Shorebird population plummets in Cairns
The death knell hasn’t sounded over the Cairns Esplanade as an internationally recognised shorebird habitat. But it is imminent.
It is mid-September, and although there has been a bit of an influx in recent days, the total number of returned migratory shorebirds along the city’s waterfront is painfully small. It’s stretching it to say there are 200.
By my ad hoc observations, that represents a drop of about 90% in a very short time.
Conventional opinion will say the crash in migratory wader numbers is mostly the result of changed conditions elsewhere in the world. But there is strong evidence to suggest the major cause of the Cairns catastrophe is local.
Almost certainly, the real culprit is a sand-spreading regime introduced a few years ago by the Cairns Regional Council (CRC), which has adversely affected the nutrient value of the inshore mudflats.
Just four years ago, it was common to see a couple of thousand waders ‘working’ the intertidal area every day during the non-breeding season. Then came the CRC’s beach-creation and foreshore ‘beautification’ campaign, which resulted in vast quantities of relocated sand being spread by tide and weather across the mud.
Warning the council
Local environmental consultant Paul Fisk is part of a group that has been warning the council for several years about the ecological impact of its actions. He says there is little doubt that introduced sand is a major reason why wader numbers on the Esplanade have plunged.
He has been conducting bi-monthly shorebird counts at 1.6m – 2.0m high tides across Trinity Inlet for the past three years and, depending on the time of year, he says there has been a decline of between 50 and 80%.
“Data from similar studies I undertook back in 1988 show there were over 2000 birds on the Esplanade during peak periods [September/October], but from 2015-17, the average had dropped to around 700.
“And it is getting worse. The number of over-wintering birds in 2018 was less than half that of the previous three years.”
Paul’s graphs accompanying this post show dramatic declines across all of the major species, and his projection is a continuation of the trend.
From my own observations, it would seem that of those birds hard-wired to come to the Cairns waterfront, most are not sticking around like they used to. The menu at Café de Sand is obviously not to their taste!
From several rough counts I conducted in the first two weeks of September, the strongest numbers on a given day were: 150 great knots, 17 grey-tailed tattlers, 5 black-tailed godwits, 2 bar-tailed godwits, 5 curlew sandpipers, 4 sharp-tailed sandpipers, 2 lesser sand-plovers, 2 eastern curlews, 8 resident whimbrels and 2 terek sandpipers.
A clearer picture will emerge by the end of September when most of the migratory birds that are returning to Cairns (and other regular East Coast destinations) will have arrived.
Better news from Broome
Meantime, a quick check with the good people at the Broome Bird Observatory (BBO) on the other site of the country produced encouraging early indications. BBO warden Nigel Jacket says although it is still too early to tell (late August), “First juveniles are arriving, including heaps and heaps of sharpies and curlew sandpipers.” (The BBO conducts its major counts in November.)
FOOTNOTE: Following submissions by Paul Fisk and others, the Cairns council has agreed to construct foreshore groynes along the southern end of the Esplanade to curtail sand creep. They will be small and hidden from view below the boardwalk, and it remains to be seen if they will be enough to prevent more sand choking the mudflats. Hopefully some birds will hang around to find out.
©Natural Images 2018