Parking Lot Theory

Why that warbler you desperately want to find might actually be hanging out next to your car.

Welcome to Owl My Children, a monthly newsletter where I recount my exciting bird moments from the past month and posit unfounded ornithological theories.

HAPPY SPRING MIGRATION!

It’s the best time of the year! Kinglets and thrushes and vireos and tanagers and WARBLERS IN BREEDING PLUMAGE!!!! You may remember that a few months ago I wrote a post about fall warblers. Well, spring warblers are better. #Sorrynotsorry.

I was thinking about skipping this month’s newsletter so that I could go birding instead, but I’m trying not to tire myself out too quickly this spring. Patience is the key to spring migration. Patience, and BirdCast. (BirdCast is radar for spring migration. Just like radar for the weather, it’s not the only source you should trust. Also trustworthy: Your eyes! Your ears! Your birder friends!)

At the beginning of migration, warblers come through in fits and starts, beginning with yellow-rumped warblers, AKA butterbutts. In Pittsburgh this year, a few early migrants started coming through on April 13. This included butterbutts as well as some of my non-warbler faves, including blue-headed vireos and blue-gray gnatcatchers. When I saw them, I said to Michael: “Fetch the camera. It has begun.” (I didn’t really say this. Michael does carry my camera, though. He even recently confessed, “I think I might be getting into birds.” You heard it here first!)

That first week, I saw a few warbler species, including a pine warbler and lots of black-throated green warblers, but mostly I saw butterbutts. Butterbutts, butterbutts everywhere. Every day since mid-April, I’ve gone out to Frick Park expecting to be swept away in a tide of warblers, only to see a bunch more butterbutts.

Luckily, this past weekend was a big migration weekend, with 23 warbler species seen by other birders around town. I personally saw seven.

In the last five years, 36 warbler species have been seen in Allegheny County. I’m greedy; I want all 36!! I’m at the point now where I see a butterbutt and roll my eyes, like, “Wow, cool, a butterbutt AGAIN.” But that’s no way to live! I love butterbutts, I do! (I’d just love a rare warbler even more.) (I’m kidding!) (No I’m not.)

(Photo of a yellow-rumped warbler by me)

Here’s an anecdote which I think demonstrates my current level of obsession. Michael, as you may know, is a night owl. He likes to stay up much later than I like to stay up. Every once in a great while he goes to bed before midnight, only to then get out of bed because he isn’t tired, play video games, and come back to bed at 2 AM. This happened over the weekend, and, according to Michael, when he tiptoed into the bedroom in the dark, I lifted my head and asked, “What birds did you see?” He was like, “Come again?” So I asked, more insistently, “What birds did you see?” He realized he needed to appease me, so he said he saw a yellow warbler. I smiled, nodded, and went back to sleep.

Now for a theory about spring migration

I recently met a person at a friend’s board game night who was wearing a hat with a mallard on it. I asked if he was a birder, and he waffled a little and said he sort of was, so I proceeded to grill him on whether or not he had seen anything good during spring migration. (I’m fun at parties!)

We started chatting about warblers. He said that the first time he ever saw a warbler, it was right there in the Frick Park parking lot. And it wasn’t just any warbler; it was a CONNECTICUT WARBLER. One of the hardest warblers to find, a warbler that I’ve often suspected is completely imaginary because I’ve never seen one and simply do not believe that anyone else has ever seen one, either.

Ever since I started looking for warblers in earnest, I’ve heard lots of tales of people finding rare warblers “right next to the parking lot.” I’ve also had a few memorable parking lot experiences, like last year when Michael and I heard a hooded warbler calling in the parking lot of Harrison Hills County Park, then went on a two-mile walk where we saw no warblers, then saw the hooded warbler again as we got into our car to go home.

Over the last five spring migrations, Michael and I have developed a theory about this phenomenon which we call Parking Lot Theory. The theory states: If you’ve spent hours looking for a bird, it’s probably back at the parking lot.

(I was in a parking lot when I took this photo of a brown thrasher. Not a warbler, but still cool, if you can look past the taunting.)

5 reasons I believe in Parking Lot Theory

The first time Michael and I stumbled upon Parking Lot Theory, it was May 2021. We lived in Madison then. I had dragged Michael to Lake Kegonsa at 6:30 AM in the hope of finding warblers.

It was so cold we needed gloves. We trudged down the White Oak Trail, which is a lovely wooded trail where, one would think, there’d be a lot of warblers. (Warblers here in the Western Hemisphere are also known as wood-warblers!) But it was completely silent on that trail. It was also freezing because we were in the woods, so we were mostly in shadow. The measly rays of sunlight that had come out that morning weren’t powerful enough to reach us on the forest floor. We walked around for 30 minutes, 45, and then we gave up and went back to the car. I was disappointed; just the day before, at this exact time, several people had eBirded lots of different warblers at this very park.

Wait, what were all those things moving in the branches of the stubby tree next to our car?

WARBLERS. (And gnatcatchers.) And MORE WARBLERS.

The few trees lining the parking lot were spaced far enough apart that the sun could finally reach us, and there were lots of tiny birds flitting around the budding leaves. The park bathrooms were a few feet away, emanating a strong and unpleasant stench. We lingered and tried very hard to tell all these tiny birds apart, but we weren’t great at warblers back then. Still, we got back into our car feeling victorious, the sun warming us through the windshield.

Which brings me to the first reason I believe in Parking Lot Theory: Heat.

1. Heat

Paved parking lots (whether they’re asphalt or concrete) have a higher heat capacity than the woods or the prairie surrounding them. This means that they can get a lot hotter during the day and stay hotter overnight. (For people like me who don’t remember a single thing they learned in science class: the meteorologists of Louisville, KY demonstrated this.)

In terms of warblers: Warblers like heat, and more specifically, sun. The sun heats up the leaves where all the bugs are sleeping in their weird bug comas. Once the bugs are nice and warm, they wake up and fly around, doing their bug thing. And then the warblers can find them and eat them! How nice.

Trees at the edge of a parking lot also get more direct sunlight than the trees that are smooshed between other, taller trees in the woods. More sunlight, more bugs.

I hypothesize that in the morning, after warblers have been flying all night long and they desperately need to refuel, the parking lot might be a better place to find active bugs than the colder woods nearby. If I were doing a project for the fifth grade science fair, I would try to measure this somehow. (I ended up doing a project on fertilizer and tomatoes, if I remember correctly. I also remember another occasion where I had to present a scientific concept to my class, and I stood at the front of the room and frantically combed my hair to make static electricity. If only birds were in my life back then!)

2. Water

In my last newsletter about the yellow-billed loon (will I mention this loon in every newsletter I write for the rest of my life? Probably), I mentioned that some loons land in paved parking lots by accident. According to BirdNote, many waterbirds make the mistake of landing in parking lots because “to a bird flying at night, they resemble bodies of water, especially if their surfaces are wet. Even more so if made to glisten by artificial light.”

(By the way: turn off your lights at night! Lights can attract migrating birds, freak them out, and throw them off course.)

Warblers also migrate at night, and they need both food and water on their journey. So is it possible that warblers make the same mistake as loons? Maybe. But unlike loons, if a warbler lands in a parking lot by mistake, they won’t get trapped there. They can just fly somewhere else. So why would they stay?

This brings me to reason 3.

3. Edge

I’ve mentioned the phrase “edge habitat” in this newsletter before, and how birds seem to like it. Edge is the place where two different habitats meet. This means that wildlife on the edge have access to two different habitats, which increases their available resources.

Some folks over at NC State wrote an article on the importance of managing forest edge for plant and wildlife diversity; they define edge as “the boundary between two adjacent land cover types, such as a forest and a meadow or a forest and a parking lot.” Notice how they include a parking lot here!

Parking lots have more sunlight than a dense, shady forest, which means that lots of plant species can grow there (attracting insects and critters for birds to eat). It helps when there are knowledgeable people maintaining the edge, ensuring that invasive species are managed and that there are nice brush piles and fallen logs and things for wildlife to enjoy. I often see crews of people at Frick Park removing invasive species, planting saplings near the parking lot, maintaining deer exclosures so that the deer don’t eat the native plants, etc. Good job, Frick Park!

I’ve also heard that open spaces, like parking lots, can allow birds a quick escape when being chased by predators. The downside of that, of course, is that predators might be able to see their prey more easily in a parking lot-type environment. The same article says that “predators may concentrate their hunting activities near edges because of the abundance and variety of prey animals present.” Know what that means?

Hawks and owls know about Parking Lot Theory. Heck, maybe they even invented it.

(Here’s the parking lot at Frick Park. A family of red-tailed hawks live nearby. I also just saw two Cooper’s hawks flying through today! #ParkingLotTheory. Photo by me)

4. Trash

You can’t have a parking lot without trash, right? Is it possible that birds are drawn to parking lots because of the availability of trash and human-discarded food?

Corvids, such as crows, are big trash fanatics, as are gulls. I even attended a Feminist Bird Club outing at a Kohl’s parking lot across the street from a dump, where we witnessed a gull flying away with a large piece of pizza in its beak. (Fly like the wind, Pizza Gull!) But as far as I know, warblers aren’t eating out of trashcans. They mostly eat bugs.

Still, does the presence of trash increase the presence of bugs that warblers eat?

I can’t find the answer to this online. Someone conduct some studies for me, please.

I’ve also wondered about trash in terms of its smell, and whether or not birds are attracted to stank. (Birds CAN smell—a fact that a lot of people don’t know, because John James Audubon himself claimed that birds CAN’T smell, and everyone believed him. Sigh.) Whether they enjoy the smell or not, migrating birds often stop at stinky wastewater treatment facilities; I had some of my best birding days at Nine Springs back in Madison, which is directly across the street from a sewage plant. A blog by the Audubon Society suggests that the surrounding water at these facilities tends to be warmer and full of nutrients, which causes insect populations to thrive, which creates a buffet for birds. So maybe birds just put up with the smell in favor of a good meal. Or maybe positive associations lead them to seek out sewage plants and garbage heaps and trash cans. Hear me out: What if the stinky bathrooms at Lake Kegonsa that day in 2021 were warbler-magnets??

5. Persistence

Time for the final and most ridiculous reason I believe in Parking Lot Theory:

The birds are watching you. And they know.

They know how much you care and how hard you tried to find them. They will reward your persistence and passion, or they will make fun of you for not trying hard enough. They live by the saying, “Good things come to those who wait.” They want you to appreciate them and also to suffer, just a little bit.

(A pine warbler I suffered for. Photo by me)

A different theory

I have to admit: Parking Lot Theory might be wrong.

Maybe migrating birds don’t actually flock to parking lots, but more people have the chance to encounter them there and report them to eBird, inflating our sense that all the good birds show up in parking lots.

This relates to a known phenomenon (and problem) related to community science apps like iNaturalist and eBird. The data collected from these apps can be biased based on who is using the apps, when they submit reports, where those people are located, and what those people are reporting. A biologist in St. Louis noticed the problem when she found that the majority of squirrels reported in iNaturalist were in the southern (and white) part of the city, even though squirrels definitely exist in other parts of the city, too!

So just because it seems like all the best birds are in parking lots, I suppose it doesn’t mean they actually are.

For the record, I also think people tend to tell their parking lot stories more often than they tell other bird stories. “Can you believe I hiked for three miles and got eaten alive by mosquitoes, only to find the bird at my car?” It’s a lot more fun to tell that story than to say, “I found the warbler in a tree! Exactly where I expected it to be!”

Final parking lot thoughts

Even if you don’t see warblers in the parking lot at your local park, you might still see other birds. My most common parking lot sightings involve cardinals, house sparrows, house finches, and robins. If you’re at a grocery store parking lot, you might see some gulls (as described in this article published by my hometown’s Times Gazette). Huge flocks of great-tailed grackles enjoy Texas shopping center parking lots.

I’ve also found over the years that the parking lot at your favorite birding hotspot is a good barometer for whether or not you’ll have a good birding day. If it’s going to be the kind of day where warblers fall out of the sky and land in your lap, you’ll probably know the second you open your car door and start listening. But that doesn’t mean you shouldn’t try, even on a quiet day. It’s about the journey, not the destination. Right? Right??

I’ll conclude with a great-tailed grackle from my recent trip to Las Vegas, who seemed eager to jump into a nearby trashcan.

(Great-tailed grackle photo by me)

May you find some magical parking lot birds this month!

Holly