Tuesday, 23 February 2016


Knots, not reef knots and the like, but birds of course, are the subject of this post. Australia has two species of knots, the Great Knot (Calidris tenuirostris) and two sub species of Red Knot (Calidris canutus rogersi and piersmai), both knots are summer migrants from the northern hemisphere. Most Great and Red spend our summer in northern Australia, especially the north west, across the top end and in the Gulf of Carpentaria, with some moving further south and east and a small number reaching the south east – they are uncommon visitors to East Gippsland.

Great Knot on left and Red Knot on right. Both birds are in non breeding plumage and look similar. In breeding plumage, they are very different with the Red Knot moulted to a rich red colour.
 Knots belong to the Calidris genus and are the largest sandpipers in this genus. There are six other species of Calidris sandpiper found in Australia, all are international migrants and include the Sharp-tailed, Curlew and Pectoral Sandpipers, Red-necked and Long-toed Stints and last but no least the Sanderling. Knots, sandpipers, stints and sanderling are all of the Calidris genus however their common names do not reflect their close relationship.

Recently on a trip to Crescent Island in the Gippsland Lakes Coastal Park to check on progress of a Little and Fairy Tern breeding site a few unusual shorebirds were spotted resting with a group of Bar-tailed Godwits. They looked like knots so a few photos were taken for identification later at home. The photos revealed two Great and two Red Knots which at a glance or from a distance look very similar. A report of these unusual Gippsland Lakes visitors to “Eremaea Birdline Victoria interesting and unusual bird observations” scored one blue star from the Moderator, a highlight unusual report (two stars is mega unusual).

A long shot showing mixed flock of birds at the western end of Albifrons Island. The knots are resting in close company with Bar-tailed Godwits, Crested and Common Terns and Chestnut Teal. It always pays to look carefully at flocks of shorebirds as you never know what species might be present.
 So a week later following some poor weather a trip was made back to Crescent Island to look for the knots and try and get some photos if they were still there and we could get close enough. Our luck was in, after a short search of Albifrons (from Sterna albifrons the scientific name for the Little Tern) and Crescent Islands we found two Great and one Red Knot sleeping amongst Little and Fairy Terns at the small tern breeding site on Crescent Island. No doubt these were the birds we saw the week before though one of the Red Knots was missing.

Like motor vehicles, boats can be good hides allowing close approach to many species that don’t see boats as a threat. The same birds would not tolerate close approach on foot. We cut the motor and drifted the boat onto the sand at the shoreline very close to the sleeping knots. All three, standing close together, stayed put and simply looked up to note our arrival and with no sign of nervousness at all, resumed sleeping with bills tucked under their back feathers.

The knots stayed put as we nosed the boat onto the shore. Two Little Terns were resting with the knots. This was on the edge of a flock of about 260 - mainly Little Terns plus some Fairy Terns.
I was hoping the Little Terns would move on so there was a clear view of the knots. This bird is moulting from breeding back to non breeding plumage. The Little Tern on the left side of the previous photo is in non breeding plumage.
A stretch of the wings can be a sign the bird is about to take off. Fortunately the Little Tern decided to move closer to its mates leaving a clear view of the knots.
Sleeping birds beyond a certain point do not make for interesting photos. The Great Knots flanked the Red. The Great were more alert with eyes open more often than the more relaxed Red.
Some action, the Red commenced some grooming showing some barred feathers above the tail. The Great remained at rest but still alert with eyes open.
After some time all three were awake with bills on display.
The closer Great Knot, perhaps not surprisingly, became restless.
The restless bird set off on a walk.
The bird walked a looped path.
Returning to the group.
The restless Great Knot is still restless though the other Great is trying to sleep. The Red has turned around and is also now more alert. I sensed they were going to fly.
Sure enough they exploded into flight. It took me three shots to finally capture them together and in focus just as they were moving beyond the range of a good photo. The Red, showing bars on the rump, is flanked by the Greats which have whitish rumps.
Perhaps against the odds we managed to find these uncommon visitors to the Gippsland Lakes and get close for some photos.

From the photos it can be seen that Great and Red Knots look very similar – I assume they have evolved from a common ancestor in the recent past. When one checks on their breeding areas it becomes apparent that the very different breeding areas and habitats have over time led to the development of separate species. The Great breeds at high elevations on alpine tundra in north east Siberia whereas the more widespread Red breeds at high latitudes on moist tundra and glacial gravels at lower elevations.

Both species feed on insects, fruits and seeds at their breeding grounds which are away from the coast. In Australia both species are strictly coastal inhabitants feeding more or less exclusively on worms and bivalve molluscs gleaned from mud and sand.

I never cease to be amazed by our migrant shorebirds and their long distance migration flights, often exceeding 13,000 kilometres one way, which they complete twice a year and their high latitude tundra breeding grounds and very different summer coastal habitats. It is a shame we don’t get to see them in breeding plumage in south east Australia. A trip to Broome in April before they set off for their breeding grounds is the best way to see the knots and many other shorebirds species in breeding plumage in Australia.

Unfortunately I am ending on a sad note. The Great and Red Knots along with many other migrant shorebirds have suffered large population declines in recent years due to reclamation of tidal mud flats around the Yellow Sea by both China and South Korea. The loss of refuelling habitat along their migration flyways has been devastating. Let’s hope that further loss of habitat can be halted and that at least some of the birds can find new staging habitat though this is a long shot given the birds have evolved over thousands of years to use flyways and stopping points that are now programmed in their genes.

Members of BirdLife Australia will know of the shorebirds campaign in 2016. Let’s hope progress can be made to improve the lot of knots and other migrant shorebirds.

No comments:

Post a Comment