Category Archives: Conservation Issues

Avian Collision Team: First Season Updates

Since mid-April, a team of Mass Audubon volunteers has combed the streets of downtown Boston in search of migratory birds killed by collisions with windows. Here are some preliminary results of our first season running the Avian Collision Team (ACT).

The first statistic that jumps out is the higher-than-expected number of live, injured birds found by our volunteers. Based on what we heard from New York, Chicago, and Toronto, we had told volunteers it was highly unlikely they’d be able to save any injured birds. This ended up being far from the truth! Here’s one video of a Brown Creeper that was well enough to be released after suffering non-life-threatening head trauma:

The Five “Hardest-hit” Species

Some patterns are also beginning to emerge in the species of birds we’ve been finding. Here’s the full breakdown:

The five most frequently-encountered birds (in bold text above) have something in common: they’re all low-flying migratory species, and they’re relatively common. Certain buildings also seemed to kill a disproportionate number of birds that climb trees vertically, like woodpeckers, nuthatches, Black-and-white Warblers, and Brown Creepers. Other cities have reported similar species profiles with an emphasis on common migratory birds that fly low and weakly.

The Bottom Line

A few dozen people surveying a thin slice of the city for an hour or so per week found 119 window-struck birds of 38 species.

Other cities report that certain seasons have up to four times the number of strikes than others. The wide variability of window strikes makes it difficult, after just one season, to make broad statements about how many birds die from collisions in Boston annually, or establish how Boston shapes up compared to other cities. That said, our numbers fall roughly into the range reported by similarly-sized programs in other cities, like Baltimore, Detroit, and New York.

After accounting for scavengers, industrious building cleaners, and low volunteer detection rates, it’s estimated that only 10-20% of window strikes on a given route are actually recorded. That makes our numbers all the more sobering, especially considering our volunteers covered less than 1/50th of the street area of Boston.

That said, window strikes by themselves may not drive bird declines in Massachusetts. Window strikes are an additional stressor, however, on top of a laundry list of human-caused threats to bird populations. In today’s world of climate change, habitat loss, and invasive species, every bird counts– which is why window strikes are worth understanding.

Cities Are Only Part of the Problem

Outside the study areas in Downtown Boston, our volunteers reported many casualties even without focused searching. Their findings emphasize what other studies already suggest: window strikes are at least as much of an issue at single-family homes and low-rises as they are at tall urban buildings.

The good news is that there are lots of ways to make your home or office windows bird-safe. Here are some tips:

Screens on windows are the cheapest and perhaps simplest option: they break up reflections and also provide a springy barrier that collision-bound birds can bounce off of.

Where screens are impossible, consider buying or building an Acopian Bird Savers (hanging lengths of bird-deterring string). Learn how to build your own here!

Window decals only work when spaced less than 2” apart vertically and 4” apart horizontally, but when used correctly, they’re another great option. Certain kinds are transparent to human eyes, so even narrowly-spaced ones won’t interrupt your view.

Installing UV-reflective patterned glass like Ornilux is extremely effective, and by far the most discrete option– but also the most expensive.

Finally, turning unneeded lights off at night helps conserve energy and avoid drawing birds into strike-prone areas.

(Disclaimer: Mass Audubon has no affiliation with any of the above vendors).

Barn Swallows at Conte Refuge, Hadley

Since mid-May, Jon Atwood has been collaborating with US Fish and Wildlife Service (USFWS) managers at the Silvio O. Conte National Fish & Wildlife Refuge in a study aimed at monitoring Barn Swallow use of an abandoned stable located on the refuge’s Fort River Division in Hadley, MA.

Barn Swallows © Kim Caruso

Barn Swallows Are Declining in Some Places and Increasing in Others—Why?

Barn Swallows, along with many other aerial insectivores, are showing serious population declines in many portions of their North American range. However, the causes of these declines are uncertain. Pesticide impacts associated with large-scale agriculture, reduction of flying insect populations, landscape conversions, habitat changes along the species’ migration pathways, unknown impacts on the species’ Central and South American wintering grounds, and loss of barns and similar structures that are often used as nesting sites have all been postulated as possible factors.

The question is complicated—Barn Swallows in the northern portions of their range are mostly declining, while those in the south and west are increasing. If there is a single explanation, presumably the “answer” needs to make sense throughout that extensive range—why are populations increasing in some areas but decreasing in others?

Barn Swallow population trends in North America. Red areas highlight substantial declines, while blue areas reflect increasing populations. From USGS Breeding Bird Survey data, 1966-2015.

Understanding Barn Swallows in MA

In this year’s work in Hadley, our focus is on starting to understand the population dynamics of Barn Swallows nesting in this portion of the Connecticut River Valley. About 30 pairs of swallows have nested in the abandoned stable in the last few years, making this site one of the largest known colonies in Massachusetts. Unfortunately, as is often true of aging barns in New England’s agricultural landscape, the stables in Hadley are in serious disrepair, and the Fish and Wildlife Service has recommended that the building be taken down over a several year period, while simultaneously making efforts to attract the birds to alternative nesting sites.

Mass Audubon and USFWS are studying this situation to collect information that will help inform the policy decisions. This work includes regular censusing of nesting efforts in the stables and banding of nesting adults. At the end of the season we will issue a final report that details our findings, so stay tuned for more information.

Help Us Learn About Bird-Window Strikes Downtown

Calling all citizen scientists near Boston!

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

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

The Problem

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

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

How to Help

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

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

We are looking for two kinds of volunteers:

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

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

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

If this sounds interesting, sign up here!

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

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

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

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

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

Caught Between a Fox and a Hard Place

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

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

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

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

Saltmarsh Sparrows are in Trouble

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

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

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

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


Bald Eagle via USFWS

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

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

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

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

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

Second-generation rodenticides: the worst of a bad bunch

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

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

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

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

Rats are a human-made problem

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

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

(Don’t) pick your poison

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

 

Cities Need Bird-Friendly Buildings

Between 100 million and 1 billion birds die annually from collisions with windows. Glass windowpanes can reflect nearby trees, shrubs, and sky. Birds’ eyes aren’t able to distinguish clear reflections from the real thing, so they sometimes aim for a reflection and fly smack into a pane of glass.

Earlier this year, Mass Audubon’s advocacy team expressed concern about a plan to install an all-glass façade on a building facing Post Office Square in Boston. An island of green in downtown’s sea of concrete, Post Office Square is a locally important stopover site for migratory birds. A few plantings in the middle of a nearly treeless part of the city attracts a surprising diversity of species, and adding a wall of glass panels across from one side of the park increases the risk of collisions . The well-meaning developer wanted to add a perimeter garden and a green roof to the site, which ironically would increase window strikes by attracting birds to reflections of the greenery.

Luckily, when told about the risk the project posed for birds, this developer was willing to make the site safer. They are in the process of installing glass with non-reflective stripes, which will break up reflections of what’s outside and steer birds away from the windows. Many similar technologies exist to make windows visible obstacles to birds without interfering with peoples’ view—from glass incorporating ultraviolet patterns that only birds can see, to entire panes made of non-reflective material.

Post Office Square, an urban stopover site for migrating birds (Photo by Will Freedberg)

You Can Help!

Skyscrapers account for disproportionate numbers of bird deaths, but the number of single-story buildings in the US make them an equally important front for reducing window strikes. Every homeowner interested in conservation can take steps to make their homes safer for birds:

  1. Keeping window screens on year-round. This is a great option because it provides a visual barrier as well as soft, springy physical barrier to incoming birds.
  2. Purchase and apply a one-way, see-through film to your windows, which both cuts reflections for birds and blocks the view into your home from outside.
  3. Finally, any birdfeeders close to your house (within 15 feet) should be even closer to windows (less than 1.5 feet away). While this sounds weird, birds do slow down before perching, so any window collisions as a bird comes in to land at your feeder is unlikely to injure the bird.

 

 

 

 

 

 

 

References: Daniel Klem, 1990: Collisions Between Birds And Windows: Mortality And Prevention