Laura Erickson's For the Birds

Saturday, February 11, 2012

Rehabbing Nighthawks

Fred the Common Nighthawk

During the 1980s and 90s and a bit into the oughts, I was a licensed wildlife rehabber. I mostly took care of non-raptors, keeping hawks and owls here only until they could be transported to the Raptor Center. I became fascinated with nighthawks (belonging to Caprimulgiformes, and so only distantly related to owls and not at all to hawks) the moment I held my first. I got a call one spring morning from a construction worker north of Duluth. I went to the site, and three young, rugged men were standing together, one holding the nighthawk close to his breast. He looked at me and asked, “Can you make it better?” The bird, an adult male, had a broken wing, apparently caused by a collision with an overhead power line. Most nighthawks brought to rehabbers have been injured in collisions. Either sex may be hit by cars, often when chasing an insect illuminated in headlight beams. And either sex may collide with wires, but adult males seem to be the ones most often hurt by them in spring, presumably when doing their booming courtship dives.

Although the wing was broken and skewed, there was no external bleeding, so it at least wasn't a compound fracture. If the men's pleading eyes weren't enough to make me want to do my best, something about the bird's calm, dark eyes, looking directly into mine, touched me deeply. This was the most Zen-like bird I'd ever touched.

When I brought him home and opened the box I'd carried him in, I was greeted by the most horrible smell I'd ever experienced—worse even than from a Great Horned Owl that had spent time with a skunk—along with a slimy liquid, very dark brown mess. I figured that under the stress of being injured and handled by people, the poor bird had developed diarrhea.

I opened and thawed a small container of unflavored Pedialyte (whenever I bought a bottle, I divided it up into smaller portions which I froze and kept on hand for emergencies). I dipped my index finger into it, and then brought the one drop clinging to my finger up to his bill. As it dribbled onto the tip, the sensitive feathers along the sides of his mouth detected the fluid and he sipped it up, and looked eager for more. I gave him several drops—this would help prevent dehydration and also shock if his electrolytes had gotten out of balance.

I had some Vet Wrap on hand (that 3M special tape used by veterinarians and, under a different name, by doctors. It sticks to itself but not to skin, fur, or feathers) so I very carefully aligned the wing bones, held the slit half of a plastic drinking straw against the wing to brace the radius and ulna in place, and wrapped the wing against his body with Vet Wrap.

Then I had to figure out what to feed him. I called my good friend Koni Sundquist, who had cared for many nighthawks while she was rehabbing, and she said to give him mealworms, crickets, and a mixture she'd developed over the years based on mashed dry dog food, crumbled hard-boiled egg yolk, and several other ingredients to provide the vitamins and minerals he needed. (This was before Kaytee Exact was available.) She said to mix it with enough water to make a mash the consistency of cookie dough, and to feed it to him in pea-sized morsels. She said it might be tricky to get him to open his mouth at first.

Tricky didn't begin to describe it. I'd never fed a bird by hand before except nestlings which eagerly opened their mouths for food. His beak was so tiny! When I tried to open it, the upper and lower mandibles seemed barely attached to his mouth, which was enormous. The soft edges of the two sides seemed extremely fragile. And his tongue was just a vestigial flap way in back--useless for helping him swallow.

Fred the Common Nighthawk

Holding this poor injured bird and teasing his mouth open, I felt so clumsy and brutish. I finally opened it wide enough to pop in a plop of food, and closed his mouth, but within moments, the food popped back out covered with slime. I tried over and over, each time petrified that I was going to injure that fragile mouth, but each time I finally got a plop of food in, it came back out, sometimes within seconds, and sometimes after a minute or more, right when I was thinking he'd finally swallowed it. Finally I figured out that his tongue was too tiny to help the food down his throat. So when I got another plop of food in, I tried gently stroking his chin and throat to see if that would help. Victory! For the next couple of days, every time I fed him, I first had to work that fragile mouth open, and then when I got food in, had to stroke his throat to help work it down the hatch. After a couple of days, he'd open his mouth when he saw that I had food, but the food would still pop back out, glistening with slime, whenever I didn't stroke his throat. By the next week, he'd run up to me, holding his good wing up and his capacious mouth wide open whenever he wanted food, but for a good three weeks I had to rub his throat to get him to swallow it down. Eventually he finally got whatever muscles he needed to use to swallow in shape.

I went through this experience with several adult male nighthawks. Meanwhile, adult females often had the same difficulty swallowing at first, but in a day or two, and never longer than a week, they were swallowing food on their own. Chicks never needed help swallowing.

I finally realized what was going on. In nature, chicks are fed regurgitated food by their mothers until they can catch it themselves. So naturally, they can swallow food placed in their mouths. As they learn to fly, they quickly learn to fly straight into insects with their mouths open. During the time they're still learning, their mother continues to feed them, but little by little, they're getting most of their food on the wing. I suspect the tongue is reduced to help the food go straight into the throat without any obstructions, and as they hit a moth, beetle, or other flying insect at about 15 miles per hour, the food goes straight down the open throat, thickly covered with cushioning mucus, and straight into the esophagus without any real "swallowing." Young birds still have the ability to use muscles in their mouth and throat to swallow, and adult females must keep those muscles working at least well enough to regurgitate food to their young, but males have no need to use them after becoming independent from their mothers' feedings. So it takes them time to get good at swallowing again.

Over the years, I also found that once a nighthawk—adult or immature—started running to me with the mouth agape for food, it invariably held its wings straight up (unless it was restrained by an injury) while approaching. This is the way young nighthawks beg for food from their parents. Adults usually kept the wings lowered while actually eating, though.

Fred the Common Nighthawk

I expected that first nighthawk's droppings to clear up once he became more relaxed in captivity, but they never did. That is, most of his droppings were typical bird droppings, with brown fecal matter and white urates. They were a bit smellier than the droppings of most species, but I got used to that. But once a day, he'd make that same smelly, slimy dark brown liquid. I figured he had some kind of intestinal disorder. But as I took care of other nighthawks, I discovered this was characteristic of every single one of them. I had no idea what was going on, so I started asking people who'd handled them. Banders complained that nighthawks often released one of these awful liquid messes right while being handled, and rehabbers knew exactly what I was talking about, but people who'd studied them in the field never seemed to know about this and no one seemed to know how or why they produced yucky droppings in the first place.

I started buttonholing ornithologists at meetings asking about this, but none of them had a clue. I wrote to Joe T. Marshall at the Smithsonian because I knew he'd kept nighthawks in captivity for study. (After Edmund Jaeger wrote some papers about torpor or hibernation in Common Poorwills during the 1940s, Dr. Marshall tried to induce torpor in some young nighthawks that he had raised.) He wrote back saying he'd never noticed their droppings at all, and noted that perhaps I did because I still had children in diapers. Oh, dear—the scariest thing is that perhaps this was indeed why I'd paid so much attention to the issue!

Finally, I read a book about Ruffed Grouse by Gordon Gullion in which he made reference to the grouse's "caecal droppings." I went back to my ornithology textbooks looking up whatever that might be, and found that these would be ejected by the "caeca" or "ceca," paired offshoots where the large and small intestines meet, where our appendix is. My textbooks stated that caeca are found in gallinaceous birds and some others, but didn't say which others or what the function was. Gullion stated that in Ruffed Grouse, the caeca grow enormous in winter and atrophy in spring. This is where anaerobic bacteria digest the cellulose in the woody buds that grouse eat all winter. Gullion noted how smelly the once-a-day caecal droppings were, due to these anaerobic bacteria.

Nighthawks don't have any cellulose in their diets, so I was mystified. And I still wasn't sure that they even had caeca. I dissected one bird that had been brought to me dead (for some reason, I couldn't bear to dissect the few that died under my care), and saw what looked like caeca, but wanted someone more knowledgeable than I to verify this. Finally I found a book about avian morphology by Beddard from 1898, and sure enough, the family does indeed have well-developed caeca. But why? Suddenly it hit me! Nighthawks may not digest cellulose, but they do have to digest an equally difficult substance, chitin. Perhaps the caeca have anaerobic bacteria that digest that material!

I was getting so fascinated with the question that I got the contact information for one of the world authorities on avian digestion, Gary Duke, who was co-founder of the Raptor Center and was right down in the Twin Cities! I called him on the phone to explain what I knew and what I wanted to know, and he got so excited that he asked me if I wanted to put together a Ph.D. program to figure it out! This was before he even knew that I'd won the Frances F. Roberts Award for a paper I'd presented at a joint meeting of the Cooper and Wilson Ornithological Societies in 1992. I was thrilled!

My Ph.D. never panned out. I took a term of full-time classes in the Twin Cities in veterinary and avian physiology, but my kids were in elementary school and still pretty young, so spending Monday through Friday in the dorm down there was tricky even with my most cooperative husband. I was doing a lot of research at home after that, and Gary and I videographed the entire digestion process of two nighthawks, beginning when they each swallowed a bolus of barium-coated food and tracing the food's progress all the way through the digestive tract and out again. Then Gary developed Alzheimer's disease and had to retire early. Some of his work, including the videotape we'd made, are lost. But he was certain that I'd worked out the reason nightjars and owls have well developed caeca. (Many owls also eat insects, and my education Eastern Screech-Owl's droppings have the distinctive odor of a nighthawk's droppings, though not as strongly odoriferous.)

Gary Duke's death was an enormous loss to me personally, and to the ornithological world. I've so treasured his knowledge, the fun yet wonderfully practical ways he approached solving problems, and his amazing knowledge of how bird bodies work. The world lost a valuable scientist and wonderful person when he died. But that same world already has one-too-many Dr. Lauras, so my losing my shot at a Ph.D. was not that big a deal.

The nighthawks I kept for extended periods were almost all adults with injured wings. They never required caging--I had a special room for them, and they could walk around or jump onto low perches to look out the window.

Common Nighthawk

Nestlings and fledglings could not be caged either, because their flight feathers (wings and tail both) are extremely fragile. When they'd be captive for more than a day or two, I used waxed paper or cut up a stamp-collection envelope to make little light-weight wrappings for each non-broken feather.

Nighthawk legs are so short that even without banging wings against the bars of a cage, the tail and wing tips can be abraded simply by contact with the floor, as happened to this nighthawk who was kept in a small box until brought to me. I had to over-winter it while the feathers were replaced.

Joey holding Common Nighthawk

Nighthawk flight feathers can easily get gooped up, and then broken, and the tissue on their feet can be damaged, by extended contact with their own poop, so even more than most birds, their surroundings need to be kept very clean. Those extremely smelly and very liquid cecal droppings, produced about once a day, make this especially crucial.

Nighthawk feet are flat and delicate, and their legs short. Their claws are somewhat flattened, especially the center one, which is pectinated, or comb-like. I've observed them preening and scratching a lot, and that pectinated claw seems to be effective at pulling out loose down feathers.

Pectinated claw of Common Nighthawk

I kept one adult male nighthawk (no idea how old he was when he first arrived, but I suspect he must have been several years old because it took him three weeks to be able to swallow food) for eight years as a licensed education bird. I named him Fred for Mr. Rogers, because he was so gentle and calm, because his flat feet reminded me of Mr. Rogers's sneakers, and because after about a half hour being stared at by children, he suddenly reached the end. He'd suddenly turn his back on them and look at me with pleading eyes. That was my signal to put him back in his carrier.

Fred was a steadying influence on other nighthawks that came to me. They were always drawn to him, and usually pressed themselves against him. One active young female seemed to irritate him, and he'd often walk to other areas of the room to evade her, but overall, he accepted other nighthawks readily.

One of my saddest nighthawk experiences came when I was brought an adult female who had been found along a roadside in western Minnesota, and flown to me in Duluth via Northwest Airlines. One of her eyes was destroyed—I think maybe struck by an car's antenna tip, because she didn't have any other injuries. She seemed to adore Fred, and kept her blind side pressed against him all the time when she wasn't sitting on my lap with her blind side pressed against me. Unfortunately, I couldn't find a vet who was willing to enucleate her, and the poor bird was constantly battling infections. She would have made a superb education bird and wonderful lifetime companion for Fred because of her calm and trusting ways. I still miss her.

Three Common Nighthawks

I was doing some counting at Hawk Ridge during the years that I was rehabbing, and when the weather was pleasant, I'd bring Fred along. He'd sit on the ground at my feet all day keeping me company. When hawks passed over, he'd make a soft rit rit rit sound. Sometimes the hawks were beyond my visual range, and could only be seen if I had my 10x Zeiss binoculars on them--I'd know exactly where to scan the skies by the direction he was looking. When peregrines flew over, he not only called--he waddled into the very back of the carrier. Minutes later he'd start inching his way back to the front, and very carefully scanned the skies, sometimes for 15 minutes or more, before coming out again. I made the mistake one day of bringing along a still-flightless chick along with Fred. She kept wandering off and getting into trouble, but I couldn't imprison her in the carrier because she'd have damaged her feathers, so I had to hold her on my lap all day.

Laura with Common NIghthawks at Hawk RIdge

I've successfully "hacked out" two chicks by releasing one in my own backyard and one at my mother-in-law's place in Port Wing, where the birds returned to me several times a day for feedings as they grew more independent. Nighthawks and their relatives are so difficult to rear in captivity that this issue hasn't been faced or written about by many people.I feel lucky that they knew me and recognized my voice well enough to return when I called.

The first nighthawk I ever released, that one that came to me at that construction site, healed well. One night in August he grew suddenly very restless, and when I looked out the window, I saw hundreds of nighthawks flying over my yard. Back then, we had nights when thousands, or tens of thousands, migrated along the North Shore. I took him out. Russ came out with me. I held him in my opened hands for several minutes as he watched dozens, hundreds of nighthawks wending their way all toward the sunset. (Along the north shore, birds are moving west-southwest.) Suddenly he opened his wings and rose into the sky and moved with the others into the beautiful sunset sky. I kept my eyes on him as he grew smaller and smaller. At just the moment when he was about to disappear, suddenly he turned around and flew directly toward me. He flew over my head three or four times, looking down at me. I was sobbing—filled with a joy I'd never known even as I knew I'd never see him again.

Russ witnessed the whole thing. Twice after this a nighthawk has returned like this, as if saying farewell, or thank you, or something. I can't explain it. The third time this happened was the day after I'd gotten word that Jeff Sonstegard, the illustrator of my first book, was dying. I rushed to Longville to see him one last time when I happened to have a nighthawk due to be released. Weather conditions sounded better in Longville than in Duluth, so I brought it along. Jeff had drawn several nighthawks for my book but had never seen one personally. So I let him hold the bird in his hands and he was the one to release it. That bird flew up, joining with other nighthawks, and then returned to fly over our heads. Jeff talked about the experience with his family on the way to the university hospital the next day, and soon went into a coma.

My love for nighthawks is so deep-rooted that I can't even begin to express it, but it's rooted in these experiences, in watching them booming in spring, and in sitting on my roof or on a rock along Lake Superior watching hundreds migrating in the sunset sky. This gentle-spirited bird has vanished from most of the places where it used to be common or even abundant, and attention must be paid. I hope my experiences help rehabbers, and hope you'll share any additional information that should be here.

John Schoenherr's drawing of nighthawks
from the book Rascal