Environment – Fancy feet

Every time I see a heron, I take an extra close look at it – especially when I am on the Hibiscus Coast.

The majority of the time it will be our familiar white-faced heron – but every so often one might spot a Pacific reef heron. You can tell a reef heron from a white-faced heron because, as well as lacking the white face, they are typically darker and have a single dark tone under the wing instead of two tones – dark and light grey.

Reef herons are native to NZ but are much rarer than the white-faced heron. It is estimated there are only about 500 individual birds in the country.

Reef herons (in common with white-faced herons) also have very colourful yellow feet that contrast conspicuously with their dark plumage.

Many bird species have bright colouration that they use to communicate with potential mates or competitive rivals: the colourful displays basically help them get mates. But in the case of reef herons, the flashy foot colour has a very different function: it helps them get food.

If you get the chance, take some time to watch reef herons as they feed. They eat small fish and crustaceans and employ a range of techniques to catch their prey. They may remain motionless for ages and then pounce, dash about in a seemingly chaotic fashion stabbing at anything that moves, or bring their wings forward to create a parasol for prey to gather under. And often they will just stir their feet about in the water to scare up anything lurking underneath. This is where the bright yellow feet come in – the yellow is highly visible in the murky water that they are stirring about, and when the prey sees it, they flee. This makes the prey much more apparent to the reef heron waiting to pounce.

It is exactly the same strategy that fantails (piwakawaka) use when they expose the bright white feathers of their fanned tails to startle their prey, little flying insects.

Natural selection has no problems with adopting the same solution to similar challenges.