No Bitterns at Kiwiriki?

I recently walked to Kiwiriki Bay with Emma Hunt and Amanda Yates, who achieved ornithological fame in 2006 when a spotless crake attacked their tape recorder on Kaitoke swamp (Environmental News. Issue 8. p.9  by John Ogden
 

As we sat beside Kiwiriki creek near it’s confluence with the sea, we heard a strange ‘booming’ noise. I thought it might be a bittern, although it was not as loud or as long as bittern ‘booms’ I’ve heard before. Anyway this pesky noise set in motion a plan to kayak from Fitzroy to the Kiwiriki at dawn the following weekend to search for bitterns in the salt marsh. This plan was carried out, albeit that thanks to a cold westerly I arrived on site a bit later than intended.

I kayaked around there for a bit, and had a ‘walk’ through the salt marsh, but neither heard nor saw any bitterns. I tied up in some large old mangroves on the southern shore of the bay, but there is not as much tall reedy vegetation (bittern habitat) as I expected. However, I had the pleasure of watching an adult pied shag (Phalacrocorax varius) teaching its juvenile how to catch fish! They were racing about in 30 cm of clear water in the mangroves, chasing parore. I was sitting in the kayak not paddling, and one of them passed right under me. Later I went up Coffin’s Creek and again drew a blank on bitterns.

Adult Pied Shag at Kiwiriki creeek


On the positive side I saw a pair of reef herons (Egreta sacra) on the Kaiaraara mud flats. They are seen fairly frequently at Okupu (Emmy Pratt), and I occasionally see one on the east coast near Awana. Seeing a pair together suggests possible nesting in the area. Reef herons are ‘Nationally vulnerable’ in New Zealand (MisKelly et al. 2008) although the species is quite widespread in Australia and the Pacific. We have only the grey form –a more dramatic white version of the same species occurs in the Pacific.

Shag skull - it demonstrates the efficiency of the shag jaws
as a fish catching structure and the large eye socket.

 

Bitterns are rare on GBI but judging by the occasional report of their booming calls they are not extinct. Their decline is due partly to habitat loss (swamp drainage) and partly to predation on eggs and juveniles.  The Trust would appreciate any reports of sightings or of their distinctive calls.  There is a recording of such on Radio National’s website if you wish to hear an original at  www.radionz.co.nz 

 

• Sir Walter Laury Buller’s painting of the New Zealand Bittern or Matuku (botaurus poeciloptlius) extracted from his landmark text “A History of the Birds of New Zealand”.

 

STOP PRESS:
A NEW RECORD FOR GREAT BARRIER

While in Kiwiriki Bay I nearly tipped up the boat pulling out a different-looking brown seaweed over a metre long. Subsequent consultation showed this to be Sargassum scabridum, a new species on Great Barrier. This find simply demonstrates that there is still plenty to discover about the island’s flora, and brings the total number of marine algae (seaweeds) here up to 139.

 

 

 

 

 

 

 

 

Sargassum scabridum from the northern shore of Kiwiriki Bay.  The photo shows the end of
a frond which was c. 1.2m long.

 



 

 

 

 

 

 

Some of the old mangroves (Avicennia marina) in Kiwiriki Bay.  All photos by John Ogden.