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.

A New Tool For Identifying Threats to Migratory Birds: the Motus Network

Across the US, conservationists are expanding a network of radio towers that automatically record the positions of radio-tagged birds as they pass nearby.

Data from this initiative, called the Motus network, is helping scientists understand what factors influence bird declines and what it will take to stop them. In mid-2021, Mass Audubon will use the Motus network to identify where threatened American Kestrels faces the most risks and mortality after leaving Massachusetts.

Here are some other examples of recent studies that have used nanotags to change how we understand bird migration—and specifically, how birds’ health during migration influences their survival and breeding success.  

Pit Stops can Make or Break a Gray-cheeked Thrush’s Migration

A Gray-cheeked Thrush on its nesting grounds on Kodiak Island. Image: Dave Menke/US Fish and Wildlife Service

One study used Motus stations to link how much weight Gray-cheeked Thrushes put on at stopover sites in Colombia with their migratory schedule (and, indirectly, to their breeding success).

Gray-cheeked Thrushes stop along Colombia’s coast on their journey from their wintering range further south to their breeding grounds in boreal Canada.  Massachusetts birders know them as an uncommon migrant on the ground, although their flight call is fairly frequently heard from night-migrating birds overhead.

This trend lines up with the Colombian study’s first surprising finding: many of these thrushes make direct, continuous flights to Canada from stopover sites in Colombia, instead of hopscotching through the Caribbean and North America. One bird averaged 46 miles per hour as it covered the 2100 miles between Ontario and Colombia in less than two days!

But not all thrushes have enough fat reserves to power them through these marathon flights.

Researchers analyzed the amount of fat thrushes packed on at their stopover sites, as well as the amount of time spent refueling. They found that the longer birds spent feeding on the north coast of Colombia, the earlier they arrived on their Canadian breeding grounds—allowing for a longer window to breed and raise young successfully.

Most interestingly, the researchers found that most thrushes arrived in Colombia with similar levels of fat reserves—suggesting that food availability on their Amazonian wintering grounds had less of an impact on their migratory success than their ability to refuel during stopovers in Colombia. This suggests that Gray-cheeked Thrushes face a bottleneck specifically in Colombia, and that conservation efforts [JA1] on their breeding grounds or wintering grounds could be weakened if their stopover sites are degraded.

Horseshoe Crab Eggs are Critical Fuel for Red Knots

Red Knots feeding on horseshoe crab eggs in Delaware Bay. Photo: Gregory Breese/USFWS

Conservationists have long been concerned about horseshoe crab harvesting along the Atlantic Coast and its effect on Red Knots, a chunky shorebird that feeds on horseshoe crab eggs during migration.

New evidence from a study of nanotagged knots validates concerns that food availability at one key stopover site influences their eventual success on the breeding grounds.

Some Red Knots were fat, healthy, and well-muscled at the time they were fitted with nanotags in Delaware Bay, which hosts more migrating knots than any other East Coast estuary. Motus receivers detected these birds leaving Delaware Bay on nights with favorable winds, which the birds rode nonstop to their breeding grounds.

Birds that failed to find as much food in the bay, however, left sooner— whether or not they had to fight the wind the whole way. These birds could be cutting their losses and giving up on feeding in the bay, the study authors speculate. Alternately, and perhaps more likely, these birds are aware that they weren’t in good enough shape to make a non-stop flight—and so leave earlier in order to arrive on time.

But that decision (whether conscious or not) came with a trade-off: by flying in poor conditions, these birds eroded their fat reserves even further. Because these birds had to fight the wind, the effect of malnourishment on the East Coast was magnified by the time they reached the Arctic.

Ultimately, the birds that showed up in poor condition to their breeding grounds also returned south before the breeding season was over—suggesting they had not been able to successfully raise young.

Pesticides Disrupt White-crowned Sparrows’ Journeys

Motus stations can also help track how tagged birds fare on migration after they’ve been exposed to an environmental hazard.

One study used geolocators to follow White-crowned Sparrows that had been exposed to seeds contaminated with a neonicotinoid, a class of pesticide widely implicated in some bird declines.

They found that while unexposed birds moved on after less than one day, birds that ingested a non-lethal dose of neonicotinoids—less than 1/10 of the amount present in a fully-coated seed—stuck around for an average of 3.5 days.

More worryingly, the birds lost weight. Within just 6 hours of ingesting contaminated seeds, the sparrows lost an average of 6% of their body weight. The loss deepened to 17% for birds that were exposed to neonicotinoids for three days straight. While these birds wree shown to eventually recover, these losses jeopardize White-crowned Sparrows chances of arriving on the breeding grounds with enough time to hatch and raise young.

Collaboration Is Key to Raising Motus Towers

While tracking birds with radio tags is not new technology, the Motus network dramatically expands its reach. Receiving stations across the continent can now pick up birds that would have previously only been detectable locally, either by a human carrying an antenna or by a single-site, stationary receiver.

This isn’t possible without a huge range of partners on public and private land who can host Motus stations, which now number nearly 1,000 across 31 countries. Mass Audubon is proud to be offering a few sanctuaries as potential sites for towers, and to be participating in the Northeast Motus Collaborative.

Abundant Deer are Bad News for Understory Birds

Human activity has caused white-tailed deer numbers to swell beyond sustainable levels in the Northeast, which spells trouble for birds that nest in the forest understory. At certain Mass Audubon sanctuaries, staff scientists monitor deer density to keep tabs on their ecosystem impacts.

Deer eat some birds out of house and home

Deer are “ecosystem engineers,” capable of changing the physical characteristics of their habitat by eating plants that grow low to the ground (aka understory). While a few deer per square mile can help plant diversity by creating gaps in the understory, much higher densities—often caused by an absence of natural predators—can spell trouble for plants and wildlife.

It only takes eight deer per square mile begin to reduce the number wildflowers, like trilliums and lady’s slippers. With wildflowers devoured, deer shift their diet to plants with tougher leaves, like birches, blueberry, and greenbrier. As deer thin out the forest understory and eventually remove it entirely, birds that normally rely on this vegetation to cover nests and raise young, like Ovenbirds and Black-and-white Warblers, struggle to persist. Even species that nest in the mid-levels of the forest, like Indigo Buntings and Yellow-billed Cuckoos, are affected when deer reduce the number of tree saplings.

Studies of protected areas show that nearly a third of migratory forest birds are more likely to disappear from forests with overabundant deer populations. It’s not just birds: more than 20 deer per square mile are enough to have severe impacts on bird, amphibian, insect, and mammal species diversity.

Heavily deer-browsed understory. The forest floor is mostly bare, with few low, leafy plants. Growing saplings are limited to species that deer don’t eat, like white pine.
In forests with fewer grazers, the forest floor is almost totally obscured by shrubs, grasses, ferns, and saplings that will grow into the canopy as older trees die.

Certain kinds of human disturbance help deer

Deer may never have lived as densely in Massachusetts as they do now. Wolves and mountain lions kept deer numbers in balance with their ecosystem until humans exterminated large predators from Massachusetts in the mid-1800s.

In the pre-colonial past, subsistence hunting also helped keep deer numbers in balance with the ecosystem. Sport and commercial hunting had nearly eliminated deer from Massachusetts in the mid-20th century, but their numbers began to bounce back as hunting declined—even though deer’s key predators were never allowed to return to the state.

In the meantime, suburbanization has created a nearly ideal landscape for deer in the Northeast. Suburbs mimic the patchwork of fields and forests that deer love, with open areas for nighttime feeding, sheltered woods for raising young, and landscaped backyards providing a steady supply of ornamental plants that are replaced as deer eat them.

Deer impacts endure

Even if the deer population crashes due to lack of food, disease, or a tough winter, their browsing has long-term impacts. Since deer avoid eating hay-scented fern, a plant that acidifies the soil, the fern can dominate the understory making it inhospitable to other plants. In addition, deer browse gives an advantage aggressive invasive plants with spines or thorns that deter grazing.

In the long term, over-browsed forests go into “regeneration debt,” which is when there are more mature trees than young saplings growing to replace them. Without sapling growth, the forest thins as more mature trees die. And since deer avoid eating some unpalatable saplings, especially pines and conifers, this eventually reduces diversity among mature trees as well.

Black-and-white Warblers require intact forests with a thick understory layer to breed. Photo: Davey Walters

How densely do deer live on Mass Audubon sanctuaries?

For the past several years, Mass Audubon scientists have employed a variety of methods to estimate deer density. Since 2018, deer monitoring has involved pellet counts and browse surveys at 16 of our sanctuaries.

Pellet counts take place in February and early March, after deer pellets have accumulated through the winter on the forest floor. Pellets decompose slowly because of the cold temperatures, and there isn’t much vegetation that can fall and accumulate on top of it. Browse surveys involve looking for deer impacts on plants, like nibbled-down twigs, to establish if deer are reducing tree regeneration or plant diversity.

Data from the 2020 season (which was interrupted by the pandemic) yielded deer densities ranging from 19 deer/mi2 at Elm Hill in Brookfield, to 31 deer/mi2 at Moose Hill in Sharon, to as many as 66 deer/mi2 at Daniel Webster in Marshfield. Some sanctuaries in Central and Western Mass, like Rutland Brook (Petersham) and Canoe Meadows (Pittsfield) have deer populations closer to the goal of 6-18 deer/mi2 suggested by state biologists.

To ensure that our properties are providing habitat for as many plant and animals as possible, Mass Audubon has implemented controlled, selective hunting programs during hunting season at sites where deer populations are growing unsustainably. After evaluating a variety of options for reducing deer density, we concluded that carefully managed hunting program is the only feasible and effective approach. We will continue to work with conservation partners and the state wildlife agency to maintain deer at appropriate densities so that our forest ecosystems continue to thrive. 

Coming Soon: Tracking American Kestrels with New Technology

Tracking migratory birds is getting much easier, thanks to the expansion of a continent-wide network of antennas that automatically receive signals from radio-tagged birds. This network, called the MOTUS network, enables scientists to use much lighter transmitters called nanotags, and study the movements of birds that are too small for older transmitter technology.

By tracking birds during migration, MOTUS data can answer a host of questions about bird biology and conservation—like where birds face the highest mortality, which habitats they rely on most during migration, and what determines whether they successfully reproduce. 

These are some of the questions Mass Audubon is trying to answer for migratory American Kestrels, which weigh only 4 ounces and are too small to carry most tracking tags. Kestrels have declined steeply across the state even as habitat loss has slowed, leaving apparently good-quality habitat unoccupied. Beginning in 2021, Mass Audubon will track Massachusetts-breeding kestrels with nanotags (or similar LifeTags) to see what happens to these birds on migration.

American Kestrel. Photo by John Flagg.

How MOTUS Nanotags Work

All nanotags give off bursts of signal on the same frequency, so any MOTUS antenna can detect any tag. To differentiate one tagged bird from another, each tag has a “signature” with different burst lengths, pauses, and spacing—almost like Morse code. When a tagged bird flies within about 9 miles of an antenna, the antenna picks up its signature and records the bird’s position on a connected computer.

Older tracking technology presented many challenges for studying small birds. Tags that transmit GPS data to a satellite are too heavy for most small birds, and there’s still no clear way to make them smaller. Plus, such satellite transmitters are very expensive. For many years, the only tags small and light enough to use on most small birds were less accurate, and required the recapture of any tagged individual in order to download stored location data.

Building a Nationwide Network of Receivers

MOTUS antennas are an improvement over older technologies, but only in areas where there are enough of them to detect birds as they pass through. Now, the focus is on creating rows, or “fencelines,” of evenly-spaced antennas to intercept birds as they pass by on migration.

One of these rows of antennae crosses Pennsylvania and parts of New York State, and soon, there’ll be additional MOTUS “fencelines” across inland areas of New England. Mass Audubon has proposed placing antennae at some of our sanctuaries, although coordinators of the New England MOTUS Collaborative will ultimately determine which sites make the most sense in terms of monitoring migrating animals.

When a city shut down, White-crowned Sparrows sang quieter, more complex songs

You may have heard it or even said it. “Nature is healing” has become a common refrain during the COVID-19 crisis, perhaps as a way to look for a bright side of a tragedy.

And while some examples are simply wishful thinking, like false stories of dolphins’ return to the canals of Venice, there is real evidence that less human disturbance during the pandemic changed how Californian White-crowned Sparrows sing.

A Eastern White-crowned Sparrow– a different subspecies than on the West Coast—at Ipswich River Wildlife Sanctuary

Less Noise, More Song

Researchers conducting a long-term study on White-crowned Sparrow songs saw an opportunity in the lull of a lockdown. Before the pandemic, the San Francisco-based team had studied how increases in city noise changed birds’ singing behavior. But this April, traffic noise fell to its lowest level since 1954.

In normal years, the researchers had found that White-crowned Sparrows compete with city noise by singing louder, higher-pitched, and simpler songs.

While simpler, louder songs rise above the hum of traffic, they come at a cost: males can’t sing both loudly and well. That disadvantages the fittest male White-crowned Sparrows, which advertise themselves with more complex songs. For females, which pick mates based on song quality, a city full of males shouting a limited series of notes curtails their ability to choose a good partner.

But just days after a stay-at-home order went into effect, urban sparrows reverted to singing the soft, complex songs of their rural counterparts.

The researchers found that their calls carried twice as far as before, both because of the varied tones of the song and because of lower ambient noise. And according to the team, males fight less over territory when they can hear each other’s songs from further away.

This study shows how quickly birds can return to natural behaviors after human disturbance are removed. Of course, there are many other kinds of human pressures on ecosystems that leave long-lasting or permanent effects– just not in this case.

So, if you think you heard more birds this summer during the pandemic, you might be on to something. Regardless of whether local birds change their singing behavior, less noise pollution probably means that we hear more birdsong– a thin silver lining in itself.

Flyways: a poem for our lost birds by nature poet and new member, Hayley Kolding

Flyways

I lived a good life
and was reborn a sparrow.
Towhee-like
I scratched meals 
on the ground
with both feet
but mostly I flew,
threading a needle
through dense thickets,
wheeling in legions
above power lines.
My breast was streaked
white and brown,  
my bones  
an invention of light.
Crossing low alone
in clearings I felt 
I soared: 
then a pane of glass
in what had seemed  
a clearing.
So the reality
I meant only to pass through
contracted
to an instant 
and killed me.

God had mercy
and remade me as
a blackbird. 
In the marsh
it was sweet:
I built my nest,
wove a wet cup
about the cattails.
The walls
were bur-reed and rush
the bed inside
grass dry and soft. And oh
I loved the brood
with eyes tight shut.
For my baby
seed of the field,
damselflies
for my baby. But you
do not grow fat–
I paired again,
my mate distinguished
by song:
a choking,
scraping noise
made with much
apparent effort.

Expiring
without legacy
I begged to still
be winged An ivory
gull A plover
A thrush
And mercy
was endless
As a guillemot
I returned
starving slick
in my own color
as murre in
Alaska I starved
as one penguin
of 40,000
Then God blessed me
at last I was a sea bird
in Australia I floated
in the water
I ate everything
the world gave me
And then I was full
O Heaven Then
I realized my need
could not be met


There is an emotional toll, for birders and nature-lovers, in reading so frequently about the scale of bird declines. Summaries of recent scientific papers, updates on population trends, and calls to action can fail to address the sadness and loss readers feel at more bad news. These reactions are just as real as the ecological damage that provokes them, and scholars increasingly recognize them as “ecological grief.” For all the successes of conservation movements, the declines of many species continues unabated, and each feels like a defeat.

Kolding approaches these defeats from a bird’s perspective— in fact, from the perspective of several birds. She treats an indefinite number of birds killed by human activity as reincarnations of one consciousness, condensing a wide and complex range of conservation threats into a linear, tragic story. In so doing, Kolding’s poem resists the treatment of bird deaths as statistics.

While this poem takes ample (and poetically necessary) liberties in ascribing feelings to birds, its poignance is grounded by accurate natural history details and descriptions of real threats. The last passage (“I ate everything the world gave me/ And then I was full… Then I realized/ my need could not be met”) both describes a complex emotion— the dread of living in an unsurvivable world, or of asking in vain for what you need— while also reflecting the reality of how some seabirds die. Plastic pollution kills seabirds because they eat indigestible plastic debris, which accumulates inside them until they starve with a full stomach. (Plastic in the ocean smells like food to seabirds because it grows the same algae as decomposing fish).

In each of Kolding’s vignettes, she frames a scientist’s perspective on birds with a poet’s sensitivity and imagination. The result is a both refreshing and profoundly sad approach to thinking about conservation losses.

Tropical Storm Isaias doused Massachusetts in Sooty Terns—and one is still around

Tropical Storm Isaias arrived in Massachusetts on August 4, 2020, pushing heavy wind and rain through the Berkshires in the early evening before continuing northward. The storm also brought a slew of rare seabirds into the state, with sightings of at least 34 Sooty Terns, 2 Brown Boobies, a Franklin’s Gull, and a handful of other rarities on inland lakes as well as on the coast. This event was part of a rare but regular pattern of vagrant birds associated with hurricanes and tropical storms.

A close up of a hillside

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Sooty Terns rarely come ashore except to breed on islands in the tropics. Photo: USFWS/Duncan Wright

All hurricanes and strong tropical storms in Massachusetts have the potential to carry vagrant birds with them. Generally, the best sightings come in the wake of storms that spend time offshore over the Gulf Stream, before weakening or dissipating over southern New England.

But storms that hug the coast from the southwest can also carry exciting birds. Most storms are big enough that even if their center sits over the New Jersey or New York coast, violent southerly winds sweep from the Gulf Stream into southern New England. This was certainly the case with Isaias, as seen in the wind speed graphic below.

(image via EarthWindMap)

From here, Isaias tacked directly inland through the Berkshires, making it a great candidate for delivering pelagic species to large inland lakes. Indeed, while there were some reports of strong pelagic birding from coastal sites like Gooseberry Neck in Westport, there were equally exciting reports from Wachusett Reservoir, Quabbin Reservoir, and even smaller lakes in the Berkshires. Sooty Terns, Phalaropes, Jaegers, and shorebirds dropped onto many large bodies of water throughout the state.

Stronger storms in the past have produced even more spectacular results. In 2011, Hurricane Irene brought an incredible variety of seabirds into Connecticut and Massachusetts. and resulted in at least one eBird checklist from Quabbin Reservoir that reported a Sooty Tern, an incredible White-tailed Tropicbird, a Leach’s Storm-Petrel, and more.

Often, storm-blown birds arrive at inland sites in bad shape. Many perish, and some return to their offshore or coastal habitats. Very few stick around for several days.

Remarkably, one Sooty Tern that appeared during Isaias has hung around on Wachusett Reservoir. The bird was reported feeding actively as of August 13th, more than a week after the storm, probably taking advantage of the reservoir’s abundant smelt. Smelt resemble Sooty Terns’ favored marine baitfish—mostly clupeiformes—in the subtropical Atlantic. This makes it the longest-lingering storm-driven Sooty Tern in Massachusetts, and quite possibly, in New England. It may leave any day now, and in fact, it’s likely to depart sooner rather than later. If you haven’t seen it yet, it’s worth looking for!

Warmer springs mean birds breed earlier—but also on tighter schedules

Climate change is not only shifting the breeding season for northern forest birds, but it is also shortening it for some, according to a 43-year study co-authored by a UMass Amherst ecologist.

The study examined 73 species of boreal birds in Finland, but the results reflect patterns in bird observations from other parts of the world as well.

Ecologists have shown how climate change effects birds’ ranges, as well as the timing of some of the key phases in their lives. For background, many birds of the Northeastern US will experience range shifts (many of which are already underway) as global temperatures increase, according to models in Mass Audubon’s 2017 State of the Birds report. Climate change tends to affect birds’ ranges by moving their habitat or food supply further north or to higher elevations. While birds are somewhat temperature-sensitive, the plants and insects they rely on tend to respond much more sharply to changing conditions, bringing the birds with them.

Climate change will alter Massachusetts’ forests suitability for Ovenbirds between 2017 and 2050. (Source: Mass Audubon’s 2017 State of the Birds report.)

Other long-term studies have shown that seasonal peaks in insect abundance no longer line up with the arrival of migratory birds that feed on them— and that other factors, like weather patterns, make it difficult for birds to change their schedules accordingly.

But the new 43-year study from Finland is the first to look at the duration of the breeding period from start to end. Around a third of species examined by researchers showed some shortening of their breeding period. Most of the study species started or ended breeding slightly earlier.

At first glance, a reader might worry about the third of birds that breed on an accelerated schedule, and assume that the other two-thirds of species were unaffected. Indeed, the study noted that shorter breeding periods increased competition among individuals of a species— for example, by synchronizing the times that adults were arriving or that chicks were hatching and leaving the nest.

But that’s only part of the problem. In fact, the species that showed no indication of changing their breeding schedule may be cause for greater conservation concern. Just because only some birds are adapting to a shorter “ideal” breeding period doesn’t mean that other birds aren’t feeling the squeeze; other species could be failing to adapt to changing conditions, even if they face the same challenges. The study’s authors pointed out that most of the birds with a curtailed breeding season are either short-distance migrants or year-round residents. Long-distance migrants— whose breeding schedule showed fewer changes— are less able to adjust their migration and breeding dates because of constraints at stopover sites or wintering areas.

Take a Climate Pledge

Climate change affects so much more than birds. Everything from pollinators that maintain food crops, to shellfish and ocean ecosystems, to the cities we live in are facing new climate-related threats.

We can help when we come together to act on climate! It’s easy to reduce your personal carbon footprint by taking one of our climate pledges to commit to greener transportation, sustainable eating habits, or easing pressure on the energy grid when demand is highest. While advocacy, activism, and systemic change are also key to stopping climate change, adjusting our consumption habits is an excellent first step to protect the planet we love.  

Our Sanctuaries Need Your eBird Reports

As we begin to again safely visit our wonderful system of Mass Audubon sanctuaries, this post is a reminder of how you can contribute to our knowledge of birds at these sites. Mass Audubon uses eBird data as part of bird monitoring and inventory efforts, and visitors’ observations help demonstrate how birds use the places we protect. The more information we have, the more we can bolster bird populations amid changing climate conditions and surrounding land use. Your observations help us help birds!

Mass Audubon has updated guidelines for submitting sanctuary observations to eBird, some of which may be new even for experienced eBirders. Most importantly, we ask that, unless you are contributing to a specific project, eBirders only submit sightings under the most general eBird hotspot for each sanctuary, instead of using latitude/longitude coordinates or specific locations within each sanctuary.

Click here for a beginner’s guide to contributing sightings on eBird!

Loons Return to Plymouth County after a Century-Long Absence

Fast on the heels of Bald Eagles’ exciting return to Cape Cod, another iconic species of the north has recolonized Southeastern Massachusetts after more than a hundred years’ hiatus. This summer, Common Loons are raising chicks in Plymouth County for the first time since at least 1872.

It started with an oil spill

A pair of Common Loons in Maine, the birthplace of most of Massachusetts’ reintroduced loons. Photo by Will Freedberg.

Loons used to be common in some of the deep, clear lakes of Plymouth County until the 19th century, when sport hunting and state-sponsored extermination programs removed them from the state entirely. While loons that breed in New Hampshire and Maine spend winters off the Massachusetts coast, it wasn’t until 1975 that they started nesting here again. In fact, Massachusetts is the only state where loons have returned of their own volition, and they now number over 100 birds—but only in the north-central and western parts of the state.

Strong, proactive environmental laws are enabling loons’ renewal to this part of their original range. The male of the Plymouth County pair arrived as part of a reintroduction program, funded by a legal settlement over a Buzzard’s Bay oil spill.

In 2003, the population of overwintering loons in Buzzards Bay took a hit when an oil barge spilled 100,000 gallons of oil into the water after striking a rock. The spill killed over 1,000 marine birds (the total loss, accounting for those birds’ future contributions to their populations, is closer to 20,000 birds). 

Under the Oil Pollution Act of 1990, the barge company had to pay to clean up its mess. (At the time, the Migratory Bird Treaty Act also required that companies pay to restore any birds they accidentally killed, whether or not an oil spill was involved). Some of the funds went towards habitat protection, lead fishing tackle cleanups, and artificial nest sites in areas with existing populations. But there’s no easy way to quickly replace 530 Common Loons, especially when it’s not clear which breeding areas the dead birds came from.

So, the remainder of the funds went towards facilitating loons’ return to places they had historically occupied by translocating “excess” birds from upstate New York and Maine. When loons have two chicks, one often outcompetes the other, which is less likely to survive—making the second chick a great candidate for captive rearing.

Giving loons a head start

Local loon reintroduction efforts formally began in 2015, when the Biodiversity Research Institute began raising loon chicks in captivity in partnership with state wildlife agencies. For the next few years, they managed to release around eight young-adult loons annually into unoccupied, good-quality habitat in Massachusetts.

The project’s success would only become clear a few years later. Young loons don’t breed until they reach several years of age, spending at least the first three years of their life at sea. The marine areas they use as juveniles continue to be their wintering grounds as lake-breeding adults.

While one of the (now fully-grown) male loons has returned to the Plymouth County lake where it was raised for the past couple of years, it was joined by a fully wild female in the spring of 2020. Their chick— the first of what will hopefully be many to come out of the translocation effort—was spotted a few weeks later.

Strong conservation laws yield results

In this case, loons’ reintroduction into southeastern Massachusetts was part of a larger vision for restoring public resources—from fisheries, to swimming beaches, to migratory birds—after they were accidentally damaged by a private company.

But were the damage to bird populations not caused by an oil spill or other pollution that affected people’s health, only the MBTA could have been used as a legal tool to require that a company make amends. Now, that framework is gone—and the current administration’s decision may soon become difficult to overturn

Birders have already observed several other loons from the reintroduction project at different sites across eastern Massachusetts. If you see a loon with a leg band, or on fresh water inside of route 495, let us know in the comments!

Looking for Love in All the Wrong Places: The Woodcocks of Alewife Reservation

American Woodcocks appear to be thriving at the Alewife Reservation in Cambridge, an urban wild sandwiched between office complexes and a subway garage. Despite the myriad dangers of city life, up to a dozen woodcocks perform their aerial mating displays over Alewife every March.

Resilience against the odds

Alewife is awash in threats to these hapless birds. Peregrine Falcons occasionally snag woodcocks in midair as they hunt along the clifflike walls of a brutalist-era parking garage. The expansive glass façade of the recently-expanded office park looms over the adjacent greenspace, causing fatal window collisions. Feral cats prowl around the urban wetland’s thickets. Heavy metals and pollutants from long ago still linger in the soil.

At Alewife, small patches of woodlands, wetlands, and fields persist amid urban infrastructure and new development.

And yet, at least a handful of woodcocks return here every year. In early spring, they give their explosive, nasal calls at dusk, leap into the sky, and twist and turn in midair to attract a mate. Once paired off, they nest and raise young in nearby woodlands.

Is it a trap?

It’s worth considering that this urban wild might be what’s known as an “population sink,” or “ecological trap.”

An ecological trap is any low-quality habitat where more birds die than can successfully reproduce, but which attracts birds even when there’s safer places for them nearby. Traps can appear to have a stable population of birds, when in fact most of those birds die before being replaced as more birds are lured in from safe areas.

A population sink, on the other hand, doesn’t necessarily attract birds more than areas with suitable habitat. Rather, birds end up there as “overflow,” when better territories are fully occupied or made inaccessible. Sinks don’t cause as steep declines, but do put a cap on the birds that can successfully reproduce in an area.

So, it’s entirely possible that Alewife isn’t doing the woodcock population any favors. No woodcock nests have been found in the area, but that doesn’t necessarily mean they’re failing to reproduce.

Brushy fields are all you need

Whether or not Alewife is a net plus or minus for its resident woodcocks, data from the rest of the country show that habitat availability is the main factor limiting woodcock abundance.

The strange, lumpy, long-billed form of an American Woodcock (Scolopax minor). Photo: Will Freedberg

Woodcocks love fields with low, woody brush, and adjacent mature forest. They display in springtime over open, grassy areas, but need some cover—ideally patches of shrubs or grass 2’-5’ high—for shelter. They use forest to forage during the rest of the year, especially when they’re raising young.

Without disturbance, either by fire, mowing, or agriculture, brushy fields revert to forest in a couple of decades. This is the story of woodcock habitat across Massachusetts: most ex-farmland has reverted to forest. Remaining fields are farmed more intensively, leaving less and less brushy patches and edge habitat, and fallow fields are becoming rarer.

Mass Audubon’s Foresters for the Birds program is emphasizing the value of young forest and shrubland habitat for birds. By educating foresters and landowners on bird-friendly forestry practices, we’re trying to create more habitat for woodcocks and other young forest specialists.