Declining Insects

By in Bird Conservation, Conservation, Insects, Population Dynamics

In the last post, I discussed two recent scientific articles that presented depressing and convincing evidence of broad declines in the birds of North America. I want to follow that up with a discussion of a couple of recent articles on insect declines.

The fate of birds and insects are tightly linked. Some birds like flycatchers, swifts and swallows capture insects on the wing. Others like cuckoos, warblers and vireos glean larval insects from leaves. Nectar-feeders like hummingbirds and seed-eaters like sparrows capture insects as a great source of protein for their nestlings. Many insects are critical components of food webs on which hawks and owls depend.

A review by David Wagner showed that flying, ground and aquatic insects are declining worldwide and some extinctions have been documented. A paper by van Klink and colleagues compiled data from 166 long-term surveys. They found that terrestrial insects are declining by 9% per decade. That is frightening!

References

van Klink, R., Bowler, D. E., Gongalsky, K. B., Swengel, A. B., Gentile, A. and J. M Chase. 2020. Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundance. Science 368: 417-42

Wagner, D. L. 2020. Insect Declines in the Anthropocene. Ann. Rev. Entomology 65;457-480.

The Pace of Climate Change and other Natural Phenomena

By in Bird Conservation, Weather

Timing is everything. In 1980, I was living in Washington state. In March, a large earthquake in the vicinity of Mount St. Helens, an active volcano, rocked the  landscape and soon thereafter steam began to vent from the mountain. By late April, a large bulge appeared on the north side of the mountain. On May 18, a massive eruption occurred, taking off the top 1300 feet of the mountain. The devastation was awesome. Although 57 people died, geologists were able to warn nearby residents of the risk and many evacuated the area. The risk was imminent so people reacted.

We see the same behavior with hurricanes. When a hurricane is likely to hit the coast, residents are warned and many evacuate with just a few days warning.

Now we are experiencing the COVID-19 pandemic. The pace of the pandemic is more moderate and will certainly occur over many months. In some states like Maine, the number of cases is modest with around 20 new cases reported each day. Stay-at-home mandates, social distancing and the closure of non-essential businesses are taking a toll on all of us. But we know these responses are necessary because the COVID-19 virus can spread so quickly and models tell us we can flatten the curve of cases by reducing contact with each other. However, we are starting to see flouting and protests of stay-at-home mandates across the country. I think one explanation is that COVID-19 is spreading slowly and the urgency of our response is seen by some as overreacting.

With Earth Day recently passed, I want to continue this theme of timing by considering what I think is the greatest threat to our earth: climate change. From the origin of humans about 150,000 years ago until 200 years ago, carbon dioxide levels in the atmosphere were steady around 275 parts per million (ppm). But with the rise of the Industrial Revolution, CO2 levels have been steadily rising, now over 400 ppm. The greenhouse effect produced by the ever increasing CO2 in the atmosphere is a major driver of global warming. These changes are incremental, occurring over many years so many people, including many politicians, do not see an imminent threat and hence feel no urgency to try to curtail CO2 emissions.

Two recent scientific articles sound the alarm for our bird populations with respect to climate change. In September of 2019, an article  appeared in the journal Science by Ken Rosenberg and colleagues. Using Breeding Bird Survey data and other long-term data sets, they found that North American bird populations have lost three billion birds compared to populations 50 years ago. That is a reduction of 29%. Of the 519 species analyzed, 57.4% are in a state of decline. Climate change is an important factor in driving these declines.

In April,  an article by Christopher Trisos and colleagues appeared in the journal Nature. The researchers used temperature and rainfall data since 1850 to predict the environmental limits of 30,000 species of plants and animals from both the terrestrial and marine realms. 

If global warming continues at its current pace, their model predicts not just isolated extinctions but the collapse of entire communities and ecosystems. These collapses may occur in the oceans by 2030 and in terrestrial habitats by 2050. These drastic extinctions would be devastating. The authors argue that if we can keep the earth from warming by 3.6 degrees Fahrenheit, these abrupt losses of biodiversity can be averted. We have to get global warming under control.

Some people who oppose efforts to halt global warming argue that there have been times in earth’s history when the climate was much warmer than it is now. That claim is absolutely true. However, the rate at which the earth warms and cool was much more gradual than the rate in our current time. Ancient organisms had time to adapt to a warming or a cooling earth. The rate at which human activities are warming our globe is unprecedented. Timing is everything.

Migratory Bird Treaty Act and Earth Day

By in Bird Conservation Tags:

We celebrated the 50th anniversary of Earth Day on April 22. The first one in 1970 was a seminal event in the growth of the environmental movement.

The impetus for the creation of Earth Day was manifold. Smog had become oppressive in southern California. River pollution was causing fish kills. The Cuyahoga River southeast of Cleveland had caught on fire. The Cuyahoga was chronically polluted and the 1969 river fire was actually the thirteenth since 1868 but the 1969 fire made national headlines. In 1969, a massive oil spill occurred off the coast of Santa Barbara, California.

In  1962, Rachel Carson published her Silent Spring, alerting the world to the impact that DDT and other pesticides were having on birds and other wildlife.  The Breeding Bird Survey was launched in 1966 as a way to document the decline of our birds. Ospreys, peregrine falcons and bald eagle populations were plummeting. In the 1960s, Louisiana, the Pelican State, experienced a dramatic decline and ultimately elimination of brown pelicans in the state. State wildlife officials brought in young brown pelicans from Florida and introduced them onto Queen Bess Island in Louisiana in 1968. These birds imprinted on the island and produced 11 nests in 1971, the first successful pelican nests in Louisiana since 1961.

These birds were all negatively affected by  DDT. This organic insecticide was effective against mosquitoes but the compound was ingested by many terrestrial, freshwater and marine organisms. DDT also biomagnifies; it becomes more and more concentrated as one moves up the food web. Small fish to big fish to pelicans.

In birds, DDT interfered with normal calcium metabolism. The result was that female birds laid eggs with thin shells. How heart-breaking it was for incubating birds to crush their eggs.  DDT was banned in 1972 and happily brown pelicans are thriving as well as other large predatory birds that were nearly destroyed by DDT.

These environmental insults collectively were too much to bear. On the first Earth Day, events were held  at  2000 U.S. colleges and universities, thousands of primary and secondary schools as well as many cities and towns. Over 20 million Americans participated. In New York City, Major Lindsay shut down Fifth Avenue for Earth Day participants and made Central Park available for talks and other activities. In Philadelphia, Maine’s Edmund Muskie was the keynote speaker.

Now, Earth Day is celebrated in over 190 countries. The scope of Earth Day is a testament to the power of the environmental movement.

Like most aspects of our lives, COVID-19 has cast a pall over Earth Day celebrations. There will be no parades, no group demonstrations, no talks. But we can reflect on the need to continue our efforts to protect the planet and redouble our efforts to make our individual footprints smaller.

The  focus of this year’s Earth Day was climate change. We need to work to reduce the  emission of greenhouse gases and promote renewable energy sources. Just like with  COVID-19, we are all in this together.

As important as the creation of Earth Day was, effective conservation programs preceded it. One of the most important dates back over a century. In 1918, the Migratory Bird Treaty Act (MBTA) was signed into law.

Birds were being persecuted by overhunting of species like the passenger pigeon and the slaughter of egrets for their plumes to decorate women’s hats. Two constituencies found common ground: hunters who were concerned about overexploitation of game birds and naturalists concerned about birds in general.

The treaty was signed between the U.S. and Great Britain (acting on behalf of Canada). The MBTA prohibits the hunting, killing, capture or selling of any migratory bird listed in the treaty. The treaty lists over 800 species so virtually all North American birds are listed. Without a permit or waiver, even the collection of feathers, nests, eggs or dead birds is prohibited. The MBTA has teeth and has withstood many court challenges.

Birds of the World Website – Wow!

By in Identification, Migration, Morphology, Species Accounts, Taxonomy Tags:

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!

More on the Etymology of Bird Names

By in Migration, Taxonomy

 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

(https://www.inaturalist.org/guide_taxa/399878)

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.

 

 

The Etymology of Common Names of Birds

By in Taxonomy, Vocalizations

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.

Where Are My Feeder Birds?

By in Christmas Count Summaries, Population Dynamics

Christmas Bird Count (CBC) season, organized by the National Audubon Society, is now finished. Between December 14 and January 5, birders around the continent fanned out to count the birds of North America. Each count was conducted on a single day within a 15-mile diameter circle. The center of each circle is a permanent landmark, ensuring that the same area is counted from year to year.

Sighting unusual species or encountering particularly large numbers of some species adds spice to a CBC. However, the greatest value of the massive CBC database is to document changes in abundance of our regularly occurring birds.

Begun in 1900, the CBC program has allowed us to conclusively document  the expanding range of House Finches in eastern North America, following their illegal release by disreputable cage bird dealers in the 1940’s in New York City. The invasion of Red-bellied Woodpeckers and Tufted Titmice is crystal-clear when looking at the Maine CBC records.

In coming columns, I will describe some of the highlights of Maine CBCs as usual. But today, I want to focus on the abundance data for some resident birds. In particular, I want to address a question that has been posed to me frequently this fall and winter: Why are birds not coming to my feeder?

Let’s start with some specific explanations. It might be that your feeders are dirty. Feeders should be taken down and cleaned regularly, removing rotting seeds and debris. Second, birds may be snubbing your birdseed. You can’t go wrong with black oil sunflower seeds, some suet and some niger seed. Avoid the cheap birdseed mixes; those seeds are shunned by most birds except House Sparrows. If you live in an urban or suburban area, you likely have neighbors that feed the birds as well. Their buffet might be better than yours.

These explanations aren’t adequate on their own. The dearth of birds at feeders is widespread. So, we have two more general explanations. First, the resident birds that frequent our feeders (Black-capped Chickadees, White-breasted Nuthatches, Downy Woodpeckers, House Finches) may be declining in abundance. Alternatively, these birds may be finding adequate food in nature without taking advantage of our largesse.

Let’s use Maine CBC data to see if we can disprove either of these possible explanations. On a CBC, counters count birds everywhere within their assigned area. Some of those birds are encountered at feeding stations and others are found away from human habitation.

We do have a complication when we try to compare bird abundance between years within a circle. Different numbers of observers have participated over the years. The more observers, the more birds will be seen. So, looking at the sum of all chickadees seen is misleading without adjusting for differences in effort.

To permit comparisons, we calculate the number of birds seen per party-hour where a party is one to many people counting in a particular section of a count circle. Think of birds/party-hour as the average number of birds seen in an hour.

I randomly picked three Maine CBC circles (Mt. Desert Island, Thomaston-Rockland and Waterville) and plotted the abundance of Black-capped Chickadees over the past 15 years. Although the number of chickadees/party-hour is a bit on the low side for all three counts in 2019, none of these values indicates a significant decline. We should be diligent in monitoring the abundance of chickadees but I see no reason for alarm. We are left with the explanation that chickadees don’t need our hand-outs yet this winter. Keep those feeders stocked!

I did the same sort of analysis for White-breasted Nuthatch and Downy Woodpecker. Again, I found abundances of these birds in the normal range of variation. The populations of these birds seem to be holding steady.

Crossbill Curiosities

By in Reproduction, Species Accounts, Vocalizations

In the last column, I wrote about the unusual bills of crossbills http://web.colby.edu/mainebirds/2019/12/08/bills-as-tools-specialized-versus-generalized/. These remarkable structures are perfectly adapted to pry apart the scales of conifer cones, allowing a crossbill to extract the seeds at the base of the scales. We’ll explore some more aspects of the biology of these birds today.

A look in your field guide will find that we have two crossbills in Maine: the Red Crossbill and the White-winged Crossbill. The Red has a more massive bill and can extract seeds from cones as large as pine cones. The daintier bill of a White-winged Crossbill restricts these birds to smaller cones of spruce and larch.

Heavy cone production is not synchronous among conifer species so getting large numbers of both crossbills in the state is an unusual event. Sadly, a much more common event is for neither species to occur commonly during the winter.

Ron Pittaway, a birder in Ontario, assesses the cone crop of various  conifers each fall to predict whether crossbills and other northern finches will move south from their boreal haunts to our part of the country in search  of food. Ron reports that spruce crops vary  from excellent to bumper in the boreal forests of Ontario, Quebec and Newfoundland. As a result, he does not expect that crossbills will irrupt very  far south  this winter. Bummer for us!

Crossbills wintering at high latitudes serve as a reminder of the importance of food for wintering birds. As long as birds can get sufficient food, they can pay  the high energetic cost to maintain their body temperature in cruel winter weather.

The White-winged Crossbill is known to nest in every month of the year. One of my most cherished birding memories is the sight of White-winged Crossbills feeding nestlings in January in the Northeast Kingdom of Vermont with a temperature of -35 degrees! Obviously, cones were abundant.

Red Crossbills provide a real challenge to our understanding of what a bird species is. Beginning with the work of Jeff Groth published in 1993, we know that there are at least 10 types of Red Crossbills  The types are defined by distinctive flight calls. Differences exist in size and bill shape, patterns of geographic occurrence and preferred food among call types but some overlap in these features muddies the water. At this point, we do not have good information on the genetics of flight calls and on interbreeding between types. Some ornithologists argue that each of these call types could be considered a separate species.

A challenge is that recognizing the calls is difficult by ear. The definitive way is to record the flight call and then analyze it with sound analysis software. Clearly, a challenge to field identification.

But, adequate recordings of the flight calls can be captured with your smartphone. Matt Young, a researcher at the Cornell Lab of Ornithology, monitors recordings of Red Crossbills uploaded to eBird and can provide a type identification. He has a great site describing the different call types: https://bit.ly/2DA78NH

A couple of years ago, one  of these call types was elevated to species status. These birds, with the common name of Cassia Crossbill, are sedentary birds. Their range is solely within  two mountain ranges in Cassia County, Idaho. With their large, thick bills, these crossbills feed on the cones of lodgepole pines.   Other crossbill types do not have large enough bills to separate the scales of these large cones.

For unknown reasons, red squirrels are lacking in the two mountain ranges. Squirrels compete with crossbills and other finches for seeds. Without squirrels, the Cassia Crossbills have an abundance of food and need not wander widely like other crossbills to find patchy food.

Climate change is a challenge to the Cassia Crossbills. First, warm summer days cause the cones to open prematurely, greatly reducing the seed availability. Second, increasing temperature is reduces the germination of lodgepole pine seeds. One model predicts that lodgepole pines will be extirpated form Cassia County by 2080.

Maine Winter Bird Atlas

By in Bird Conservation, Population Dynamics

The second year of the five-year Maine Breeding Bird Atlas Project is now history. Over 1,200 birders in the state have submitted over 30,000 checklists with 1.2 million records of evidence of breeding in Maine. Wow!

The first breeding bird atlas for the state (1979-1983) documented nesting for 201 species. The current project involves many more observers and we have evidence for nesting in 224 species after only two years.

Over 50% of the roughly 4,000 blocks in the state have some data but only 11% of the 974 priority blocks have been completed. The goal of the project is to complete surveys of the 954 priority blocks as a bare minimum. There  is plenty  of work to do in the next three summers.

A companion project to the Breeding Bird Atlas Project has just been  kicked off: the Maine Winter Bird Atlas. We need your help.

The goal of the Winter Bird Atlas is to document the presence of birds found in Maine between December 14 and March 15. By mid-December, the last of the fall migrants have passed through. Very few birds will begin nesting before March 15. Therefore, the period chosen for observation will capture only wintering birds.

You might be asking why do we need this winter atlas effort when the National Audubon Society Christmas Bird Count (CBC) has been providing abundance data on our winter birds since 1900. Three explanations spring to mind immediately. First, the CBC is conducted only from mid-December into the first few days of January. It is therefore an early winter count. Some wintering birds don’t arrive in Maine until later in the winter. This pattern is particularly true of irruptive finches like Common Redpoll, Pine Grosbeak and White-winged Crossbill as well as Snowy Owls, Bohemian Waxwings, Northern Shrikes and Red-breasted Nuthatches.

Second, the roughly forty CBC areas in Maine sample only a small fraction of the area of our state. The Winter Bird Atlas project therefore promises to yield insight into winter bird abundance throughout the state over the duration of the winter.

Third, the more information we have on current abundance of birds, the better. We can establish a more accurate baseline for judging future changes in abundance.

The Winter Bird Atlas differs from the Breeding Bird Atlas in that counts of all birds seen is all that is required. The Breeding Bird Atlas requires longer observations to see behaviors indicative of breeding.

To get started with the Winter Bird Atlas, visit this webpage: https://bit.ly/2szWxA3

Check the map on the website to find a block (each is about nine square miles in area) near you or in a part of the state you would like to visit. Color-codes  indicate blocks that have not been completed. To complete an unfinished block, all you need to do is to spend three hours birding in the area in early winter (December 14 – January 31) and three hours in late winter (February 1 – March 15).  You do not have to survey all of the block but should try to sample the different habitats in the block.

Your data should be entered into the Maine eBird portal: https://ebird.org/me/home

In addition to the counts of each species, notes on behavior (e.g., food eaten, interactions with other species) are encouraged to advance our knowledge of Maine wintering birds.

You may not wish to concentrate on a  particular block. Your incidental observations are welcome on the Maine eBird portal.

Some observers may not be eBird users. No problem. You can submit your data in written form and Maine Bird Atlas volunteers will enter the data for you.  See the Winter Atlas website for details on the procedure.

You do not need to be an expert birder to participate. Contributions are welcome from anyone with an interest in our winter birds.

Bills as Tools: Specialized versus Generalized

By in Foraging, Morphology

I have a cleverly designed, multi-purpose tool that fits into a credit card slot in my wallet. This metal tool is roughly rectangular. Three of the corners of the tool are projected out to form a slot-head screwdriver, a Phillips-head screwdriver and a micro screwdriver one can use to repair glasses. Various parts of the center of the card are removed to make a bottle opener and slots to loosen or tighten five sizes of hex nuts. But sometimes the tool can’t produce enough torque to remove a stubborn screw; a good, old-fashioned screwdriver is needed. Similarly, a ratchet or adjustable wrench may be needed to loosen really tight bolts.

I describe this tool as a metaphor for the old adage, which in its entirety is “A jack of all trades is a master of none but sometimes better than a master of one”. Is it better to be a specialist or a generalist?

One of the most important tools that a bird has is its beak. Depending on its shape, a beak can be used to tear flesh, deftly capture small insects, extract nectar from the base of long flowers, crush seeds and even, with the aid of the baleen-like tongue of a duck, filter microscopic algae from the water.

The bill of a European Starling falls on the generalist side of the spectrum of beak function. A starling’s bill is relatively long, stout at the base narrowing to a fine tip. It serves pretty well as a forceps, as a crushing tool and a probing tool for these birds with a notably broad diet.

Most birds have bills that tend to fall on the more specialized end of the spectrum of bill function. The bill of a chickadee is great for capturing small caterpillars in the summer but not powerful enough to crush sunflower seeds. These adaptable birds can feed on sunflower seeds but have to hold a seed  against a hard surface with their toes and use their bill as a chisel along the suture line of the seed to get at the tender kernel inside. Compare chickadees with House Finches or Evening Grosbeaks that can rapidly eat large numbers of sunflower seeds with their crushing bills.

To me, the most specialized bills of our Maine birds occur in the two species of crossbills: White-winged Crossbill and Red Crossbill. The upper bill is curved in one lateral direction and the lower bill in the opposite lateral direction. In some individuals, the upper beak bends to the right; in other individuals it bends to the left.

This crossed bill is a perfect tool for extracting seeds from the cones of coniferous trees. Let’s consider the cone of a spruce or fir tree. The cone has a number of overlapping woody scales. These scales serve to protect the seeds, which are located at the base of each scale. Most birds have no chance of extracting a seed from the base of the scale.

Not so for a crossbill. These birds insert their bill between two scales and then open their bills. The bill essentially pries the two scales bracts apart. Then, using its long tongue, a crossbill can reach down to the base of the bract and extract a seed.

The crossed bill is, as you would expect, useless in more standard feeding activities. Crossbills are therefore dependent on the cones of spruce and other conifers.

We know that conifers vary greatly in cone production  from year-to-year and from place-to-place. In some years, a particular species in a local region will show the phenomenon of masting, the production of a profusion of cones. We believe this masting is a way to overwhelm seed predators like squirrels, crossbills and some insects.

The dependence of crossbills on cones means these birds live a nomadic existence, wandering widely to find a masting population of conifers when local cones are depleted.

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