Killer kōtare

When we moved into our new home at Arkles Bay in 2015, I did not realise that our section was already occupied by another family.

A pair of kōtare (sacred kingfishers) occupied a hole in a rather nasty Phoenix palm in our garden and every summer since they have successfully raised a brood (or two) of nestlings.

The pair has returned again this Spring, and we hear them every morning making their characteristic “Kie! Kie! Kie!” calls. If you know (or learn) their call you will be aware that these gorgeous native birds are common throughout the Hibiscus Coast.

Over the years this pair of birds have astonished me with the diversity and abundance of prey items that they deliver to their youngsters. Despite being kingfishers I have yet to see a single fish fed to their chicks. Their favourite food itemis lizards – more specifically two species of skinks.

Most of the skinks they feed the young are plague (aka rainbow) skinks, a small species accidently introduced to New Zealand from Australia. But they also catch a lot of ornate skinks, a larger endemic (NZ only) species that is classified “at risk” by the Department of Conservation. The many ornate skinks the kōtare have caught over the years indicate we have a healthy population of these lizards around here. Good to know!

Last summer I decided to get a better handle on the full repertoire of food items that the busy parents bring their young. For the last week of the nesting cycle, just before the chicks leave the nest cavity, I recorded parental feeding behaviour with GoPros. To help analyse over 300 prey items brought to the nest, I enlisted the help of Massey University BSc Zoology student Treasa Pool.

As expected, we observed both species of skink, but also weta, crabs, earthworms, walking sticks, praying mantises, beetles, baby birds, mice and on three occasions, adult tauhou (silvereyes). The chicks swallow the prey items whole, even the mice and silvereyes. It is extraordinary!

Treasa's analysis also showed that mum and dad were catching different prey. They both shared the feeding duties equally, but the female was a specialist predator catching almost exclusively skinks. The male however was a generalist, catching skinks but also most of the crabs, insects, worms, mice and birds. Why the difference? We do not know, and it is only one nest, but it is likely that having one specialist and one generalist help the kōtare efficiently provide the most food to the young as a team.

We want to keep monitoring the diet of sacred kingfishers, so this summer if you know of any nests that might be amenable to monitoring let me know – contact details at the top of the column.