Pterodroma Petrels

By Bob Flood

The second title in the well-received series North Atlantic Seabirds. Utilises the innovative new concept to seabird identification presented in ‘Storm-petrels & Bulwer’s Petrel, the first guide in the series, to identification of Pterodroma Petrels. Endorsed by world leading experts Peter Harrison, Steve N. G. Howell, Killian Mullarney, and Hadoram Shirihai. Covers all Pterodromas known to occur in the North Atlantic, adjacent seas and the Western Palearctic. The only guide with the depth of information needed to identify the more tricky species. Thorough cross-comparison of all species/taxa covered. Original and highly detailed text, over 350 photographs, 40 beautiful illustrations by Martin Elliott, and 11 large format range maps. Two support DVDs available via hyperlink contain at sea footage of all species. Species covered: Trindade Petrel, Kermadec Petrel, Atlantic Petrel, Great-winged Petrel, Bermuda Petrel, Black-capped Petrel, Soft-plumaged Petrel, Cape Verde (Fea’s) Petrel, Desertas (Fea’s) Petrel, and Zino’s Petrel.

• Language: English
• Publisher: Pelagic Birds & Birding Multimedia Identification Guides
• Release date: Mar 3, 2015
• ISBN: 9780956886750

Book preview

MULTIMEDIA IDENTIFICATION GUIDE TO

NORTH ATLANTIC SEABIRDS

Pterodroma Petrels

Bob Flood & Ashley Fisher

Illustrations by Martin Elliott

Pelagic Birds & Birding Multimedia Identification Guides

Purchase DVDs via http://www.scillypelagics.com/store.html

First published 2013, e-published 2015

by Pelagic Birds & Birding Multimedia Identification Guides in association with www.scillypelagics.com

ISBN 978-0-9568867-1-2 (hardback)

ISBN 978-0-9568867-5-0 (ePub)

ISBN 978-0-9568867-6-7 (Mobi)

© text: Bob Flood and Ashley Fisher

© maps: Bob Flood and Ashley Fisher

© illustrations: Martin Elliott

© artwork – feae-complex underwings, and Black-capped Petrel head patterns: Ashley Fisher; feae-complex head and bills: Ren Hathway

© video clips: the copyright in the video clips shall remain with each individual videographer, named in the timelines

© photographs: the copyright in the photographs shall remain with each individual photographer, named in the caption of each photograph or in the timelines

Design and DTP by Bob Flood and Ashley Fisher

All rights reserved. No part of this publication – DVDs and book – may be reproduced in any form or by any means – graphic or mechanical, including photocopying, recording, taping or information storage and retrieval systems – without the prior permission in writing of the publishers.

Conversion and distribution Vivlia, Hockley, Essex

CONTENTS

Guide introduction

Key

Topography

About this guide

Species covered

Overview

Identification

Species accounts

Trindade Petrel

Kermadec Petrel

Atlantic Petrel

Great-winged Petrel

Bermuda Petrel

Black-capped Petrel

Soft-plumaged Petrel

Fea’s Petrel

Cape Verde Petrel

Desertas Petrel

Zino’s Petrel

Confusion groups and confusion pairs

Group 1

Bermuda and Black-capped Petrels

Black-capped Petrel and Great Shearwater

Group 2

Light-morph Soft-plumaged Petrel and the feae-complex

The feae-complex

Group 3

Atlantic and light-morph Trindade Petrels

Group 4

Dark-morph Trindade and Great-winged Petrels

Dark-morph Trindade Petrel and Sooty Shearwater

Dark-morph Soft-plumaged and Great-winged Petrels

Dark-morph Soft-plumaged and dark-morph Trindade Petrels

Kermadec and Trindade Petrels

The problem of jaegers and South Polar Skua

Illustrations of the confusion pairs

References

Acknowledgments

Appendices

Appendix 1 Series introduction

Appendix 2 Species, speciation, and taxa

Appendix 3 Recent taxonomic developments in the feae-complex

Appendix 4 Jamaica Petrel

Appendix 5 Humphrey-Parkes system

Appendix 6 Scientific names of species/genera used in guide

DVDs

Credits

Timeline Disk 1

Timeline Disk 2

ID jogger

About the authors

Inset 1 First impressions and confusion groups

Inset 2 Saving the Bermuda Petrel

Inset 3 Saving the Zino’s Petrel

Inset 4 The ‘snowy-winged’ petrel Pterodroma sp. off Madeira

Inset 5 ID of the 2009 Varanger petrel

Inset 6 ID in the feae-complex

Inset 7 ID of a Zino’s Petrel off the Azores

Inset 8 ID of Kermadec and Trindade Petrels: interpreting photos

Inset 9 Additional South Atlantic gadflies

Inset 10 Pterodroma sp. seen off Gwennap Head, Cornwall, UK, in 2005

Inset 11 The Azores: the northeast Atlantic’s Pterodroma hotspot

Front cover: Bermuda Petrel Pterodroma cahow, off Bermuda, 15th November 2012 (Mike Danzenbaker). Title-page: Black-capped Petrel P. hasitata, white-faced, off Hatteras, North Carolina, USA, 20th May 2008 (Brian Sullivan). Frontispiece: Fea’s Petrel P. feae and seabird feeding frenzy (Martin Elliott).

GUIDE INTRODUCTION

Pterodroma Petrels is the second multimedia ID guide to be published in the series North Atlantic Seabirds, and follows Storm-petrels & Bulwer’s Petrel. These guides cover all of the species/taxa recorded in the North Atlantic, and incidentally all of the species/taxa recorded in the Western Palearctic. The series introduction from the first guide is included as Appendix 1, which we suggest you read if you are new to the series. This guide requires its own introduction since pterodromas are quite different from storm-petrels, resulting in some notable differences in content that we wish to draw to your attention. For easy reading, though admittedly introducing field-birder slang, we use ‘ID’ for ‘identification’ and ‘pterodroma’ for ‘Pterodroma petrel’ (and make pterodromas its plural). Pterodroma has a silent ‘p’ and is pronounced ter-oh-droma.

Pterodromas arguably are the most desired of the tubenoses by the great majority of North Atlantic seabirders. This is not surprising. In the North Atlantic, pterodromas are mostly rare, or very rare, sport attractive plumage, are beautifully shaped masterful fliers, and they give breathtaking encounters. An encounter with a pterodroma leaves you with a strange kind of euphoria, a tingle or buzz that does not wear off for days, even weeks, and resurges every time that you recount the story to others, or think about it in a quiet moment. Pterodromas are very special!

Acquiring moving footage of seabirds over the open ocean is about as difficult as it gets in bird videography, and in our experience no group is more challenging than North Atlantic pterodromas. There are not many left, so finding one at sea is a major challenge in itself. Bermuda Petrel and Zino’s Petrel are classed as endangered in the IUCN Red List of Threatened Species (International Union for Conservation of Nature) with perhaps just 300–350 individuals per species, and there are two million square miles of the North Atlantic Ocean in which to find them! Indeed, as far as we are aware, our video footage of Bermuda Petrels at sea is practically the only footage in existence. Of the remaining breeders, Black-capped Petrel is classed as endangered, and the two taxa of Fea’s Petrel taken together are classed as near threatened (the terms ‘taxa’ and ‘species’ are explained in Appendix 2). Trindade Petrel is the only South Atlantic breeder that is a regular, though rare, visitor to the North Atlantic, and it is classed as vulnerable. Potential vagrant pterodromas from the South Atlantic have larger populations – most of their breeding islands remain uninhabited by humans and introduced invasive species are often easier to control, but to video them means joining a number of long-haul expedition cruises into the remote South Atlantic.

The key with North Atlantic breeders, of course, is to film them near to their breeding grounds. This can be done, but short expeditions are expensive and can pose logistical problems (e.g. getting around the Cape Verde Islands). There is often much frustration when arranging boat charters, in particular explaining chumming methods to the skipper and crew (chum is smelly fishy substances put overboard to attract seabirds, and there are several ways to do this called ‘chumming methods’). This often leads to confusion owing to language problems and because chumming seems odd to newcomers. However, with much effort and patience, it is possible to get to sea, and pterodromas can be lured to a boat by deploying chum made up of the right ingredients. But the story does not end there.

A typical North Atlantic pterodroma encounter is different from a typical storm-petrel encounter. With storm-petrels there is plenty of opportunity to try, try, and try again to get the clips needed for our DVDs, because storm-petrels normally stick around for a while to forage and feed over a chum slick, often in flocks. A pterodroma encounter away from the breeding grounds usually involves a single bird that flies in, wheels around for a minute, then flies away (numbers of Black-capped Petrels off the eastern USA are an exception). That might be it for the day, if one comes in at all. And at the very moment of the event, often unannounced after hours of waiting, will the light be good, will the camcorder power up fast enough, will hands be tied in a much needed though badly timed tea break? Often we end the day saying, ‘try again tomorrow’. Persistence and sheer doggedness are requisite to securing North Atlantic pterodroma footage!

The main consequence for the DVDs is that the clips on average tend to be shorter than the ones used in Storm-petrels & Bulwer’s Petrel, particularly of the rarest pterodromas that breed in the North Atlantic. Even so, the total duration of footage is about the same. It has also been impossible to attain quite the same quality of footage, but we are confident that the quality achieved is more than adequate for our purposes.

The best pterodroma encounters are typically on windy days. The wind achieves two things. First, like all tubenoses, pterodromas find chum/food by smelling it. On a calm day the smell lingers around the boat and even nearby pterodromas will not smell it. On a windy day the smell of chum blows downwind and pterodromas many miles away will smell it and head toward the boat. Second, like all seabirds, pterodromas find chum/food by observing the behavior of other seabirds. When they see a feeding frenzy around a boat, they come to the vessel expecting to find food. Wind provides energy that supports efficient long-distance journeys and high arcing flight. This increases the probability that a pterodroma will see feeding seabirds around the boat, and come in to explore the activity.

On the down side, wind creates difficult conditions for videoing:

It makes the sea rough, which in turn makes the boat an unstable platform from which to video.

It creates sea spray that gets on camcorder lenses and spoils filming, and in certain cases irreparably damages equipment.

It encourages a pterodroma to fly fast with maximum agility, making it hard to follow with a camcorder and zoom in and out to keep the right-sized image.

A rocking boat, swirling spray, and an acrobatic pterodroma result in a fairly low filming success rate. On a calm day the boat is stable, the air is dry, but there are rarely any pterodromas nearby to video. Not surprisingly, this almost always results in a zero success rate. So, it is better to have wind and take on the challenges that the conditions present.

Video is pivotal to Storm-petrels & Bulwer’s Petrel because ID of storm-petrels is based largely on flight behavior, at least to begin with, and moving footage is the primary medium by which to capture and show flight behavior. However, the flight behavior of all pterodromas is similar, so ID of pterodromas focuses on a combination of the main features of jizz, plumage aspect (plumage colors and patterns) and structure. Does this mean that our at-sea video footage of pterodromas is less relevant to your preparation? Not in the slightest. Video is equally important as it presents typical pterodroma encounters by showing the birds as they appear at sea. Moreover, it gives you the opportunity to apply knowledge about field ID acquired from the text, photos, and illustrations in preparation for your next pterodroma encounter.

In addition to all of this, video at times has a fun element to it, for example, by capturing the excitement of a pterodroma encounter. In the Bermuda Petrel species account, you will watch a Bermuda Petrel fly past the boat and hear the whoops of joy and colorful language from 30 or so seabirders who simply cannot believe their luck. No other media captures the moment so vividly. After watching this clip you may find yourself going online to book your next Hatteras pelagic trip (North Carolina, USA).

That said, within a confusion group (similar-looking species/taxa) separation of the species/taxa may come from the particulars, so getting to grips with the details of plumage aspect and structure is imperative, indeed in certain cases absolutely critical, in securing a safe ID. We use some in-hand and at-colony footage to explore structure and plumage aspect. However, digital photos are particularly useful because they capture much more detail. Like Storm-petrels & Bulwer’s Petrel, this guide includes lots of photos showing many examples of structure and plumage aspect. We are very grateful to the photographers who have made this possible.

Furthermore, we incorporate a suite of illustrations commissioned from leading bird artist Martin Elliott. These are not simply ‘nice to include’ but give added value because both individually and together the illustrations provide a different and insightful angle on pterodroma ID. Illustrations are images created from the artist’s mind that encapsulate what a perceptive human eye sees. They depict postures, structure and plumage aspect, which resonate with human experience in a way that photos rarely achieve. That is why Martin’s work contributes its own know-how to the process of ID of our pterodromas.

Our concept is the multimedia ID guide. Pterodroma Petrels brings together the media of text, photos, illustrations, and moving footage to provide you with multiple ways by which to get to grips with these truly enigmatic petrels. Indeed, we believe that synergy comes from bringing these types of media together, where the whole is more than the sum of its parts. Feedback received from readers/viewers of Storm-petrels & Bulwer’s Petrel supports our vision, for example (but see www.scillypelagics.com for much more feedback):

‘I cannot think of a better set of tools for highlighting and educating birders on this amazing group of birds.’

‘I would say that your multimedia guide (format and content) of this difficult group is nothing short of brilliant.’

‘If only other ID guides could be like this …’

Let us briefly turn attention to the choice of species for Pterodroma Petrels. Naturally we deal with North Atlantic breeders and regular visitors to the North Atlantic. In addition, we include vagrants from the southern oceans. This puts vagrants on your radar. You do not want to be left wondering: was it, wasn’t it, what was it? We include under vagrants all species that have been the subject of publicly discussed claims. In some cases there is disagreement about the ID, or the ID remains unresolved. Inclusion of these species reflects our longer-term intention to extend the multimedia ID guides to cover tubenoses of the Atlantic as a whole. Note that we treat the two taxa of Fea’s Petrel as one species, but cover both taxa in detail because they are dealt with as full species in other taxonomic schemes. (Fea’s Petrel is named after the Italian Leonardo Fea who collected the original type specimen in 1898; thus, the correct pronunciation of Fea’s written phonetically is Faya’s or Fayers.) In total we cover 10 species/taxa in Pterodroma Petrels, the same as in Storm-petrels & Bulwer’s Petrel.

We have seen all 10 species/taxa multiple times in the field. The way that we present our ID criteria is shaped by what we have experienced at sea, and by videoing and studying them. We have observed and videoed pterodromas from vessels of various sizes, from a 12-seater RIB (rigid-hulled inflatable boat) to ocean-going cruisers, and we have observed a number of them from land through telescopes. In the North Atlantic, over the last 10 years, we have made many trips to the breeding grounds to carry out our research: twice to Bermuda, four times to Cape Verde, twice to the Canaries, once sailing Madeira to the Selvagens return, and four times to Madeira and the Desertas. We have also participated in 19 day-trips out of Hatteras, on consecutive days, and were lucky on these trips, with pterodroma sightings including ‘the grand slam’ on one day (Bermuda, Black-capped, Fea’s, and Trindade Petrels). We have seen six Fea’s Petrels off Scilly (UK). In the South Atlantic, we organized several trips out of Cape Town in the late 1980s with the help of the late Jim Enticott, worked in two seasons on Antarctic expedition cruisers (2006/2007, 2007/2008), and joined the Atlantic Odyssey in 2006, 2010, and 2012 (a ship-based odyssey of five weeks in duration that takes the route: Argentina, Antarctica, South Georgia, Gough, Tristan da Cunha, St Helena, Ascension, Cape Verde). We have seen Kermadec Petrel in the Pacific Ocean on several occasions. In addition, we examined museum skins at Tring NHM and Bermuda NHM, covering all of our pterodroma species/taxa, and have studied several of the species/taxa alive in the hand.

Last and by no means least, it is not possible for us to produce this guide on ID without highlighting the plight of pterodromas that breed in the North Atlantic. They are in trouble. Most notably, one is presumed extinct (Jamaica Petrel), and two are kept from extinction only by careful management (Bermuda Petrel and Zino’s Petrel). The remaining species/taxa require the assistance of survival and recovery programs. There would be no hope of seeing some of these species/taxa if it weren’t for the actions of a few exceptionally committed conservationists, and recently the added weight of several large organizations with a mission for seabird preservation. We dedicate this guide to the committed few.

Bob Flood and Ashley Fisher, Isles of Scilly, UK, June 2013

For further information on the series see www.scillypelagics.com

KEY

GENERAL TERMS

ALPHA CODE (SHORTHAND BASED ON ENGLISH NAME)

TOPOGRAPHY

MAPS

Keys on maps

TOPOGRAPHY

The topography of a bird identifies regions of feathers and bare parts that are used to describe its appearance in terms of plumage aspect and structure. The following photos of pterodromas are annotated with topographical terms. These terms are building blocks that permit us to make a detailed description of each species/taxon and thereby to compare species/taxa, particularly important in the ID of confusion pairs (along with size, jizz, flight behavior). Note that we use the anatomically correct term ‘ulnar bars’ for wing bars across the arms, not the anatomically incorrect ‘carpal bars’.

Light-morph Kermadec Petrels Pterodroma neglecta, Pitcairn, South Pacific, 27th September 2009 (main photo & noseband); New Zealand, 2nd April 2007 (upperwing) (Brent Stephenson).

Bermuda Petrel Pterodroma cahow (main photo), off Bermuda; uppertail (inset), Nonsuch Island, Bermuda; 15th November 2012 (Mike Danzenbaker). A hooded petrel with thick dark ulnar bars.

Zino’s Petrel Pterodroma madeira, Pico do Areeiro, Madeira, 23rd April 2010 (Frank Zino). Typical ZIPE bill: slight build, including shallow latericorn and slightly domed maxillary unguis, so that the tip of the nostrils to the top of the maxillary unguis is wedge-shaped (see below).

Light-morph Soft-plumaged Petrel Pterodroma mollis (top left), southwest Indian Ocean, 11th November 2007 (Peter Ryan); Fea’s Petrel P. feae (middle), off Desertas Islands, 27th May 2010; Zino’s Petrel P. madeira (right), off Madeira, 25th May 2010 (both Mike Danzenbaker).

Light-morph Kermadec Petrel Pterodroma neglecta (main photo), Meyer Islets, Kermadec Islands, 7th November 2004 (Brent Stephenson); Zino’s Petrel P. madeira (‘wedge’), Madeira, 7th April 2009 (Frank Zino); Cape Verde Petrel P. f. feae (‘notch’), Fogo, Cape Verde Islands, 17th February 2012 (Jacob González-Solís). Bill structure is critical to ID in the feae-complex.

ABOUT THIS GUIDE

The main aim of this guide is to get you to correctly identify the pterodromas that breed within or visit the North Atlantic Ocean (and adjacent seas). It comprises two DVDs and a book (with illustrations, photos, maps, text accounts, and more).

In many ways, the book tells you what to look for in the DVDs and where to look for it. It supports the DVDs with a range of other media.

The first section of the book ‘Species covered’ summarizes the taxonomy of our petrels and their status in the North Atlantic. The second section ‘Overview’ introduces the genus Pterodroma and covers morphology, biology, molt strategies, ageing, colonies, conservation, and more (link Disk 1 chapter ‘Group introduction’). The third section ‘Identification’ presents the details of our approach to pterodroma ID and covers jizz, size, plumage aspect, flight behavior, and structure (link Disk 2 chapter ‘ID’). The fourth section ‘Species accounts’ describes each species in detail; each account begins with a range map, then reviews taxonomy, other names, conservation status, population size, Atlantic range, main characteristics, and molt (link Disk 1 chapter ‘Species accounts’).

The fifth section ‘Confusion groups and confusion pairs’ explains how to separate pairs of species that look similar by pointing out the characteristics that set them apart. Color illustrations of each species/taxon highlight characteristic plumage aspects and structures (link Disk 2 chapter ‘Confusion groups and confusion pairs’).

We include 11 insets. Most of the insets deal with ID issues, though a few of them cover other topics. For example, research into North Atlantic pterodromas in part was rather depressing because populations have been devastated by human activity. Consequently, we feel that it is important to cover conservation issues in more depth than you might expect in an ID guide, in order to raise awareness. To this end we include two insets, ‘Saving the Bermuda Petrel’ and ‘Saving the Zino’s Petrel’ (link Disk 2 to chapters with same title). Another inset briefly introduces Kerguelen and White-headed Petrels, the two remaining gadflies that commonly occur in the South Atlantic, which to our knowledge have not been recorded or claimed in the North Atlantic. As previously mentioned, our longer-term intention is to cover all of the gadflies/pterodromas that occur in the Atlantic Ocean (with the exception of the few vagrants to the South Atlantic from the Indian and Pacific Oceans). Finally, the Azores is rapidly gaining a reputation as the northeast Atlantic’s pterodroma hotspot and so we include an inset that highlights this point.

Following the main text are References, Acknowledgments, Appendices, and the timelines for the two DVDs.

The last section ‘ID jogger’ at the back of the book provides you with a complete bullet-point summary of all the key ID criteria for North Atlantic pterodromas. We call it ID jogger because it jogs your memory with the many important ID points that are hard to remember as a whole. It is an extra resource that can be photocopied or scanned, added to the ID jogger of Storm-petrels and Bulwer’s Petrel, made into a small booklet, and taken on seawatches and pelagic trips.

We use hundreds of color photographs throughout the book to illustrate important issues covered in the text (most published here for the first time).

The book does its best to introduce and describe the 10 species/taxa that we cover – using text, photos and illustrations; but nothing can replace the video on the DVDs for ‘real-life’ encounters with our petrels. The DVDs take you that one big step closer to the birds – to experience them as you would at sea.

On the first DVD the opening chapter is the ‘Group introduction’. The introduction covers some important aspects of morphology and biology. As in Storm-petrels & Bulwer’s Petrel, the DVD also visits many of the remote islands that our petrels depend upon to breed. The DVD then presents the main chapter ‘Species accounts’. Each account aims to get to grips with the main characteristics of the species/taxon under investigation, concentrating on what it looks like under field conditions.

The second DVD begins with a brief chapter ‘ID’ that introduces the main identification issues; the unique characteristics of the genus Pterodroma that separate them from other petrels, and the shared plumage aspect types that group pterodromas in what we call confusion groups. The second chapter ‘Confusion groups and confusion pairs’ then works through the key ID criteria that we use to separate the confusion pairs categorized within each confusion group. The third chapter ‘ID challenge’ presents a series of clips of pterodromas; and you are asked to identify the confusion group to which each one belongs and, where possible, to identify the species/taxon (the confusion group and species/taxon are named in the timeline). In Storm-petrels & Bulwer’s Petrel, we organized the clips into ‘beginner’, ‘intermediate’, and ‘advanced’. ID of pterodromas tends to be more tricky because views are often briefer, pterodromas move faster, and noting all of the important field characteristics in the time given is more challenging. We acknowledge this by dropping the ‘beginner’ section in this guide.

The second DVD then presents a special feature of this guide in the form of two short documentaries, ‘Saving the Bermuda Petrel’ and ‘Saving the Zino’s Petrel’. The documentaries are built around interviews with the three conservationists central to saving the species involved, and who implemented the critical recovery programs that ensure that the species survive today: Bermuda Petrel – David Wingate and Jeremy Madeiros, and Zino’s Petrel – Frank Zino. All three of them kindly provided many archive photos that we have used to illustrate the documentaries. The two short documentaries bring home our concern over the plight of North Atlantic pterodromas.

The first time that you watch the DVDs, we recommend that you watch Disk 1 before Disk 2, and view the chapters in the order that they are presented (although you could watch the short documentaries at any time).

Each DVD has informative narration throughout and each clip has a caption that gives summary information about the clip (except ‘ID challenge’, of course). Captions are numbered and tie-up with the DVD timelines set out toward the rear of the book, where you will find complete information about every clip (date, location, and, where they can be identified, the incidental species).

SPECIES COVERED

This section summarizes the taxonomy and the status of North Atlantic pterodromas. The taxonomy follows Brooke (2004), who acknowledges that genera in the subfamily gadflies, incorporating pterodromas, may not be very closely related (e.g. Bretagnolle et al. 1998, Nunn and Stanley 1998). Brooke gives a conventional view, but there is no obvious improved taxonomy in more recent literature. That said, taxonomic developments, potential changes, and proposed changes relating to our pterodromas are mentioned elsewhere in the text. This section is no more than a summary and citations for the specific points that we make about the species/taxa are given in the more comprehensive species accounts. A brief definition of species, speciation, and taxa is given in Appendix 2.

We treat Fea’s Petrel as a species comprising the two subspecies Cape Verde Petrel and Desertas Petrel (see recent taxonomic developments in Appendix 3). However, we cover both Cape Verde Petrel and Desertas Petrel in detail because a number of researchers treat them as full species. To aid ID, species/taxa are presented in an order that places similar-looking species/taxa side by side:

Trindade, Kermadec, Atlantic, and Great-winged Petrels

Bermuda and Black-capped Petrels

Soft-plumaged, Fea’s, and Zino’s Petrels

The status of each species/taxon in the Atlantic is summarized below. The at-sea range of North Atlantic breeders was poorly known until very recently. The lack of knowledge is easily explained: some species/taxa have very small populations and are rarely if ever seen away from their breeding grounds, some look very similar to other species/taxa making ID away from the breeding grounds very difficult (these form confusion groups), while some have very small populations and look very similar to other species/taxa. However, knowledge about at-sea ranges is rapidly improving with modern geolocator technology. A geolocator is a lightweight data logger that is attached to a petrel’s leg at the breeding colony (normally adults). It logs a bird’s position day by day, over weeks, months, or years. Data on the logger is transferred to a computer when the petrel returns to the colony, creating a record of the petrel’s movements. Technology is improving, but the accuracy of such devices has a mean figure of about 50–100 miles (e.g. Phillips et al. 2004). We use results from geolocator studies, available only in the last few years, to help in the construction of our at-sea ranges for Trindade, Bermuda, Cape Verde, Desertas, and Zino’s Petrels.

Trindade Petrel Rare but regular in the North Atlantic, with most records to date in the northwest Atlantic. Rare year-round breeder (1,130 pairs) on Trindade Island, southwest Atlantic, roughly 700 miles east of the Brazilian coastline. Also breeds on Round Island, near Mauritius in the Indian Ocean, where it hybridizes with Kermadec Petrel and probably Herald Petrel. The at-sea range of Round Island birds is unknown. Knowledge about the at-sea range in the Atlantic is based on a relatively small number of sightings, and recent geolocator results for eight breeding adults. Recorded mainly in the southwest Atlantic (exceptionally south to the Falklands/Malvinas), occasionally in the central South Atlantic, and exceptionally in the southeast Atlantic. In the northwest Atlantic it is regular though scarce off the east coast of the USA (mid-May to late September). It has been recorded in the West Indies, and mid-way between the Lesser Antilles and the Cape Verde Islands. In the northeast Atlantic, there is one record for the Cape Verde Islands, and the number of records around the Azores is 11 and steadily growing with recent increased observation. Evidence suggests that adults forage in the southwest and central regions of the South Atlantic during the breeding season; birds of unknown age disperse more widely in the South Atlantic, and some move into the North Atlantic.

Kermadec Petrel There is dispute about whether Kermadec Petrel breeds on Trindade Island in the South Atlantic, and whether it has occurred in the North Atlantic. So we include it in this guide and analyze the claims. It is a fairly common breeder (c. 35,000 pairs) during November–May, locally year-round, in a tight latitudinal band 24–35°S in the tropical South Pacific, from islands off Australia in the west, to islands off Chile in the east. There are two subspecies. It disperses over much of the tropical and subtropical Pacific within 35°S–40°N, and apparently is most frequent in the North Pacific during November–January. Also breeds on Round Island, near Mauritius in the western Indian Ocean, where it hybridizes with Trindade Petrel. The at-sea range of Round Island birds is unknown. There are no records in South African waters, though.

Atlantic Petrel No definite record for the North Atlantic, but it has been claimed and it is a potential vagrant. There have been two records in the Western Palearctic, both at Eilat (Israel), in May 1982 and in April 1989. The route to Eilat, if oceanic, may have been via the North Atlantic and the Mediterranean, or more likely the Indian Ocean and the Red Sea. It is a common breeder (c. 1.8 million pairs) in the southern winter, during March/April–December/January, on Gough Island and possibly nearby in the Tristan da Cunha group, in the South Atlantic. It forages across the South Atlantic, from the east coast of South America to the west coast of southern Africa, and is most frequently encountered in the latitudinal band 33–50°S. Reaches the South Indian Ocean, and there is one record for Australia.

Great-winged Petrel No definite record for the North Atlantic, though a petrel apparently showing characteristics of Great-winged Petrel was seen off Flamborough Head, East Yorkshire (UK) in September 1986. It is a fairly common breeder (10,000–11,000 pairs) in the southern winter, during mid-March to November, on Gough Island and in the Tristan da Cunha group, in the South Atlantic. It forages in the central and eastern South Atlantic, rarely west to the continental shelf of South America, mainly in the latitudinal band 25–50°S. Moves north into temperate waters in the southern summer.

Bermuda Petrel Extremely rare breeder (103 pairs, 2012/13 breeding season) in the northern winter, during mid-October to late June, on a small number of the rocks/islets adjoining Bermuda, in the northwest Atlantic. To date, the only at-sea records away from Bermuda involve one photographed in the Gulf of Maine in June 2009, and a small number seen during short-range pelagic trips into the Gulf Stream off Hatteras, North Carolina (USA). Off Hatteras, it is a very rare but fairly regular visitor May–June, rarer and irregular July–September (though also recorded April and December). One was captured in 2002 in a burrow on Ilhéu da Vila, Azores, and at the same location in 2003 and 2006 (November/December). Very recent geolocator studies of adult birds, giving 15 lots of usable data, indicate that foraging trips in the breeding season involve three concentration points: waters off North Carolina, waters south and east of Nova Scotia (Canada), and the central Atlantic northeast of Bermuda. Dispersal in the non-breeding season is shown to have two concentration points: west and north of Bermuda, and off the Azores Islands in the northeast Atlantic. Several post-breeding individuals were recorded off northwest Europe, at times between southwest Ireland and northwest Spain, coming fairly close to land at these two locations (about 125–150 miles).

Black-capped Petrel Rare breeder (600–2,000 pairs) restricted to islands in the Caribbean Sea. Possibly polytypic. It breeds in the northern winter, during October to early July, in the mountainous border region of Hispaniola Island,