Native Predators.

We haven’t that many avian predators on Stewart Island and the incident with the Morepork below got me thinking about them.

MorePork

A couple of days ago on Ulva we noticed the pair of morepork mentioned in a previous post were back in the same Juvenile Rimu tree.

And at the same time we had quite a substantial number of Yellowhead feeding just a few metres away.  The yellowhead  usually chatter and sing when in a flock,

but all of a sudden one of the flock noticed the morepork, and what had been  normal flock noise exploded into an indignant scolding as they reacted to “The Enemy”. A Robin and a couple of Bellbirds joined in and we even saw a tiny Rifleman close by. I can’t hear Rifleman call as at around 24000 cycles per second they are far too high pitched, but it too was probably adding to the din.

Weka

Weka have all of our ground nesting birds well terrified, and Robins in particular “loose the plot” in a big way whenever they see a weka close by. If on or very low to the ground the robins nest will be well hidden. When their family fledges they will take the fledglings quite high up into the trees, and feed them there, allowing them down onto the forest floor only once they have perfected their flying skills and have learnt that weka are bad news. Black Oystercatchers nests are out in plain view on beaches. Their strategy is aggression and they will attack any weka near their nest. It’s always entertaining to watch a prowling weka bolt under the aerial onslaught.

Australasian Harrier (Hawk)

Hawks are not particularly common on Stewart Island, although we have a couple of resident pairs. I once spotted one fishing several hundred metres from shore in Paterson Inlet, someting I was unaware they did. On another occasion one was flying several hundred metres from Post Office Cove on Ulva when it was spotted from shore by a pair of nesting Black Oystercatchers who immediately attacked it. A tribute to their eyesight as the hawk was only barely recognisable to us. I’ve only once sighted one over the Ulva forest, as I would think they wouldn’t do too well down in the trees. On that one occasion we were in a very small clearing with lots of bird song about when suddenly everything went quiet. One of our guests looked up and spotted a hawk drifting over just above the tree tops.

 

Southern Skua

I’ve never seen a Southern Skua around Ulva, but several nest on the islands out from Halfmoon Bay. And they too will be mobbed by smaller seabirds seeking to drive them away. The “NIMBY” syndrome is alive and well even in birdland. Several years ago I watched a pair of Skua hit a black backed gull  flying 60 or 70 metres above the water. It was dead when it hit the water. The skua then proceeded to tear the carcass apart. They usually patrol the seal colonies over the birthing season. The afterbirth being a good meal of course, as are any stillbirths. I would suspect that they, like black backed gulls with young lambs, would also hit any very young unattended pup.