ON THE WING
The first piece of the jigsaw of bird migration was put in place in the last weeks of August when I heard a fan-tailed cuckoo calling in the Waterworks Valley.
Next day straited pardalotes arrived from the mainland.
The swallow might be the traditional harbinger of spring but it is the fan-tailed cuckoos and pardalotes who arrive first, a little later this year on August 18 and 19.
I suspect the cold snap that brought snow in late August and early September delayed their arrival, and also put the swallows a little behind schedule.
Each spring I marvel at how the tiny pardalotes — at 9cm, they are far smaller than sparrows — cross Bass Strait. They are followed by welcome swallows and tree martins. The four cuckoo species visiting Tasmania generally arrive next although, as I have said, individual fan-tailed cuckoos always seem in a hurry to get here first.
The cuckoos time their arrival to coincide with the breeding season of the smaller birds which will rear their young as surrogate parents in late spring and summer.
The migrants arrive sporadically but warm weather and strong winds from the north can create what ornithologists call “wave” days when hundreds of birds of myriad species arrive at the same time.
It is not long before black-faced cuckooshrikes, appropriately called summerbirds in Tasmania, are flying across the canopy of the gums in the Waterworks Reserve. The contact call of the summerbird is a familiar but unusual sound in summer. It sounds like someone shuffling a pack of cards.
As the days warm and insects take to the wing more insect-eaters arrive. The staccato call of the dusky woodswallow rings out as the woodswallows launch from perches in the highest white peppermint gums on the reserve’s sunny southern slopes.
Also arriving are species that can be seen in winter, grey fantails and silvereyes.
Only half Tasmanian-born populations of these species migrate and research is ongoing into why some warmth over Bass Strait and others chance Tasmanian winter.
The new arrivals boost the resident population and in the spring and summer fantails and silvereyes form the bulk of bird numbers in the reserve.
Against the backdrop of interstate migrants, a domestic migration is taking place, with some species moving from wintering grounds near the coast to breeding grounds in the high country, notably kunanyi/Mt Wellington in Hobart.
In late winter, flame robins not normally seen at Waterworks Reserve move through, along with crescent honeyeaters and eastern spinebills.
As spring progresses birders eagerly await the last piece of the migrant jigsaw — the satin flycatcher which arrives well into October and fills the woods with a rasping call which belies its shimmering beauty.