The Philadelphia skyline will be a bit dimmer and bird-friendly at key times of the year after Bird Safe Philly announced March 11, that Philadelphia is joining the national Lights Out initiative, a voluntary program in which as many external and internal lights in buildings are turned off or dimmed at night during the spring and fall bird migration seasons. Millions of birds annually migrate through Philadelphia during spring and fall and many are killed when they fly into buildings, confused by the bright artificial lights and glass. Joseph Kaczmarek/Associated Press

Recently Philadelphia and Fort Worth declared lights out in their cities during migratory bird season beginning April 1. Why is Maine not doing the same thing?

– Walt Dunlap, Freeport

The migration period is very challenging and often deadly for birds, not just because of the rigors of flying thousands of miles (often using only a few grams of “fuel”) but also because of the increasingly abundant anthropogenic barriers, or those coming from human activities. One of the leading anthropogenic causes of mortality in birds, second only to outdoor cats, is collisions with building windows, accounting for 599 million deaths each year in the United States. While this is an annual figure, a large number of birds that strike buildings are migratory species and these strikes are mostly happening during the migratory season.

Buildings present a multifaceted problem for migratory birds. The first issue is glass, which is a double-edged sword. It can appear reflective (when it is lighter outside than in) and a bird sees reflections of treetops or a clear sky and thinks it can keep flying – straight into the glass. Or glass can be see-through (when it is lighter inside than out) and again the birds think they can keep flying right through it. For most birds, a window collision is fatal: they die immediately from impact, due to injury like internal bleeding, or a stunned (concussed) bird gets picked off by predators.

The other problem with buildings is lighting. Lights from cities are so abundant and bright that it is disorienting for nocturnally migrating birds. Birds will often descend into cities because of the lights, which increases the opportunity for collisions with glass.

One of the best things that can be done to help birds during migration is shutting lights off. As Walt says, this is happening in cities like Philadelphia and Fort Worth, and also in New York City and many other big cities across the country. These larger cities have more buildings, and a lot more lights, which unfortunately results in many more mortality events. A great website,, uses information from weather radars to forecast and count birds migrating at night. Using these forecasts they are able to create “alerts” for cities (still in beta this year) that indicate there will be large numbers of birds passing overhead.

Here in Maine, we are fortunate to have small cities so light pollution is not as big an issue, but that doesn’t take us off the hook for doing our part. There is actually very little data, most of it anecdotal, about building strikes in Maine. That’s one reason why Maine Audubon started a project called BirdSafe Maine, partnering with the University of Southern Maine, the Portland Society of Architecture, and Avian Haven, with the goal of educating Mainers on the problem of bird collisions, and to get the city of Portland – and eventually other municipalities – to update their building codes to require bird safe technologies.

This project kicked off in the fall of 2020 with one of the first steps being the start of walking surveys through Portland to systematically document the number of fatalities. A team of students and volunteers are currently walking routes during this spring migration to collect more data. To learn more, check out

Those ants go marching

I’m wondering if you could identify what is happening in this video? It’s of a swarm of ants found on the brick sidewalk in front of my house in Portland. Many thanks,

– Ali Mann, Portland

If I were to make a list of natural history topics I know virtually nothing about, ants would be pretty high on that list. So while I don’t have much to dwell on here, I do have some context for Jackie’s swarm only because I was captivated by the same event in my own driveway just days before getting her inquiry. A little research led me to the perfectly named pavement ant.

Also known as immigrant pavement ant, Tetramorium immigrans is a non-native pest in North America and gets its name from its habit of making nests under pavement. These “swarms” that we observed were between colonies as new ones fought to establish their territories. Looking very closely at Jackie’s daughter’s video, I could see many of the ants are paired off with mandibles locked as they fight.

Most articles about pavement ants seem to focus on pest control, as they can be a nuisance indoors if they are finding food. Once they’ve found food, they’ll lay a chemical trail back to their nest to allow others to find it too. Since colonies can contain over 10,000 workers, it is no wonder why they are so quickly labeled a nuisance. While they have a stinger, they rarely bite or sting people, but if you don’t want them in your house, clean up any crumbs and food scraps that might attract them.

Do you have a nature question for Doug? Email questions to [email protected] and visit to learn more about virtual and backyard birding, online classes and other programs about wildlife and habitat.

Only subscribers are eligible to post comments. Please subscribe or to participate in the conversation. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.