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Tuatara: Volume 21, Issues 1 and 2 (New Zealand Albatrosses and Petrels: an Identification Guide)

Introduction

page 5

Introduction

New Zealand and its neighbouring islands are surrounded by a great expanse of ocean stretching away beyond the horizon for thousands of kilometres. Over these restless waters, a multitude of large and small oceanic birds rise and fall with the sea, and beat their way into the wind. What birds are these? How do I identify them? This guide has been written in response to many requests by both seafarers and interested ‘landlubbers’ for an accurate, easy to use guide to the oceanic birds frequenting New Zealand waters.

The authors are convinced that elaborate keys by which seabirds are carefully stereotyped for identification are generally useless to the observer at sea. They have been avoided here in the belief that ‘a picture is worth a thousand words’. Accordingly, all but 3 species mentioned in the text are figured in the plates, which are based upon the authors’ field observations, flight photographs and museum specimens.

Sixty-one birds are listed in this guide and only 5 of the rarest petrels ever reported from New Zealand have not been included for obvious reasons. These are: Black-footed Albatross (Diomedea nigripes), Manx Shearwater (Puffinus puffinus), North Atlantic Shearwater (Calonectris diomedea), Leach's Fork-tailed Petrel (Oceanodroma leucorhoa) and South Georgian Diving Petrel (Pelecanoides georgicus).

The key is greatly simplified for clarity and ease of use, and is based upon each bird's size and distinguishing plumage characteristics. Each of the 61 birds covered in this guide is prefixed by a number which is retained for each species in the key, on the plates and in the text. The reader can thus quickly find a sketch and information on any oceanic bird likely to be seen in the area defined in Fig. 1.

The plates are arranged in such a manner that birds appearing similar to each other are grouped together on the same plate wherever possible. We have also attempted to assemble birds typical of certain areas on the same or adjoining plate to prevent time-consuming turning of pages. This explains why the illustrations of some birds appear out of numerical order.

Comparative sizes and outlines of the more commonly encountered petrel types are shown in Fig. 2, where some well-known inhabitants of in-shore waters are also figured for comparison.

To help an observer to recognise and describe particular patterns and plumage characters, the upper and lower aspects of a generalised petrel are given in Figures 3 and 4.

The text is concise, with technical language reduced to a minimum; we have attempted to characterise birds, not words. The nomenclature (both the vernacular and scientific names) follows the Checklist of the Birds of New Zealand, 1970. Each bird's description in the text page 6
Fig. 2: Comparative sizes and outlines of commonly encountered petrels compared with well-known inhabitants of inshore water.s 1. Gannet 2. Shag (Cormorant) 3. Gull 4. Tern 5. Gadfly Petrel 6. Shearwater 7. Albatross 8. Prion9. Diving Petrel 10. Storm Petrel

Fig. 2: Comparative sizes and outlines of commonly encountered petrels compared with well-known inhabitants of inshore water.s
1. Gannet 2. Shag (Cormorant) 3. Gull 4. Tern 5. Gadfly Petrel 6. Shearwater 7. Albatross 8. Prion9. Diving Petrel 10. Storm Petrel

page 7 is prefixed by the appropriate wing-span and total length (separated by an oblique stroke), given in centimetres. Conversion to inches can be made by dividing the measurements given by 2.54. The text itself is made up of a description of each species as it appears at sea, followed by its flight behaviour and general distribution. Key points for a bird's identification are italicised. Check these before reading the detail. Where one species looks similar to another, this is stated in a simple cross-referencing system to avoid possible misidentifications. For completeness, subspecies varying in identification characters from the nominate race are noted, and some vagrants (mostly tropical species) are shown in two separate plates (20 and 21).

In order to begin observations on oceanic birds, it is imperative to be able to identify the bird being looked at with some degree of accuracy and consistency. In addition to being an enjoyable pastime, specific records of seabirds are scientifically valuable in assessing species distribution and the routes followed by seabirds on migration. Several New Zealand petrels, for instance, migrate annually into northern Pacific waters for the southern winter (e.g. Buller's and Sooty Shearwaters, Cook's Petrel, Mottled Petrel, Black Petrel), while others travel in an east-west direction, sometimes to encircle the earth before returning to their breeding grounds. Most of these epic journeys are imperfectly or little known, and it is here that observers at sea, in fishing vessels or larger ships, can be invaluable in providing pertinent observations.

The increasing use of small power boats and sailing craft for offshore cruising also gives many opportunities for noting seabirds frequenting off-shore waters, and it is worth stressing that any observations pertaining to the albatrosses and their kin are valuable, and should be properly recorded and passed on to the appropriate authorities.

Equipment is minimal. A good pair of binoculars, preferably 9 x 35, 8 x 40, or 7 x 50 will suffice, a waterproof notebook, this guide(!) and some optimistic perseverance are the primary essentials of the beginning seabird observer.

Peter C. Harper


Zoology Department Victoria University Wellington

F. C. Kinsky


National Museum Wellington

Species identification:

Prior to setting out on his first observational ‘patrol’, the observer should familiarise himself with the birds likely to be encountered on the voyage. This can be done by visiting the local museum or seeking out friends ‘in the know’ (a list of organisations and museums is given in Appendix 1).

Identifying a petrel or albatross at sea is not always easy. They fly with speed, often with weaving flight, and frequently page 8
Fig. 3: Topography of a petrel: upperparts.

Fig. 3: Topography of a petrel: upperparts.

page 9
Fig. 4: Topography of a petrel: underparts.

Fig. 4: Topography of a petrel: underparts.

page 10 disappear from view behind a wave or heaving deck. Many seabirds are not attracted to ships and ignore them completely but other species, notably some albatrosses, the Giant Petrel and the Cape Pigeon, will regularly pursue ships for scraps thrown overboard. Fishing vessels are prime targets for several other inquisitive oceanic birds. These visitors can be readily identified and watched for hours on end. For most species, however, patient observation and careful documentation is the only way to gain confidence in identifying oceanic birds accurately, particularly those species which look very similar to each other. For example, the Grey-faced Petrel, Black Petrel and Flesh-footed Shearwater are three dark petrels frequenting subtropical seas; they can appear identical to the inexperienced observer.

The following parameters for seabird identification should be checked when an observation is in doubt.

(a)Size: The wing-span and total length of each species is given in the text, but the size of a bird can be difficult to judge from a distance if nothing else is about to compare it with. Gauging size differences between petrels comes with practice, but the common wake-following birds will provide an initial clue to the size of any other bird observed.
(b)

Shape: The shape and proportions of a bird to be identified are extremely important. Check the following:

Bill shape — long or short, slender or stout, light or dark.

Head — large or small, slender or rounded.

Neck — long or short, thickset or slender.

Wings and Tail — very important; wings can be long, short, narrow, rounded or pointed at the tips; tail usually fairly short, contours can be rounded, wedge-shaped, square or pointed.

(c)Colour: Petrels are not particularly colourful, but patterns of black or brown and white are important. Check the items below:
  • dark cap, black feathering about eye
  • dark or light eyebrow
  • light or dark collar, chin, throat, or breast patterns
  • any conspicuous dark patterning across upper or lower surface of wings; axillary colours
  • tail colour
  • eye colour — light or dark iris
  • foot colour — all black, bi-coloured, or pale
  • over-all impressions of colour; some species are wholly black or brown, or all white, but check that poor visibility or shadowing isn't deceiving you; if in doubt, check the bird again if possible.
page 11
(d)Flight behaviour: How a bird moves through the air is another important field character. Oceanic birds can soar, glide, sail on stiff wings, flap the wings rapidly, and glide in quick succession, weave in bat-like fashion, or hover over the sea's surface when feeding. Most petrels (and albatrosses) are rapid fliers; estimates of their speed can generally be gauged from the speed of the ship. The height to which a petrel flies above the sea can be a useful identification character; most fly low to the sea, generally just above the waves, but there are notable exceptions.
(e)Feeding behaviour: Seabirds feed both by night and day, depending upon their requirements and food availability. Shearwaters often catch surface fish during the day; the albatrosses and gadfly petrels chiefly eat squid at night, and many other petrels voraciously feed upon zooplankton (particularly crustaceans) which rafts on the sea after dark. Many petrel species are good divers (particularly the shear waters) but others may forage on or near the surface. Feeding flocks should be noted.
(f)Voice: Petrels generally are not noisy birds at sea unless quarrelling for scraps, when their guttural croaking cries are uttered. Some gadfly petrels call when performing courtship flights at sea. Many species use characteristic calls when flying near their breeding colonies.

Number:

Some oceanic birds travel about in huge flocks consisting of many thousands of individuals. Others are solitary, flying alone or in small groups. In any event, the number of all birds seen should be noted and variations regularly recorded.

Date, time and Location:

All entries in the bird-watcher's notebook should be properly dated, with each set of observations prefixed by the time. The ship's position can be obtained from the navigator in larger vessels, and is usually posted in a conspicuous place with cruise ships. The noon position will generally suffice, unless the ship is proceeding rapidly, when more regular position plots may become necessary. Conspicuous or interesting avian events should be able to be accurately plotted.

Weather conditions and sea-surface temperature:

The conditions under which observations are made should be regularly noted. Cloud amounts, haze, mist, fog, rain, hail, or snow; wind speeds and direction, state of the sea (rough, moderate, slight or calm) are important (although subjective) environmental page 12 data. The temperature of the sea is very important and should be obtained at noon or more regularly, if possible. The crossing of convergences which delimit water and life zones should be carefully monitored both with thermometer and binoculars.

Sea productivity:

The amount, distribution and availability of food sources largely controls where birds are to be found. If possible, the variety of marine organisms in the upper reaches of the sea should be sampled, particularly if large numbers of birds are present. This can be done both by night or day with the aid of a finely meshed net towed slowly (2-4 kts.) behind or alongside a small vessel. Samples can be preserved in 70% ethyl alcohol for identification by the appropriate authorities (see Appendix 1).

Obtaining specimens of seabirds:

All oceanic birds are protected by law within twelve miles of the New Zealand coast. We suggest you refrain from shooting or snaring any seabird under any circumstances. If, however, a seabird collides with your ship and injures itself, it may be collected. If you do this, you must be prepared to retain the specimen in a fresh condition until it can be forwarded to a museum for permanent preservation. Birds can be frozen in a freezer, placed in alcohol, or skinned if there is a proficient taxidermist aboard. Please note that it is unlawful to retain bird specimens in your possession. If a live bird is found wearing a leg band, the number should be recorded and the bird released promptly thereafter. Do not remove the band.

Final comments:

Field sketches should be a feature of every logbook. Pay particular attention to the conspicuous field characters mentioned in this guide, and sketch the silhouette of each new entry as accurately as possible. Photography is particularly useful for recording the activities of oceanic birds. Telephoto lenses of about 200-300 mm. are most suitable but shutter speeds slower than 1/125th sec. should be avoided with long-range lenses. In conclusion, never guess a seabird's identity; queried observations and mystery birds are always to be expected.