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.
It was a buggy, humid morning over the fields of Conte National Wildlife Refuge in the summer of 2021, and the Barn Swallows were loving it.
Fanning and tilting their forked tails, the birds feinted left and right to catch insects. Their two long outer tail feathers trailed behind them as they steered towards prey.
Looking closely, a careful observer might have noticed a third filament dangling behind more than a dozen of the birds— the antenna of a tiny radio transmitter, attached noninvasively to the birds’ rumps and destined to fall off by the end of the summer.
Mass Audubon’s Bird Conservation department had been at work tagging these swallows with transmitters all morning. Along with state biologists and refuge staff, the Mass Audubon team caught swallows as they entered their colony—a wooden building used to store the refuge’s boats— fitted the birds with transmitters and released them in a matter of minutes.
Where are Swallows Finding Food?
When the tagging effort wrapped up, the work of following the birds’ feeding patterns began— part of an ongoing study of what these birds need to survive and raise young successfully. Jon Atwood, Director of Bird Conservation, and Marie Rhodes, a student at Unity College in Maine, tracked the birds on foot with handheld receivers over the course of the summer, keeping tabs on how many birds fed over farm fields and native grasslands.
Jon Atwood extracts a Barn Swallow from a mist net, a fine mesh designed for banders to catch birds safely.
Swallows are open-country aerialists that pay little attention to what kind of shrubs or grasses cover the ground where they feed, at least as long as they can find insect prey above it. One possible reason swallows are declining is agricultural intensification— that is, growing more food on the same amount of land with heavier pesticide use and monocultures, which makes it harder for them to find food, both in farm fields and in nearby patches of native grassland.
So far, Jon and Marie’s work bore out the expectation that swallows find food more successfully over native grassland than more human-impacted open habitats (whether agriculture or development). They also foraged most frequently within a home range of just 2/3 of a mile— perhaps surprisingly close to the colony for a bird that covers hundreds of miles a day on migration. This reinforces the importance of preserving native grassland immediately adjacent to swallow colonies (in addition to accounting for other factors like grasslands’ size, habitat quality, and exposure to disturbance).
Next steps: Understanding the Diet-Habitat Connection
In the coming year, graduate researchers working with Mass Audubon will analyze DNA fragments in swallows’ excrement to identify what kinds of insects they’re eating across different habitats.
Hopefully, this will point to where swallows are (and aren’t) getting the nutrition they need, and establish whether local declines of the largest and most protein-dense insects are contributing to Barn Swallows’ shrinking numbers across their range.
Anyone can view a list of radio-tagged migratory birds in transit over Drumlin Farm Wildlife Sanctuary in Lincoln—and follow their next stops in real time.
An antenna installed at the sanctuary earlier this summer is part of an international network of receivers (the Motus project) that detect tagged birds as they pass by, helping researchers trace individual migrations across continents.
Fly-by-night Visitors
So far this fall, the antenna has picked up some interesting species that began their journeys from as far away as the northern Canadian Maritimes and ended up in Florida and South America.
Most birds that migrate long distances travel at night and feed during the day, making just a handful of stops on thousand-plus mile journeys. As expected, none of the birds stopped near Drumlin, taking just a few minutes in the middle of the night to pass through the area in which the antenna detect birds (about nine miles east-to-west—from the skies over Stow and Sudbury to Watertown and Arlington).
The Cast of Characters
Swainson’s Thrush (Photo: Anne Greene)
Four Swainson’s Thrushes were among the birds detected, all of which came from a group of 42 tagged in New Brunswick this summer. One bird took a leisurely journey after passing near Drumlin Farm, stopping five days later at a large wildlife refuge between Baltimore and Washington DC, and island-hopping around the coast of South Carolina two weeks afterwards. While Swainson’s Thrushes are a somewhat uncommon sight for birders in the Metro– West area, they’re one of the most abundant species detected by people listening for nocturnal flight calls, suggesting that they pass overhead in larger numbers.
Bobolink (Photo: Phil Doyle)
A Bobolink also passed by under cover of night in late September. While Bobolinks breed in the fields at Drumlin (which Mass Audubon manages specifically for them), this individual was from a radio-tagging project based in Maine. It was detected on the DelMarVa peninsula a few days later, but wasn’t picked up by any receivers further south—suggesting it may have made a beeline to South America straight over the west Atlantic, or possibly died.
Red Knot (Photo: A. Grigorenko)
One Red Knot, a species known for marathon migrations, set the most ambitious pace of any of the detected birds, passing through the Metro –West area before it was detected just two days later by antennae in Tampa and Sanibel, Florida. Tag data from earlier in the year shows this bird spent five days in May of 2021 refueling and moving around the South Carolina coast before rocketing up through Pennsylvania and Toronto over another nonstop two-day journey. Eventually, the signal was lost in central Ontario, with the bird appearing to be on its way to the species’ breeding grounds in Hudson Bay.
Visualizing Migration, Naming Threats
Following pieces of these birds’ routes is more than an interesting and fun window into their world—it provides valuable clues to why some species are declining.
Take Red Knots, for example. Researchers are already using Motus data to show how Red Knots’ reproductive success on their Canadian breeding grounds depends on how much food they can find at stopover sites in the Chesapeake Bay—where their preferred diet, horseshoe crab eggs, is dwindling due to overharvesting.
Other studies have shed light on what stopover sites are most critical for migratory birds, or examine the impact of extreme weather, the overuse of certain pesticides, or other threats.
Meanwhile, Mass Audubon and MassWildlife received a grant together in 2020 to track American Kestrels to their wintering grounds and see if mortality there might be driving their decline (although the pandemic put this work on hold until 2022). We’re also tracking local Barn Swallows—another declining open-country bird—during the summer months, to understand if they forage more successfully over native grassland than farm fields.
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.
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.
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.
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.
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.
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 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.
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.
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!
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.
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.
