Category Archives: Birds and Birding

Predicting Spring Migration: Part 2

Posted on May 1, 2018 by William Freedberg

Last week, we posted an article on predicting bird movements with radar. Here’s what we went over:

—How birds show up on Doppler radar as solid, expanding circles of radar interference around radar stations, and why this happens

—How to tell these signals apart from precipitation or normal weather patterns

—How larger circles don’t necessarily mean more birds

This week, winds over Massachusetts are shifting. Steady southwest winds may bring a major influx of migrants as early as Tuesday night. So, here’s the rest of what you’ll need to know about watching birds on Doppler radar!

A Need For (Wind) Speed

it’s possible to see airborne objects’ speed relative to the ground using Doppler radar. Birds fly at about 10-15 knots, and know where they want to go. So, they’ll either be moving 10-15 knots faster than the wind if they’re flying in the same direction as the wind, or they’ll be moving in a different direction entirely. Other airborne objects, like insects or dust particles, will always move with the wind.

Here’s how to see the velocity for radar-detected objects online:

Go to the national website for radar data.

In the top left, click on “0.5° Velocity”. (Selecting “reflectivity” will show you the density of the signal, but not the speed. Velocity, on the other hand, won’t show you how thick the air is with birds—it will only show their speed).
In the top right, go to the drop-down menu for “end time” to select the end time for the series of radar images you want to view. It’s in Universal Time, which is 4-5 hours ahead of Eastern Standard Time. Selecting “0500” is best if you want to look at last night’s migration, and selecting “most recent” is best if it’s the early nighttime and you want to see what birds are currently passing overhead.
Go to the drop-down menu for “loop duration” and select 5 hours (or however long you want the series of radar images to be).
Click on the letters “BOS” over Eastern Massachusetts to view radar images!

Image modified from the National Center for Atmospheric Research

In radar images, velocity is always measured relative to the radar station. So, parts of a cluster of birds with “negative” velocity are moving towards the radar station, and parts of a cluster with positive velocity are moving away from it. The red areas in the image show movement away from the radar station (the dark dot drawn in the center of the image), from southwest to northeast. Blue areas show movement towards the radar station—also from southwest to northeast. Birds in the yellow, gray, and green areas are slower-moving relative to the station: as they pass by it, they are neither moving towards it nor away from it.

The wind was about 20kts (knots) from the southwest when this image was taken. Since this radar signal shows objects moving NE around 35kts, it’s clear they aren’t just drifting with the wind. These are bona fide birds!

To check wind speed and direction in your area (to compare to clusters of airborne objects on radar maps), try using Wind Map. Just click to zoom, and hover your cursor over Massachusetts to see the wind speed.

Where Will Airborne Migrants Land?

Velocity data can also tell us where birds are going to end up. Birds usually migrate for between 5-7.5 hours a night, so multiplying their airspeed by around 6 gives us a very rough approximation of how far they’ll travel in one night. On most nights, this works out to be around 150-200 miles. This means that you can often get a general sense of how good the birding will be in Eastern MA based on early-evening images from Southern CT and New York.

For example, when there’s a big early-evening movement of birds over OKX (the radar station for Southern Connecticut and Long Island) and the radar velocity data show birds moving to the east or northeast, chances are that birding will be good in Eastern MA the following morning. If migrants are moving steadily due north, however, that can be a good sign to head further inland the next day. Of course, it’s always best to check early-morning radar images as well—on some nights with north winds, migrants will pour in from the Atlantic Ocean right before dawn, making for great coastal birding.

In our next post, we’ll discuss radar images from the night before the best day of spring migration in 2017. It should serve as a case study in how watching the weather and radar can lead to encounters with incredible concentrations of migratory songbirds. Stay tuned!

Predicting Spring Migration: Part 1

Posted on April 27, 2018 by William Freedberg

If you ask birders what their favorite holiday is, a few will always smile and reply, “spring migration.” Protracted over several weeks, spring migration can indeed feel like a holiday, or at least an annual ritual: time off from work (to go birding), reconnecting with community (other birders), and seasonal gifts that nature drops off in our yards (in the form of colorful warblers).

For beginning birders, mornings in spring can feel as unpredictable as waking up on Christmas as a child to see what Santa brought. Migratory birds appear (or don’t) as if by magic, and the species differ from day to day. There’s no telling what a morning in May can bring. But birds are creatures of habit; with a few tricks, it’s easy to take the guesswork out of birding during spring migration.

Warblers Follow The Wind

West and Southwest winds bring us the greatest numbers of migrants, which would ordinarily move straight North from their Mid-Atlantic stopovers. In Westerly winds, warblers sometimes build up against the coast as they try to avoid being blown out over the water. When the wind is from the South, the Berkshires and Pioneer Valley hold more migrants.

Read the Radar

Doppler radar, mostly used by forecasters use to track weather patterns, also readily picks up signals from migrating birds. Radar works by emitting radio waves that are reflected back to the transmitting antenna by any objects in the way. It’s sensitive enough to detect droplets of water in the air, so it was no shock when ornithologists in the 1950s realized radar could pick up birds as well. Now, advanced birders as well as scientists rely on radar to understand birds’ mass movements at night.

A Brief Radar Primer

There are many ways of accessing radar data online, but the most beginner-friendly is Paul Hurtado’s bird radar website. Just click on the date you want to see radar maps for and you’re good to go!

The most important part of reading the radar is distinguishing birds from weather patterns. Rain or hail shows up as denser interference (represented on this map by green and yellow colors) in irregular, ragged shapes. Birds, on the other hand, appear on the map as distinct circles, and show up as lower-density (pictured on this map as blue and light blue). Hard to believe as it may be, most of what the radar is picking up in the image below are birds.

Visualization by Paul Hurtado; modified from www.pauljhurtado.com.

Why do these birds show up as clusters or circles around radar stations? Radar antennae point their beams up at an angle, creating a funnel-shaped zone of detection. Groups of migrating birds fly relatively low compared to rainclouds and so only pass through a circle-shaped cross-section of radar beams. Think of a cone-shaped searchlight- the lower down in the beam you go, the smaller its area is.

So, larger circles don’t mean more birds—they just mean birds flying higher up, where the radar beam is broader. (You can see in the image below that some of the blue circles have started to overlap). But more birds filling the sky will mean that more of the radar beam is reflected, creating a higher-density signal. Dense areas of migrating birds are represented by lighter blues and greens (see Texas and Maine on this map).

Stay Tuned For More

This is just the tip of the iceberg! There’s much more to learn. In a few days, we’ll follow up with a post on how radar can show birds’ speed and direction, and where they land after a long night migrating. Subscribe to our blog to get part 2 in your inbox!

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

Posted on April 24, 2018 by Wayne Petersen

In a word: Genetics.

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

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

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

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

The Rhyme and Reason

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

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

Behind the Curtain

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

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

Thank you to our Bird-a-thon sponsors!

ARE Demo & Excavation, Inc.

Dune Jewelry, MetLife, Lennox & Harvey

Wood Ducks Are Upon Us!

Posted on April 12, 2018 by William Freedberg

Photo © Will Freedberg

Every year, Wood Duck sightings swell in late March and April. Some wintering birds always linger in Massachusetts, but most of our population is migratory, and only visible here during the breeding season. The April pulse of Wood Ducks represents birds that breed to our north, passing through at the same time our local breeders arrive.

True to their name, Wood Ducks prefer flooded forests and wetlands with standing trees (or at least lots of cover). During migration, you can look for groups of them in more open water, and even on urban ponds.

A Population On The Rebound

Wood Ducks are doing well in Massachusetts, although populations in some parts of the USA are shrinking. Overall, Wood Duck numbers are on the rise, despite the species’ precipitous decline in at the turn of the century. In the late 1800s, the persecution of American beavers slowed the creation of wooded wetlands, and existing habitat was cleared or drained for agriculture. Unregulated hunting for Wood Duck feathers and meat continued into the early 20th century until their total extinction seemed like a real possibility.

Wood Ducks’ decline coincided with the dawn of the conservation movement, and bird-lovers, biologists and concerned outdoorspeople all rallied to bring Wood Ducks back from the brink. Wood Duck protection was a strong motivator in passing the 1918 Migratory Bird Treaty Act—the keystone of legal protection for wild birds—which remains critical for Wood Duck populations today. Overzealous pesticide application after WWII dealt another blow to their population, which lasted into the 1970s. Luckily, Wood Duck populations have been on the rise again—in stark contrast with historically common species which faced ultimately insurmountable threats (like the Passenger Pigeon).

Help Wood Ducks— Get A Nest Box

Nest boxes made their debut as a conservation tool during early efforts to protect Wood Ducks. As cavity nesters that prefer sites high up and away from predators, Wood Ducks struggle to nest in wetlands without standing trees- but nest boxes provide a great alternative! If you live near a marshy wetland, consider building one or buying one at the Mass Audubon store.

Gearing Up For Bird-A-Thon 2018

Posted on April 10, 2018 by William Freedberg

May might seem like a long way off, but the Conservation Science department is already planning our team’s strategy for bird-a-thon. We’re also trying to build as big a team as possible for fundraising and birding, so consider joining us!

You can join us as a “Bird-a-thon booster” and help fundraise, or join as an official birder by emailing our team captain Margo.

Bird-a-thon is not only a fun birding event, but also a huge help to Mass Audubon. Our team uses donations from Bird-a-thon to support our conservation programs, like Foresters for the Birds and the Bobolink Project.

Last year, we tied for second place in the Hatheway Cup for most money raised— help us win it this year! A subgroup of our team will also attempt a big day on the 11^th, and try to beat our team’s species total from last year.

Some of us get very serious about the competitive aspect of Bird-a-thon, much to everyone else’s amusement. Have you ever wanted to watch our program assistant Will try to hold it together after an all-nighter? Is Jeff, the woodland bird conservationist, willing to belly-crawl through tidal mud to glimpse a Least Bittern? Does lead ornithologist Jon Atwood get hangry if he misses a meal over a last-minute Wilson’s Warbler chase?

Of course, other participants are not obliged to go all-out, as some of us do—you can bird at your own pace, or join for just a few hours of the day!

Jeff and Margo scouting sites for our team (photo: Will Freedberg)

Last year, the Conservation Science team recorded 179 species. Come out and see if you can help us beat our total.

A Final Push For Bobolinks In 2018

Posted on April 6, 2018 by William Freedberg

A Bobolink in a field with Oxalis (wild clover) and Vicia (cow vetch). Photo by Allan Strong.

The Bobolink Project is almost ready to go! With one week left for donations, we’re just $2000 away from protecting 1,000 acres of grassland bird habitat this year. That would be nearly twice as many acres as when the project started! With this year’s increase in farmers applying to protect habitat on their land, we need to ask for more help to accept as many applicants as we can.

The Bobolink Project works through a reverse auction, meaning farmers name the lowest per-acre price they’ll accept in exchange for a delay in mowing their fields. We select the lowest bids and work our way up the list, making agreements with more farms until we reach the limit of our Bobolink donations for the year.

Delaying hayfield mowing is a tried-and-true way of protecting Bobolinks. Hayfields provide an excellent surrogate for the tall grassland Bobolinks require to nest- such an excellent surrogate that Bobolinks can rarely differentiate wild grassland from agricultural hayfields. But when fields are mown before the end of nesting season, eggs and nestlings are destroyed during the harvest. Unfortunately, early-season hay is protein-rich and valuable, and some working farms cannot afford to delay mowing and drive down the value of their hay.

That’s where we come in—we use donations to cover the cost of mowing later, essentially buying the birds time to raise their young and move out.

Every donation directly protects acreage of fields and their resident Bobolinks. Please help us make it to our goal of 1,000 acres this year!

Birding Ecuador: Travel & Grassroots Conservation

Posted on April 4, 2018 by William Freedberg

A wintering Blackburnian Warbler in the Ecuadorean rainforest. Photo ©Will Freedberg

More than a dozen species of migratory birds from Massachusetts also depend on Ecuadorean forests for wintering habitat. At the intersection of five tropical biomes, Ecuador packs 1,600 bird species into an country the size of Oregon, making it a hot destination for international bird tours. But as in any part of the world, bird conservation efforts succeed far more frequently when adequately funded, or when they contribute to peoples’ livelihoods.

If You Build It, They Will Come

Take the case of the Amagusa reserve owned by two farmers, Sergio and Doris Basantes. When the young couple inherited some land in northwestern Ecuador, they wondered about hosting ecotourists as an alternative to clearing forest for agriculture. They thought that tourism would never come their way– they normally saw tourists visiting towns much closer to the capital, with better infrastructure.

They may have underestimated how motivated birdwatchers are. Word got out about some rare species nesting along the road near their land, and lo and behold, birders began to make the trip to see them. Doris and Sergio quickly set up feeders and trails on their own property, and started planning to construct cabins.

The site abounds with flashy tropical birds. Migratory Blackburnian Warblers mingle with resident Glistening-green Tanagers, and other species unique to the region. Some of these endemic birds, like the coveted and clownish Toucan Barbet, nest in plain view.

Feeders at Amagusa attract globally rare Moss-backed Tanagers. Photo ©Will Freedberg

A Toucan Barbet at its nest cavity. Photo ©Will Freedberg

Take A Trip For Conservation!

Sergio and Doris are proud to make a living off of their bustling ecotourism operation. But as a strategy for bird conservation abroad, ecotourism is limited mostly by demand. Only increased interest on tourists’ part can allow sustainable birding lodges to multiply and protect more land.

To help ecotourism grow in Ecuador, simply visit! Small-scale birding lodges abound. There’s even an upcoming Mass Audubon tour that visits hotspots in a different region— the eastern Andes and Amazon—featuring two locally-owned lodges, and a dazzling surfeit of tropical birds.

Where Do Woodcocks Go In The Snow?

Posted on March 27, 2018 by William Freedberg

When winter weather drags on into late March, our earliest spring migrants still show up on schedule! Birders often hear the sharp, reedy “peent!” of American Woodcocks in mild weather amid other spring sounds, like the clamor of wood frogs and spring peepers. Hearing them calling from fields covered in several feet of snow can seem incongruous. So how does lingering snow affect these enigmatic birds’ ability to find food?

Beak Superpowers

Woodcocks find insects by probing underground with their beaks. The tips of their beaks pack a bundle of highly sensitive nerves, which they use to pick up on vibrations from insects moving in the soil.

The tip of their beak can also flex open while the rest of it stays closed, allowing woodcocks to delicately pick up food without having to pry their whole bill open underground. The ability to open just the end of the beak is called distal rhyncokinesis (rine-co-kin-EE-sis), or simply rhycokinesis when discussing beak flexibility more generally. It’s a trait shared by many members of the sandpiper family, woodcocks included.

This photo only partially shows how flexible the tip of a woodcock bill is– underground, they can close the lower two thirds and move just the outer third. (Photo: Will Freedberg)

With such particular feeding habits, spring snowstorms might seem to spell trouble for these ground-dwelling insect-eaters. In particular, 2018 has seen a spate of nor’easters barreling through New England, dumping foot after foot upon snow.

Snowed-in Woodcocks Seek Open Ground

Woodcocks can often feed successfully through a shallow layer of snow, but only if the ground is not frozen through. If the ground has already thawed, a covering of snow will in fact keep the ground from freezing fully again, if temperatures return below freezing.

But March 2018 has seen snowpack deeper than a woodcock’s bill is long, even when the ground hasn’t been frozen solid. In years like this, woodcocks feed near any natural features that keep snow off the ground—along the banks of streams and flowing water, or under coniferous trees that partially shelter the ground from snow.

Birders in the know will look for them in these areas, and are careful not to scare or flush these easily-stressed birds. Their flight displays have continued along the edges of fields so far regardless of snow cover, and should keep going into April.

For more tips on how to find woodcocks, check out our list of sites and programs!

A River Of Crows

Posted on March 15, 2018 by William Freedberg

Every night between November and March, a steady trickle of American Crows pours through the skies of Lawrence and Andover, MA. The trickle quickly becomes a stream. Soon, a deluge. Crows spread from horizon to horizon as they fly together to their communal roost. The number of crows varies every year, but there can be as many of 12,000 or 15,000 at a time.

The word “Hitchcockian” does not accurately describe every mass gathering of birds, though the term is used broadly. Murmurations of European Starlings dance and contort themselves in the sky, recalling a moving sculpture. Staging flocks of migratory Tree Swallows are clamorous and chaotic, but the birds move with a light and airy agility that lends a whimsical feel to the spectacle. American Crows, on the other hand, flow by steadily in a single direction. Their pace is deliberate, and their rowing wingbeats inexorable. Uniformly black, crows appear at dusk as large, dark shadows against the sky. They even sometimes approach people out of curiosity and stare at us with an unreadable avian gaze. These are the birds that inspired Hitchcock’s eponymous movie, playing off humans’ unease. In reality, though, members of the crow family are harmless, cooperative, and even empathetic. And while some causal observers might find a crow roost uncanny, birdwatchers and nature-lovers often find in them a source of wonder and beauty.

Why Roost in Numbers?

As some of the world’s most intelligent birds, what could American Crows be up to at these roosts? Traditional theories dictate that crows roost together for safety or warmth, or use communal roosts to be able to select mates from a larger pool of candidates. But hungry crows also follow better-fed birds from the roost in the morning, suggesting they are seeking out productive feeding sites, and that roosts can facilitate cooperation. Some roosts are furthermore located strategically near feeding sites, such that crows can grab a reliable snack when they leave for the day and when they return at night.

Thousands of crows gathering together in the same place every night make easy pickings for predators like Great Horned Owls. As a result, American Crows gather at a secondary location, or “staging area,” before continuing on to their real roost after nightfall. American Crows will further confuse predators by changing the location of the staging area, or even the roost itself, every few nights. Some human observers confuse these staging areas for the actual roost, not knowing the roost is several hundred feet to several miles away— unless they stay after dark to watch the crows move a second time.

The American Crows in Lawrence are surprisingly wide-ranging when not at their roost. Pellets they cough up have revealed saltmarsh snails, telling us that they forage at least as far away as the New England coast. Some of the birds are seasonally migratory, and spend the breeding season far to the north on the St. John’s River in Canada.

Viewing The Mass Roost

To find the crow roost in Lawrence, park in the lot for the New Balance factory on the east side of South Union Street. Cross the street and slowly, quietly, walk partway over the bridge on the Merrimack River. The crows should be in the trees on the north side, numbering into the thousands. Check out the surrounding area for the crows’ staging grounds as well- they have a particular affinity for the parking lots in the industrial park between South Canal Street/Andover Street and the river, as well as Island Street and Pemberton Park.

Some of these birds will be returning to their breeding ground soon, with the rest pairing off and dispersing throughout the state- shutting down the roost until November. Try to catch the spectacle while you still can, or make a plan to check it out next winter.

Backyard Oddball: A “White-capped” Chickadee

Posted on March 14, 2018 by William Freedberg

In case our readers are tired of the endless news stories about the yellow Northern Cardinal in Alabama, a surprising color variant of a Black-capped Chickadee has shown up recently in our home state of Massachusetts.

A private homeowner in Charlton sent us some pictures of the bird, which was coming to her feeders.

In some ways, this bird looks more like a tit from the Eurasian genus Cyanistes—a group very closely related to North America’s chickadees.

However, Wayne Petersen and David Sibley confirmed that this bird’s body shape and plumage is indeed consistent with a partially leucistic Black-capped Chickadee.

What is Leucism?

Leucism is a genetic condition that prevents a bird’s body from depositing pigments in feathers, leaving some parts of the bird white or paler than normal. Leucism is not to be confused with albinism. Albino birds only lack a single pigment (melanin) responsible for producing blacks and browns, but the issue is not getting the pigment where it needs to be—albino birds simply do not produce melanin at all. While these birds end up with no black or brown anywhere (even in the eye!) they might retain other colors like reds and yellows. In leucistic birds, any or all colors could appear paler than normal, but their eyes (and often their skin) will be dark.

This bird is particularly fascinating because while it has retained some pigment in its feathers and its legs are partially dark, its toes are pink and unpigmented. Normally, a bird with partially pigmented feathers will have full pigmentation on its bare parts. Transporting pigment to living tissue (skin) is biologically easier than to dead tissue (feathers). It’s quite rare for a bird with partial leucism to have bare parts that are pale, and even rarer for a bird’s bare parts to be half dark and half pale.

Bird Pigments: Form Meets Function

Pigments often serve vital functions for birds beyond what we might expect. Feathers with melanin, for example, are stronger and more resistant to wear and tear than unpigmented feathers. This may be why some birds, like many gulls, have black outer edges on their otherwise-white wings. Female birds may also read certain plumage traits to indicate the physical health of potential mates. Several studies have correlated bright pigmentation with healthy immune systems in species from Zebra Finches to Red-winged Blackbirds (although never any chickadee species), and many birds with aberrant plumage show decreased mating success. Finally, birds with abnormally pale feathers tend to stick out visually, and run a greater risk of predation.

But even if this particular Black-capped Chickadee has a difficult (or short) life ahead of it, we think it’s beautiful just the way it is.

A Mass Audubon Blog