The Hidden Lives of Common Nighthawks

[Robyn Bailey] Hello everyone, and welcome to today’s webinar from the Cornell Lab of Ornithology. We’ll be hearing from Gretchen Newberry about her research with Common Nighthawks. My name is Robyn Bailey. I’m the project leader for the Cornell Lab’s NestWatch program, and I will be facilitating today’s conversation.

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The Confederacy precedes the establishment of Cornell University, New York State, and the United States of America. We acknowledge the painful history of Gayogoho:no dispossession and honor the ongoing connection of Gayogoho:no people, past and present, to these lands and waters.

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Welcome, Gretchen. One of the reasons I invited Gretchen to speak to us today about Common Nighthawks is because they are a type of specialized forager called aerial insectivores. This just means that they primarily eat insects on the wing, similar to swallows, swifts, and martins.

As we’ll learn about in a short while, many species in this group have been exhibiting population declines over the past several decades. Crepuscular and nocturnal aerial insectivores are even less understood than their daytime counterparts, which is why we’re so lucky to have Gretchen here to help shed some light on this subject.

Gretchen Newberry earned a PhD in biology from the University of South Dakota where she studied Common Nighthawks. While earning her degree she writing The Nighthawks Evening, a book about the bird, the aerial insectivores guild, and the hidden world of nocturnal animals. She now promotes biodiversity and maintains a personal blog called A Feathered Reptile. Thank you for joining us, Gretchen, and take it away.

[Gretchen Newberry] Thank you for having me. I’m really excited to give this talk for Cornell. I’m really impressed by their work with outreach on so many things. And so I am going to share my screen here before I forget. All right, switch over to my talk.

I studied nighthawks for six years in South Dakota. I went there to study Nighthawks in grasslands. I am from originally Minnesota, and I love grasslands. And what’s interesting about the grasslands in eastern South Dakota and Minnesota where I grew up as those grasslands are disappearing. And so my study became about something different, and I think something more interesting as I hopefully you’ll see.

So this is the call of the night hawk. Maybe you’ve heard this call around sunset. I’ve heard from people who hear it a lot that it keeps them up at night. You might see this in urban areas, beaches, open forest, southeast. The Pine Barrens in New Jersey is a famous place for them, or in the sagebrush out west, but maybe less and less as the years go by especially in the east.

Oops, my videos are always tricky. Here we go. These are migrating nighthawks in Wisconsin, where I used to live. This is along the Mississippi River. You see them flying during the day. So enormous flocks travel down the Mississippi River every year.

So why are they called nighthawks if they can fly during the day? Well, they are mostly active around sunset, but they are neither strictly nocturnal nor a hawk. That’s for sure. And it’s becoming less common. So the Common Nighthawk really has one the worst names ever.

So if they’re not a hawk, what are they? They are a member of the nightjar order. Oops, I think I skipped this one. Here you go. This is the nightjar order in cartoon form. So the nightjar order named Caprimulgiformes. That’s Latin for goat sucker. And they were named for a legend that said they drink milk from livestock.

And people might not have known what these birds were. They saw them only in the dark. They were eating insects that really may have been vectors for disease for their livestock. So while they may have been part of it a legend, they are often misunderstood, the nightjars.

So what are the nightjars here in the US? We have the eastern whip-poor-will, the chuck-will’s-widow, the common poorwill lesser nighthawk in the Southwest. So they are nighthawk, but they’re concentrated on desert areas. They’re a little smaller. Like a lot of hot hotter environment animals are, they’re a little smaller. The Common nighthawk and then the Italian Nighthawk lives really in the Caribbean. And it will sometimes visit Florida, so I included it here.

And I should say the common poorwill was first described in writing by Lewis and Clark. They are the only bird that hibernates in the world that we know of. And other birds we have the Mexican whip-poor-will and other common pauraque. These are found in southern Texas and New Mexico.

So where is the Common Nighthawk? They’re found coast to coast, less and less in some areas, as you can see there in white. In blue, those are places where they are increasing as of 2015. And in red, those are places where they’re decreasing. So overall, they’re down by 60% since the 1960s. And that’s typical for a lot of birds. This is breeding bird survey data.

So this is the bird I studied in South Dakota, where they use open forests along the river and also some pine forests in the Black Hills. They also use sandbars in the Missouri River. They use urban areas and they use grasslands.

And so nightjars are really found all over the world. There are 96 species of them. Most of them live in the Southern Hemisphere. All but the nighthawks are completely nocturnal. Other notable nightjars of the world include this guy. This is the great eared nightjar, which gets a lot of attention on social media. This is a really funny little drawing that Birds in Shoes made for Instagram.

And I think this bird really inspires a lot of people, but I also think it inspired, perhaps, this animal Toothless from How to Train Your Dragon. It seems so similar to me. I can’t help but wonder if they were inspired by nature. Nightjars have that flattened face and big eyes.

So the great eared nightjar lives in India and Indonesia. It is the largest of the family at 12 to 16 inches long. It’s a pretty cute bird. Let’s see if this video works. There it goes.

[Robyn Bailey] Hey, Gretchen. I just wanted to pop on and say that the sound isn’t being shared.

[Gretchen Newberry] Oh, it isn’t?

[Robyn Bailey] No. So maybe if you stop sharing screen and pop it back up and hit the Share Sound, we might be able to troubleshoot that.

[Gretchen Newberry] I am so sorry about that.

[Robyn Bailey] That’s OK. The audience just really wants to hear the bird.

[Gretchen Newberry] Then again. Oh, you know what? Now I can’t click those buttons. The Share Sound in optimized video clip.

[Robyn Bailey] Oh, darn.

[Gretchen Newberry] Yeah. So I’m going to share anyway.

[Robyn Bailey] I’ll put the links into the chat, Gretchen, so people can hear the sound on their own, OK?

[Gretchen Newberry] Yeah. And I would also say that I have a YouTube page where you can see all these clips. So if you search for me on YouTube, you’ll see them. So we’ll breeze past this guy. For some reason, this bar for Zoom is in my way. Here we go.

OK. So also we have the common potoo. I recommend following the nightjar hashtag in whatever social media you use. It’s not only fun stuff like this, like the common potoo, which looks like a Muppet. But the beautiful diversity of nightjar is all over the world.

So he also has a pretty weird, call that common potoo. And he’s not an owl. That video describes it as a potoo owl. Anyway, back to nighthawks, so they can live in prairies. So that’s the lower left in your screen, open forests on the upper left that was taken by a colleague of mine Elly Knight in the boreal forest in Canada.

Open forest like that and beaches even, that’s on the upper right, and then they are also ground nesters. But most of my research was on rooftops in places where they can’t find an open ground. So that lower right picture is something I took on a rooftop.

This is a pair that I studied on a hospital roof in a small town in South Dakota. But they can use rooftops anywhere as long as they are flat and have gravel to disguise the eggs. So that’s the male that’s flying up ahead. And then that is the female down in the gravel. So you can see the male has that big white throat patch, but it also has those white little bits on his tail feathers. So that identifies the male.

So this is me doing some surveys on these rooftops. And what’s interesting is, when you do these surveys, you’re walking along and all the gravel looks alike and then all of a sudden, you see this scattering of feathers across the rooftop. And you might be tempted to follow those feathers, but really what you have to do is train your eye on exactly where they came from because that is where the eggs are. So on the left that’s me approaching a nighthawk. That’s about as close as I ever got to one before it flew away.

I should say that a lot of time people didn’t know that they had nighthawks on their roof. They were so great at camouflage. They tend to only come out at sunset. So part of my work was explaining what a nighthawk was. And so which makes me think of nighthawks and art, so they nested on rooftops. They came out at sunset, and they hang around downtown. Maybe you’ve seen this painting before. This is by Edward Hopper called The Nighthawks.

Maybe people saw these birds flying around bars and restaurants and started naming their bars and restaurants after them, just a thought. So a lot of cities all over the world have bars named the nighthawk or the nightjar. I visited one in London in Soho. So perhaps people once knew these birds better once when they were more numerous in towns and then named their bars after them.

Incidentally, Hopper painted this at the beginning of World War II as an homage to the nightlife that he missed when blackouts had started. I find that really poignant. I know I missed going out at night and during the height of the pandemic. So it’s quite poignant that this painting describes a bird and a place all at night longing for a more lively nightlife. And I think that’s interesting thought about nighthawks.

So back to biology, why did they like gravel? They need the camouflage for their eggs and chicks. And while I’m talking, you can try to find the eggs and chicks in these pictures here. They don’t make a nest, and so they need to stay with their young for thermoregulation. The eggs and chicks need their parents. They don’t have a feathered nest to keep them warm.

And staying camouflage keeps the adults eggs and chicks hidden during the day. Here they are. In case you miss them, that’s the chicks on the right, a bit of fluff and then the little round stones there on the left.

Roofs are hot, so when it’s 90 degrees Fahrenheit on the ground, it’s 120 degrees Fahrenheit on the roof. Nightjars are drawn to heat. They are second to pigeons and doves in terms of heat tolerance among the bird orders. So these chicks here on the right are three or four days old.

And in my study on these rooftops, only 10% of my nest survived from egg, to fledgling. Most died as eggs, but many died in the first one to two days of life before they could walk to shade. So these birds are considered semi-precocial. They’re not as naked at hatching as songbirds are, but they’re not ready to run like a crane. So they’re somewhere in between.

This is probably true of a lot of ground nesting birds in terms of their vulnerability in an open habitat like beaches, rooftops, grassland. They are vulnerable as eggs and especially in the first couple of days when they are chicks. So they need minimal disturbance to survive. And if you flush the parents, that’s time away that they could be keeping their chicks cool.

So they are generalists in theory because they can live in a lot of habitats, but they’re becoming more and more of a specialist in their habitat. They like forests, but a lot of those are disappearing. They like beaches, but those are getting crowded with tours and dogs affiliation, those sorts of things.

They like grassland, but we like to plow over grasslands and grow raw crops. And they like gravel rooftops, but we are starting to remove those gravel from the rooftops, and those rooftops are getting really hot, even for a heat tolerant bird like a nighthawk.

So don’t lose hope. You can see them in lots of places. This is Malheur National Wildlife Refuge near where I live in Portland, Oregon. There are lots of good places to see them. If you like a bird and you visit Malheur, you will see lots of them in the wetlands scooping up insects, great clouds of them during the day sometimes, and probably nesting in those surrounding sagebrush.

That’s the first place I ever saw one. EBird, of course, is a great tool for finding nighthawks. And if you stay at the Malheur Field Station, they will be resting on the trailer railings during the day.

So here’s where they are observed in the breeding bird survey. The redder areas are where they spotted more nighthawks within the 2 and 1/2 hour period of the survey, so lots of nighthawks in those south central plains. And then in sagebrush areas, those are hotspots for nighthawks. They like it in Florida apparently too.

Here’s an interesting tip for finding urban nighthawks. This is eBird data. So this is La Crosse, Wisconsin, where I used to live. And you can see these are urban areas in their spot. You can see where people had spotted them. But when you zoom in, you notice there’s some large flat rooftops. And these lighter gray or beige rooftops have gravel on them. Those darker gray, that’s a different material.

So you can scope that out and then go back to that same spot over and over again all summer during June and July when they breed and see that same nighthawk calling over that same rooftop every night if the weather’s right.

So they like hospitals, schools, strip malls, really old strip malls, box stores if they’re old. And if they’re nesting there, you might see them. They have one of the shortest breeding seasons of any bird. They tend to arrive late May, and then they start leaving in August.

All right, cool facts about nighthawks. They have really short legs, and so they walk around really clumsy like this. They’re just not built for walking. They are built to fly, and they eat insects which allows them to eat while they migrate.

It’s a feast or famine kind of life. Big payoffs for big gambles. But without a constant supply of food, they are pretty vulnerable like a lot of insect eaters like bats, which bats are really vulnerable to winter diseases like white nose syndrome, and that’s wiping out entire species. But without a constant supply of food, which seems to be ephemeral with the weather, that makes them vulnerable at times.

So what you don’t hear is at the bottom of that dive, there was a whirring sound. And that is where they spread their feathers. And wind rushes through their feathers, and so this is called a boom call. And they use this to establish their territory. They might boom-call over and over and over and over again. Some people think that both males and females do this.

And I mentioned this challenge of a ground nesting bird is that if they are disturbed too much that means they have to lure the predator away from their chicks. That’s time that they lose helping their chicks stay cool. And their chicks are more exposed to the weather than cavity or tree nesters. And they are especially vulnerable in the first couple of days because they’re not mobile enough to find shade or sun to counteract the sun, wind or rain or whatever the case may be.

In addition, every instance of stress due to interaction with a predator, whether that’s people or your very friendly dog, activates their stress hormone system. So it activates the hippocampus, and then that sends a signal to the pituitary and the adrenal stress hormone pathway that diverts resources from building fat and tissues to grow strong enough to fly away and live independently for a few weeks until they have to migrate to South America. Everything is on a very short timeline with nighthawks. They live in the wing. They don’t have a lot of time for this.

So what they do have a lot of is a lot of attitude. They have hummy bills and claws. So even their chicks have to have a lot of attitude if they’re discovered. But they don’t have any weapons to back that up. Have you noticed that big mouth.

He’s built to fly around and eat, and he has that big mouth to dissipate heat, so a lot of cooling air can move through that big mouth of his and help him stay cool. So he’s pretty great at it. And even if he’s struggling, it’s kind of weird.

Let’s see. So females can be a little aggressive in their own way at the nest. This one is making a rasping, a clicking, and a squeaking noise all at one. She was doing this repeatedly while I was measuring her chicks. And they like to use this broken wing routine to attract my attention, like the killdeer neighbors that they.

They also like to lure people away. So she just moves a little bit away and wants to attract my attention away from her eggs. It’s pretty effective. I mean, who wouldn’t want to follow that around? They have a pretty interesting social life, like this bird.

So this is a male on a rooftop. He sat and that same spot for four years. It came back every year, sat in the same spot. He lived on a very large roof. This is where he sat. He’s very vigilant. He sometimes met me at the parking lot and let me know that he was not happy to see me.

This is a school, so there are a lot of students running around during the summer doing sports, and he didn’t care about them. But he knew me because I’m the person who comes on the roof and harasses his birds, his females and his chicks. So it’s pretty interesting that he recognized me every time.

So this is where you sat, which is there. This is the roof. This is Elk Point-Jefferson Elementary School in South Dakota. That’s where you sat every year. These were his females on the first year. And then on the second year, they like to use the same spot over and over again, and then on the third year.

So interestingly enough, this one on the lower left that’s interesting bird I called Lady Sisyphus. She never hatched an egg in the years that I studied them, perhaps because she was pretty far away from the males. Really couldn’t keep track of what was going on with her. That structure in the middle is pretty tall actually.

And it’s possibly because also there may have been a sneaker male who kept distracting her from hatching the first male’s egg. So this is her, and then this other male shows up. And then she would abandon her eggs and try again with him. And there wouldn’t be enough time, and those eggs wouldn’t work out either. This happened over and over again for four years.

So sneaker males are really interesting in ecology and the classic study elephant seal. So here we have this big male in a big harem, and then another male shows up and wants to fight. And while that’s going on, this guy shows up. I mean, look at him. He’s pretty sneaky looking.

Interestingly, enough this only works out like 10% of the time. So the sneaker male, 10% of the time manages to meet with a female. And then she’ll like give up on her young and start up with this new guy. But it’s a pretty good gamble. He doesn’t do any work. He just shows up and does this.

And so a lot of that was happening with nighthawks. So here here’s another pair. She was on a set of eggs and then this male shows up, and then she abandons that. So it happened a couple of times, at least. But males are really beneficial to nighthawks. So here we have the male with the big white throat patch. Excuse the mourning dove that is in so many of these pictures.

So, yeah, here’s the male who’s keeping cozy with the female who is thermo-regulating the chicks. He’s really effective at keeping them together. But not only that, but he will also incubate the eggs. This is a female on some eggs, and the male shows up and then she can take off and eat for a while. So he can incubate eggs.

Some males don’t do any of that. They just move around from roof to roof and do a little bit of work here and there. But they will also feed chicks. So here is the male with the big white throat patch feeding the little fuzzy pointed thing, that’s a chick, while the female is sitting over here.

So I mentioned that the success rate for these nests was 10%. And when a male was present, that went up to 50%. So having a male around was really a good thing for nighthawks. So I mentioned that these rooftops are going away.

This is a rooftop that was in the middle of transitioning from one rooftop type to another. So on the bottom is the gravel that’s classic. And then that middle rooftop is the rubberized structure underneath that gravel. So the gravel is meant to keep that rubberized part down from flying up in the wind and protects that part.

And then that top white roof is what people are moving toward, the sort of plastic white canvas material. And this white plasticised canvas material at the top has the potential to be more energy efficient. So I can’t really blame people for wanting to do this. I mean, can you imagine trying to haul a bunch of gravel onto a rooftop. I’ve seen it done, and it’s really quite a production.

So interesting strategies, here is the New Hampshire Audubon Society. They went out and found some rooftops that had been converted, and they sent out teams of volunteers to rooftops to put out small gravel patches. And sometimes the nighthawks didn’t show up. And then sometimes if they did, there would be a predator because there was this weird thing going on, this weird gravel patch that wasn’t there.

That accept all kinds of predators, and most of it is seagulls and crows, the usual suspects. But these volunteers are still working on the problem, so perhaps they have better solutions. I don’t want to dismiss their work. I applaud their effort for sure.

So nighthawks are considered aerial insectivores. These are animals that fly around and eat insects. So you can see swallows, swifts, and bats in this group. And that’s their guild. So a guild is a group of animals that make their living in a similar way. And I made this drawing back in Wisconsin when I lived along the Mississippi River.

And so this is the ecosystem of why aerial insectivores matter. So you have leaf litter that comes down from the tree that feeds invertebrates, that feed emerging insects, and also fish and turtles. And those emerging insects feed the aerial insectivores. And then those fish feed a great blue heron, who then drops a fish matter on the banks, which then in turn fertilizes the tree. So it’s all part of this ecosystem.

Aerial insectivores, they don’t live in a vacuum. They are the fastest dwindling guild of birds in the world. This is why I keep talking about them. So that lavender line, those are the aerial insectivores. And then the next line up is this mustard colored line, and those are the grassland birds. And nighthawks are members of those guilds.

But they do have a superpower. They can withstand a lot of heat. They do this by panting and entering torpor. So that’s a shortened version of hibernation. All the nightjars really use torpor, the shortened version of hibernation in which they lower their metabolism. Sometimes they match their body temperature to the environments. There’s no heat loss or exchange. And then they hunker down until there’s food to eat. So they might do this during a thunderstorm, or they might do this when it’s extremely hot.

So if these champions of thermoregulation are struggling, what does that say about less heat tolerant organisms in hotter environments? So this graph is the anomalies in temperature. In the upper left is North America. Lower left is Europe. Lower right is Asia. Upper right is Africa. And you can see the Americas are not experiencing as extreme anomalies as other parts of the world. So nighthawks breed in the Americas.

And so if they’re struggling in the heat and they’re extremely heat tolerant, it’s just a whole lot of cascade of questions that I have about the rest of the world and the rest of the organisms.

So what can we do? Well, we can do a lot of things. So these are ground nesting birds. We can keep our pets from roaming freely. These are my cats in South Dakota that I used to take out on a leash. They didn’t love it, but I knew that they were cold blooded killers straight up. So lots of critters live on the ground, including nighthawk chicks that recently fledged. So I worked in an urban environment with a lot of feral cats. And I worried about the chicks that would fledge to the ground.

We can also spread awareness about ground nesting birds. This is a campaign by the Audubon Society at the National Wildlife refuges on the East Coast on behalf of shorebirds. This is a really interesting sign. It’s saying, hey, we love dogs, and we get that even your friendly dog can frighten birds sadly. And here’s a QR code to show you where there are off-leash areas that you can take your dog because we all love dogs.

This is really interesting. So this is the Thames Basin Heath Partnership out of London, UK. So European nightjar nest in the heath. That’s like their version of grasslands. In the US, we’re not super aware about ground nesting nightjars, but they are super aware, or at least they’re trying really hard.

In my book, I talk about the efforts to protect nighthawks in British Columbia beaches. But this is pretty cool too. So they have signs asking folks to keep their dogs leashed on behalf of the nightjars that nest on the heath. They also lead nightjar walks, which I would love to go to.

No one’s ever led a nightjar walk to my knowledge. I’m sure there’s people elsewhere in the world. Nightjars are everywhere. Anyway, I would love to go some time in the summer and see this nightjar walk. So they do this at night so people can see them in action. So if you’re in London during some summer, I recommend looking these folks up. They are on Instagram.

This is a senior warden Zoe putting up signs. They have multiple wardens and a lot of great info-graphics about ground nesting birds. They not only have nightjars. They have warblers and wood larks. And their logo is a nightjar. So who can say no to that?

Other things we can do. We can create eco-roofs. So these are green roofs. And I like this one because it has gravel as well as some greenery to keep the roof cool. So not only nighthawks use rooftops, but killdeer.

And where I live in the Willamette Valley in Oregon, both nighthawks and killdeer are species of concern for the State Department of wildlife. And the fact that they’re both on that list says a lot about grassland being gone and then these birds moving onto rooftops to replace that grassland habitat. We can also conserve habitat when we can.

This is a map of the Missouri River where I studied nighthawks. In the 1890s, that upper map, that’s the 1890s with lots of sandbar in that light beige grassland and green, and then the forest in dark green. And then the lower map is the 1950s onward, that darker beige, that is row crop agriculture. So you can see what is happening to grasslands in a lot of areas.

Another thing you can do is buy duck stamps. Because of the ethanol boom in the decade from 2000 to 2010, we lost the equivalent in North America of the size of Kansas. So I’ll say that again. We lost Kansas in terms of grassland in 10 years in North America.

So while I was studying nighthawks, I was trying to study them in grasslands but they were really weren’t there anymore because they disappeared from Eastern South Dakota where I lived and was studying them. Western South Dakota is a very different story, lots of grasslands. So it’s really interesting.

Duck stamps, what that does is when I was at University of South Dakota, I volunteered for the National Wildlife Refuge System. And the Refuge manager said, all of a sudden during this ethanol boom, the prices of corn suddenly dropped, overproduction. And then people were trying to get rid of row crop areas that could then be converted back to grassland or at least wetland.

And so they were just dying for them to become easements. So a lot of those easements were paid for with duck stamp money. So these duck stamps can be bought at your local National Wildlife Refuge. Every year the Fish and Wildlife Service holds a contest for artists to paint the duck stamp and has a junior contest for kids too. So one fell swoop, you can support art and conservation. Go check them out at your local Wildlife Refuge.

So why is migration so important in the middle of the country? Well, this is a study by my colleague Elly Knight. She led a team of nighthawk researchers all over North America. We put satellite transmitters on birds in Florida and Alberta and Saskatchewan, Ontario, Nevada, New Jersey.

The west coast birds traveled over the Rockies and joined up with the central plains birds. So that prairie pothole region in the middle of the country is super important for migrating birds including nighthawks. So we often think about waterfowl, but lots of birds use this central corridor to migrate.

And these migration sites are so important. One spring, a third of the nighthawks in my study didn’t return. Migration mortality is a great unknown for many birds. Lack of stopover points could be a reason why. Coincidentally, if you want to see a nighthawk show, check out the nighthawk and other hawk migration in Duluth, Minnesota during the fall migration at Hawk Ridge. You’ll see thousands of birds every day.

Also we can keep an eye on pesticide use. Lots of it ends up in wetlands. These are nurseries for the insects that nighthawks eat. A lot of it is runoff from our urban areas. There’s lots of alternatives to pesticide use. Insects serve as an important base for an ecosystem, and pesticides don’t really differentiate between insects, whether they’re beneficial or pests.

So with that, I want to thank you all for having me and for coming. I’m super excited that I got to talk about nighthawks. I have a book. It’s available at bookstores, libraries, and on Kindle. Here in Portland, it’s sold in the big Powell’s Bookstore here in Portland who filed them under raptors. Sorry, I just have to point that out that they are not a raptor.

And let’s see. Lots of people I have to thank, including Cornell for having me, OSU Press for the book, and the University of South Dakota, of course, for allowing me to do this research. So I will stop sharing.

[Robyn Bailey] Thank you, Gretchen. That was wonderful. We had so many questions come in to the Q&A while you were speaking. And I’ve tried to condense them as best I can. And so let’s just jump in and ask some audience questions. How about that?

[Gretchen Newberry] Great. Sounds good.

[Robyn Bailey] One common question was, when nighthawks are not nesting on rooftops and when you see them outside of the city, what kinds of places are they nesting on in grasslands like forests when we know there’s– we see them not in a city area?

[Gretchen Newberry] Yeah. Well, they will find gravel, even in a forest. So an open forest, they really like little gravelly bits. It has to be pretty open forest because they have long wings, and they’re pretty clumsy in tight spaces. So they have these giant seagull wings and like a little dove body.

They’re really acrobatic in the air, but they can’t really handle a lot of tight quarters kind of stuff. So they love gravel in grasslands, in forests, on beaches, anything that matches their pattern and the pattern of their eggs.

[Robyn Bailey] That’s so interesting. You talked about this a little bit, but another question that we saw was, given their habit of nesting on rooftops, are nighthawks experiencing nesting fatalities due to increased temperatures?

[Gretchen Newberry] Yes, I definitely found that. Yeah, I found the greatest source of their mortality was unhatched eggs. So they just cooked in their shell and that was the end of it. But I did collect a lot of those eggs and use them for a genetic study.

So it didn’t go completely to waste. It was pretty sad sometimes. And then occasionally chicks would die in the first couple of days because they couldn’t find shade. They weren’t very mobile. There was some sort of disturbance where their parents couldn’t hang around.

[Robyn Bailey] And as a follow-up to that, one person did mention whether there could be some kind of shade or shelter provided for the chicks. And we sometimes see that with beach nesting birds, like a little shade platform that they can get under and hide. I don’t know if anybody’s ever thought about that for nighthawks or if that would work, but that was a suggestion.

[Gretchen Newberry] Yeah, there’s actually quite a lot of places for nighthawks to find shade on rooftops. There’s all kinds of things on top of rooftops, little transom and chimneys and things. The problem is they can’t walk until day two. And once they can, then they’re pretty good at finding that.

[Robyn Bailey] How does increasing light pollution affect nighthawks?

[Gretchen Newberry] That’s a really good question. I don’t know that anyone has studied that. Light pollution. I imagine it probably bothers them. They’re a lot more adaptable than a lot of birds because they can fly around during the day. Maybe it would affect.

Well, the thing is they are drawn to light. So a lot of times you can see them in urban areas around giant light fixtures like ballparks or mall parking lots because that’s where the insects are. So they’re probably OK with a fair amount of light. I think they just eat at night because that’s when the insects are really out.

[Robyn Bailey] Thanks for that. One person wants to know– well, I combined two questions. Did you observe crows and/or gulls predating their nests on the rooftops?

[Gretchen Newberry] I did not observe that, but I had a very interesting incident happen where a bunch of morning doves mobbed a nest. Sometimes I give talks and I show the progression of photos where it’s like one dove and then another one and then it’s like a mob, and they’re like staring each other down. And they look really benign doves. You don’t expect them to be predators, but they’re hungry, just like everyone else.

Then you see like the female opening your mouth and flapping her wings. And they can’t really physically fight. They can just put on a really good show nighthawks. And then in the morning doves just swamped her. And then the male shows up, and there’s more of a bigger show. And then eventually, they just both leave because they just don’t have anything to back it up.

And then next time, I visited that nest there was just no sign of anything, no eggshells, no chicks, no nothing. They just ate it all. There was nothing to find. And so then I took my nest camera home and watched the whole show. It was very strange.

[Robyn Bailey] That’s very strange. I’ve never heard anything like that. Very unusual observation. Two people wanted to know about solar panels on a gravel rooftop. Can they coexist? Are there positives and negatives of having solar panels alongside common nighthawks?

[Gretchen Newberry] Oh, that’s another good question. I don’t know that anyone has studied that. I have to tell you nighthawks are a rare thing to study, especially in the US. They’re not listed here, and so a lot of studies are driven by finding funding and also addressing an animal that may be at a critical spot.

A lot of the studies for nighthawks have been done in Canada. My outside committee member was Mark Brigham, Regina Saskatchewan, and all of his students. They do a lot of the nighthawk work. And I don’t know that they did a lot of rooftop work. I think I might have been the only rooftop person working at the time. And I didn’t have any solar panels in South Dakota when I was working, but that would be a fascinating question to answer for sure.

[Robyn Bailey] You may have answered inadvertently another question that was asked, and that was about green roofs. Have they been found on green roofs, did you find any, does anybody know anything about whether they would use a green roof?

[Gretchen Newberry] So I did not encounter any green roofs in where I was in South Dakota. I worked in pretty small towns in southeastern South Dakota. I wish I could remember her name, but there was a graduate student in planning for University of Oregon. And she did a whole study about green roofs and how this green roof could be adapted for wildlife as well as thermal regulation of the building itself.

So I wish I could remember her name, but I’m sorry. So she did a really interesting study about it. I’m not sure if she really ever tested it out. But I’m supporting of that because I think it’s an improvement over nothing for sure.

[Robyn Bailey] So maybe one kind of question that we could ask, maybe your research didn’t necessarily speak to bats, but do you think nighthawks and bats compete in terms of insect food?

[Gretchen Newberry] Yes, I do. There is a colleague of mine named Gabriel Foley. He worked out of the Mark Brigham lab. He wrote a paper about this because he had observed nighthawks and bats foraging at the same time. And what he noticed is that when bats are present, nighthawks will fly higher.

So in the bird world, oftentimes the advantage is for the smaller, speedier animal. So nighthawks are bigger than North American insect eating bats. So the bats would take the prime location for insects and then force the nighthawks higher in the column to eat. So that was a really interesting observation.

And also they don’t really overlap that much. So oftentimes, I would see nighthawks flying around sunset. And then they would lower their activity level once it was fully dark, and then the bats would come out. This is the idea about resource partitioning in ecology where no two animals can have the same niche. And so among the aerial insectivores they differ by where they are in the air column and then also the time of day. So interesting question. I’m glad you asked it.

[Robyn Bailey] That was a good question. We have lots more questions, and they continue to come in. So you’re doing a great job of getting through them. Let’s switch tracks a little bit and talk about their nesting. Do they mate for life? And do both male and females incubate the eggs?

[Gretchen Newberry] It varies widely. So sometimes there is a male who doesn’t hang around at all. He just visits a number of nests. Perhaps, he mates and just disappears. Some of them are very tied to one female. They will just hang out with this one female in this one small roof and go nowhere else. Or there’s the guy I showed you who had multiple females. And then there’s like sneaker males who show up.

And it’s all over the map. And it has a lot to do with where is the food and how much can I eat and where do I need to go to eat, and can I do that all at the same place where I have my female? How much do I want to protect this site from other males? So it can depend on probably food and also personality of the bird. So each bird, there’s a variation in behavior between individuals in so many species.

[Robyn Bailey] How about that camouflage, does their plumage change based on where they are and what region they’re in?

[Gretchen Newberry] For sure, yeah. So the forest birds tend to be darker. The beach birds tend to be lighter. The Great Plains birds tend to be lighter. Their size also varies. They can be 55 grams in Florida, and they can be 70 grams in South Dakota and 90 grams in the upper boreal forest of Canada.

And we know this because of our study where we put transmitters on birds. And the minimum size of the bird that you needed was 55 grams. And the southern bird sometimes we had a hard time getting them to be big enough to carry a satellite transmitter.

[Robyn Bailey] Interesting. We did have a question about the duck stamp. Is that something that the US Post Office carries? Can you buy them at the post office?

[Gretchen Newberry] You can’t. I think they’re only sold either– they might be sold online, but they’re definitely at the wildlife refuges. If there’s a visitor center, then they will sell them. So they’re sold primarily because if you want to hunt on a refuge, you have to have a duck stamp. But it’s also a good idea for birders to own one too, take part in supporting your local refuge because it’s pretty important too.

[Robyn Bailey] Here’s a question that I really enjoy because it looks like it would be true. Can they bite? And obviously, you would probably never get close enough to one to be bitten. But if you were capturing them and measuring them, did they ever try to bite you?

[Gretchen Newberry] No. They never did. Their bills are so tiny and so fragile. They have big, wide mouths, but it’s only the rim of their mouth that actually has a beak. So it’s mostly pouch. They’re really lightweight birds. They’re really not very sturdy. They’re kind of a kite, holding like a very feisty kite, not a kite bird but actually owning a kite. They’re really lightweight. And they’re a lot of attitude and nothing else.

Their claws are really tiny. They’re just a whole lot of show. I’ve been bit by other birds, by the way. And gross beaks are really painful. They love this part of your hand. But a nighthawk tries nothing except scramble away from you.

[Robyn Bailey] I have had that exact experience with the gross beak finding that piece of flesh between the fingers. They’re very good at that.

[Gretchen Newberry] For some in mist netting, my coworker was like, oh you get to do all the gross beaks? And I was like, why? And he’s like, oh you’ll find out.

[Robyn Bailey] I love it. We have a poop question, but there’s a purpose. Has anyone analyzed their poop because they would like to know what kind of insects they rely upon?

[Gretchen Newberry] Yeah. There are people collecting poop for genetic studies I believe. And then there are people who are collecting poop for their diet. So their diet really varies on where they are. They’ll eat beetles in forests. They’ll eat mostly mosquitoes and other Diptera in urban areas.

They can digest a lot of kinds of insects. They’re really opportunistic. They’ll just eat anything. They’ll eat moths. They’ll eat anything they find really. I don’t know that they have any preferences. If you read the literature about their diet, it’s widely varying.

They have a really interesting part of their stomach called the cecum. It’s like an extra pouch. And not a lot of birds have these. It’s like a little extra area where they can digest hard things like chitin and stuff. Whereas I think a lot of other birds would spit that kind up, they can digest that I believe.

Yeah, I’ve heard from other people that their poo is really smelly. I did not experience that, but I think it might have something to do with what they ate. And in South Dakota, they just ate a lot of mosquitoes I believe. And other areas, they might have eaten some pretty stinky bugs.

[Robyn Bailey] Maybe stink bugs. So you told us that they eat on the wing, meaning as they’re flying around and moving. Can you maybe go into a little bit more detail about how they eat? We saw that giant mouth. Is it just open on all the time filtering or do they sense when an insect is nearby and catch it? How do they eat?

[Gretchen Newberry] Yeah. With that big mouth, you would think they would just fly around like a whale shark and eat everything. I don’t get close enough to see if they actually do that. But what I do notice is they will make little minor adjustments as they fly around. So they definitely see their prey and then get it. So I think it’s probably a combination of both.

[Robyn Bailey] We have another question about migration. Do they follow insect migrations when they’re migrating?

[Gretchen Newberry] Wow.

[Robyn Bailey] That’s a tough one.

[Gretchen Newberry] That’s a really good question. I bet it has everything to do with it because they don’t show up until the insects emerge. I don’t know a lot about migrating insects or which ones migrate. I always think of migrating insects is like monarchs.

And I don’t think they would ever eat a monarch. I don’t think they can eat a monarch. Yeah, that’s a really good question. I would love to know more about insect migration so I can answer that question. I’m sorry. That’s like my dream job. If I couldn’t study nighthawks is to study insects.

[Robyn Bailey] Interesting. We have just a few more minutes. I’m trying to look through and see if I have missed any more common questions. Let’s see. We had one question about how did you capture them to put on the transmitter?

[Gretchen Newberry] Very good question. So we use mist nets. Like a lot of birds, we set up these really fine mesh nets on these poles. It looks like a volleyball net. And we did it in urban areas. So sometimes you were like in a playground and you couldn’t stick things into the ground, so you made this little contraption which was freestanding with like a tire on the bottom to anchor it down. And then we put some really loud nighthawk calls underneath it to attract them.

And the theory behind mist netting is that you put it in a darkened place where birds don’t see it, and then they accidentally fly in. With nighthawks, it’s a different story. They have really good eyesight, and so they would often fly laps around the net. And by playing the call, we were basically making them mad. They would get so mad. They would just fly into the net to attack it, and that’s how we would catch them.

They’re pretty wiped out by the end of it. Poor guys. It was mostly males who we caught because it was aggression focused.

[Robyn Bailey] We have another question about, how do they feed their young? Do they bring live insects and put it in their mouth, or do they give them some kind of digested bug mash? How does that work, do you know?

[Gretchen Newberry] I don’t know. I wish I knew. I used to study swallows before nighthawks. And swallows do like a combination of things. They would go out and forage for a period of time, maybe 10, 15 minutes, and they’ll have partially masticated insects in their throat called a bolus, and then they’ll have some live ones hanging out in their bill. And then they will slowly stuff chicks full of both things.

And I did this study where I intercepted that and caught the bird at the moment they were about to feed their chick and then removed that from their bill and stuffed it in a vial to study later. And often I noticed that it was just like, here’s the ball of massive insects.

And you identify them by little parts, and then there’d be like a full on insect in there. I suspect nighthawks and swallows forage in much the same way. They disappear for 15 minutes and gather everything and then come back. So they might have a combination of dead and alive.

[Robyn Bailey] OK. And then we had a question that you talked a little bit about, and that was how we can help Common Nighthawks, and you gave us some great tips like keeping the gravel on the roof and buying a duck stamp and preserving habitat.

I also wanted to point out that the Cornell Lab has also just recently created a guide for how to help aerial insect divorce in general. It’s not specifically about nighthawks, but it does mention nighthawks. And I’m going to put the link in the chat.

And I think it’s called Creating an Insect Buffet for Birds. So this is just a quick guide to help, and it’s free to download to help you remember some of the things that we can do to help aerial insectivores because it can be a bit challenging for us individuals to help them because they do eat those flying insects, and we need to be having insects for them. So

With that, we are at 8 o’clock Eastern Time, so we’ve reached the end of our hour. And I wanted to let everyone know that I’ll be emailing our attendees tomorrow with the recorded webinar and all of the resources we discussed. Thank you again so much, Gretchen, and to our audience for such great questions. And have a great evening, everyone.

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