It was not long before the first seabirds were seen: Fluttering Shearwater (individuals and small groups, max. 28 birds); Cape Petrel (ones and twos); Little Blue Penguin (1); Common Diving Petrel (ones and twos); and the occasional Black-backed Gull (ones and twos). Fortunately, we had Brent Stephenson and Sav Saville onboard. Not only did they see most of the birds before we did, but they served as instant identification guides as well (we just added water
).At about 08h30, 29 km due west of Wanganui and 12 km SSW of Waiinu, we came upon the first of a number of dense flocks of feeding seabirds, comprising an estimated 1500 Fairy Prions, 500 Fluttering Shearwater, up to 15 Cape Petrel, at least 1 Common Diving Petrel, and a solitary adult White-capped Albatross. The birds were feeding over a roiling mass of fish just below the surface. Water depth was about 35 m. Estimating the numbers of birds present in these whirling flocks is an exercise in clairvoyance, but counting the numbers of birds in subsets of photographs later suggests that our estimates were reasonable.
We continued WNW for about 8 km, stopping over a rocky bank 12 km SW of Waverley Beach for a spell of fishing. Water depth was only about 19 m. Here there was a constant west to east movement of Fairy Prion, with 20-60 birds flying past per minute. None were attracted to the boat. During this period, occasional White-capped Albatross would appear, circle the boat then fly away. Other species seen included Fluttering Shearwater and Black-backed Gull.
We moved on to a large flock of mostly prions and shearwaters, feeding frenziedly over a shoal of kawahai about 15 km SSW of Waverley Beach. This flock, the largest seen that day, consisted of more than 5000 Fairy Prion and 200 Fluttering Shearwater. A Northern Giant Petrel and 3 White-capped Albatross flew past but did not stay.
We continued westward, visiting various fishing spots, eventually reaching a spot about 20 km SW of Waverley Beach in water just under 50 m deep. A few Fairy Prion continued to fly purposefully past the boat, perhaps heading for one of the feeding frenzies further east. Very few were attracted to the boat and the chum being thrown overboard. Those that came did not stay. White-capped Albatross appeared and were gradually drawn to the boat, attracted by the bits of fish being thrown to them. Eventually, 11 birds were sitting around the boat, although they fed in a somewhat desultory manner. We also attracted 2 Northern Giant Petrels, 1 Cape Petrel, and 7 Black-backed Gulls. The Giant Petrels, however, kept their distance from the boat, even with all the fish being thrown overboard.
We moved again to survey another flock of prions, about 22 km S of Patea. This one consisted almost entirely of Fairy Prion (1500-2000 birds). A solitary Fluttering Shearwater and one Common Diving Petrel were also noted. Again, the prions were feeding over a mass of shoaling fish, but activity was less frenetic than before; perhaps most of the birds were satiated.
At 13h00 we headed back to Wanganui, 46 km and just over two and a quarter hours away, stopping off to inspect various prion flocks on the way, including what was probably the remnants of the first flock seen that morning. By this time, the flocks were small, comprising mainly Fairy Prion (400-700) and Fluttering Shearwater (10-200). The last flock recorded, 12 km SW of Waiinu, also contained about 200 Red-billed Gulls. The prions were also numerous and widespread outside these flocks, with individuals and groups mostly flying east to west, the opposite direction to that recorded in the morning. White-capped Albatross (2), Cape Petrel (10), Northern Giant Petrel (1), Common Diving Petrel (at least 4), and Black-backed Gulls (up to 25 adults and immatures), were also recorded along the way. The last of the Cape Petrels was seen 18 km W of Wanganui and 11 km SSE of Waiinu, just inside the 30 m depth contour.
Overall, the day was a great success. Although the diversity of birds was low, the large number of prions was notable. All those that we could identify were Fairy Prion, which breed on islands in the Marlborough Sounds and the stacks off New Plymouth. On a couple of occasions we saw individual birds that looked and flew differently—slower wing beats and more undulating flight—but we did not get good enough views to identify them. Almost all the seabird flocks were recorded in water deeper than 30 m, which in this area is 10-15 km offshore. This may explain why pelagic seabirds are so seldom seen from the coast here, other than occasionally as stranded birds. A notable absentee was the Australasian Gannet, small numbers of which can often be seen from land. Most are probably back at their breeding colonies now, and may not range far.
The following summarises the birds seen:
White-capped Albatross Thalassarche steadi 26 counted but some may have been recorded twice; 11 birds around the boat at one site; all adults.
Fluttering Shearwater Puffinus gavia 960 recorded but probably an underestimate. Over 200 birds seen on two occasions in feeding flocks with Fairy Prions.
Common Diving-petrel Pelecanoides urinatrix 11 counted but almost certainly under-recorded.
Cape Petrel Daption capense 37 counted but almost certainly includes birds counted more than once. Maximum number recorded at one location was 15.
Northern Giant Petrel Macronectes halli Recorded on 6 occasions but probably no more than 2-3 birds involved.
Fairy Prion Pachyptila turtur Over 10,000 birds estimated. No doubt some of these are duplicate counts but, equally, many more were uncounted as they flew past when the boat was moving. Maximum number estimated at one location was more than 5000.
Little Penguin Eudyptula minor 1.
Black-backed Gull Larus dominicanus 48 counted but probably more.
Red-billed Gull Larus scopulinus Up to 800 roosting in Wanganui harbour overnight 7th/8th August. About 200 recorded at sea in one of the seabird feeding flocks closer to land; otherwise only scattered individuals.
White-fronted Tern Sterna striata 2.
We aim to repeat the exercise some time in the future to see what effects different sea conditions and seasons might have. A couple of pictures:
- Part of a flock of an estimated 5000 Fairy Prion
- Fairy Prion_flock_small.jpg (125.68 KiB) Viewed 192 times
- One of the White-capped Albatross attracted to the boat
- White-capped Albatross_small.jpg (89.84 KiB) Viewed 192 times
Peter Frost
87 Ikitara Road,
Wanganui 4500
