Bird Fact Friday – Traditional Gull ID Problems

Adapted from pages 20-22 of Gulls Simplified:

Why has gull identification been presented as such a feather-splitting challenge? First, we humans seem obsessed by the need to find and classify differences, whether these have a bearing on species differentiation or not—that is, we like splitting hairs, or in this case, feathers. Fine and well; who doesn’t enjoy a challenge?

This photo shows two common species in the left foreground. Photo credit: Kevin Karlson.

But gulls, because of their complex plumage array, simply overwhelm most observers.

Also exacerbating the challenge of gull identification is the avocational focus on finding birds that are outside their conventional range—that is, “rare birds.” By placing added value on finding Slaty-backed Gulls or Yellow-legged Gulls
among the ranks of far likelier but similar species, we at times complicate the identification challenge. This almost mandates that plumage be the foundation of gull identification insofar as differences between similar species, particularly
those found within an evolving species complex, are mostly feather deep.

But if we embrace the nature of probability and accept that rare and unusual species are unlikely to be encountered, the challenge presented by North American gulls becomes greatly simplified, reduced to telling Ring-billed Gull from Herring Gull and California Gull, birds whose size and structural differences do readily distinguish them. Instead of fighting probability by aspiring to find birds outside their normal range, we advocate embracing probability and letting it work for you, not against you.

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull

Bird Fact Friday – Iceland Gull

Adapted from page 118-119 of Gulls Simplified:

An adult Iceland Gull has a round head; gentle expression; very pale silver-gray back; short pink legs; and a short, slender, bullet-shaped bill. Photo credit: Lloyd Spitalnik.

The Iceland Gull is a smallish, plumpish-bodied, round-headed, petite-billed, short-legged, uniformly pale gull nestled amid the collage of contrastingly patterned Herring Gulls clustered on the beach.

This medium-large, pleasingly proportioned gull is smaller, plumper breasted, and shorter legged than Herring Gull, and typically distinctly smaller and less bulky than the similarly plumaged Glaucous Gull, from which Iceland may be distinguished by its longer wings that extend well beyond the tail of standing birds (generally a bill length beyond the tail). In adult birds, primaries range from white or light gray to charcoal gray, and to black in Thayer’s Gull, a subspecies of Iceland Gull.

Iceland’s bill ranges from petite and bullet shaped to fairly long, with a decurved tip on larger birds. The bill is mostly dark on immature/1st winter birds, but some birds can show a pinkish to yellowish bill with an ill-defined black tip at this age. Immature Glaucous Gull’s larger bill is richer pink and has a more sharply demarcated dark tip compared to that of immature Iceland. A round head, short neck, and shortish legs
impart a plumpish, pigeon-like impression to many Iceland Gulls (an attribute never applied to the bulky, barrel-chested Glaucous Gull). In winter, the head of adult Iceland shows limited to no streaking, except for the Thayer’s subspecies, which can show a heavily streaked head and neck. In a mixed flock with Herring Gulls, Iceland’s (Kumlien’s) smaller size and plain, pale, uniform plumage stand out.

Thayer’s subspecies of Iceland Gull (thayeri) averages intermediate in size and structure between large Kumlien’s Iceland Gull and small Herring Gull, but its adult plumage is much closer to that of Herring Gull with respect to the gray shading of its upperparts and black wing tips. While many adult Thayer’s have dark eyes, some birds on the Pacific coast have pale to dusky eyes, so this field mark is not absolute. Rather than including extensive ID criteria for the Thayer’s subspecies here, we ask that you please refer to captions in the Thayer’s subspecies section of Iceland Gull at the end of this account for characteristics that distinguish it from Kumlien’s Iceland Gull and Herring Gull.

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull

Bird Fact Friday – Antpittas

Adapted from pages 310-311 of Birds of Central America:

A table of different Antpittas. Illustrated by Dale Dyer.

The Black-Crowned Antpitta is a distinctive species with no close relatives in the region, specifically Cemtral and Sothern America. They are uncommon and local residents in south foothills (mainly 300 to 1200 m, locally near SL in east PA). These birds are large and robust with very short tail, long legs, and heavy gray bill. Identifiable by the bold black- and- white scaling on underparts. Note the white spots on wing coverts, and that the males have black throats. Pairs or solitary birds bound rapidly over forest floor pausing briefly to stand on fallen log or other low perch. They are generally reclusive but attends ant swarms where it forages boldly. Habitually flicks wings and tail. Song (1) a very long series of loud, sharp notes wi- i- i- i- ii- i- i- i . . . that gradually slow and drop in pitch. May continue for almost one minute. Also (2) an abrupt, low- pitched, guttural three- to ten- note rattle kuk kuk kuk . . . or wucwuc- wuc- wuc . . ..

Meanwhile, the Scaled Antpitta is found from Mexico to Southern America. It is an uncommon to rare and local resident in foothills and highlands (100 to 2850 m in north, 450 to 1650 m in south). Also home to the volcanic highlands of El Salvador (Santa Ana), and recently reported from Cerro Musún in central Matagalpa, Nicaragua. These birds are plump and short- tailed. Note the gray crown scaled with black and pale malar and lores. Underparts mostly cinnamon with variable, narrow, pale crescent dividing throat and breast. Rump and wings are rufous- brown. Juveniles are mostly dusky with fine whitish and buff streaking on crown, nape, mantle, and breast. Adults from north CA are less richly colored below. These birds hop rapidly over ground and are secretive, but may forage in open on muddy forest trails or in shaded clearings. May also attend ant swarms, but are usually solitary. They are also known to sing briefly at daybreak. Song (1) a series of low- pitched, resonant notes that start as a trill, rise in pitch and volume, then slow to form distinct, hollow, individual notes before stopping abruptly huhuhuhHUHUuhuhu hu hu hu. Compare with song of Black- headed Antthrush. Calls include (2) a low- pitched grunt or croak.

Birds of Central America
Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama
By Andrew C. Vallely and Dale Dyer

Birds of Central America is the first comprehensive field guide to the avifauna of the entire region, including Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama. Handy and compact, the book presents text and illustrations for nearly 1,200 resident and migrant species, and information on all rare vagrants. Two hundred sixty detailed plates on convenient facing-page spreads depict differing ages and sexes for each species, with a special focus on geographic variation. The guide also contains up-to-date range maps and concise notes on distribution, habitat, behavior, and voice. An introduction provides a brief overview of the region’s landscape, climate, and biogeography.

The culmination of more than a decade of research and field experience, Birds of Central Americais an indispensable resource for all those interested in the bird life of this part of the world.

  • Detailed information on the entire avifauna of Central America
  • 260 beautiful color plates
  • Range maps, text, and illustrations presented on convenient facing-page spreads
  • Up-to-date notes on distribution supported by an extensive bibliography
  • Special focus on geographic variation of bird species

Anurag Agruwal: Great News for Monarch Overwintering Population

The estimates of the monarch butterfly overwintering population were announced today (Wed. Jan. 30th 2019) by WWF Mexico.  The butterflies are so dense at their dozen or so mountain-top clustering sites that overwintering butterflies cannot be counted individually.  Instead, the area of forest that is densely coated with butterflies (at about 5,000 butterflies per square meter looking up into the canopy) is estimated as a measure of monarch abundance.  Butterflies arrive to Mexico around the day of dead in November and stay until March each year as part of their annual migratory cycle.  Butterflies have been declining over the past three decades, and the annual announcement is a welcome addition to our understanding of the long-term dynamics of our beloved monarch.

The annual multi-generational migratory cycle of the monarch butterfly. The southernmost red dot indicates the high elevation overwintering grounds in central Mexico where populations are censused. North pointing arrows indicate the spring and summer generations that migrate, breed, and eat milkweed. Learn more in my book Monarchs and Milkweed.

This winter season (2018-2019), there were approximately 6.05 hectares (nearly 15 acres) of forest occupied with dense monarchs in the Mexican highlands (somewhere in the neighborhood of 300,000 million overwintering butterflies).  The monarchs end up congregating in a tiny area, with the bulk of the butterflies concentrated among twelve mountain massifs (clusters of peaks) within three hundred square miles (eight hundred square kilometers), an area smaller than New York City. In other words, most of the monarchs from eastern North America, from Maine to Saskatchewan, and south to Texas, probably covering two million square miles, funnel down and overwinter in a location 0.015 percent the area that they occupy in the summer!  Unbelievable. This year’s estimate is well over double compared to last year, great news for monarchs!

Where does this leave us?  The good news is that this year’s population was huge in the summer months throughout the USA and Canada, and the resulting migration and overwintering population in Mexico was the highest in 12 years, higher than predicted by many.  The season started with a very early spring and a far reaching northern migration.  As I have previously argued, there is often a disconnect between summer breeding populations of monarchs and the overwintering population — that seems to not be the case this past year.

With 26 years of data, there are various ways to plot and assess the trends.  Below I have plotted four year averages for seven periods working backwards (so the first average on the left is only for 2 years).  Any way you slice it, the trend has been negative, and the population is not what it was.  Nonetheless, the extreme downward trend seems to have bumped up in the last period of four years.  Is this the new norm, a winter population hovering between two and five hectares?  How dangerously low are these numbers? And what can be done to continue to reverse the trend and buffer the population?  I have recently written more about this issue in a scientific article as a well as my book.

For now, let’s celebrate. The government is open, and thus the Fish and Wildlife Service will be deciding on the petition to list monarchs as threatened under the Endangered Species Act this summer. Looking forward to seeing butterflies and their caterpillars once Ithaca, NY thaws in spring. Thanks for reading! 

Anurag Agrawal is a professor in the Department of Ecology and Evolutionary Biology and the Department of Entomology at Cornell University. He is the author of Monarchs and Milkweed and lives in Ithaca, New York.

 

 

Browse our Birds & Natural History 2019 Catalog

Our new Birds & Natural History catalog includes the first comprehensive field guide to the birds of Central America, a lavish photographic celebration that captures the fascinating behaviors of land and sea animals in the Galápagos Islands, and a simpler and more user-friendly visual approach to gull identification.

[PDF]

Birds of Central America is the first comprehensive field guide to the avifauna of the entire region, including Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama. Handy and compact, the book presents text and illustrations for nearly 1,200 resident and migrant species, and information on all rare vagrants. Two hundred sixty detailed plates on convenient facing-page spreads depict differing ages and sexes for each species, with a special focus on geographic variation. The guide also contains up-to-date range maps and concise notes on distribution, habitat, behavior, and voice. An introduction provides a brief overview of the region’s landscape, climate, and biogeography.

The Galápagos Islands are home to an amazing variety of iconic creatures, from Giant Tortoises, Galápagos Sea Lions, Galápagos Penguins, and Ghost Crabs to Darwin’s finches, the Blue-footed Booby, and Hummingbird Moths. But how precisely do these animals manage to survive on—and in the waters around—their desert-like volcanic islands, where fresh water is always scarce, food is often hard to come by, and finding a good mate is a challenge because animal populations are so small? In this stunning large-format book, Galápagos experts Walter Perez and Michael Weisberg present an unprecedented photographic account of the remarkable survival behaviors of these beautiful and unique animals. With more than 200 detailed, close-up photographs, the book captures Galápagos animals in action as they feed, play, fight, court, mate, build nests, give birth, raise their young, and cooperate and clash with other species.

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

Bird Fact Friday — Hybrid Gulls

Adapted from page 189 of Gulls Simplified:

Many gull species are closely related, with their evolutionary divergence fairly recent, and their geographic isolation is not always absolute. In fact, the ranges of some genetically similar species overlap. Because of this fertile combination of genetic similarity and physical proximity, hybridization between similar species currently considered distinct is both likely and problematic.

The offspring of theses hybrid combinations often show traits of both parent species, making identification challenging, or may show the physical traits of one species but some plumage features of the other species. Being themselves fertile, these hybrid gulls may then backcross—that is, breed with either parent species or with another hybrid gull—further muddying the ID picture. Hybrids are not countable as distinct species by any ornithological organization.

The Glaucous-winged × Western Gull has the stocky body and heavy bill typical of Western Gull, as well as the head shape of that species with a bump on the crown. However, the back is gray like that of Glaucous-winged, but the wing tips are too dark for that species. Photo credit: Kevin Karlson

For example, the Glaucous-Winged × Western Gull is the most common hybrid gull encountered in North America, and it occurs mostly on the Pacific coast from California to British Columbia. In certain areas of northern Oregon and southern Washington, hybrids may outnumber pure individuals of both species. Some hybrids resemble Western Gulls,especially in body and bill structure, but show some plumage traits of Glaucous-winged, while others resemble Glaucous-winged in structure and bill shape but show some plumage features of Western Gull.

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull

Bird Fact Friday — the Ivory Gull

Adapted from page 177 and 182 of Gulls Simplified:

The Ivory Gull is a “Dark Horse Gull” or, a gull you are most unlikely to encounter in North America, but should be aware of. Some of these may be found at appropriate times of year in very remote locations that average birders don’t typically visit, while others are rare vagrants whose presence cannot be predicted.

An immature Ivory Gull, photographed in New Jersey. Credit: Kevin Karlson

Smaller than Iceland Gull, Ivory Gull is slightly smaller than Ring-billed Gull but stockier and plumper overall. Ivory Gull is our only pure white gull with black legs and black eyes (thus eliminating the possibility of albinism in other species).

Ivory Gull is often described as an aggressive and voracious feeder—a trait that serves a bird that lives very literally on the edge. It is somewhat pigeon-like on land but wheeling and nimble in flight, with quick wing beats. Mostly solitary and somewhat nocturnal, it is reported to investigate anything red. It is always found near water, even cattle watering troughs if nothing more suitable is around.

This distinctive but rarely seen all-white Arctic gull is typically found foraging around pack ice, where it makes a decent living scavenging the remains of polar bear kills. Vagrants often feed on fish scraps near fishing piers or docks where boats dump their bycatch.

They are rarely away from their high Arctic breeding locations with pack ice, in Greenland and extreme northern Canada. In winter, they are found almost exclusively near pack ice, with wintering areas in the Bering Sea and Labrador Sea to Davis Strait. Occurs casually to the Canadian Maritimes and is accidental south to New Jersey and other scattered locations. There are a few inland records, including Tennessee, with most clustered around the Great Lakes. It is very rare south of Canada.

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull

 

Luke Hunter on Carnivores of the World

Covering all 250 species of terrestrial, true carnivores, from the majestic polar bear and predatory wild cats to the tiny least weasel, Luke Hunter’s comprehensive, up-to-date, and user-friendly guide, Carnivores of the World, features 93 color plates by acclaimed wildlife artist Priscilla Barrett that depict every species and numerous subspecies, as well as more than 400 drawings of skulls and footprints. Features new to this edition include revised and expanded species coverage, a distribution map for every species, 25 new behavioral illustrations, and much more. Detailed species accounts describe key identification features, distribution and habitat, feeding ecology, behavior, social patterns, reproduction and demography, status, threats, lifespan, and mortality. An introduction includes a concise overview of taxonomy, conservation, and the distinct families of Carnivora.

What’s new in the second edition?

The text has been completely revised for the second edition, with new data and observations published since 2011 to update and improve the original text throughout. By way of one example, most reproductive data for the Andean Bear in the first edition had been collected from captive animals, but the first population-level information from long-term research on the species in the wild (in Peru) was published in 2018, and has been incorporated in the book. Similarly, some species which were very poorly known at the time I wrote the first edition have since been the focus of at least one dedicated research effort, providing much better information for the new book; examples include the Bush Dog, Fishing Cat and Narrow-striped Boky.

A major addition in the new edition is the inclusion of 9 new species delineated since 2011, largely as a result of recent genetic analyses. Perhaps the most dramatic example is the African Wolf, formerly believed to be an African population of the Eurasian Golden Jackal.  The new book covers numerous cases where one species has been re-classified into two or even three, e.g. European, Asian and Japanese badgers, Northern and Southern Oncillas, and Mainland and Sunda Leopard Cats.

Finally, the IUCN Red List category indicating degree of endangerment has been revised for most carnivores, I provide a new assessment of Population Trend for each species, and the second edition includes distribution maps for every species based on the most recent IUCN Red List population data.

It is surprising that so many new species have been described since the first edition was published. How did these discoveries arise?

All new species in the book arose largely as a result of advances in genetic technology which has made very powerful and cost-effective analyses widely accessible to researchers. It has allowed geneticists to look with ever-increasing resolution at the differences between populations which, in some cases, turned out to be a so-called “cryptic species.” The same process has also revealed cases where populations formerly considered to be separate species (based mainly on appearance) actually have minor genetic differences, subsuming two former species into one. For example, Grandidier’s Vontsira is now regarded as a distinct population of the Broad-striped Vontsira. Whereas the first edition included accounts of 245 species, edition 2 covers 250 species, nine of them newly described.

To many readers, uncovering new species by genetic differences probably does not have the same excitement as news of an entirely unknown animal never before seen by scientists being discovered in a remote corner of the globe. Do you think the new species in the book are as interesting or even valid?

The question of validity is an interesting one; even geneticists debate the degree of genetic divergence indicative of two distinct species (versus lower-level delineations, for example, indicative of sub-species). There is the genuine danger of a ‘gold-rush’ in which researchers rush to publish new discoveries based on relatively minor distinctions between populations: there are already examples in the scientific literature. I took a conservative approach in the book, and included only those new species supported by strong published evidence and that are generally accepted by relevant authorities e.g. the International Union for Conservation of Nature Species Survival Commission (IUCN SSC) Specialist Groups devoted to carnivores.

Even with that, the question of validity remains a moving target. I believe that any newly discovered genetic distinctions must reflect other significant biological differences, such as in morphology, ecology, distribution and especially in reproductive isolation, the classic (some say old-fashioned!) defining characteristic of species. This is not always well understood, even for some of the new species included in this new edition. In an introductory section on the 13 families of terrestrial carnivores, I list other cases that I consider borderline or questionable; these are not treated as full species in the book but some may eventually be recognized as such with better data and analyses in future. This is a story that will continue to unfold.

Priscilla Barrett’s artwork is superb, with many species which have never been so accurately and beautifully painted. What was it like working with her?

Priscilla is an exceptional collaborator. With her zoology background, she brings a scientist’s rigor to the process. She draws on her vast collection of reference material- photos of museum skins and samples, sketches and notes from the field- and we also used hundreds of recent camera-trap images, supplied by colleagues from around the world, including of many species or forms that have otherwise never been photographed in the wild. The result is art that is not only beautiful but also highly accurate; viewing Priscilla’s carnivores, I always feel a surge of recognition, that she has captured the true essence of each species.

Beyond each individual piece of art, each plate benefits from Priscilla’s very intuitive sense of design. The process started with her sketching rough lay-outs to decide the poses for each species or form, and how each interacted with the others on the page. Once we had decided that a plate worked, she painted all of the components. It has been very rewarding for me to come to understand how that process produces complete plates with both balance and life.

Field guides to mammals are becoming more common. Do you think this reflects greater interest in watching mammals?

Two colleagues who recently published a review of mammal-watching put it nicely when they said ‘Mammalwatching today is arguably where bird-watching was a century ago.’ That said, the same paper notes how mammal-focused tourism has increased dramatically in the last couple of decades, not only for the large charismatic species that every safari-goer to Africa wants to see, but increasingly for small and often difficult-to-see species requiring specialist guides and local knowledge.

Amateur mammal-watchers have also contributed to scientific discoveries including the first documented record, with terrific photos, of the virtually unknown Pousargues’ mongoose in Uganda since the 1970s, and the first records of Pale Fox and Rüppell’s Fox from northeastern Ethiopia; I referred to both papers for the second edition. I also had access to many dozens of trip reports written by mammal-watchers since the first edition. There’s little doubt all this reflects an increase in mammal-focused tourism, a trend that I am sure will continue. And one, I hope, that helps foster the growing demand for more and better mammal-focused field guides!

 

Luke Hunter is one of the world’s leading authorities on wild carnivores. His books include Wild Cats of the World and Cheetah. He lives in New York City.

Bird Fact Friday — the Great Black-Backed Gull

Adapted from page 155 & 158 of Gulls Simplified:

This very large, menacing-looking gull (it truly is the largest gull in the world) has a big, squarish or oval-shaped head and a heavy bill. This barrel-chested gull is typically noticeably larger and always chestier than Herring Gull, with a larger, broader head, thicker neck, and distinctly heavier bill. Dull pink legs are long, thick, and set at midspan, accentuating the bird’s barrel-chested appearance.

Adults have a dark charcoal to black back and a white head, while immature birds are spangled or granite patterned with gray, white, and black upperparts and a white head. This contrasting pattern stands out among the brownish-gray immatures and gray-backed adult ranks of Herring Gulls.

Great Black-backed is a fairly sedentary gull, spending much of its time loafing on the beach, resting on the water, or standing atop an elevated post or light fixture. It walks somewhat reluctantly, with a waddling sailor’s gait. This species generally dominates other gulls when food is available and frequently displaces other gulls from prime perches. It is often found with other large, white-headed Gulls, especially Herring Gulls. Much smaller Ring-billed Gulls go out of their way to avoid any interaction with this species.

Great Black-backed Gull is typically the largest and huskiest gull on the Atlantic
beachfront or Great Lakes shorelines, or anywhere else it is found, since it is the largest gull in the world. Photo credit: Kevin Carlson

A consummate kleptoparasite (stealer of another’s food), Great Black-backed often robs cormorants, other gulls, and seabirds of fish and other food items. This species is also highly predatory. It is known to harass diving birds, such as coots (which can’t stay underwater very long), to exhaustion and then grasp the debilitated bird by the head, killing it outright or, failing that, drowning its victim. Kevin [Karlson, co-author of Gulls Simplified] once saw an adult Great Black-backed kill and swallow whole a Northern Flicker that had been sitting exhausted on a beach in New York during fall migration.

This is a fairly common gull that is typically found on Atlantic coast beaches, where it is a resident species, as well as on the Great Lakes, where it is also resident and increasing in numbers. Lesser numbers are found south to Florida (mostly on the Atlantic coast), where it is also increasing.

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull

 

Bird Fact Friday — Western Gulls

Adapted from pages 143-146 of Gulls Simplified:

A large gull with an overall stocky, robust profile, Western Gull is about the same size as Herring and Glaucouswinged Gulls, but adults show a darker, charcoal-gray back. The large head supports a stout, bulbous-tipped bill (smaller and straighter on some birds) and a curious bump or peak on the head (just above the eye, or sometimes above the nape)  that makes the head of Western Gull more convex (rounded) than the overall thinner head and drawn-out face of Herring Gull. The bill of Western typically appears thicker, shorter, and more bulbous tipped compared to Glaucous-winged’s longer, straighter bill, with the exception of some smaller Westerns that have slender bills. Standing birds with neck retracted often appear to slouch. When birds are standing, wing tips extend well beyond the tail and are often elevated, leaving a slight gap between wings and tail.

Western mixes freely with other gulls, especially Glaucous winged, and is often found where humans concentrate. It feeds primarily by scavenging over ocean waters for marine invertebrates. Its large size and bulky profile result in dominance over most gulls in its range. A Western Gull standing atop some elevated point on an ocean pier is a typical and iconic image. In the wave zone, it typically forages alone. 

Western and Ring-billed Gulls, adult. Photo credit: Kevin Karlson.

Two subspecies exist in Western Gull, with subspecies occidentalis occurring in northern California and farther north, and subspecies wymani occurring in southern California and farther south. Southern-breeding birds have a slightly darker back than northern ones, but recognition of this shading difference requires a good amount of study and exposure to both, and birds in the broad overlap zone show intermediate gray shading.

A common and highly coastal West Coast gull, the default dark-backed gull of the West Coast. Breeding range is from the central Washington State coastal zone south to the coastal zone of the central Baja California Peninsula, Mexico. Winter range includes the breeding range and smaller areas north to the Canadian border and south to the southern tip of Baja, as well as the northern Gulf of California.

In winter on California beaches, Western is typically the most numerous gull species. If you are standing on a California beach and you are looking at a large, dark-backed gull, STOP; you are most likely looking at an adult or 3rd winter Western Gull. Western Gull also frequents landfills, harbors, lakes, and rivers. No other large, charcoal gray–backed gull typically occurs within its range along the Pacific coast.

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull

 

Bird Fact Friday — Mew Gull

Adapted from pages 112, 115 of Gulls Simplified:

Mew Gull is a medium-small, nimble, somewhat elegant gull with a refreshingly uncomplicated plumage pattern. Physical profile is horizontal, somewhat tern-like, with a short neck, round head, and petite bill. Ring-billed and California Gulls have longer, blunter, and more classically hooktipped bills.

As our smallest “white-headed gull,” Mew Gull is most commonly confused with the larger Ring-billed Gull but is more delicately proportioned, with a rounder head and a more slender, pointy, thrush-like bill. Dusky eyes on Mew Gull impart a gentle expression (although some individuals have paler, amber-colored eyes). Darker primaries extend well beyond the tail and are often slightly elevated. Observers may find structural commonality between this species and kittiwakes (mostly pelagic gulls).

This classic adult breeding Mew Gull shows an unmarked yellow bill, yellowish legs, and a dusky eye with a red orbital ring. Photo credit: Kevin Karlson.

Mew Gulls are very social and are often seen loafing on beaches or foraging together. They use several foraging techniques: fluttering low and slow over water with their head turned down and legs dangling; sitting high on the water and swimming buoyantly while turning in the manner of a feeding phalarope; or swimming hard against the current, snapping up edibles as they pass. Loafing birds tend to cluster, sometimes near Ring-billed and California Gulls, but in general they avoid larger species. On land they forage by walking and sometimes catch insects in flight.

Common far-northern breeder from Alaska east to upper western Canada, and a common winter visitor along the West Coast from Washington south to the upper Baja California coastline, but rare elsewhere. Mew Gull occurs year-round in lower coastal Alaska.

In winter, Mew is usually found in nearshore ocean waters, often foraging over kelp beds, and it occurs inland in several locations where it follows large rivers. It also frequents inlet estuaries, sewage outflows, and treatment facilities. Inland it visits short-grass pastures, plowed fields, and sewage treatment ponds, but less typically landfills. Mew Gull also inhabits cities and towns, such as Anchorage, Alaska, where it sits on buildings and forages for scraps of human food in streets and parks. While this species feeds primarily on natural food sources in winter, it occasionally mobs humans for handouts near breeding sites in Alaskan cities when people foolishly take out a few morsels of food to feed the cute gulls nearby.

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull

 

Bird Fact Friday — Sabine’s Gull

Adapted from pages 69-70 of Gulls Simplified:

A small, trim gull that is smaller than a kittiwake or Mew Gull and most commonly seen in flight over ocean waters (less commonly found sitting on beaches with similarly sized gulls). In flight, Sabine’s appears short bodied, with broadbased, angular wings and a fairly long, uniquely forked tail. 

The bold tricolored upper wing pattern (black, white, and gray) is somewhat similar to that of other species but is distinctly bolder on Sabine’s and thus more visually grabbing. Stiff, shallow, steady wing beats reveal flashes of the bird’s wedge-like white wing patch. Flight is overall lofting and buoyant, but not as nimble or tern-like as that of Bonaparte’s Gull.

Sabine’s forages mostly by swimming and snatching prey from the surface of the water while at sea, and it feeds in shallow pools at breeding sites by stirring up aquatic invertebrates by stomping the substrate with its feet (see Sabine’s Gull 1). It does not respond to chum as readily as kittiwakes on pelagic birding trips. It also hovers and plucks prey from the surface. When foraging on beaches, Sabine’s walks nimbly.

This small, smart-looking, Arctic-breeding gull with a deep charcoal hood going blacker at the collar and front of the face is unique. Photo credit: Kevin Karlson.

In migration, birds resting on the water gather in tight (typically small) clusters. Sabine’s is fairly tame while on the water, allowing close approach by boats before flushing. On West Coast pelagic trips, Sabine’s Gulls are usually seen in small groups. In the interior, single birds are the norm, and these may mix with Bonaparte’s Gulls.

This localized Arctic breeder is fairly common during migration in fall, primarily in offshore northern to central Pacific coastal North American waters; very rare along East Coast in fall. Winter records are extremely rare in North America, with only a few instances of birds remaining until January. Subadult (1st winter) birds typically remain in southern waters until their 2nd year. 

This handsome, mostly pelagic gull breeds in Arctic and subarctic regions but winters in tropical seas off western South America and southern Africa. In North America, it breeds in coastal tundra of western Alaska, the North Slope, and islands of the Canadian Arctic Archipelago, which are far from most human population centers. It also breeds in northern and central Greenland.

There are numerous records of Sabine’s Gulls in the North American interior, mostly in fall, and regular records in the Great Plains and Great Basin regions (Gulls of the Americas, Howell and Dunn, 2007). Fall migration is from late July through October; spring migration is from March through May (occasionally into June).

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull