Why are kiwis going blind?

Why are kiwis going blind?
 
The New Zealand kiwi is the country’s most iconic bird, and an article in New Scientist has suggested that they may be losing their sight.
 
In fact, the article found that three kiwis from a South Island forest were ‘profoundly blind’, which could suggest that this species is evolving and losing its sight. The study examined 160 Okarito brown kiwi and determined that there was a very high rate of birds with eye lesions, with as many as a third of them suffering from eye issues.
 
The reason for kiwis’ blindness is speculated that sight is not essential for their survival. These small birds have excellent senses of touch, hearing and smell, and the fact that they are nocturnal means they don’t rely on their sight much at all.
 
Some scientists have even suggested that the loss of eyesight could be thanks to a particular gene that restricts eyesight, but could also mean that kiwis experience greater smell and touch senses.
 
While it may still be unclear exactly what’s going on with kiwis’ eyesight loss, the article also pointed out that they would not be the first species to lose its eyesight over time. Other examples of animals that have gone through this process include cave-dwelling fish and moles, as they also live in the dark and don’t rely on their sight to survive.
 
At Habitat Tours, we’re lucky enough to spot a kiwi or two in the wild on roughly 70 per cent of our New Zealand nature tours. Join us for a night-time tour in Tawharanui to see if you can ‘see’ a kiwi for yourself.