The Owl That Fell from the Sky (4 page)

 

Every natural history museum around the world has its own store of fabulous tales. These stories—of which a selection from my own experience make up this book—show how developing, curating and understanding collections can provide richness and endless fascination. Even more importantly, museum collections help us understand, and so protect, the vital biodiversity on which our existence depends.

 

The owl that fell from the sky

Towards the end of 1955, a man and his young son were driving along a road a couple of kilometres from the mouth of the Haast River in south Westland, a remote and isolated part of the South Island of New Zealand. Suddenly, ahead of them, a bird with a rat in its talons rose up from the road and they couldn't avoid hitting it. The pale bird was so unusual that they kept the body for a few days to show people. Nobody in the small town of Okura where they lived, not even the schoolmaster, had seen its like.

A couple of years after the death of the pale bird, the boy, then fourteen, visited Wellington with a friend and the two of them went to the Dominion Museum to give further details to Dr Falla. Bob Falla—later Sir Robert—was the museum's director, and New Zealand's best-known ornithologist through his newspaper articles and radio programmes. The out-of-town visitors were no doubt a little nervous walking up the hill to the imposing museum building, where they were ushered into the staff-only precinct, but the legendary Dr Falla, tall and lanky, would soon have put them at ease with his broad smile and pleasant manner.

In a back room where the museum's bird reference collections were stored, Falla first showed them some study-skins of the morepork, the common New Zealand owl, which the boy knew. Then came specimens of the larger laughing owl, one of New Zealand's many extinct birds. Finally, he produced a selection of foreign owls, and from among them the boy did not hesitate to pick out the specimen of a barn owl.

Common barn owls—
Tyto alba
—are one of the world's most widely distributed land-birds, living on all continents except Antarctica. In most parts of the world, people grow up knowing these pale ghostly owls but not in New Zealand: it is one of the few places from which they are absent. The 1955 Haast River bird was only the second ever recorded: one had been shot at Barrytown in north Westland in 1947.

Birds fairly regularly straggle from Australia to New Zealand, carried across the Tasman Sea by the prevailing westerly winds, so it was not surprising that these owls—assumed to be Australian—fetched up on the West Coast. In 1960 a third would be found dead in a disused house at Runanga, also in north Westland.

 

 

An unexpected telephone call or visitor, heralding what may be a rare or unusual find, adds spice to the natural history curator's day. Amid routine interruptions there will sooner or later, and quite at random, be an event to write home about.

In March 1983 Graham Turbott, an ornithologist and the former director of Auckland Museum, rang me to say that a schoolgirl from Papatoetoe in south Auckland had found a strange white bird. She had been walking through the grounds of her school when she had seen the bird huddled on grass under a tree. She had thought it was dead, but then it flew off weakly. She caught it and took it home. However, despite care and attention, the unfortunate bird died in the night.

Graham Turbott brought the corpse to the museum, and when we unwrapped the package on the workbench it was immediately clear it was some sort of barn owl. I had never seen a fresh one before, but obvious at once were the soft pale plumage, the facial feathers arranged in a characteristic large heart-shaped disc, the long legs with talons, and the small, sharp beak. A creature superbly adapted for night-time hunting, with acute hearing and silent flight, it was also beautiful, with feathers of white, grey and ochre, many of them barred or spotted.

From the museum library upstairs we brought down bird books from around the world and studied their photographs and drawings of owls. From the museum's reference collection of bird specimens we pulled out the handful of study-skins of tytonid, or barn, owls. Museums need natural history collections from their own country and region, but representative examples of key foreign animal groups have their uses as well.

We took standard measurements of the dead owl, including the length of the wing, tail and beak, and soon confirmed from its size, and the colour and pattern of its plumage, that it was the widespread common barn owl and not one of the several other species of barn owl that live in Australia. The common barn owl also lives on many of the island groups in the south-west Pacific just north of New Zealand, so the bird's geographic origin was uncertain.

 

 

This was, then, the fourth record of a barn owl in New Zealand. The bird may have flown across from Australia, or from a Pacific island, although this was less likely. Or it could have been smuggled in as a captive and subsequently escaped or been released. However, the girl's father had mentioned a third possibility. The suburb where the bird had been found was close to Auckland International Airport and, depending on the wind direction, lay immediately under the flight path of jets as they came in to land.

The museum's reference collection was not extensive enough to include representative samples of barn owls from the Australian and Pacific island populations against which we could compare the mystery bird and come to a conclusion about its place of origin. The differences between these populations are not dramatic anyway, and the measurements we took, and then compared to published dimensions, were in the region of overlap and hence inconclusive.

I now made a post-mortem examination. By locating the gonads inside the body cavity, I discovered the owl was a male. There was considerable fat around its stomach and large intestine, and a large mound of fat lay just beneath the belly wall. Inside the intestine, along its length, there was merely a paste-like residue of digested food remains. However, the gizzard, or muscular part of the stomach, contained a dark ball of matter. When I teased this out, I discovered a quantity of hair and small bones that proved to be the remains of a house mouse. This was no help to establishing what country the bird had come from, since the introduced European house mouse is found in Australia and most Pacific islands.

In the gizzard, however, I also found a tiny insect head about one millimetre across. I consulted the museum entomologist, Keith Wise, who said this was probably from an ant.

On Wise's advice, I sent the tiny specimen to a curator at the Australian National Insect Collection in Canberra, who was able to identify it as belonging to a species of ant unique to Australia and common in grassy areas in and around cities of the south-east. The ant, presumably eaten accidentally while the owl was swallowing the mouse, pinned down the bird's geographic origin.

 

 

We next approached the New Zealand Meteorological Service for information on wind strength and direction in the days leading up to the owl's discovery. Winds had been strongly from the west and the conditions suggested that a bird at low altitude could have flown to Auckland from south-east Australia in under two days. But even after such a relatively short flight from Australia a bird would be expected to be lean, with an empty stomach, empty intestines, and little visible fat in its abdominal cavity. Given the fat condition of the owl, and the presence of food in its gut, it seemed far more likely that it had been foraging around an Australian airport, had roosted in the undercarriage bay of a large jet as dawn broke, and had become trapped there when the plane took off.

Several types of Australian birds survive cold nights in the Outback by entering a physiological state of torpor: their metabolism slows until sunrise and the return of warmer daytime temperatures. The extreme cold in the jet's unpressurised undercarriage bay may have forced the owl into some sort of torpid state and come close to killing it outright. When the wheels went down three hours later over Papatoetoe, the owl fell out and came to ground fatally sickened.

A taxidermist transformed the owl's body into a permanent dry study-skin by skinning it, meticulously cleaning and de-fatting the inside of the skin and the remaining attached bones (skull, and outermost wing and leg bones), replacing the separated body with an artificial form of the same shape and size, and sewing the skin back together along the incision lines. After drying and labelling it joined 5,000 other bird skins in Auckland Museum's collection, a testament to the important role of the public in reporting unusual finds.

 

 

As a postscript to this story, in April 2008 a pair of barn owls were found breeding in farmland near Kaitaia in New Zealand's far north. The birds were thought to be unassisted vagrants, most likely from Australia. If a population establishes, it will represent the barn owl's colonisation of one of its last unoccupied corners of the world.