Our knowledge of birds is daunting. Professional and amateur ornithologists have amassed a huge body of knowledge on our feathered friends. There is clearly a need for summary publications or avian encyclopedias to make this information accessible.
Efforts to review our knowledge of groups of birds goes back over a century. In 1910, the ornithologist Arthur Cleveland Bent received a request from the Smithsonian Institution to write species-by-species accounts of North American birds to serve as a repository for current knowledge. This project dominated the last 44 years of his life.
The entire series includes 23 volumes with summaries of published information as well as Bent’s own prodigious observations. The series began in 1919 with the diving birds and concluded in 1968 with the last of the songbirds. Bent passed away in 1954 so the final two contributions were finished by collaborators and published posthumously. What a landmark for North American ornithology.
Knowledge of North American birds continued to grow at an accelerating rate and, like any scientific publication, Bent’s work became dated.
To provide a more current summary, the American Ornithologists Union in collaboration with ornithologists at the Academy of Natural Sciences in Philadelphia began The Birds of North America (BNA) project. Between 1992 and 2003, 716 accounts of North American bird species were published. Each account was written by one or more ornithologists with research experience in particular species. A total of 863 ornithologists, including yours truly, contributed.
Each account follows a particular format, summarizing such topics as morphology, range, foraging behavior and diet, nesting and population dynamics. Citations to the original articles cited in the account are provided.
In 2004, the Cornell Laboratory of Ornithology (CLO) provided an on-line version of the BNA accounts. The conversion to digital format has two big advantages. One is that each account can be updated to reflect current knowledge. Second, links to videos and sound files can be included. Access to the on-line BNA is by paid subscription.
Cornell developed a similar resource, Neotropical Birds Online, to cover the birds of Central America and South America. The species accounts follow the BNA format.
The need for encyclopedic coverage of all the birds of the world has been met by the Handbook of the Birds of the World (HBW) project. This project consists of 16 large-format books, published between 1992 and 2013. A 17th volume on new species was added to the series.
Every bird species in the world is included. Each species is magnificently illustrated and many extraordinary photographs are included as well. Like the BNA accounts, text is provided to give our current knowledge of each species.
This project involved over 200 specialists as well as 35 illustrators and 834 photographers. The contributors hail from more than 40 countries.
Each volume is a joy to hold, read and admire. They are big books, weighing up to 10 pounds apiece. They are expensive with current prices around $150 per volume.
The HBW publishers saw the value of making the HBW accounts available on-line. In 2013, they launched HBW Alive. This web resource provides all of the species accounts presented in the hard-copy volumes. Like the digital BNA, HBW Alive is available by subscription.
The big ornithological news this month is that the online BNA and HBW resources have been combined to provide a one-stop repository for information on any bird species. The project is called Birds of the World (https://birdsoftheworld.org). The site is linked to the Macaulay Library at CLO where thousands of videos and sound recordings of the world’s birds are available to study.
Access to the Birds of the World site is by subscription at reasonable rates: $8 per month, $49 per year or $129 for three years. You might encourage your local library to inquire about institutional rates.
Particularly in this time of restricted travel, taking a virtual trip around the world to learn about the amazing birds on this planet is a joy. Give it a try!
Spurred on by comments and questions on the last post on the origins of bird names, I will continue with a variation on the theme. This week I will concentrate on bird names that are based on faulty observations. I am conflicted about these misleading names. The scientist in me cringes at some of these names but the poet in me is delighted.
Let’s start with the group of birds that include our Common Nighthawk and Eastern Whip-poor-will. These nocturnal birds are classified into an order often referred to as goat-suckers. What’s up with that?
We need to go back to the 18th century when the Swedish biologist, Carl Linnaeus, was working on a catalog of all living things. He came up with the modern classification system of nested groups (classes, orders, families, genera, species). He had museum specimens of the undescribed European nightjar, a close relative of our whip-poor-will.
Linnaeus was aware of reports that these nocturnal birds flew into barns at night to suckle female goats, essentially stealing milk from the nanny goat’s kids. Of course, we now know that this claim is a myth based on no verifiable evidence. Nevertheless, Linnaus unwittingly perpetuated the myth by assigning the nightjar to a new genus Caprimulgus that translates into English from the Latin as goat-sucker.
Scientific names are cast in stone so it is not possible to replace Caprimulgus with a less confusing genus name. But, we can change common names. Many ornithologists use nightjars as a name for this group of birds rather than goat-suckers. The loud song of a whip-poor-will after dark can certainly be a jarring experience for an unsuspecting person.
From October to December, Maine birders keep an eye out for rare geese among the thousands of migrating Canada Geese. One of those rarities is an Old-World species called the Barnacle Goose. We have six accepted records of this handsome goose from Maine.
How did the Barnacle Goose get is common name? The barnacles in this story are not the conical, acorn barnacles that are so abundant on rocky intertidal shores in Maine. Rather, the barnacles are stalked or goose-neck barnacles
These barnacles often attach to floating logs and so can be found far from land.
We attribute Gerald of Wales, a historian and church official in the 12th century, for perpetuating the myth that the stalked barnacles are baby Barnacle Geese that will slip their calcareous skeletons and become free-living Barnacle Geese. Versions of this myth had been kicking around for nearly a millennium so we can’t pin all the blame on Gerald.
This myth may have arisen because bird migration was not recognized as a feature of the biological calendar. The disappearance of Barnacle Geese and their subsequent return demanded an explanation. The alternation of a barnacle stage and a goose stage provided an adequate explanation for some folks in the Middle Ages and beyond.
Some European swallows were involved in a similar fanciful explanation because of the ignorance of migration. As swallows prepare to migrate, they often coalesce into large flocks, sometimes near bodies of water. Large numbers one day and then none the next. What could the explanation be? The myth is that they go underwater and spend the winter beneath the ice of lakes. Fortunately, this debunked explanation has not been perpetuated in either the scientific or common names of these birds.
A more recent observation explains the Evening Grosbeak’s name. In 1823, a Major Delafield, a United States Boundary Agent, noted that these birds approached his tent at twilight and began to vocalize loudly. He inferred that Evening Grosbeaks spend the day in dark retreats, only leaving them at the approach of night.
Of course, Evening Grosbeaks are active during the day and roost at night like most perching birds. Nevertheless, this misunderstanding lives on nearly 200 years later in the common name of this bird.
As a word lover, I find bird names to be an endless source of fascination. Some intriguing common names are folk names or regional names. For instance, bluebill, baldpate, log-cock, high-hole and rain crow are all species that occur in Maine.
Waldo McAtee, an avian etymologist, has been collecting such colloquial names of North American birds. His list now exceeds half a million common names for the roughly 800 species that occur regularly on our continent.
The difficulty with common names is that confusion may arise over the particular species in question. For instance, the colloquial name of log-cock for the Pileated Woodpecker could reasonably be used to describe a Ruffed Grouse.
Biologists avoid the uncertainty of common names by using the standardized scientific name which consists of a genus name and a species name. However, most birders don’t care to commit lots of Latin names to memory.
Fortunately, the Check-list Committee of the American Ornithologists’ Union published a list of standard common names in 1957. The checklist is periodically revised to reflect increasing knowledge of bird classification. The common names used in field guides are these standardized common names. Use of these names rather than colloquial names reduces confusion. It is also a lot easier to say you saw three Evening Grosbeaks rather than three Coccothraustes vespertinus!
Some standardized common names are descriptive and easily understood. For instance, woodpecker is a highly appropriate name for those birds which probe dead wood for insects. Flycatcher is another straightforward descriptive name.
Other names are more obscure but interesting in terms of their word origin. Cormorants are often seen along the seashore, major rivers and on larger lakes in our region. Cormorant comes from two Latin words: corvus , meaning crow and marinus, meaning marine. So, cormorant is another way of saying sea-crow. Cormorants have little in common with crows besides their black plumage but the derivation of the word is charming.
Loon is a term derived from the Shetland word loom or the Icelandic word lomr. Both words mean lame and aptly describe the awkward walking of loons on land.
Hooded and Common Mergansers are frequently seen on larger bodies of water in our area. Merganser comes from two Latin words: mergus, meaning diver and anser, meaning goose. A perfectly apt description of these birds.
Falcon comes from the Latin falx, meaning sickle. The powerful bill of a falcon certainly bears a functional similarity to a sickle.
Gull comes from the Latin gula, meaning throat. Just like a person who is gullible, a gull will swallow anything!
Color may be the basis of the common name of birds. The Northern Cardinal is named for the high church official who wears a bright red robe. The Northern Oriole’s name comes from the Middle Latin oriolus or the Latin aureolus, meaning golden.
The Eastern Kingbird is so named because of the small patch of red feathers on the top of its head that the male exposes when it is excited. The Ruby-crowned Kinglet is a much smaller bird but males have the same type of red crown as the kingbird.
We often say that birds chirp. This trait has given rise to at least two standardized common names. The American Pipit, a bird that breeds on Mt. Katahdin and may be found in our state in agricultural fields in the spring and fall, has a name derived from the Latin pipo, meaning to chirp. The Swedish word siska means a chirper and gives us the common name for the Pine Siskin.
Finally, some standardized names are based on the calls or songs of birds. Good examples of this type of common name are chickadee, whip-poor-will, cuckoo, curlew and towhee. The doleful call of the Mourning Dove gives this bird its name.
Lots of birders and ornithologists keep an eagle eye out in the summer for the annual supplement to the AOU Check-list of North American Birds. This check-list is maintained by a committee of distinguished ornithologists well-versed in avian taxonomy and morphology. These scientists constitute the North American Check-list Committee (NACC) of the American Ornithologists Society.
The charge of this committee is to evaluate recent changes in distribution of North American birds and research on variation in species. They then amend the list of common and scientific names of our birds based on this research. The committee also sets the order in which species are listed to reflect current understanding of the relatedness of different species. The NACC accepts proposals from anyone but proposals but must be strongly argued to receive NACC support.
Birders who are active list-keepers are keen to read the annual report because one’s life-list can be affected by NACC decisions. For instance, Thayer’s Gull was combined with Iceland Gull a few years ago, so many birders saw their life-lists decline by one species. But a split of Winter Wren into the eastern Winter Wren and the western Pacific Wren gave some birders an arm-chair life-bird.
This year’s report had little effect on North American life-lists. White-winged Scoter was split into three species but only one of those occurs in North America. The new species split off are called Velvet Scoter found in western and central Eurasia and Stejneger’s Scoter found in northeastern Eurasia and occasionally in Alaska. Our species remains the White-winged Scoter.
The only other change affecting Maine birds moving Tennessee Warbler, Nashville Warbler and some storm-petrels into a different genus and changing the check-list order of plovers, swallows and sparrows. A concise summary of the changes can be found at:
To me, some of the proposals that were not accepted were thought-provoking. One proposal advocated changing the common name of Salt Marsh Sparrow to Peterson’s Sparrow to honor the contributions to ornithology of Roger Tory Peterson. Accepting that proposal would set a new precedent. No bird has been described with petersoni as its species name. As well-meaning as this proposal might be, I am not surprised that it was rejected.
On the western plains, McCown’s Longspur is a common member of the New World sparrow family. It’s scientific name is Rhynchophanes mccownii. The species is named after Captain John Porter McCown of the U.S. Army. In 1851, McCown shot at a flock of Horned Larks and discovered he had killed a different bird as well as many larks. He gave the specimen to the ornithologist George Lawrence. Lawrence described the new species and named it after McCown. Note that McCown was not an ornithologist and collected the bird inadvertently. Nonetheless, the scientist who describes a new species has the right to attach a species name of her/his choice.
The person who sent a proposal to the NACC asked that McCown’s name be stripped from the common name. The reason is that McCown resigned his U.S. Army commission in 1861 and joined the Confederate army. The proposer argues that the American Ornithologist Society needs to promote the inclusion of diversity by not recognizing someone who promoted slavery. The NACC was not compelled to change the common name. Even if a new common name was assigned, the scientific name would have to remain mccownii.
Ted Floyd, the editor of Birding magazine, proposed a change in spelling for common names honoring people. His argument is that the possessive form of the name is grammatically peculiar and misleading. Cooper’s Hawk is not a hawk owned by Cooper. Floyd argues that Cooper Hawk should be the form used. We do not use the possessive form in other uses: Washington County, Kennedy Memorial Drive, Douglas fir, Heimlich maneuver, Mark Twain Prize. He argued we should use Swainson Thrush, Bonaparte Gull and Lincoln Sparrow. I found his arguments compelling but the NACC rejected his proposal.
I have a few miscellaneous topics in this post. The first concerns woodpeckers with a sweet tooth. I received two emails recently from bird observers whose hummingbird feeders are being dominated by Hairy Woodpeckers and Downy Woodpeckers. The hummingbirds don’t have a chance against these larger birds.
Woodpeckers, orioles and bees will often take advantage of the sugar water we put out to attract hummingbirds. I have several suggestions to deter woodpeckers and orioles from a hummingbird feeder.
Use a hummingbird feeder with no perches. A hummingbird can hover in front of a flower or hummingbird feeder and drink its fill of nectar or sugar water. Other birds must be perched to lap up the sugar water.
Some hummingbird feeders come with bee guards, small inserts that surround the feeding ports. These bee guards will discourage woodpeckers as well but pose no obstacle to the thin bill and long tongue of a hummingbird.
Sometimes, woodpeckers and orioles will perch on the wire or string that supports the hummingbird feeder. You can easily make a baffle with an old CD or DVD. Drill a small hole in the center and thread the supporting wire or strong through the CD. Raise the CD to an appropriate height and then wrap some tape or string just below the CD to keep it in place.
One final suggestion is to put out multiple hummingbird feeders.
Around the first of July, lots of birders look for the annual Check-list Supplement from the American Ornithological Society’s Committee on Classification and Nomenclature of North and Middle American Birds. This committee, the NACC, is responsible for maintaining the official checklist of the birds of North America and Middle America.
Life lists can change because of NACC decisions. Recently, many birders lost a life bird as Thayer’s Gull was lumped with Iceland Gull but gained a species when the Winter Wren was split into the eastern Winter Wren and western Pacific Wren.
The 2018 update doesn’t have any lumps or splits affecting the Maine avifauna. One common name change has relevance for Maine. The official common name of the Gray Jay is switched back to Canada Jay. This decision is unusual because the committee usually will not change a common name unless a split or lump is involved.
The decision to revert to Canada Jay appears to be influenced by a movement in Canada to designate the Canada Jay as the national bird of that country.
Many of the taxonomic changes in the current update are based on DNA comparisons that lend insight into how closely related different species are.
The Hairy Woodpecker and Downy Woodpecker are now placed in the genus Dryobates, if you want to update your field guide.
Prior to the new checklist supplement, five North American sparrows were classified in the genus Ammodramus. Now, only the Grasshopper Sparrow remains in that genus. Nelson’s Sparrow, Salt Marsh Sparrow, LeConte’s Sparrow and Seaside Sparrow are now moved into the genus Ammospiza.
The Hydrobatidae, the family of the storm-petrels, is split into two families. The Hydrobatidae now includes species that nest in the northern hemisphere so our Leach’s Storm Petrel, a breeder in Maine, remains in the family. A new family the Oceanitidae, contains storm-petrels that nest in the southern hemisphere. This family contains Wilson’s Storm-Petrel, an abundant summer visitor to our pelagic waters.
A record of a singing Chuck-will’s-Widow in Blue Hill for the past three weeks is remarkable. Another was heard in Wells on July 1. Perhaps we will be able to add this species to the list of species that have expanded into Maine in the past 40 years. This list includes Turkey Vulture, Red-bellied Woodpecker, Tufted Titmouse, Carolina Wren, Northern Mockingbird, Blue-winged Warbler and House Finch.
Oceanic islands are fascinating to anyone with an interest in biology. Thrust up from the deep ocean floor, oceanic islands are blank canvases. Colonization of plants and animals from continental areas occurs by rafting or by being carried on the wind. Some of these colonists establish a stronghold on the new island, enriching the diversity. Over time, these colonists often diverge from their mainland relatives, producing new species. Thus, endemic species are born, found nowhere else.
Oceanic islands often occur in groups so adjacent islands serve as sources of colonists as well. A group of oceanic islands may have shared endemic species as well as species endemic to a single island.
The Caribbean islands offer the opportunity to see a diversity endemic species. For birds, Cuba has 30 endemic species, Jamaica has 30, Puerto Rico has 18 and the winner in the endemic species contest is Hispaniola (the island shared by Haiti and the Dominican Republic) with 32 endemic species. Other smaller islands have their own endemic species. In addition, some species are restricted to the Caribbean but are found on multiple islands. Altogether, the Caribbean offers over 170 bird species that can be seen nowhere else.
In January, my wife Bets and I along with our friends Pat and Dave Lincoln participated in a guided tour of the Dominican Republic with the goal of finding all 31 endemic bird species (one Hispaniolan endemic is found only in Haiti).
As a hedge against a winter storm in Maine, Bets and I booked a flight a day early to make sure we would arrive in the Dominican Republic when the tour started. We used that extra day to explore the colonial area of Santo Domingo. We had no trouble finding our first endemic, the Palm Chat. This streaked bird, about the size of a Blue Jay, is common everywhere. It is the Dominican national bird. This species is so different from other birds that it is placed in its own family, the Dulidae. DNA comparisons tell us that waxwings are its closest relatives.
We found Hispaniolan Parakeets as well. Oddly, this species seems to be most common in urban areas. Other species seen included Antillean Palm Swifts, Gray Kingbirds, Magnificent Frigatebirds and Bananaquits.
Our tour began the following day with a trip to the National Botanical Garden in Santo Domingo.
Antillean Grackles greeted us at the gate. The cement trails through the extensive garden made for easy walking.
We saw lots of familiar birds, particularly warblers. Black-and-white Warblers, Cape May Warblers, American Redstarts, Northern Parulas and Prairie Warblers were common.
Stolid Flycatchers flitted around as well. A Red-legged Thrush was spectacular in the sunlight.
With considerable effort, we got good looks at Black-whiskered Vireos. We got great views of a Hispaniolan Lizard-Cuckoo and Hispaniolan Woodpeckers, our third and fourth island endemics of the trip.
A few West Indian Whistling-ducks, included eight polka-dotted ducklings, showed nicely. We saw a few tiny Vervain Hummingbirds, the second smallest bird in the world, barely larger than the Cuban Bumblebee Hummingbird.
On the way out, we found a Black-capped Palm-Tanager, another endemic I was keen to see. This species, along with three other Hispaniolan species, is placed in its own family, the Phaenicophilidae.
With five endemics under our belt, we headed to the southwestern part of the country. Our home for the next two nights was Villa Barancoli, a field station in Puerto Escondido. Arriving late in the day, we got a nice look at White-necked Crows for another endemic species under our belts. A brief walk at dusk yielded Common Gallinules, Green Herons and a Baltimore Oriole
After a nice dinner, we all hit the sack. We departed at 4 AM in three four-wheel drive vehicles the next day for one of the most memorable birding days of my life.
We departed at 4:00 AM from Villa Barancolí in Puerto Escondido to visit the mountainous region of Sierra de Bahoruco National Park at Zapoten, just east of the Haitian border.
We departed in three four-wheel drive, high-clearance vehicles for the eight-mile ride to the field site. The last six miles of the trip were over a boulder-strewn road with frequent wash-outs. It took us nearly two hours to drive those six miles.
It was still pitch-dark when we arrived and our first quarry of the day, Hispaniolan Nightjar, would not begin to vocalize until closer to dawn. Attracted by a recording, one male perched briefly over a branch spanning the road and we got short but satisfying looks at this island endemic.
Our next target was La Selle’s Thrush, a dead ringer for an American Robin in silhouette but strikingly colored and furtive. The birds come out on the road to forage at dawn but are difficult to see at other times of the day. This species became our nemesis. Several whizzed across the track, affording no views. Our leader walked further up the track and found one foraging on the road. By the time our party had gotten to the scope, a Zenaida Dove had landed on the road and scared the thrush away. But a White-fronted Quail-Dove, an endemic even more secretive than La Selle’s Thrush, walked onto the road.
As the sun rose, we gave up on the La Selle’s Thrush for the morning and concentrated on other birds. Where to start? Hispaniolan Emeralds, an endemic hummingbird, flitted about as we had our picnic breakfasts.
Different species kept popping up, each as wonderful as the one before. We had Hispaniolan Trogons, Antillean Piculet (a woodpecker relative), Hispaniolan Pewees, Golden Swallows and wonderful flutists, Rufous-sided Solitaires.
We saw several delightful Narrow-billed Todies. These are small but feisty green birds with long, thin bills. The four species of todies are all endemic to the Greater Antilles and two of them are only found in Hispaniola.
I was most eager to see several species whose taxonomic position has only recently been clarified. We saw some Western Chat-tanagers, one of two members of the endemic family, Calyptophilidae. These are skulking birds, difficult to see well.
We found White-winged Warblers and Green-tailed Warblers, both now classified in the Phaenicophilidae family along with the Black-crowned Palm-Tanager. Common names can be confusing!
We also found the stripe-headed endemic Hispaniolan Spindalis, one of four species in the family Spindalidae, found only in the Greater Antilles and Bahamas.
We drove around mid-day to a stand of pines in hopes of finding Hispaniolan Crossbill (a dead ringer for our White-winged Crossbill). We heard lots of Pine Warblers and finally spotted a couple of crossbills at the top of a large pine.
All of these endemic birds were joined by familiar friends: Northern Parulas, Black-and-white Warblers, Cape May Warblers and Black-throated Blue Warblers.
Later in the afternoon, a few of us were walking along the track and we heard a call note that seemed identical to a call note I have heard at tree line on Mt. Katahdin. Patience rewarded us with views of a Bicknell’s Thrush. Nearly all of these birds winter in Hispaniola and nest mainly in northern New England.
Determined to see La Selle’s Thrush, we decided to pile into a single pick-up and drive the track, hoping a thrush would be found foraging on the road at dusk. We got to hear several singing and had brief views. A Hispaniolan Parrot was a nice addition.
Departing in darkness, we arrived at Villa Barancolí for a late supper after an exhausting but exhilarating day.
After a spectacular day in Zapoten in the southwestern part of the country, we had found 24 of the 31 endemic species. The following morning, we left for La Placa with to search for three target species.
Our first target, Flat-billed Vireo, was easily found along with a couple of Broad-billed Todies. A Merlin whizzed by.
The second target, the Bay-breasted Cuckoo, is a species that most visiting birders fail to find. Our hopes were up when a large cuckoo appeared. Alas, it was the endemic Hispaniolan Lizard-Cuckoo, an endemic we had already found.
Our local guide suggested a different site. Sure enough, we heard the call of the Bay-breasted. It responded to a tape of its call and perched in view for several minutes. We were sky high!
A road alongside pastures and occasional trees held our last endemic of the morning, Hispaniolan Oriole. We also had nice views of Yellow-faced Grassquits.
After a nice lunch in Puerto Escondido, we departed for our motel in Pedernales. We made our usual pre-dawn departure the next day for the Alcoa Road in search of Ashy-faced Owl. No luck that morning so we headed to Cabo Rojo (Red Cape) after dawn to look for seabirds. Several White-tailed Tropicbirds delighted us there.
We continued from Cabo Rojo to a lagoon teeming with birds.
We saw dozens of Snowy Egrets, Great Egrets, Great Blue Herons, Little Blue Herons, American Wigeons, Northern Shovelers and Stilt Sandpipers. The assemblage could have been seen in Scarborough Marsh except for the Reddish Egrets, Roseate Spoonbills and White Ibises.
Back to the Alcoa Road, this time in search of Hispaniolan Palm Crows. We knew that a local ranger fed them and they usually arrived mid-morning. So we began a vigil, enjoying the Pine Warblers and Hispaniolan Parrots in the area while we waited.
A couple of crows called to announce their arrival and then landed on the ground, affording great views. Our 28th endemic species! A Hispaniolan Crossbill was an added bonus.
After a delightful lunch, we headed east for Cachote. We began the drive up the very rough road at dusk in search of Ashy-faced Owl. Our leader walked a bit ahead and located a perched owl. He about to call us when two mopeds drove past from one direction and a pick-up truck form the other, blaring loud music with a bunch of adolescent girls singing along from the back of the truck. The owl was gone!
Fortunately, our leader was able to relocate the owl and we all got great looks at this Barn Owl relative.
We descended to our motel, departing pre-dawn the next day.
We returned to Cachote, proceeding much further up the mountain. Our goal was the Eastern Chat-Tanager, an endemic that is mostly found in the eastern part of the country. Arriving at the site just after dawn, we got many brief but ultimately satisfying views of these skulkers.
We then began the long drive to Caño Hondo in the northeastern part of the country in search of our last endemic, the rare Ridgway’s Hawk.
We arrived after dark in heavy rain that continued all night. The next morning, we slogged along the muddy trail with a local guide to an observation site.
A bridge across a small stream was underwater from all the rain. We had to take off our boots, roll up our pants legs and wade across. It was worth it: a female Ridgway’s Hawk perched out in the open for over 15 minutes.
The hawk was our final target. Thanks to our knowledgeable leaders, we managed to find all 31 of the endemic birds of the Dominican Republic.
The next day, everyone got to see Caribbean Martins at the Santo Domingo Airport for a nice parting gift from this wonderful country.
Humans have a penchant for organizing. We like order. This need for organization certainly drove Karl Linnaeus, a Swedish naturalist, to published the first catalog of life, the Systema Naturae, in 1735. He devised the framework we still use in our taxonomy.
In the last post, we explored the challenges of recognizing species. New knowledge forces us to re-examine our understanding of the limits of variation of species. We regularly gain or lose species on our life lists as former species are divided into two or more new species or others combined into a single species.
Taxonomists do have methods for defining a species. The problem is that there is more than one method and the different approaches do not always get to the same conclusion!
This post is a follow-up to the previous one in which I discussed some of the recent decisions by the North American Checklist Committee. This committee of ornithologists makes decisions on whether some species should be split and others should be combined into a single species.
Many were surprised that the Committee did not vote to split the Yellow-rumped Warbler into three species. The votes on this issue was not unanimous. Today, we will discuss three different definitions of species, each of which has its champions.
The first efforts to classify life on earth hinged on a morphological definition of species. Individuals that look alike are combined into a single species. This definition works pretty well for most birds. However, pitfalls lurk.
In early July, many birders eagerly await the annual report of the American Ornithological Society’s Committee on Classification and Nomenclature of North and Middle American Birds. This committee of professional ornithologists is responsible for making decisions on the splitting or lumping of species, changes in common and scientific names of birds and changes in the order in which birds appear in official checklists.
Like any scientists, ornithologists revisit bird identification and classification as more information becomes available. Requests for consideration of thorny taxonomic problems are accepted by the Committee and sometimes the Committee decides to reconsider decisions on their own.
Recognizing the limits of species is one of the great challenges of biology. Some species are remarkably variable; humans with our ranges of skin color provide a nice example. On the other hand, some separate species can scarcely be separated based on their morphology. The Willow Flycatcher and Alder Flycatcher are dead ringers for each other yet the distinctive songs of the males ensure that only Willow females will mate with Willow males and Alder females with Alder males.
A branch of biology called sytematics is devoted to identifying the limits of species and to understanding the relationship among the species. We still follow the basic classification scheme erected by Charles Linnaeus nearly 300 years ago. Closely related species are placed in the same genus. Closely related genera are placed in the same family and so on upward in the scheme to orders, classes and phyla.
Systematic classifications were initially based on the structure of organisms. Over the years, systematists have used other traits to help understand species limits and interrelationships. Behavior can be an informative trait. The ability to interbreed is used by some systematists as an indication of a “good” species. In the past few decades, comparisons of DNA has greatly clarified and refined our understanding of the relatedness of various groups of organisms.
Like any scientist, a systematist regards her understanding of the relationships of a particular group of organisms (like the shorebirds, for instance) as a working hypothesis. The hypothesis is provisionally regarded as true but needs continued testing. As our knowledge grows, hypotheses have to be rejected. Like any science, systematics is a dynamic field.
A nice example of our changing understanding is the Yellow-rumped Warbler. Western birds have yellow throats while eastern birds have white throats. These birds were initially treated as separate species. The Black-fronted Warbler in Mexico and Goldman’s Warbler in Guatemala, similar to Myrtle Warbler and Audubon Warbler, also were described as distinct species. However, all of these four species based on additional systematics work were combined into the Yellow-rumped Warbler in 1973. It’s possible that some or all of these forms will be split back into separate species in the future.
To keep track of these taxonomic changes for birds, the American Ornithologists Union erected a Check-list Committee. This committee is charged with producing the Check-list of North American birds, the official source on the taxonomic classification of birds of North and Middle America. The current version is the seventh, published in 1998. You can see the check-list on line at http://www.aou.org/checklist/north/print.php
The committee monitors the publications on bird systematics and revises the check-list if necessary. The committee usually publishes a supplement in the ornithological journal, the Auk, every July to describe any changes to official Check-list.
Most of the changes in the 2013 supplement pertain to birds of Middle America so I will not cover them here. The supplement does describe some taxonomic changes to some shorebirds: Surfbird, Buff-breasted Sandpiper, Spoon-billed Sandpiper, Broad-billed Sandpiper. The Buff-breasted is a regular passage migrant in Maine and Ruff is an occasional vagrant. Each of these species was formerly placed in its own unique genus. Recent systematics work has shown these species are not sufficiently different from other shorebirds to merit their own genus. Each of these five genera has now been eliminated and all five species are now placed in the genus Calidris, the genus that includes a number of shorebirds including Sanderling, Semipalmated Sandpiper, Red Knot and Dunlin. If you are a stickler for the scientific names of birds, make those changes in your field guide.
The other change may affect your life list if you have birded in the West. The Sage Sparrow has been split into the northern Sagebrush Sparrow and the southern, Californian Bell’s Sparrow.