Meadowlark Project 2019: Birding for Conservation

Now in its third year, the Eastern Meadowlark Project is a great way to support bird conservation by simply going birding.

By checking for meadowlarks at a list of sites and entering observations on our project webpage, citizen scientists help piece together the reasons for this species’ decline.

Eastern Meadowlark (photo by Phil Brown)

We know that meadowlarks are in trouble. Between 1974-2011, meadowlarks disappeared from over 78% of their Massachusetts breeding sites, according to Mass Audubon’s Breeding Bird Atlas.  This decline is only partially explained by meadowlarks’ habitat requirements.

Our 2018 volunteers found meadowlarks at just 3 sites out of over 100 protected grasslands across the state. While meadowlarks do persist at a handful of known agricultural sites outside our survey areas, these results suggested they aren’t using all of the habitat ostensibly available to them. So, while we know habitat loss is a major factor, we also know that it’s not the only part of the meadowlark decline equation.

Our next step is to check sites where meadowlarks were historically seen–including areas that might not be textbook habitat for them. This year, surveys will take place at sites where Eastern Meadowlarks were spotted during the past two Breeding Bird Atlases (1974-1979 and 2007-2011). This will help us both establish where meadowlarks have disappeared from their historical range, and what kinds of habitats meadowlarks are using aside from natural grasslands.

Go Birding—For Science!

First, visit our Anecdata webpage to select sites where you can help look for meadowlarks.  You’ll need to create an account by clicking “register” in the top right corner and creating a username and password. Then, return to the meadowlark project page and click “join project” (just under the photo of the meadowlark). To view a map of sites, click on “add an observation,” then click “use a hotspot” in the upper left, and then click “map.”  Finally, be sure to sign up for the hotspots you choose on the signup list mentioned in the project description!

To keep our data uniform and reliable, a volunteer should survey a site three times between April 10 and June 15, for any 10-minute period between 5:00 am and 9:30 am.  Not all of our sites may have meadowlarks, and that’s perfectly fine— knowing where they aren’t, and figuring out why, is just important to us as knowing where they are.

Thanks for helping us help grassland birds– and good luck finding meadowlarks!

Help Us Learn About Bird-Window Strikes Downtown

Calling all citizen scientists near Boston!

Mass Audubon needs your help monitoring an underappreciated threat to migratory birds: window collisions. We’re looking for volunteers to collect data on bird-building collisions and rescue birds that survive a strike.

A Black-throated Green Warbler that died on migration from a window collision.

The Problem

Window collisions are a surprisingly significant source of bird mortality in the US, causing several hundred million casualties annually.

Birds struggle to distinguish reflections from reality, and often strike glass windows that reflect the sky or nearby greenery. City lights also confuse night-migrating birds, which use the stars to navigate, and which often land near sources of light pollution. Many window strikes occur as birds try to re-orient in the morning, after being drawn in to an unfamiliar concrete jungle.

How to Help

The Avian Collision Team (ACT) is a new volunteer initiative to get as much data as we can about building strikes in Boston. We want to understand the scale of the problem in Boston, where the trouble spots are, and which species are most affected.

The program runs from April 13–June 4. Volunteers need to sign up for 1-4 weekly shifts, Saturday–Tuesday, from 8 am to around 9 am.

We are looking for two kinds of volunteers:

1. Monitoring volunteers who will walk predetermined routes to collect deceased specimens, fill out data sheets, and occasionally rescue live birds.

2. Transport volunteers who can pick up specimens from monitors and bring them to a collection site at Harvard. Drivers will also bring occasional injured, live birds to Tufts Wildlife Clinic in Westborough as needed.

Similar programs have shown that in parts of some cities, there are practically no casualties. In others, certain buildings can kill a dozen birds a day during peak migration. Scientists have developed guidelines for what makes buildings especially dangerous to migrating birds, but they’re still pretty rough. The best way to know where and to what extent there’s a problem in Boston… is to check! 

If this sounds interesting, sign up here!

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.

Birders’ Meeting 2019: Coming Up on 3/3!

While past iterations of the annual Massachusetts Birders’ Meeting have centered on specific groups of birds, habitats, or conservation issues, this year’s theme is a little more abstract: the beauty of birds. All of this year’s presentations address some aspect of what avian beauty means to us and to birds themselves.

Headlining this year’s meeting is Dr. Richard Prum, an evolutionary ornithologist working at Yale. Prum received a Pulitzer Prize nomination for his most recent book, The Evolution of Beauty: How Darwin’s Forgotten Theory of Mate Choice Shapes the Animal World—And Us.

Nathan Pieplow, a scholar of birdsong and author of the Peterson Field Guide to Bird Sounds, will share and discuss some remarkable audio from nature’s strangest-sounding birds. MIT professor Dr. Lorna Gibson will speak on the structure of feathers, from the microscopic forms that give them iridescent colors, to how feathers make owls silent and ducks waterproof.

Artists and humanists will also be among those speaking on avian beauty: Susan Edwards Richmond will give us a tour of bird-inspired poetry from the first known verse spoken in Hindi, to Shakespeare’s writings, and contemporary work by Mary Oliver and Gary Snyder. Mass Audubon’s Chris Leahy and Amy Montague will speak about birds’ many roles in visual art through the ages.

Additionally Joan Walsh, Mass Audubon Bertrand Chair of Natural History and Field Ornithology, will discuss how the fashion of the mid-1800s, namely bird plumes on hats, gave rise to the conservation movement.

Of course, there will be a number of other draws in addition to speakers. We’ll have a vendors’ area staffed by nature tour agencies, booksellers, and local bird-related companies. A number of raffle items will include field guides, bird feeders, and other birding goodies. Most importantly, there’s the chance to meet new community members, catch up with old friends, and stay up to date on news in the Massachusetts birding world.

Whether you come out to learn, socialize, or both, we hope you’ll join us this year!

This year’s meeting will take place on Sunday, March 3rd from 8am-4:30pm, at College of the Holy Cross in Worcester.

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!

Rising Seas are Flooding Saltmarsh Sparrow Nests. Can They Adapt?

A recent study showed that Saltmarsh Sparrows choose nest sites based on past experiences. If a pair’s nest floods, for example, they’ll build their next on higher ground.

While this behavior might seem to show resilience to rising seas and climate change, the authors note that populations have still declined by over 75% since the 1980s.

In fact, nesting further away from the water a risky proposition for Saltmarsh Sparrows, and flooding is not the only threat to their nests. As with any species threatened by climate change, what appears to be a successful adaptation to environmental change often turns out to have unforeseen repercussions for the species.

A Saltmarsh Sparrow in the cordgrass (Spartina sp.) of a New England Marsh. Photo by Shawn Carey.

Caught Between a Fox and a Hard Place

Nesting further from the high-tide mark comes with trade-offs. Nests over drier ground are most vulnerable to predators, which are the second-greatest cause of nest failure in Saltmarsh Sparrows aside from flooding. Small carnivores like raccoons, foxes, and even snakes have been spotted feeding on Saltmarsh Sparrow chicks in nests far from the water’s edge.

Ticks, isopods, and other parasites also prefer drier nests. Some tidal flooding deters invertebrate pests, and may actually contribute to nestling survival as long as the nest isn’t completely inundated.

Nests are most likely to be successful in a narrow band near the high-tide mark where they are safe from predators, parasites, and flooding. Researchers found that Saltmarsh Sparrows that lost their nests to predators would re-nest closer to the waters’ edge, just as birds with flooded nests would move to higher ground. But as increasingly severe storms now regularly push spring tides past their normal height, they wash over what was once the “sweet spot” between safety from predators and safety from flooding.

So, even though Saltmarsh Sparrows adjust their behavior to manage risks, they’re still only resilient to mild disruptions like steady and gradual sea level rise. Regularly-occurring extreme floods, coupled with

Saltmarsh Sparrows are in Trouble

Climate threats to Saltmarsh Sparrows are borne out by the data. Their population is currently around 30,000 birds– half of what it was in 2010, and a shadow of the original population of 250,000. They continue to decline at around 9% annually nationwide, but in Massachusetts, careful management of saltmarshes has kept their numbers comparatively stable. 

Climate change is not the only issue facing Saltmarsh Sparrows. Over 1/3 of Massachusetts’ coastal wetlands have been developed. Dikes, railways, and other infrastructure disrupts the drainage of many remaining saltmarshes, raising the threshold for flooding but causing them to retain floodwaters for longer periods.

Mass Audubon continues to monitor Saltmarsh Sparrows in Massachusetts and advocate for the species, including submitting a proposal to list them as an Endangered species at the state level in 2017.

For tips on combating climate change, find out how to reduce your carbon footprint. For more information on Saltmarsh Sparrows, feel free to ask us a question in the comments!


A Birder’s First Christmas Bird Count

This is a guest post by Nick Tepper. A recent graduate from the University of Vermont, Nick is an up-and-coming expert on New England birds, a lifelong naturalist, and is currently fulfilling an AmeriCorps service year with Mass Audubon.

It was 5:30am on a frigid causeway in the middle of Lake Champlain– technically Colchester, VT, but we may as well have been in the Bering Sea given the arctic wind and cold. I remember stepping out of the car at our first site and walking the first steps of a two-mile icy bike path into the freshwater ocean. This was the inauspicious start to my first-ever Christmas Bird Count (CBC), in the winter of 2017. We could barely see, perhaps because the sun had not yet risen, or perhaps because of the 20mph winds that froze our eyelids shut. I spent the next hour or so shivering and trying to figure out what we were doing out there!  Why torture ourselves? Had we no self-respect?

Finally, the sun rose over the trees, and somehow in the –12-degree weather, it was warm. Looking towards the sunrise, we saw birds begin to appear in the dawn. A Snowy Owl was the first species we saw, glowing orange in the early light. What a moment to behold… its yellow eyes opening for seconds at a time to scan the lake for ducks, just as we did with our binoculars. That bird kept us warm all day. We ended up tallying 48 species, and I learned more about birding than I had in all my younger years memorizing plumage patterns, molts, and call notes.

A distant Snowy Owl perched on a block of ice in a watery, frozen marsh. Photo by William Freedberg.

Birding as defined by my first CBC was not a hobby, a job, or a passion— it was a mindset. More importantly, it is a mindset that people could share. If you participate in a CBC, you will inevitably make acquaintances, connections, and very likely some lifelong friends. For me, the best part of the CBC is that you do not need to be a seasoned birder to participate, you need only have an interest in birds and a pair of binoculars.

CBCs, Formerly Known As Christmas Bird Hunts

The Christmas Bird Count, now a grand tradition understood as an all-hands-on-deck census, was borne out of a more grisly 19th-century rite. CBCs were developed by conservation-minded ornithologists as replacements for a tradition known as the Christmas “Side Hunt.” Hunters would celebrate the season by taking “sides” after Christmas Day and filling the sky with bullets, with the goal of (quite literally) stacking up as many species as possible.

During the holiday season of 1900, noted ornithologist Frank M. Chapman piloted the idea for a Christmas Bird Census instead of a competitive hunt. On Christmas Day 1900, Chapman and 26 other counters pioneered 25 counts, counting 90 species. The count has since grown. Last year, 76,987 counters completed 2,585 counts internationally, tallying a total of 2,673 species! Even so, the CBC can always use more counters, and the birding community would love to have you along for the jolliest day of the year. 

Join Your Local Bird Count!

While some CBCs have already taken place, there are plenty more in Massachusetts before the year is up. Try getting in on one of the following:

  • The Concord CBC will take place on Sunday, December 30, and includes the towns of Concord,Lincoln, Acton, Maynard, Sudbury, and others.
  •  The Marshfield CBC is scheduled for Sunday, December 30 on the South Shore, and includes Marshfield, Duxbury, Hanover, and Pembroke.
  • The Newburyport CBC will take place next weekend on Sunday, December 23, and includes an abundance of saltmarsh habitats including Salisbury State Reservation, the famed Plum Island, and several towns on the North Shore.

Evening Grosbeaks Used To Be Common In MA. This year, They’re Back.

Just as ornithologists predicted, 2018 is shaping up to be a banner winter for a number of nomadic finches in the Northeast, especially Evening Grosbeaks. Having steadily declined as winter visitors since the 1970s, these predictably unpredictable birds are a welcome sight this year.

Evening Grosbeak (Creative Commons)

Irruption Years: Boom And Bust

Evening Grosbeaks, like several species of “winter finch”, rely on conifer seeds and berries whose yield in the wild (or “crop”) varies intensely from year to year. When cone and berry crops in certain areas of the boreal forest are strong, winter finches stay close to their breeding areas year-round. When cone and berry crops fail, winter finches become nomadic, sometimes moving hundreds of miles to the south and to lower elevations.

Even within the season, these birds move around a ton. After an historic number of Evening Grosbeak sightings this mid-November, things seem to have quieted down a bit. EBird records suggest that as many birds may have moved on from or even “overshot” Massachusetts and landed deeper into the mid-Atlantic.  This is unlikely to last though—new pulses of irruptive species will continue into the winter and there is still plenty of finch forage left in the trees.

Shifting Distributions

Misconceptions abound regarding Evening Grosbeaks’ status in Massachusetts, in part because this species’ distribution is in almost constant flux.

The last Breeding Bird Atlas showed these grosbeaks breeding in small but growing numbers in the western highlands of Massachusetts, despite a precipitous decline in winter observations statewide. Climate change is shifting the general range of this species northwards, and the prognosis for breeding grosbeaks in Massachusetts–which rely on climate-sensitive and declining conifer species– is grim. Indeed, eBird data suggest they may have already declined since the last atlas.

Birders who were around in the 1960s and 70s often fondly remember the times when Evening Grosbeaks were abundant every couple of winters. It’s a popular misconception that this species was naturally abundant in Massachusetts, and that climate change alone is responsible for their shifting status.

In fact, breeding Evening Grosbeaks were historically restricted to northwestern North America. Their population slowly advanced south and east during the latter half of the 19th century until a significant irruption brought them into the northeast in 1890. The 1890 irruption carried them as far east as Revere Beach, and in subsequent winters, the birds returned in larger and larger numbers. Nearly 14,000 Evening Grosbeaks were recorded in the 1972 Christmas Bird Count, but in the 1990s and 2000s, their winter range shifted away from Massachusetts dramatically– despite a modest increase in local breeders.

This Year’s Conditions

Winter finch irruptions do not only reflect a snapshot of food availability in the current year, but are affected by longer-term trends. For example, 2017 was an excellent year for cone crops in Manitoba, Ontario and Quebec, leading to increased reproductive success for seed-eating birds. This year, winter finch numbers are high as a result– in a year when food happens to be scarce.

This makes it a particularly good year to put out black-oil sunflower seeds, Evening Grosbeaks’ birdseed-of-choice. While many Evening Grosbeaks have been reported eating crabapples and ornamental tree fruits this winter, they’ve also been showing up in strong numbers at feeders.

Check out Your Great Outdoors for more information on this year’s winter finch irruption! 

Bald Eagle via USFWS

Rat Poison Is Killing Birds Of Prey, And People Are Finally Paying Attention

Note: this post contains an image of a dead Bald Eagle that some readers may find graphic.

Most rat poisons kill more than rats—they also pose a fatal threat to birds of prey. This topic recently made the news after a Bald Eagle on Cape Cod died of what appears to be rodenticide poisoning. The tragic story was picked up by several newspapers, and went locally viral on facebook.

This issue should not only get attention when a culturally iconic species like a Bald Eagle dies. Nearly every raptor species is vulnerable to rodenticide poisoning, from Eastern Screech-Owls to Red-tailed Hawks.

In fact, rodenticide poisoning is shockingly widespread. In one study, 86% of all raptors at a Massachusetts wildlife hospital tested positive for exposure to rat poison.

Second-generation rodenticides: the worst of a bad bunch

The EPA recently banned a class of rat poisons called second-generation anticoagulants from the consumer market, but licensed exterminators are still allowed to deploy them. The ban came about because of the 10,000 children annually admitted to emergency rooms for rat poison exposure. The ban certainly helps limit accidental ingestion by humans, but unfortunately doesn’t do much to prevent birds from eating poisoned rodents.

Second-generation anticoagulants don’t kill rodents immediately. While these rodenticides can kill rats with a single dose (which is why many consumers prefer them), poisoned rats can still live for a few days and continue eating poisoned bait. This delay means that rats can ingest enough poison to kill a much larger animal by the time they finally succumb. While any rodenticide can kill a raptor, second-generation anticoagulants are the most dangerous.

The aforementioned Bald Eagle on Cape Cod likely fell victim to this class of rodenticide. While vets at the Cape Wildlife Center are still waiting for test results to come back, the eagle was bleeding heavily, and its blood failed to form scabs or clots—a nearly sure sign of anticoagulant poisoning.

This Bald Eagle was admitted to Cape Wildlife Center, but sadly didn’t make it. Photo courtesy of Cape Wildlife Center.

Rats are a human-made problem

Native to Eurasia, brown rats have colonized much of the globe and become the most common urban rodent worldwide. These rats were among the first human-assisted invasive species, living aboard ships and rapidly spreading to other continents as early as the 15th century, much to the detriment of countless sensitive ecosystems. Rats and other rodents especially wreak havoc on species found only on small islands, and have driven several seabird species to extinction.

Rat populations are on the rise, and towns are struggling to keep up (the town of Belmont even had to close a city park over a recent rat infestation). Rodent control is sometimes critical to the health of a city or an ecosystem—so what are some poison-free ways to prevent or control rodent problems?

(Don’t) pick your poison

  • Prevention is the best cure for rodent problems. Rodent infestations only occur when there’s an easy source of food. Make sure your trash cans are scavenger-proof, cover vegetable gardens with net or wire, attach tree guards to the trunks of fruit trees.
  • Limit access to shelter and hiding places that appeal to rodents. Seal up holes in your attic, basement, crawl spaces, and shed, and remove tree limbs within three feet of your roof.
  • Consider alternatives to poison. The Tufts Wildlife Clininc points out, “People often believe poisons are more humane than snap traps, but an animal bleeding to death is neither quick nor especially humane.”
  • If a rodent problem has gotten out of hand and you choose to use an exterminator, try to pick one that practices “integrated pest management”— a multi-pronged approach that avoids chemical control methods.
  • Finally, call your town or city hall and ask how the local government addresses rodent control. Suggest eliminating rat poison if it hasn’t been done already!

 

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.

 

Give the gift of birds this holiday season. You can make a gift to Mass Audubon in honor of your loved ones.