Author Archives: William Freedberg

About William Freedberg

Studies indicate that Will Freedberg occupies the ecological niche of a semi-nocturnal generalist. His habits change seasonally, doing fieldwork and bird surveys in the summer, but also blogging, coordinating volunteers, taking photos, and doing background research. Life history traits include growing up in Boston and reluctantly graduating from Yale College. Behavioral research shows that William occasionally migrates to the tropics to seek out Hoatzins, pangolins, and sloths, but mostly socializes with his age cohort in urbanized areas of eastern North America. He is short-sighted, slow to react, and a poor swimmer.

Red-tailed Hawk copyright George Brehm

Fall Hawk Migration is in the Air

Hawks, falcons, and vultures are among the few groups of birds that migrate during the day.

Unlike songbirds and waterfowl, which migrate under cover of night, raptors are actually visible as they make their long journeys across continents.

Although hawks pass by some sites by the hundreds or thousands, that doesn’t necessarily mean you can see them from any site on any day of the season. To find your best day and destination, you have to think like a hawk.

Red-tailed Hawk copyright George Brehm
Red-tailed Hawk © George Brehm

Riding the Airwaves

Raptors have one goal when migrating: use as little energy as possible to make it to their destination. So, they seek out rising air currents to help them gain altitude without flapping. 

Air rises as it is heated by the warmth of the ground (a “thermal”), or pushed upwards by passing over a hill or mountain (an “updraft”). Raptors circle inside these columns of rising air as it carries them upwards. As the air cools and stops rising, raptors exit and glide for miles, slowly losing altitude until they find another column (or start flapping).

Hawks often end up riding the same air current together, forming a rising spiral of birds, or a “kettle.” Kettling isn’t actually a social behavior, even if it looks like the hawks are flying together. Thermal-surfing raptors are simply taking advantage of the most efficient route, like drivers on a highway.

Cool Weather, Hot Hawkwatching

Thermals are strongest when the ground is much warmer than the air. Hawkwatching can be excellent when a cold front moves through, bringing cold air over the (temporarily) much warmer ground and sending thermals spiraling upwards.

Cold fronts are often accompanied by winds from the north, which are conducive to southbound raptors in the fall. When clear, cold air moves in from the north after many days of poor migration conditions (either rain or strong winds from the south), unusually high numbers of restless raptors can be seen migrating at once.

Timing is Everything

Mid-September is prime season for viewing Massachusetts’ most numerous and conspicuous raptors, like Broad-winged Hawks and Ospreys, as well as less common species like American Kestrels and Sharp-shinned Hawks. As the season cools, the mix shifts a little, but the hawkwatching often stays good until late October and tapers off into November.

If you want to plan a trip to see migrating raptors this season, check out our list of hawkwatching sites as well as resources from the Eastern Massachusetts Hawk Watch club.

Evening Grosbeak © MDF (CC BY-SA 3.0)

An Epic Winter For Nomadic Finches

Every few winters, several bird species abandon their normal wintering areas to our northwest, and move into Massachusetts by the thousands. While distantly related, redpolls, siskins, and grosbeaks all rely on food sources that go through boom and bust cycles, peaking and crashing every 3-6 years. When conifer and birch seeds are scarce in Canada’s boreal forest, these loosely-related species irrupt southwards in search of food.

The core group of these birds are collectively called “winter finches,” and this year will be huge for them!

Species On The Move In 2018:

Evening Grosbeaks

Evening Grosbeak © MDF (CC BY-SA 3.0)

Evening Grosbeak © MDF (CC BY-SA 3.0)

This year, these sunset-yellow, black and white-patterned finches are the stars of the show. It’s been a few years since Massachusetts saw any wintertime movement of Evening Grosbeaks into the state, and the last major irruption was in the 1990s.

Unlike many winter finches, Evening Grosbeaks seem equally happy feeding on several food types—both fruits and large seeds. They’ll come to feeders, but their bulky size means that they prefer large platform feeders and will avoid tube feeders. Their fruit-eating tendencies means that they often move south with two other frugivores, Bohemian Waxwings and Pine Grosbeaks, which may show up in smaller numbers this year.

Common Redpolls

Common Redpoll © Simon Pierre Barrette

These finches specialize in eating birch catkins, and birches are the best place to look for them. Ornithologists predict a big redpoll incursion into the northeast this winter. Redpolls got a slow start in Massachusetts this year, but are starting to show up in larger numbers, especially in the Northern and Western parts of the state.

Red-breasted Nuthatches

Red-breasted Nuthatch © Richard Alvarnaz

While technically not a winter finch, this species is nearly as nomadic, and this year is big for them. Their relative, the White-breasted Nuthatch, is a year-round resident and common backyard bird.

Red-breasted Nuthatches made a very early southward movement this year, with many appearing as early as late summer, heralding a major incursion of wandering finches later in the season.

Pine Siskins

Pine Siskin © Terri Nickerson

Siskins are showing up in abundance right now! These small finches with yellow-streaked wings love small seeds. Hang up feeders filled with nyjer or thistle seeds to take advantage of their incursion.

Where To Look

In addition to feeders, groves of spruce trees can be great places to look for seed-eating winter finches like siskins and crossbills. Redpolls are drawn to birch catkins. Fruit-eating finches often take well to ornamental varieties of crabapples, which bear fruit through the winter, so look for grosbeaks and waxwings anywhere large groves of these have been planted—which sometimes means office parks, parking lots, and gardens.

Feeders Up!

Last year was an excellent year for cone crops in Manitoba, Ontario and Quebec, leading to increased reproduction for seed-eating birds. This means that while spruce seeds, birch catkins, and mountain-ash berries are scarce in Ontario and Quebec, there will be loads of hungry birds looking for them—and moving into the US in search of food.

Birdfeeders do help birds survive harsh winters when food is scarce (though there’s a some This is a great time of year to put out black-oil sunflower seeds and nyjer seeds—two of winter finches’ favorite staples at birdfeeders.

For a more in-depth look at this year’s incursion of Evening Grosbeaks and their shifting distribution in New England, check out our birding blog.

Rose-breasted Grosbeak

Spring Migration is Finally Here

On the evening of Tuesday, May 1, a wave of migratory birds arrived in Massachusetts. While some early-migrating species have been trickling in since April, Wednesday, May 2, marks the beginning of the season for our most colorful migrants. Scarlet Tanagers, Yellow Warblers, melodious Wood Thrushes, and a host of other species have finally arrived after waiting out winter in the tropics. 

Rose-breasted Grosbeaks are one of dozens of showy migratory species. Photo © Will Freedberg

Understanding Migration

Most migratory songbirds fly north under the cover of darkness, out of sight of daytime predators like falcons and hawks. Sometimes, it’s possible to hear them in quiet, open spaces: a faint “chip” noise is the telltale sign of a warbler flying overhead. Most nights, you might just hear one ever few minutes, but on nights with heavy migration, it’s possible to hear a flight call every second.

These birds prefer to migrate on nights with southwest winds, which speed them on their journey north. In fact, Tuesday’s southwest winds combined with recent bird reports from New York were the key tip-offs that migrants would arrive today.

These birds journey north over several nights, with most stopping to feed along the way and flying with a southwest wind at their backs. In fact, after staying put during last week’s steady northerly winds, this first push of birds flew into Massachusetts as soon as the winds shifted southwest.

Read the Radar

The scale of bird migration is astounding. So huge, in fact, that you can watch it unfold across entire regions on radar. Doppler radar, normally used to detect weather patterns like thunderstorms, regularly picks up “clouds” of migrating birds, allowing scientists to study migration patterns on a continental scale. To learn how to predict bird migration with radar, check out our introduction to the topic and specific instructions on how to read radar signals.

Canada Warbler. Photo © Will Freedberg

Tips For Watching Warblers

One of the joys of spring migration is that surprising birds can show up just about anywhere. While migratory species rely on undisturbed forests and shrublands to breed, many also pass through urban and suburban parks on their way north. Any grove of trees, whether in the Boston Public Garden or a suburban backyard, is a great place to check for warblers, orioles, grosbeaks, and other goodies.

Look for these colorful visitors in the highest parts of trees, but also around dense cover like thickets. But the real key is waking up early. Most migrants are active just after dawn, and turn quiet by mid-morning.

Good luck! If you see anything good out there, let us know on our Facebook page.