Saturday, 8 July 2017

Double-banded Plovers – sandworm extraction

Recently on the sand islands in Jones Bay on the Gippsland Lakes I observed Double-banded Plovers hunting a species of sand worm.

Please click on photos to enlarge.

Double-banded Plovers, in non-breeding plumage, on the sand islands in Jones Bay.
This Plover was busy looking for worms buried in the sand. 

Once the bird’s sharp eyesight had found a worm, no doubt only just visible as they are mostly buried in the sand, the very delicate process of extracting the worm begins.

The bird has hold of a worm and the careful task of extracting the worm without breaking it has begun.
The bird changes position slightly and maintains a patient tension on the resisting worm.

The worms of course resist becoming a meal and a degree of tension is required to force the worms out of the holes in the sand. Too much tension and the worm will snap, leaving at best only half a meal for the Plover. Too little tension and the worm will not be extracted.

Here another Plover works at extracting a worm.

With patience and carefully applied and maintained tension on the worm it eventually is forced to relax and it pops out like a recoiling spring.

This photo shows how the worm eventually relaxes and tension applied by the Plover causes the worm to contract like a rubber band and end up in coils around the bird’s bill.

I know animal intelligence can be a controversial topic, however watching the Double-banded Plovers deftly extracting worms from the sand I could not help thinking that I was witnessing the application of intelligence. I think the skill to extract worms is learnt and is not simply hard wired in the bird’s brain by genes. The process of extracting the whole worm requires the application of a very subtle amount of pressure which must be maintained with concentration and patience until the worm eventually yields.

The intelligent extraction of worms by the Double-banded plovers is just one of many ways birds display how smart they are.

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