The John Kieran Trail in Van Cortlandt Park in the Bronx is cut through sturdy black locust and black cherry trees, their crowns bending the day’s sunlight.

As it veers towards the water, the trail mixes with wet mossy woods with willow branches hanging over the path like Rapunzel’s hair, patches of skunk cabbage and pitcher plants, and a feathery bed of New York ferns. Soon, the trail takes its walkers into marshland, which is overgrown with reeds, sedges, rushes, and emergent water plants that flowerred, purple, and yellow in the spring.

I was standing on the trail looking out at the swan’s nest, which was built on top of an abandoned muskrat lodge. It was early spring, five months after I had started as an Urban Park Ranger. The skunk cabbage was in stinky evidence and plant buds were swollen and ready to emerge. Robins were back from the south, foraging through the soil. Male red-winged blackbirds sang their shrill high-pitched songs. The marsh was alive, after winter’s long silence, with their chorus.

The female swan was organizing her nest. Her big white body was a little awkward out of the water, waddling, almost toppling, on top of the mound of reeds that was the former muskrat lodge. The swan’s orange beak worked at the reeds, her fat belly dragged. The male was in the water, head buried underneath, feet and butt sticking up into the sky, eating vegetation. But suddenly he turned over and raised his beak into the air.

He kept his nose high for a moment, sensing something that demanded his attention. The female also stopped what she was doing, raised her head into the air, and concentrated on the olfactory message. The male then lifted himself up, started running across the water, and, like a propeller plane, took off. The female soon followed.

Since starting the job, I had observed this swan couple every day, mixing in with the ducks and geese, getting excited when someone came down to the shore and started throwing stale bread into the water. I figured that was why they had flown away so suddenly, the prospect of an easy meal too stimulating.

I turned and started walking down to the southwest corner of the pond, where the water was funneled underground. There was a little waterfall, a pool, and then a steady stream into the pipes that carried the water out and into the Harlem River. A group of people, I could see ahead, had gathered around the fence that surrounded the waterfall and pool. My fellow Van Cortlandt Park Rangers, Mike, Bill, and Rich, were also standing there.

In the pool was an adolescent male swan. He was treading water, his coat saturated and heavy, blood dripping from his wings and face. The resident swan couple was watching him from above, agitatedly swimming around. When I asked Bill what had happened, he said that the couple had attacked the interloper and had set him spiraling down into the pool under the waterfall. Hanging on for life, weak and pummeled by the waterfall, he was trying to keep from being pulled down into the pipes.

Originally introduced from Europe to decorate estates and parks, muted swans (which are silent most of the time but can utter some hisses and barks) have revealed themselves to be fierce aggressors. Some natural resource managers wanted to manage them through a hunting season. But too much of a political stir would be made if killing swans were suddenly allowed. So, we local park managers watched them with mixed emotions: they were beautiful and living, but they also symbolized the determined behavior of an invasive species. No matter how we felt, it was an Urban Park Ranger’s job to rescue injured animals. In New York City, the overt activities of nature – bugs (exempting mosquitoes), bacteria, mushrooms, lichens, and other small things that remained beyond view – were monitored closely by human spectators. No tree fell without being heard. No heron died without a eulogy. No duck vanished without mourning. No hawk fed without fanfare. It put us Rangers in an odd position. Sometimes, we wanted to leave things alone. And sometimes that included an animal’s death.

The crowd behind the fence – the ever scrutinizing eyes of the city – would not stand for our ecological politics. A mixture of joggers, dog walkers, and birders, they felt too sensitive about the park to watch as death sucked up one of its animal visitors. The city parks were very much like museums, living museums, and city residents would not allow one of the exhibits to be discarded. And in this case, we agreed.

Bill and I changed out of our uniforms, taking off our Smokey the Bear hats, walkie-talkies, handcuffs, and badges, and put on chest waders. We fetched a rope and a net. Rich tied the rope around the fence that surrounded the pool and then tied it around Bill’s waist. Dragging the rope behind him, Bill walked into the pond, out to the metal weir that sat on the top edge of the waterfall and jutted out into the pool. I followed him. Bill then tied the rope around my waist and lowered me into the pool of water. The pond, home to so many living organisms, was also a collector of waste, which was ultimately flushed into this pool and its linking pipes: I had been lowered into a toilet bowl. That day, there were several waterlogged logs, tampons, soda and beer cans, candy wrappers, a half eaten hot dog, straws, cups, and a McDonald’s bag. These were the visible things. I tried not to think about the invisible. I was happy to have waders on, protection against the infinite microscopic organisms of disease. But then I realized my waders had holes in them. I could feel my legs and feet submerged in water, cold and soggy. I looked up at Bill for sympathy. He had a round face, big oval glasses, and a sharp manner. He said, “Let’s go,” and handed me a net, which was at the end of a long metal pole. The idea was that I would net the luckless swan and hand him up to Bill, who would then hand him to Rich, who would drive the swan to Pelham Bay Park, on the opposite side of the borough, to liberate him in the Long Island Sound, where there was enough space for the swans to coexist.

The swan was on one side of the metal structure, directly under the waterfall, and I was on the other. Pounded by the water, he was losing strength quickly. There was no way I could navigate the deeper water (and I surely wasn’t swimming underneath), so we hoped to prod him into my range.

Bill jabbed him continuously with a stick. Irritated, the swan started inching closer to me. He kept looking over his shoulder at Bill, and then looking at me. Both of us made him anxious. But Bill was causing him pain, so he ultimately worked his way toward me. At what I thought was just the right moment, I leaped out from my corner, almost falling headfirst into the mucky water, and brought the net down . . . on the bird’s shoulder. Alarmed, he went back to safety under the waterfall.

The crowd sighed in disappointment. I heard one person say, “They’ll screw it up and that poor bird will die.” I looked at all the people watching me.

Mike gave me the thumbs up and Bill called down to me, “Let’s try it again. This time be more careful.”

The swan was exhausted, and I sensed that he was giving up. But Bill coaxed him out of his corner again with his constant jabbing. Slowly and nervously, the swan moved closer to me. I focussed on his orange bill, black brow, and empty eyes; I watched his stomach go in and out with each labored breath. And when he was close enough, I brought down the net over his head and body (the crowd yelped), and flipped him over in the net. He was so heavy with water that I almost slipped into the rancid pool but I was able to hand him up to Bill.

Bill gave the bird to Rich, who rushed him into his jeep and off to the Long Island Sound. Then Bill helped me out of the pool and I stood by the shore for a moment, feeling a little sick to my stomach after nearly an hour in fetid water.

I thought about what had just happened. This pond, just below the Major Deegan Expressway and home to the Golf House, was a tableau vivant of the past. And that was what Van Cortlandt Park was, extant history. Like all things, the park had its biography, and I was learning how to read it.

The pond was the chapter on the region’s wetlands. The northwest Bronx was historically dominated by water. It was sliced up and dotted with creeks, brooks, pools, ponds, marshes, and swamps. Most of the water emptied into either the Hudson River, the Harlem River, and a Creek called Spuyten Duyvil (Spite the Devil in Dutch). In the 1600s, it was a ford just west of Broadway and 230th Street that was the only natural crossing point from the Island of Manhattan to the mainland of the Bronx. It was funny to walk in the area now, with its elevated subway tracks, tall buildings, heavy car traffic, and dry cement land, and think of how the area was, just 200 years ago, so deeply immersed in and affected by water. Everywhere you went, water and its concomitant plants and animals had to be crossed, waded, and avoided. In a grainy picture of the area from the turn of the century, the landscape was dominated by reeds, small islands, slicing creeks, and, in the distance, the low hills of what was to be Van Cortlandt Park.

It was not until the King’s Bridge was built in 1693 that movement between Manhattan and the Bronx could be accomplished on horse or foot, allowing for greater travel and trade between the two sections of the city. To develop the area, the water was dredged and filled in, banned from its ancient routes, and the landscape paved over; its marshes, swamps, small islands, creeks, and brooks gone to history. In the park, Tibbett’s Brook, which started in Yonkers, flowed through its center, meandering around until it finally made its way to the Harlem River.

But when the land was purchased by Jacobus Van Cortlandt in 1699, he constructed a gristmill and sawmill, damning up Tibbett’s Brook and forming a lake, changing the environment forever. The water from Tibbett’s Brook, instead of flowing its course, got bottlenecked and stagnated, the overflow spilling out and trickling its way to the river. The brook became swollen at its knees, rounded out. The run-off was tucked underground in the early part of the century. And it was at this exact point that I rescued the swan.

Over time, the lake started to fill up with sediments, from soil erosion at first, but then pollution and runoff from cars, the nitrogen and phosphorous levels increasing and the oxygen levels depleting. Fish populations decreased, emergent water-rooted plants proliferated, algal blooms became regular, and the lake became shallow and muddy, fertile with nutrients, turning into a pond, which was turning into a marsh.

Despite all these changes and disturbances, the pond and marsh were irrepressibly a place of life, where animals carried on, with appropriate adaptations, like they had for the past five thousand years. Its soupy mix supported a countless diversity of individuals. It was such an active place, a living community focussed on the routines of survival, finding the necessary resources, getting along with their neighbors and protecting their territory, raising families, going to work.

The swan’s conflict was ancient, had happened millions of times before. Today, however, it took place in reduced space, where struggles were more amplified, where tensions rose high, where nature strove to beat the odds, and space was of such value. No more wandering swans intruded on the resident pair that entire spring or summer, as if the message was sent out loud and clear that trespassers would be dealt with. A week later, the female swan gave birth to four cygnets.