Julia's Birds, Bugs, Bikes and Boats Blog: Rock'n Robins

I am involved in a new endeavour at Zealandia. Our New Zealand robins, or toutouwai, exhibit some pretty amazing behaviour. They are not related to Northern Hemisphere robins though they occupy the same niche. The are more closely related to the little tomtit and are endemic to New Zealand. Though their numbers are declining they are not endangered. They were released into Zealandia in 2001 and were the first release able to fly over the fence if they so desired. They have been a great success and now abound in the Sanctuary. Alas, if they do fly out into the surrounding suburbs their future becomes tenuous as they have little fear of mammals and are easily preyed upon. They nest in forks of trees which also makes their eggs and chicks very vulnerable to possums, rats etc.
They are remarkable in that they indulge in caching behaviour. When full, they hide the prey they cannot eat. Very few Southern hemisphere birds do this, and fewer, if any cache live prey. Toutouwai will catch an insect, stun or kill it, then place it on the top of a branch or in a hidey hole. They have preferred hiding places. Other robins (and maybe other birds) are aware of this and may nick the cache when the original hider is distracted. The cache, being of animal matter will only last a few days before going off so it is only ever a short term food store.
Why they do this is uncertain. Some Northern Hemisphere birds store nuts and seeds for the winter, but our winters are not severe, food is always available and stored insects decay quickly. It maybe because the less time spent on the ground the better as that is where they are in danger of being attacked by a weka or tuatara perhaps.

Studies have been carried out at the University of Victoria over the last few years which have discovered just how clever our little robins are. They are able to count! They can definitely count up to seven with 70% accuracy and maybe up to twelve. One of the ways they have discovered this is by showing that robins exhibit 'expectation violation' which I think is a wonderful term for something we all experience. If you show them three meal worms then put them in a box with a false bottom so the worms disappear, the robins will be most annoyed and continue to search for the worms that are missing. They saw the worms go in and they expect to find them there and when they don't they become frustrated and show expectation violation.

They also observe other robins caching and are able to remember the spot and go and raid it when the coast is clear.

We have been taught a little routine to show the robin's behaviour. We give a little talk about robins first then move to specific sites in different robin territories. Once there we set up a bright circle of rope - an 'arena' which acts as a visual cue. In the centre of that we put a little log with a cavity drilled in it and a little leather leaf which can be rotated over to cover the hole. Next we ring a bell. Usually a little robin appears promptly looking expectant. We hide the first meal worm in the cavity and cover it with the leaf. The robin has seen us do this and quickly moves the leaf to one side and eats the meal worm. We replace it and the robin will then do one of two things. It will either eat this next worm or hold it crosswise in its bill, stun or kill it, then fly about ten metres away and place the worm in one of its caches.