By ABA Young Birder Zita Robertson
“It’s Gone…”
But Where Did It Go?
I had just managed to take the lens cap off my binoculars when it disappeared again. For the umpteenth time, the bird I had been trying to finally get a satisfactory look at dove down under water, only to resurface clear on the other side of the lake. I knew that it was a Common Loon, its shape and posture gave it away from a great distance, but I headed around the lake to get a better look from the opposite end. For me, birding is not about ticking birds off a list and finding rare birds – I would much rather spend more time observing the Mallards preening on the shore of Agate Lake than beat a previous CBC record.
I looked out across the lake one more time to see if it resurfaced again, but all I saw where the few Mallards. “It’s gone,” I said, turning back to my Mom, who got up early to take me to the State Park even on this cold, windy morning. She’s been birding with me for long enough that she’s used to these occasions of “It flew away…” and “It dove down again…”
Loons are masters of this game of disappearing… but what does it do down there?
Aquatic birds are especially hard to observe foraging in their natural environment, because waterfowl find much of their food under the surface. As a group, they have a very wide range of techniques for retrieving their food, some spend a significant time under water, some never even fully submerge. When we think of waterfowl, many of the birds that come to mind live in environments where the water is shallow enough that they can reach the food on the bottom by tipping. Dabbling or puddle ducks, geese, and swans do this. These birds have a fairly diverse diet – when there is available open water and all throughout the breeding season, they feed mainly on grass, aquatic plants and small invertebrates in relatively shallow waters. During the winter, this isn’t always an option if they can’t find open water, in which case they forage in fields for remaining grain that was not collected during harvest in the fall.
There are also many species that spend the majority of their life swimming and diving, and consequently they are not very well adapted to life on land. They have evolved in such a way that their feet are positioned very far back, not directly under their center of gravity, so they have a hard time not toppling over while standing. However, this supremely well-designed torpedo shape allows for very efficient diving.
As our trail bends around the corner of the lake, the wind picks up, blowing the leftover corn chaff into the lake. I looked out through the trees just in time to catch another glimpse of the loon. But again, it disappeared a second later. I still took a moment to scan through the flock of birds floating in the waves – most of them were snow geese, but on the far left there was a raft of small ducks, likely about ten or fifteen. I couldn’t get a precise count, though, because a few of them always dove down. Unlike the Mallards on the other side, these birds don’t just tip up to reach the bottom, they dive completely under water.
The Lesser Scaup I saw near the flock of Snow Geese swim the same way as any other duck – paddling along on the surface with alternate feet. To dive, they thrust themselves partially out of the water and head straight down. Although they can dive down to as deep as forty feet, they most often stay in water with a depth of less than seven feet. They feed on aquatic plants and small invertebrates by sticking their bills in the mud, then quickly opening and closing it, like a filter, while they continuously propel themselves forward with both feet. The kicking motion they use looks similar to the breaststroke kick of human swimmers – their two feet move in sync, unless they make minor adjustments to change direction. To return to the surface, they simply float up like a cork.
Walking along, we finally reached the next corner, where the wind coming off the nearby Mississippi wasn’t as strong. I took another moment to scan the water, but I didn’t expect to find anything here. This part of the lake is very deep, so most birds that spend the winter at the park avoid this area.
If Missouri wasn’t so far from the ocean, there would be birds that take advantage of this deep part of the lake as well. Common Eiders, for example, feed in deep, cold waters, foraging on invertebrates they find at the bottom – their favorite food is blue mussels. To get these, they have to dive down 60-70 feet, pry the mussel from the sea bed, and bring it to the surface.
Similarly to the scaup, eiders also dive from the surface of the water, straight down. However, once under the water, eiders use their wings to “fly.” They lift their wings away from their body, but do not fully extend their flight feathers: the primary feathers remain folded. With their head pointing straight down, they use an undulating movement to propel themselves downward. This looks more like butterfly kick in swimming, the front of their body initiates the motion, and the rest follows creating the same type of vortex drag that is present when the bird flies through the air. This force counteracts their natural buoyancy, helping them reach the bottom as quickly as possible. At the bottom, they fold their wings back in, squeezing as much air out of their feathers as possible, so it would be easier to stay under water.
Once they manage to get the mussel off the bed, they simply turn themselves upright with a powerful kick, and quickly float back up. Although some species actually eat their prey under water, eiders bring these mussels up to the surface. Here, they use their chisel-like bills to saw open the hard shells, and eat the animal inside. During the process, they often drop the mussel, and when they do, they quickly dive after it. Sadly, I couldn’t find any information on this behavior. Do they do it on purpose? As long as they are able to catch it, I imagine dropping the mussel could have some advantages. For example, the water could wash out the mud and make it easier to open, or it could possibly trigger the animal to relax and let go of the shell a bit.
I glanced out through the gap in the thick hedge of mulberry trees, and spotted the loon again. Its sleek body and drab colors blended in very well against the grayish water reflecting the morning sun. At times, the waves blocked the bird as it sat seemingly unbothered atop the steady rollercoaster produced by the northeast wind. Occasionally, it stuck its head in the water, as if it was looking around to see what’s going on down there. This behavior made me think. Why was it sticking its head in the water? Could it even see anything?
This was not the first time I had seen diving birds behave like this. Once, in Hungary, I observed a female Red-breasted Merganser at a local lake. This was in April, it was likely migrating and stopped by at that lake, since the fish was regularly stocked there. As it swam around near the shore of a small peninsula, it stuck its head in the water, swam about ten or fifteen feet swaying its head back and forth, lifted its head to take a breath, then continued. Occasionally, it dove down and returned with a small fish or crawdad. When I saw the loon at Agate behaving in a similar way, I assumed it was looking for potential prey.
Based on a quick search online, that is exactly what it was doing, but I wanted to know more. I was surprised that I couldn’t find any specific information on this behavior — most studies that I found on Common Loon feeding behavior focused on the diving technique itself and their diet. I went down a few more rabbit holes on random (and quite specific) topics, but still I didn’t find anyone who had given this behavior much thought. Although it seems totally logical that they are simply scouting for prey, I had many questions. Can they see well enough to recognize their prey, or do they dive after anything that moves? How far can they see? In a lake like Agate, how do they see anything at all? I turned to the Macaulay Library for answers. Here, I found a few videos of this behavior, which only further complicated the issue in my brain.
First, I searched for videos of loons feeding in the winter, and in many cases, they dunked their heads in the water at least once before diving. In the first video, taken of a wintering loon in California, the bird looks like it is finishing off its previous catch near the surface of the water. Then it is simply sitting in the waves, occasionally poking its head in, then shaking the water off and waiting a bit. This video and the second one (recorded in June in New York State) more closely resemble what I observed. An important difference, though, is that the water in the videos looks much clearer than Agate Lake – although the bird was dunking its head the same way there, could it even see anything?
In the third video, recorded in August, there are two birds. In the beginning of the video, an adult is calling and sticking its head in the water repeatedly. Then suddenly, a juvenile loon appears at its side – the young one had just caught some prey that it brought up to the surface. After the juvenile appeared, the adult didn’t repeat the head dunking, it only called once before the end of the video.
This led me to the conclusion that maybe the adult was watching its young. In August, the young loons would still be learning to dive and fish, and usually remain close to their parents. If the adult was keeping an eye out for the juvenile, though, were the calls also a part of this? Since the bird was calling above the surface of the water, is there a chance that the young one even heard any of it? If it was communicating with its young, then why didn’t it call again after the second bird came to the surface at its side? I was really excited to come across this behavior, but it only raised more questions: perhaps they do communicate with other loons in this way while diving, too.
Sadly, the loon at Agate Lake was all alone. Though the water was really murky, it must have noticed something, because it dove down again, and popped up shortly after, about fifty feet away. Fundamentally, when birds dive, they do it for one of two reasons: to reach something on the bottom, or to catch their prey at various depths. The previous birds I mentioned, the Mallards, the scaup, and the eiders all forage on the bottom. Loons, on the other hand, are totally different.
The diet of the Common Loon consists almost entirely of fish. In the summer months, they breed on large clear lakes in the North Woods, where they feed mostly on perch and sunfish. In the winter, they migrate to the coasts, mainly the Gulf of Mexico, where they also eat smallish fish like Atlantic croaker. To be able to catch these, they have to be fast and extremely agile.
As with all diving birds, their feet are located very far back, allowing them to control their movement more precisely. It’s similar to steering a canoe – the further back you are in the boat, the easier it is to turn. Not only are their feet in the rear, they are quite large, which also helps, just like it is a lot easier to steer a canoe with a paddle than by hand. When they dive, though, it’s actually more like rowing than canoeing. Similarly to the scaup, loons also kick with both feet at once, but they don’t go straight down – loons travel through the water at any depth in any direction with amazing speed.
The most interesting part, though, is how they turn. There are three main techniques they use. In the first one, the bird uses one foot as a rudder, rolls its body away from the turn and paddles with its other foot (the outer one). So, for example, if it wants to turn left, it would use its left foot as a rudder, rotate its body clockwise, and paddle with its right foot. This way, it could quickly make a turn with its inner foot as an axis.
The second technique is a lot slower and simpler: basically, all it’s doing is changing the rhythm of the kick as opposed to when it’s swimming straight. They don’t paddle with both feet at the same time, and since the timing is slightly off, one foot has already reached behind the bird (is not propelling any water), while the other is only halfway through its stroke. Again, if the bird turns left, it begins its powerful kick with the right foot first, then the left, while rolling a bit clockwise.
The third way loons make a turn is sort of a combination of the first two: the bird paddles with both feet with slightly different timing, rolls away from the turn, and it does use a rudder to pivot. However, the rudder is not either foot, instead, it extends its outer wing a bit, and spreads its tail as well. This way, it takes advantage of the power of both feet, and can, with the use of its wing, make a sharp turn without losing its momentum.
With these methods, loons are very effective anglers, even in turbulent and murky waters. The loon I was watching at Agate Lake also seemed to be pretty successful – it returned with a small fish or crustacean after about half its dives. Sadly, it soon headed back the way I had come, toward the deeper part of the lake.
After I lost sight of my loon among the waves at Wakonda, I walked back to the parking lot with a ton of questions. Since then, I have looked into these questions, like the head dunking and turning behavior. However, I still only have a vague idea of some others, such as the underwater communication of diving birds, loons especially. I did find that they sometimes chase schools of Gulf silversides on their wintering grounds – this behavior surely requires communication. I am very intrigued by the topic of group communication in birds in general, and I hope I’ll be able to learn some more about it in the future.
References:
- Species accounts on eBird and All About Birds
- Glenna T. Clifton, Andrew A. Biewener “Foot-propelled swimming kinematics and turning strategies in common loons,” J Exp Biol (2018) 221 (19): jeb168831.
(https://doi.org/10.1242/jeb.168831) - Stephanie A. Thompson, J. Jordan Price “Water Clarity and Diving Behavior in Wintering Common Loons,” Waterbirds, 29(2), 169-175, (1 June 2006)
(https://doi.org/10.1675/1524-4695(2006)29[169:WCADBI]2.0.CO;2) - Kevin P. Kenow, Luke J. Fara, Steven C. Houdek, Brian R. Gray, Darryl J. Heard, Michael W. Meyer, Timothy J. Fox, Robert Kratt, Carrol L. Henderson “Dive characteristics of Common Loons wintering in the Gulf of Mexico and off the southern U.S. Atlantic coast,” Journal of Field Ornithology, volume 94, issue 1, article 1
(https://doi.org/10.5751/JFO-199-940101)
About Zika:
If you ask Zita about birds and birding, you are likely to get very different answers depending on where she is living at the moment. In Northeast Missouri, where she spent most of her childhood, being home-schooled allows her to keep a close eye on the birds around her rural home, documenting them through eBird daily. Every year, she looks forward to the Summer Tanagers arriving to the forest behind her house.
In Hungary, she lives a very different lifestyle as a sophomore at a public high school in a big city called Székesfehérvár. If you talk to her there, she’ll tell you about her nemesis bird, the Black Stork, or the European Bee-eaters that nest at a local park. But wherever she happens to be, she is always excited to share her passion for birds and birding with others.
This essay was part of her sixth submission for the American Birding Association’s Young Birder of the Year Mentoring Program, completed in January of 2025. It is based on a true story from a few years ago, when going to Wakonda State Park every weekend with her Mom was part of her regular birding routine.
