Author Archives: Wayne Petersen

About Wayne Petersen

Wayne Petersen is Mass Audubon's Director of Important Bird Areas Program.

Celebrating 30 Years of the Massachusetts Endangered Species Act

Conservation success stories rest on a bedrock of strong environmental laws. Many of Massachusetts’ most notable species recoveries, from the resurgence of Peregrine Falcons in cities to Bald Eagles populations’ dramatic turnaround, are grounded in the legal provisions of the Massachusetts Endangered Species Act (MESA).

MESA provides robust protections for over 400 local, rare, and declining species. With the chaos of 2020 disappearing in the rearview mirror, this is also a time to reflect on and celebrate positive achievements from past years. To mark the 30th anniversary of MESA, passed in December of 1990, take a moment to learn about the history of this sweeping and ever-relevant legislation.

Laying the Groundwork

Conservation laws in Massachusetts date back to 1818, when the state passed the first bill to protect songbirds from sport and food hunting, and by 1855 a broader act was instituted that protected all “nongame” birds.  By the end of the Civil War in 1865, the genesis of today’s Massachusetts Division of Fisheries and Wildlife came about with the establishment of a two-person commission “to investigate the obstructions to the passage of fish in the Connecticut and Merrimack Rivers.”  By 1886 this grassroots political conservation effort became known as the Commission on Fisheries and Game. 

As this incipient conservation machinery continued to evolve, by 1908 Edward Howe Forbush was appointed as the Commonwealth’s first State Ornithologist.  After Mass Audubon’s Founding Mothers spearheaded the national Migratory Bird Treaty Act in 1918, the state was spurred to create the Massachusetts Department of Natural Resources. Embedded within this department, the Division of Fisheries and Game was essentially charged with conserving and managing the Commonwealth’s diversity of wildlife, plants, and habitats for the benefit of Massachusetts residents.

Conservation is a Team Effort

Through the years environmental legislation gradually grew stronger, and by 1973 the federal Endangered Species Act was passed.  This landmark legislation soon saw The Nature Conservancy (TNC) develop a network of natural heritage programs across the country that would eventually oversee state level stewardship for all elements of biodiversity, including plants, animals, and natural communities. In 1978 Massachusetts became the fourth state to formally establish a Natural Heritage Program, which by 1983 had morphed into today’s Natural Heritage and Endangered Species Program (NHESP).  By 1990, Massachusetts Governor Michael Dukakis signed the Massachusetts Endangered Species Act into law, designating species as Endangered, Threatened, or Special Concern, and providing legal protections for each status.

Since then, Mass Audubon has played a key role in partnering with the state to protect the Commonwealth’s most imperiled (“state-listed”) animals and plants through the efforts of the NHESP.  Examples include such rare species as North Atlantic Right Whale, American Bittern, Red-bellied Cooter, Marbled Salamander, Northern Redbelly Dace, Early Hairstreak, Yellow Lady’s-slipper. Massachusetts publishes a complete list of state-listed species online. In other cases the NHESP’s Habitat Management Program focuses its conservation efforts on threatened habitats (e.g., vernal pools, pine barrens, sandplain grasslands, and calcareous fens).

As we enter 2021, the conservation efforts driven by the NHESP and MESA continue apace. For more information about the history of the Massachusetts Natural Heritage and Endangered Species Program and the Massachusetts Endangered Species Act, check out the November issue of Massachusetts Wildlife magazine, or visit the Fish and Wildlife Service homepage for MESA’s 30th anniversary.

The Saga of the “Robin Snipe”—An Artful Overview of an Atlantic Flyway Tragedy

The Red Knot (Calidris canutus) is a shorebird, roughly the size of an American Robin, and similarly colored in spring, with rusty red underparts and a ruddy brownish back sprinkled with black and calico. This species’ legacy has been punctuated by eras of superabundance, intense market hunting persecution, habitat disruption, and most recently anthropogenic events that have nearly brought the Atlantic flyway population to its knees. Favored sandy beaches on the South Shore of Cape Cod Bay and outer Cape Cod in Massachusetts have for many decades hosted great numbers of “Robin Snipes” (so-called by early market gunners) during their autumn migration en route to the far reaches of southern South America for the winter. And it was on these same Bay State beaches that the Atlantic population of knots was mercilessly persecuted from July-October during much of the 19th and early 20th century. 

Red Knot (Photo by A Grigorenko)

Fast forward to the last half of the 20th century when the ornithological community, initially in the Mid-Atlantic Coast region, began systematically registering measurable declines in the vast numbers of knots that once stopped on Massachusetts shores during autumn migration and on the shores of Delaware Bay in May. These early warnings presaged what was to become one of the most precipitous declines in modern shorebird history. The sad and well-documented chronicle of the near collapse of the eastern North American Red Knot population is one of the most dramatic sagas in modern-day bird conservation.

The pathos and intimate details of this ongoing conservation drama have recently been eloquently presented in Orion magazine by author and Audubon A awardee Deborah Cramer and artist Janet Essley. To explore the details of this fascinating story, follow this link >

The Cardinal Chimaera: half male plumage, half female

Chimaera Northern Cardinal in Erie, PA (Photo by Shirley Caldwell)

Sometimes Nature offers up anomalies that seemingly defy credibility. Such was the case when a striking Northern Cardinal showed up recently at a backyard bird feeder in Erie, Pennsylvania. In appearance the cardinal appeared to have the typical red plumage of a male on its right side, and the light buffy-brown plumage of a female on the left side. So what’s the deal, you may ask?

This remarkable cardinal isn’t quite as unusual as you might suppose. It is actually a classic example of a chimaera—also known as a bilateral gynandromorph. So what does this mean in everyday-speak? A little review of Biology 101 reminds us that in humans, males have one copy of each sex chromosome (i.e. X and Y) while females have two copies of the X sex chromosome. In birds, this scheme is a little different in that in birds the sex chromosomes are referred to as Z and W, and it’s females that carry a single copy of the ZW chromosome, while males on the other hand have two of the ZZ chromosomes. Accordingly the cell nuclei of avian reproductive cells normally would possess only Z-carrying sperm cells in males, or Z or W-carrying egg cells in females.

Very rarely however, individuals occur where a female egg cell develops two nuclei — one with a Z sex chromosome and one with a W sex chromosome—and then gets fertilized twice by two Z-carrying male sperm cells. Clearly the odds of this happening are very low, but when it occurs, literally half of the double-fertilized product offspring will exhibit one set of gender characteristics while the other half will exhibit characteristics of the other gender. In the present instance, the right half of the Pennsylvania cardinal is exhibiting male features and the left side the features of a female. An ultramicroscopic examination of cells from the male half of this cardinal would reveal that it has a ZZ chromosome makeup, while cells from the female half would have a ZW makeup.

As if the circumstances described above are not improbable enough, the fact that the female (or left half) of the Pennsylvania cardinal has to be carrying both Z and W sex chromosomes, it’s actually possible that the bird could become fertilized since in birds, only the left ovary is functional! And the most exciting news of all is that the Erie cardinal is currently keeping company with a normal male Northern Cardinal, and local ornithologists are carefully tracking the chimera to see if it successfully breeds and lays eggs. So stay tuned for what could prove to be another chapter of this remarkable circumstance.

In conclusion it should be pointed out that such genetic reproductive anomalies may not actually be as infrequent as they might seem, since unless a species is strongly sexually dimorphic (i.e., males and females with highly different-looking plumages), bilateral gynandromorphism may not be as readily detectable as it is in cardinals. As an example, check out the “half-sider” images of a Rose-breasted Grosbeak that briefly attended a Newbury, MA feeder in 2015. For a full account of this individual, see Bird Observer (Vol. 43, No. 5, 2015).  Additionally, bilateral gynandromorphism is not uncommon in certain insects, fish, and even rarely in mammals. So if nothing else, not only have you possibly learned some new scrabble words, you may also now know to be particularly careful when you think you’re seeing double!

“Half-sider” Rose-breasted Grosbeak spotted in Newbury, MA in 2015 (Photo by Peter Brown)

Note: This post has been updated to remove an anachronism.

The Greatest Black Hawk: An epic journey recounted

Great Black Hawk by John Harrison

Black hawks are hefty, Buteo-like hawks not too distantly related to the widespread and familiar Red-tailed Hawk (Buteo jamaicensis). There are several species, but most common are the Common Black Hawk (Buteogallus anthracinus) that sparingly nests in the extreme southern portions of the southwestern U.S. south to northern South America, and the Great Black Hawk (Buteogallus urubitinga) that primarily breeds from coastal Mexico south through tropical South America. Both species feed on a variety of creatures including reptiles, amphibians, crayfish, crabs, small mammals, and occasionally even birds.  Both black hawks are relatively sedentary and neither species is a long-distance migrant.

With this information in mind, it understandably came as a mind-blowing surprise to several ecstatic birders who saw and definitively photographed for 20 minutes a juvenile Great Black Hawk on South Padre Island on the coast of Texas, April 24, 2018.  But this is only the beginning of a saga! 

Fast forward to August 6 in Biddeford, ME, where the same individual Great Black Hawk was again definitively photographed and the images were matched exactly to the April sighting in Texas.  The hawk lingered in Biddeford until August 9 before once again disappearing, this time until October 29, when it showed up in Portland, ME! Only this time the elusive tropical raptor only stayed under cover until November 28 when it appeared in a different part of the city only two miles away.

Virtually as I write, this itinerant tropical raptor is still present in the vicinity of Deering Oaks Park, just west of downtown Portland where it has become headline news and is happily feeding on the plethora of gray squirrels inhabiting the urban park.  What will be its ultimate fate when the snow flies and the inevitable cold becomes extreme may never be known….but for now, this has to be the Greatest Black Hawk of them all!

Licorice In The Sky: A seasonal gathering of crows

Crows © Craig Gibson

An annual late autumn phenomenon in New England is the spectacular crepuscular gathering of American Crows into large nocturnal communal roosts. Felt by many to be large, raucous, and often pesky, crows in fact are intelligent, crafty, and creative survivors in a world heavily populated with humanity.  A crow aficionado ever since kidnapping a baby American Crow from a nest for a pet in my boyhood (don’t try that at home), I have been fascinated by crows.  Their myriad vocalizations, their ability to count at least to three, to eat practically anything, and to survive seemingly everywhere are collectively worthy attributes. But to fully appreciate the magnificence of crows in all their glory is to observe them at a winter roost.

To dispel the erroneous perception that American Crows are sedentary residents in Massachusetts throughout the year is to visit any of the leading autumn hawk watching sites in Massachusetts from late September to early November. As autumn’s foliage is acquiring its brilliance and then falling, small groups of crows daily stream southward from northern New England and eastern Canada, some following ridge lines and valleys, others the course of major river ways or the seacoast. As fall transitions to winter these northern migrants join more southerly resident crows every evening to form what are often aggregations of many thousands of individuals.  Wherever these nightly roosts happen to be, the late afternoon and nightly behavior of the crows within the roosts is a matter of considerable interest to the careful and dedicated watcher.  And there are lots of unanswered questions surrounding these winter roosts.

For example one might assume that every evening crows from far and wide simply fly directly to a communal roost site for the night, or that in the morning the crows utilizing a roost might routinely head for the same daytime foraging areas.  Not only are these assumptions untrue, they also offer insight into the mysteries of crow behavior.  Normally relatively solitary during the mid-spring nesting season, by mid-summer crows become increasingly gregarious, and by winter they have gathered into large roosts that may contain many thousands of individuals from great distances away.

© Craig Gibson

The behavior of crows near these evening roosts is particularly curious, if not mercurial.  For instance, from night to night crows approaching a roost will regularly make several pre-roosting stops (called staging areas), sometimes more than a mile from the final roost site.  These short stops are generally accompanied by much raucous vocalizing, before the birds present often suddenly depart and head off to another staging site where this behavior is then repeated.  This may occur several times before dark within a several mile diameter area of the final roost, and the staging areas may change location from day to day.

Finally, during deep dusk or shortly after dark, most of the birds in these staging areas will make a last and often silent flight to the ultimate roost site.  Surprisingly for birds as timid and wary as crows normally are during the day, at these nighttime roosts the birds often perched on bare, leafless deciduous tree branches where it is sometimes possible to literally walk under roost tree without disturbing them – something that would be virtually impossible during the day.

American Crow © Craig Gibson

Undoubtedly a number of important functions occur in these enormous winter roosts.  One is the opportunity for crows in a winter roost to “meet other crows.”  Since crows do not breed in their first year after nesting, these roosts may serve as “dating bars” for un-mated immature crows to meet at the winter roost, then eventually breed for the first time in the spring with mates established in the winter roost.  Similarly, first-year immature crows probably learn what it truly means to be a crow in a winter roost.  They likely acquire important winter foraging skills, learn how to avoid predators and other related dangers, and how to modify the many nuances of complex crow vocabulary.  While seemingly speculative, there is also good evidence to reinforce and support these concepts.

To best appreciate some of the spectacular mysteries described above, currently there are few better places in eastern Massachusetts to experience them firsthand than a huge, well established American Crow and Fish Crow roost located in the city of Lawrence.  This Lawrence roost has been well described in a previous Distraction Display post.

So to appreciate one of winter’s most impressive avian spectacles, try spending a late afternoon in the months ahead near the New Balance building in downtown Lawrence adjacent to the Merrimack River and behold the sight of Licorice in the Sky for yourself.


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Remembering Kathleen S. (Betty) Anderson: June 15, 1923–August 24, 2018

Betty Anderson receives Mass Wildlife’s Sargent Award on September 10, 2007. Photograph by W. Petersen.

The conservation and ornithological communities of the Commonwealth of Massachusetts—along with the countless lives that Kathleen (Betty) Anderson touched—have sadly lost one of the Great Ones.

Betty, as she was known among her friends and colleagues, originally hailed from Montana, the state she often considered her “real home.” Regardless, she spent most of her adult life living with her beloved husband, Paul, and raising two children in Carver and East Middleboro. In the 65 years she lived at Wolf Trap Hill Farm, Middleboro, Betty “kept track of every living critter [she] could identify…not just birds but also mammals, amphibians, reptiles, insects, and plants.” (Bird Observer, February 2016). Her love and stewardship of the natural world radiated outward from the farm to the rest of Massachusetts as she taught and advocated on behalf of the environment, inspiring other people in all of her endeavors.

I want to paraphrase part of the speech Betty made upon receiving one of Mass Audubon’s most prestigious awards, the Allen H. Morgan Award, in 2009:

“From the day in late October 1949 when I first came upon a group of Mass Audubon birders at the Lakeville Ponds, this organization has enriched my life in so many ways. Foremost, always, the friends I’ve made who share my interests and my concerns. But also the events, the publications, and the incentives for providing active participation in environmental issues.”

Betty Anderson claimed that her 60 years as a Mass Audubon member offered a continuous learning and enriching experience, along with ongoing opportunities to contribute to various projects where she always felt she learned more than she produced.

Here I have to disagree. Betty Anderson gave so much of her knowledge, her friendship, and herself to so many people for so many years, that her greatest legacy will forever be her love of other people and her own incalculable ability to enthuse, enlighten, educate, and motivate others to become the best that they can be. And I’m confident that there are legions of ornithologists and conservationists throughout the country who learned from what she produced, which will long withstand the test of time.

What Betty Anderson produced throughout her life is truly remarkable.

Always curious and ever-intrepid, Betty began her professional ornithological career in 1957, working with the Massachusetts Department of Public Health’s Encephalitis Field Station in Lakeville, whereshe was employed trapping, banding, and bleeding birds in cedar swamps in Raynham as part of early research on Eastern Equine Encephalitis. When her two children were young, Betty became a Mass Audubon teacher where weekly she introduced hundreds of young children to birds and natural history in school systems in southeastern Massachusetts.

By the 1960s, Betty’s enthusiasm for research and birdbanding led to her establishment of an Operation Recovery banding station on Duxbury Beach. Betty’s active involvement with this cooperative banding project—coordinated by Chandler Robbins, James Baird, and other active banders of the day—and her long-standing friendship with John and Rosalie Fiske—whose summer home was in Manomet—ultimately led to the establishment of the Manomet Bird Observatory (now called Manomet, Inc.). She was the founding director from 1969–1983.

As Betty’s reputation and expertise in conservation-related activities broadened, her influence and experience similarly grew. In 1973, she became a founding trustee of the Plymouth County Wildlands Trust (now the Wildlands Trust). From 1981–2018, she began a continuous run as a member and eventually chair of the Massachusetts Natural Heritage and Endangered Species Program’s Advisory Committee. Betty received the prestigious Governor Francis W. Sargent Award from the Massachusetts Division of Fisheries and Wildlife in 2007.

While her many honors and tributes are legend, several of the most notable are: being among the first women elected to membership in the Nuttall Ornithological Club in 1974 and being one of only two women to serve as president of that Club in 1987; receiving the Cornell Lab of Ornithology’s Arthur A. Allen Award in 1984; being elected a Fellow of the American Ornithologists’ Union in 2005; and her service on the boards of Mass Audubon, Hawk Mountain Sanctuary, the New England Wildflower Society, the North American Loon Fund, and the American Birding Association.

Throughout her career Betty authored more than 50 professional papers and published numerous popular articles in journals and magazines. However, her personal journals documenting and detailing indications of climate change as a result of 50 years of continuous observation of events on Wolf Trap Hill Farm, her 100-acre property in Middleboro, may be among her most valuable professional and valuable contributions.

The beacon that was Betty’s life for me was a brilliant beam that significantly shaped my life and career. May her rich legacy live on forever, and the lessons that she taught me always remain a beacon for others to follow.

Reprinted with permission from Bird Observer 2018,  Volume 46, Number 5.

Wildlife and Birding in Yellowstone and Grand Teton National Parks

© David Parish

While it’s true that Mass Audubon regularly sponsors outstanding wildlife and birding trips to exotic corners of the planet, the Natural History Travel Program also features domestic departures that rival some of the finest wildlife spectacles on the planet.  One of these is the Greater Yellowstone Ecosystem—a region covering approximately 34,375 square miles in the northwestern corner of Wyoming, but also extending into Idaho and Montana.  Comprised of more than 2.2 million acres, this scenically magnificent region with an elevation averaging over 7500’ hosts the largest concentration of wildlife in the United States outside of Alaska, including the largest free-ranging herd of American Bison in the world, one of the largest American Elk herds in North America, and one of very few Grizzly Bear populations in the contiguous United States.  And thanks to a repatriation effort in the mid-1990s, Yellowstone supports 11 packs of Gray Wolves numbering approximately 110 individuals.

Bison © David Parish

From June 12-22, Mass Audubon President, Gary Clayton and Important Bird Areas Director, Wayne Petersen were able to share 21 species of mammals and 133 species of birds with an appreciative and congenial group of colleagues and clients in this extravagantly beautiful region.  Among the trip’s highlights was a wolf pack trying (in vain) to take down a young Pronghorn, baby bison practically at every turn, a Golden Eagle at its nest, a Dipper feeding and teaching a young one how to swim and dive, a fine variety of waterfowl including several pairs of rare Trumpeter Swans, and hosts of colorful wildflowers.  In addition, the food was hearty and fine throughout, the weather was variable but comfortable, and canoodling Grizzly Bears and Moose and Black Bears with young were consistently voted as favorites.  One of the most intact temperate zone ecosystems in the world, the Yellowstone is a region like few others and is destination that every American should see at least once in their life!

Pronghorn © David Parish

The Warbler Connection: Bay-breasts and Budworms

Bay-breasted Warbler © Ian Davies

Massachusetts birders this spring were thrilled by the exceptional numbers of Bay-breasted Warblers present during the May migration. Joining these inflated Bay-breast numbers were also above average numbers of Cape May and Tennessee warblers.  Was this a coincidence? Probably not.  The key to their local abundance this spring probably lies in the fact that these boreal forest breeders are “spruce budworm specialists”.

The spruce budworm (Choristoneura fumiferana) is a small boreal forest moth whose larvae periodically undergo population explosions capable of destroying huge acreages of spruce/fir forest in Canada and beyond.  Under normal circumstances, boreal forest breeding birds such as the “spruce budworm specialists” mentioned above, are major predators of spruce budworm caterpillars.  When budworm populations periodically get out of control, the numbers of these budworm-eating warblers increase substantially wherever the irruption is taking place.  When a superabundance of food exists, the warblers lay more eggs and successfully raise more young than in normal years, and often do so for several years in succession, or as long as the budworm outbreak persists.

Spruce Budworm © Jerald E. Dewey, USDA Forest Service

These “boom and bust” population cycles are similar to what periodically happens to lemmings in the Arctic, or to certain species of forage fish in the ocean (e.g., sand lance or menhaden).  When these overabundances of food exist, certain predators are capable of maximizing either their reproductive output or their local abundance.  Often the phenomenon causing a detectable local abundance is far removed from the actual cause of the event.  Classic examples detectable in the Bay State are the recent major Snowy Owl irruptions of the winters of 2013-14 and 2017-18, and the menhaden/Great Shearwater event in Provincetown during the late summer of 2017.  In the case of Snowy Owls, the lemming events responsible for the Snowy Owl irruptions into Massachusetts were far north in the Arctic, not locally in Massachusetts.  However in the instance of the menhaden event, the factors leading to the Provincetown disaster were far more local and took place in Massachusetts’ nearshore waters.

To put the Bay-breasted Warbler event into an extravagant perspective, consider a third event that took place on May 28, 2018, on the north shore of the Saint Lawrence River near Tadoussac, Quebec.  On this date six highly experienced observers tallied an estimated 144,324 Bay-breasted Warblers, 108,243 Cape May Warblers, and 72,162 Tennessee Warblers in nine hours!  Partly responsible for these unprecedented and extraordinary one-day totals was a combination of weather events that created a “perfect migration storm”—the full details of which lie beyond the bounds of the current story.

Cape May Warbler © Ian Davies

More to the point, however, these massive and unprecedented numbers of “spruce budworm specialists” were part of what are almost certainly inflated populations of these species bound for budworm-besieged areas of boreal forest.  What Massachusetts observers enjoyed this spring was clearly only a tip of a much larger iceberg whose full extent has likely been building slowly for several past breeding seasons but wasn’t fully revealed until May 28 at Tadoussac, Quebec!

Long Legs and Filmy Filigree: A Visit to Kettle Island

Colonial-nesting waterbirds are always fascinating, and because so many species nest on remote or hard-to-get-to islands, a visit to a colony typically represents an adventure.  And so it was when six intrepid staff members and volunteer bird counters visited Mass Audubon’s Kettle Island (a Massachusetts Important Bird Area) off the coast of Manchester-by-the-Sea last week.  A 17 acre uninhabited rocky island approximately a mile offshore, much of the island is vegetated with a dense cover of low trees, shrubs, thorns, and copious amounts of poison ivy. One can view the island’s birdlife from a boat, but landing is prohibited in order not to disturb this important colonial waterbird nesting site.

Kettle Island bird team ©Craig Gibson

The purpose of the island visit was to census and survey the breeding long-legged wading birds that have nested on the island for several decades.  The visit was part of a survey project initiated last year to assess the overall status and ecology of a number of islands off the Essex County coast, and also part of a greater coastal waterbird survey being jointly conducted by the U.S. Fish & Wildlife Service and Mass Wildlife.  One of the largest colonies in the Commonwealth, Kettle Island currently hosts Great Egrets (194 pairs), Snowy Egrets (99 pairs), Little Blue Herons (4 pairs), Black-crowned Night-Herons (30 pairs), and Glossy Ibises (9 pairs).  In addition, the island sanctuary is currently home to 2 pairs of American Oystercatchers, 51 pairs of Herring Gulls, and 79 pairs of Great Black-backed Gulls.

Little Blue Heron ©Craig Gibson

One of the magical aspects of visiting a breeding island at this season is seeing some of our most spectacular breeding species in their full breeding plumage—plumages that brought many species virtually to their knees in the heyday of the millinery trade during the late 1800s and early 1900s when their feathery filigree was central to the egregious fashion industry of the day.  Not only did the excesses of this worldwide feather lust bring the founding mothers of Mass Audubon to rise up in outrage in 1896, but it was this same excessive slaughter of egrets, herons, and other birds that ultimately led to the establishment of the Migratory Bird Treaty Act 100 years ago this year.

Great Egrets ©Craig Gibson

Thanks to these two historic conservation milestones, today bird watchers, photographers, artists, and everyone who enjoys beautiful living things is able to see these handsome species seasonally inhabiting the coastlines and salt marshes of Massachusetts when they are not nesting on their remote island colonies.

Great Egret chicks ©Craig Gibson

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Why does the official Bird-a-thon checklist change over time?

In a word: Genetics. 

Bird names are not set in stone. Just ask the Rock Pigeon (formerly the Rock Dove). Depending on your birding experience, you may recognize other examples of species name changes: Thayer’s Gull to Iceland Gull, Rufous-sided Towhee to Eastern Towhee, and Northern Oriole to Baltimore Oriole.

Eastern Towhee used to be considered a subspecies of Rufous-sided. (Photo by Will Freedberg)

Some names change once, only to change again. For instance, the Black Scoter was formerly the Common Scoter, and the American Scoter before that. Perhaps the most complicated name changes come from the splitting of one species into two or three different species. Traill’s Flycatcher, for example, became Willow Flycatcher and Alder Flycatcher.

Just to make sure everyone is thoroughly confused, the ordering of species on avian lists is fluid as well: falcons used to be found with the hawks before they were evicted from the group, and Snow Buntings, which were once found near the finches, are now cozied up with the warblers.

The Rhyme and Reason

While these changes may seem arbitrary or like part of a nefarious arrangement between field guide publishers and the ornithological establishment, neither is the case. There are science-based reasons for periodic changes in bird names and in the ordering of species on avian checklists. Until the 1990s, birds were grouped and classified solely by the way they looked and behaved. Today, it is the genetic makeup, or genome, of a species that is considered more important in determining its origins and its relationship to other living birds.

As genetic relationships become more fully understood, it sometimes turns out that two different-looking “species” are not genetically distinct, or that populations of another “species” are in fact distantly related.  These revisions to bird classification are the most common reason for renaming. For instance, genetic (and other) research has determined that Eastern Towhees and Spotted Towhees represent a distinct pair of species, while the Solitary Vireo has actually been proven to represent three species masquerading as one (Blue-headed Vireo, Plumbeous Vireo, and Cassin’s Vireo)!

Behind the Curtain

Maintaining these changes is the responsibility of The American Ornithologists’ Union Committee on Classification and Nomenclature. The ornithologists comprising this checklist committee (the NACC) keep abreast of the classification and distribution of all the birds in North and Middle America in order to created standardized classification and nomenclature.

The NACC regularly produces supplemental changes to the latest edition of the Check-list of North American Birds. These are responsible for the periodic name and sequence changes Bird-a-thon birders will see on the event’s official checklist.

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