus, plunging Europe into the ‘Black Death’ where, in London alone, 100,000 people died in 1665. Even today the Black Rat transmits salmonella and leptospirosis through its urine and droppings.

You don’t even have to be tardy with the housekeeping to be visited by this rat either. Because of its round-the-coast distribution in mainly disturbed habitats of Australia, and its affinity for all things human, there really are very few houses that haven’t had a call from the Black Rat. To add a beguiling touch of irony to its affinity with us, so appealing is this masquerader in its sleek suit of teel grey-black with white belly and sparkling big black eyes, that it is often mistaken (and excused - even fed and encouraged) for something native and far less noxious.

But don’t be fooled. This rat is a snake in the grass. Its long history of close association with humans has bred into it a cunning strong enough to resist the most tempting bait laid so carefully on a straining trap.

Locally, we recognise the work of Black Rats by any combination of the fol lowing:

• neat gouges drilled out of ripen ing paw paws
• mangoes hollowed out from one end
• Niagara Falls cascading from behind the washing machine through chewed-out rubber hose pipes
• macadamia nuts drilled out and robbed of their treasure
• pitter-patter and squeals-d’amour in the ceiling at night
• day-old chicks roughly scalped
• potted seedlings ripped up and their roots nipped off
• curtains stripped and stolen for nesting.

High as kites on anything from crunched-up superphosphate to old car tyres, they gormandise, run, fight, build nests and grind their teeth all night. One Australian study showed that during July, Black Rats hunted baby birds and eggs which made up 40 per cent of their diet. At other times they ate an astonish ing amount of underground fungus. But don’t conclude that the entire Black Rat story is a negative one. They do have their uses. A friend of a friend managed to inject some genuine passion into a religious revival meeting by smug gling in a wild Black Rat concealed in a bag. After a rousing sermon where the aging evangelist pleaded for signs and manifestations from heaven, the congre gation plunged into prayer. The pastor, sensing the receptive disposition of the flock, called for the praying sinners to come forward in a public display of their new commitment.
This was the awaited moment, and the livid rat was liberated among the kneel ing legs. The holy reverend, in his weak est moments of self-indulgence, had never dreamed he was capable of drum ming up such a response. He beamed as one by one bodies leapt into the air, arms were flung up above the bowed heads, and people clambered up onto their seats. The religious fervour was spread ing like a holy plague. Women were fainting like soldiers in the sun, and hardened grown men were hurling themselves into the aisles. The elated rector was beside himself. And, judging by the shouting, the unfamiliar language and the assorted calls to one or more of the Trinity, for a while he concluded that here, truly, was a return to Pentecost.

But don’t be deceived. If your belled, curfewed and sterilised cat catches a sleek rat in the laundry, see if the rodent’s tail is longer than its body. If it is, and its big ear can be pushed forward to cover its eye, then the cat deserves the meal. There is no other native, rat-sized mammal that can be easily confused with this long-tailed impostor. Rattus rattus may already be a champion climber, but no other rat so rich ly deserves a helping hand up the stairway to heaven.

BLACK RAT Rattus rattus

• Classification
  Order Rodentia, family Muridae.
• Identification
  Steel grey-black to brown, often with pure white belly; head and body length 16-21 cm; tail about 1.5 times that of the long, slender body; longish ears.
• Distribution and Habitat
  Originally from South-East Asia, and accidentalIy~introduced to Europe in 13th century, and from there to Australia with First Fleet. Lives in most of the Australian coastal cities and towns, In cool temperate to tropical regions.
• Behaviour
  Nocturnal; good climber and swimmer; builds nest of sticks, grass or leaves. Becomes sexually mature at 3 months; 5-10 young per litter; gestation period 3 weeks; 5-6 litters per year. Lifespan 1 year, although up to 3 in captivity.
• Diet
  Food straps, carrion, wide range of plant material including fruits, fungi, even baby birds and eggs. mangroves, where they are abundant and often mistaken for native Water-rats (Hydromys chrysogaster),they kill large crabs and mud lobsters leaving exten sive middens of crustacean shells up in tree hollows.