The Cook Strait ferry is indeed a great pelagic
birding opportunity. It is quite possible to do the return trip in a day, and,
as mentioned by Tom Wilson, the "slow" ferry is by far the best for birding. The
high speed cat doesn't spend so much time in the open water and the viewing
facilities are not so good.
As for the best time of year - well there really
isn't one - different times of year bring different birds, but any time is good.
The winter has more Albatrosses and certainly Cape Petrel, the summer more
Shearwaters, Fairy Prion etc though beware of the unusual flat calm day when you
are likely to see nothing at all!! Probably the best times are in spring and
autumn when there is a mixture of summer and winter species. I have seen up to a
thousand Alberts in a single crossing in October.
Regardless of Tom's posting, and several other
reports in print and websites, one has virtually nil chance of seeing King
Shag from the ferry - it certainly does not allow even distant views of the
breeding sites and I know of no NZ birders who have claimed this species from
the ferry (I have personally made the journey scores of times).
The list of possibilities is more or less endless,
but I would urge caution unless you are a very experienced observer - Hutton's
do look like Flutterers, Westland Black does look like White-chinned Petrel and
not every spec of an Albatross is identifiable at long range from a rolling
Good luck John, and I for one would love to hear
what you turn up.
Wrybill Birding Tours, NZ
+64 6 323 1441