Secrets of the Sarus Crane
By John Grant
John continues his journey through a day with Sarus Cranes on the Atherton Tableland, far north Queensland, and introduces two current studies exploring the mysteries surrounding this large and elegant, but little-known Australian bird.
Part 2: From small beginnings
The breeding grounds of the species include the wetlands of Cape York Peninsula and the Gulf of Carpentaria, where the crane was first recorded for Australia (near Normanton) in 1966. Sarus Cranes have been wintering on the tablelands – or perhaps more correctly, spending the dry season here – since at least the following year, 1967, when 23 birds were seen. Their numbers have gradually risen since, but it is only in the past seven years that any attempt has been made to make a systematic count. Tablelands ornithologist, Elinor Scambler, has coordinated an annual count at roosting sites each October since 1997, giving us a preliminary population estimate. With teams of observers covering all the known major sites, the count in most years has produced a remarkably consistent tally of around 1,700 birds. (Some smaller roosts are always missed for want of more observers, and new sites are discovered in most years, suggesting that improved estimates can be achieved if the counts are continued with increased observer support.) But where else do the cranes winter? The count in 2001 yielded a bumper total of about 3,000 birds, hinting at the possibility of other populations that normally winter elsewhere. Small numbers are seen at Cape York and Gulf of Carpentaria sites in the dry season, but these vast areas have been poorly covered historically due to their remoteness.
The nameless swamp I am watching this morning is one of the smaller roost sites, with 20-30 birds flying in at sunset on most evenings between May and November. The two visible cranes depart with more bugling calls, taking off after a short, awkward run-up and quickly transforming into the most graceful of fliers. As the mist thins, silhouettes of more cranes appear, again walking away from the marsh. Some call quietly as they go, and then they too lift off, in twos and threes mostly. Flying steadily they head purposefully west, towards the agricultural areas of the tablelands.
An hour later I am driving in the same direction, through one of the brilliantly crisp mornings that make the chilly tableleland nights more bearable. The patchily forested eastern parts of the plateau give way to an intensely fertile volcanic landscape – largely cleared and remarkably flat but for the shallow hills of the old shield volcanoes and a sweeping arc of smaller, steeper cindercones, familiar locally as the ‘Seven Sisters’. The volcanic activity that formed this landscape finished as recently as 14,000 years ago – graphically described in indigenous stories from the area – and has resulted in one of the most productive farming areas in Australia. Maize, peanuts and potatoes are among the most widespread crops, with sugar cane also becoming prevalent in recent years. The cranes are particularly attracted to the maize fields, and post-harvest, these typically harbour the largest flocks. Smaller groups also regularly feed in pastures, often alongside cattle. Today I find a flock of almost 200 birds in a regularly frequented corn stubble field, and spend some time scrutinising them through my spotting scope. Over the years it has become possible to reliably distinguish several age classes of birds, making a demographic study one of my principal goals.