The migratory birds have played a waiting game this spring.
Usually small numbers of summer visitors begin to arrive from mid-August and numbers build up in the first few weeks of September. This year, however, I have had to ask: where are the cuckoos, the swallows, the martins and the summerbirds, the latter more formally known as black-faced cuckoo-shrikes?
True, there had been sporadic sightings of swallows and fan-tailed cuckoos but the great spring migration appeared to have stalled.
At this time of the year birders direct anxious eyes to skies dreading that the projections of a decline in bird numbers across the country might be realised in surveys of migrant arrivals.
The weather certainly had slowed the migration. Although my own observations at the Waterworks Reserve might be anecdotal, severe weather events – particularly unfavourable winds – can halt birds travelling south in their tracks, or delay departure north at the end of summer.
The migrants, of course, make remarkable journeys, some like the satin flycatcher travelling from northern Queensland. The smallest visitor, the silvereye – only 12 centimetres in length and weighing a mere 10 grams – has a shorter journey, flying from the Gold Coast.
Although much has still to be learned about the wintering areas of Tasmania’s 15 migrant wood and farmland species, it is generally accepted most spend winter in a belt stretching from Victoria, through eastern New South Wales to southern Queensland.
Migration requires flights of maximum endurance in all weathers, crossing terrain ranging from mountains to wetlands. All the while the birds are harassed by birds of prey. Those travelling as far south as Tasmania have an added hazard: the dangerous crossing of Bass Strait. Without favourable winds from the north, the migrants will build up in their thousands in coastal scrub along the Victorian coast waiting for the wind to change.
The dearth of birds this spring presented a particular problem for me well into what should have been peak migration season, the last week of September.
I was scheduled to co-lead a City of Hobart Bush Adventures bird walk in the Waterworks Reserve and on the eve of the outing temperatures plunged to below freezing, and a thick coating of snow was dumped on kunanyi/Mt Wellington. I feared that I would not have any birds to show the participants.
I awoke, however, to be greeted by a beautiful if cold, sunny day. And at the reserve a host of migrants had managed to arrive overnight under what turned out to be a star-lit sky.
The fan-tailed cuckoos and shining bronze-cuckoos were in full voice, along with grey fantails which I presumed by their large number had arrived overnight, supplementing a local population who choose not to migrate.
The “cranky fans”, as they are known in Tasmania, swept about the heads of the walkers, swooping on insects disturbed by their tramping feet.