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).
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. |
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. |
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.
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