A resource of Biophilia: Pittsburgh, #bioPGH is a weekly blog and social media series that aims to encourage both children and adults to reconnect with nature and enjoy what each of our distinctive seasons has to offer. 

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By the time my beloved pumpkin sweater comes out of the closet, many of our local birds are already halfway through their journey to a tropical winter! Bird migration is a fascinating concept that we sometimes take for granted because it simply happens, but it still is mind boggling to me that even a tiny little hummingbird could flap those teeny wings all the way from PA to Central America! We have talked about bird migration here on the blog before, but today, let’s put in the greater context of animal migration as a field of movement ecology and talk a bit about how we can help our seasonal migrants.

Let’s start at the beginning: at its most basic, what is migration? Migration is long-distance, seasonal travel, usually from one habitat type to another. This movement is typically some sort of adaptive response to seasonal variation in resource availability — a fancy way of saying that migration is following the seasonal fresh foods. For example, many (though certainly not all) of our Pennsylvania birds will travel to Central America, South America or the Caribbean for our winters. This is an incredibly long, seasonal journey, and it is from a temperate, forested or semi-forested habitat to a lush, tropical forest. However, not all migrations are quite as arduous as that. Giant pandas, for example, migrate seasonally to follow bamboo availability throughout the year; but these travels are usually more along the order of tens of miles, rather than hundreds to thousands. Migration may also occur for some animals at different life stages. For example, different species of sea turtles, salmon, and lampreys have life stages that include movement to a different habitat, either for safety or reproduction.

Bird migration as we are most familiar with it here in the Northen Hemisphere generally consists of flying south in the winter and coming back north for the summer, but there is quite a bit of variation in timing and routes across the animal kingdom. Monarch butterflies, for example follow a 2,000 – 3,000 mile migratory route to wintering grounds in either Mexico or Southern California, and no single generation of butterflies actually makes the entire trip! Female monarchs lay eggs during their own migration, and those eggs hatch and rising adults later continue the trek their parents started. Representing Team Mammal, many humpback whales participate in the world’s longest mammalian migration, though not all populations migrate. Those that do will calve in warm subtropical waters during winter and feed in colder, high-latitude waters in summer. To make things even more fascinating, not all migrations solely involve a strong north-south or east-west gradient. The three-wattled bellbird of Central America has two primary populations that each follow a different complex seasonal altitudinal migration into the mountains. And we can’t have a conversation about migration without noting the “Great Migration” of wildebeests in East Africa. Often accompanied by thousands of zebras, gazelles, and other hoofstock, wildebeests will annually complete roundtrip circle of nearly two thousand miles as they follow pastures greened by seasonal rains.

For the birds and other animals that do embark on long and short distance migrations, they rely on a number of cues in nature that let them know it’s time to start moving. Some cues can include temperature, seasonality, local food availability, and photoperiod (daylength); and different species can respond to different combinations of cues. In particular, cues trigger something in birds called zugunruhe — a period restlessness or increased activity that seems to pick up right before it’s time to migrate.

Counterintuitively, zugunruhe tends to increase activity at night, but this is because many birds species travel at night. It’s actually easier travel conditions! During the night, there are fewer thermal gusts rising up from the ground, it’s usually easier to avoid predators and birds can navigate using the moon and stars. However, this does mean that birds are likely to be led astray by human light sources and large buildings, which can not only lead birds off-course, but also disorient them — possibly leading to mass casualties, like in Chicago last week.

With all of this amazing biology in mind, how can we help support migratory birds?

Lights Out! – Helping reduce light pollution is not only beneficial for birds, but it’s helpful for humans as well. Less artificial lighting means less chance that birds will be confused by dim starlight or glowing cities, and less artificial lighting can help with our own circadian rhythms — and who doesn’t love a good night of sleep? Check out BirdSafe Pittsburgh for more details.

Keep Cats Indoors – The single biggest, directly human-caused threat to birds is an outdoor cat. Depending on the estimate, outdoor cats kill 1-4 billion wild birds a year, but we can make a huge difference here by spaying/neutering pet cats and keeping them indoors. This helps prevent unwanted kittens (and perpetuating feral cat populations) and it keeps Duchess and Mr. Fluffles just a little bit safer themselves.

Preventing Window Strikes – Birds can’t process the reflective sight of a window like we can, which means window strikes (birds literally flying into windows) is one of their biggest conservation threats. And it’s not just high-rises that can be a problem; any window can be tricky to a bird. However, we can help by making windows more visible to birds! BirdSafe Pittsburgh has a number of suggestions, including adding some fun décor like cut-outs to your windows, applying films or decals, or even selecting bird-friendly glass. You can also check out this Audubon article for a complete break-down of the issue.

Protect Greenspaces – Just like we need a rest stop while on the turnpike, birds need stopover space as well. We can help protect birds on their journey by protecting the greenspaces they will need along the way.

Take Action on Climate Change - Many bird species have already begun changing their migratory behaviors due to climate change. We can take some small steps with big impact to help keep our planet healthy for future generations!

So let's all pitch in a bit to keep our birds a little bit safer on their annual journey! It's kind of exciting to think how much of a positive difference we really can make, isn't it?

Continue the Conversation: Share your nature discoveries with our community by posting to Twitter and Instagram with hashtag #bioPGH, and R.S.V.P. to attend our next Biophilia: Pittsburgh meeting.

Images: Header, Pexels, public domain; cover