As the World Terns

October 8, 2014

Least tern delivers a fish to its mate at its nest in the sand.

On a hot humid morning in late June, I got out of the truck dressed in a faded white cotton t-shirt, baggie shorts, and teva sandals, with a small backpack slung over my shoulder. I looked like I was headed out for a day at the beach.

And I was. Well, sort of.

In a matter of minutes my teenage daughter Elsa and I were perched atop a high berm, using binoculars to scan a several acre pile of sand that wrapped like an apron around a sandpit lake below. On one side of the lake, Western Sand and Gravel Company was running an active dredging operation. On another side a new housing development was under construction. Just beyond to the east was the Platte River.

 

Western Sand and Gravel Co. operates along the Lower Platte River near Ashland, Nebraska. 

A few miles outside the town of Ashland, we were watching what was likely the largest nesting colony of interior least terns in eastern Nebraska. We were waiting for the right moment to walk 50 yards across the sand pile to a hastily-made photo blind constructed of garden fence and camo-patterned burlap, held together by half a bag of plastic zip ties.

I had put the blind in place with the help of biologists Mary Bomberger Brown and Lauren Dinan a few weeks ago, and had already visited it several times since then. The blind was about seven feet long, shaped like a beer can cut in half length-wise, and anchored by six-inch-long tent stakes and two 10-pound dumbbells. It was just big enough for me to crawl into on my belly and lay there watching through a small porthole cut for the camera lens. Once inside the blind, the camera lens would not change position. It focused on a small depression of sand no larger than a saucer for a tea cup that contained three tiny little eggs tended by two very diligent parents.

Our chance came when a bald eagle flew overhead and spooked the entire tern colony up into the air. Elsa and I walked quickly in tight single-file following my tracks in the sand from previous days. Once we got to the blind I slid inside and positioned my camera, then Elsa closed the flap of the blind behind me and conspicuously walked away. This handy trick would make the birds think the blind was empty and that we had both left the scene.

Elsa Forsberg inspects the blind before I go in for the day.

I visited the blind roughly a dozen times between early June and mid-July of 2014 with the hope of capturing an up-close and intimate glimpse of how these endangered birds live their lives. And I learned a lot more goes on around a tiny little indentation in the sand than one might think.

Activity never stops on a tern nest. During the course of one day I made nearly 40 observations, recording their behavior, changing weather conditions, and an array of vocalizations. I witnessed numerous episodes of what I dubbed “fish passes,” when one adult tern delivered fish to its partner sitting on the nest. I also watched what I think was an interloping male make his rounds around the colony, offering fish in an attempt to impress any potential partners including those already with mates. But each time he was shooed away.

I am struck by our two civilizations living side by side – the terns ever aware of ours, but us barely aware of theirs. Below are highlights from my field journal from a typical day in the tern blind.

Adult tern lands on the sand near its nest.

Least terns at nest, Lower Platte River Valley, Western Sand and Gravel Co.

June 8th, 2014

6:05 Into blind. Sunny, pleasant, low 60’s. Light winds out of the north/northeast. Tern on nest with three eggs, facing into the wind and sunrise.

7:24 Fish pass. Male lands and female gets off nest to receive the fish. Afterwards, the male swells and lifts up his chest and holds beak high at an angle as if proud, then flies away. Female goes back on nest, preens briefly, then tucks her beak beneath her wing.

There is a repeated chatter that seems common on the colony that sounds like a squeaky “chee chee chew chee chee chew.” Then there is a lower, more melodic warble that comes from the female at the nest, often when the male is in close proximity. Then there is a rapid fire squawking — the alarm call when all the terns are airborne during a disturbance. Finally, at fish pass time, there is a rolling, squeaking, rapid staccato from the male that peaks after successful transfer of the fish to his mate.

There are other sounds too, in the background: birds like Canada geese, piping plovers, and killdeer which nest here. And those of trains, highway traffic, motocross over the hill, and people boating on the lake. But from where I lay, the terns are the noisiest.

A day-old least tern chick banded by biologist Lauren Dinan, who is monitoring the colony.

8:05 Watched two terns 20 feet away to the southwest warbling back and forth, one drawn to the other. One started to spin and circle, seemingly making a nest cup in the sand with its feet, wings and tail, while the other tern stood inches way and held its beak low as if staring intently at the creation. The spinning tern stopped, then dipped its beak low to the ground almost touching the other’s while the warbling continued. Suddenly another tern (likely male) flew in with a fish trying to offer it to the female and broke up the action momentarily until the other tern chased it away.

8:28 Male approached with fish to present to female on nest but she shooed him away. I think this is a male without a mate. He keeps carrying around a fish and presenting it to other terns in three distinct nesting territories in the immediate vicinity of my blind.

9:05 Wind shift out of the west. Male on the nest turns to face east. Overcast skies have moved in.

9:35 All birds in colony up in the air squawking. Some unseen disturbance in the area.

9:37 Female back on nest. Disturbance gone.

1:01 Fish pass, same as above. Heavy courtship and nest scraping activity going on just south of the blind about 20 feet away from the tern nest I am photographing. Activity has really picked up in the last half hour. Lots of “rup rup rup” and squeaking vocalizations.

1:10 Interloping male who is raising a ruckus with the other tern pair to the south just came over to the female at the nest in front of me. She set her black crown back, opened up her beak and lunged at him, scolding him away.

This small woodhouse toad was my constant companion during long vigils in the blind.

2:19 Nest exchange. Male acknowledged presence of female in the area on the ground just out of my view. He got up from the nest and started picking up small pebbles and moving them towards the nest cup with a fling of his beak. He did this for about a minute, then extended his leg and wing to stretch, then flew away. The female then moved into view and on the nest immediately.

6:00 Bald eagle flew overhead low and the entire tern colony exploded up into the air, and I left the blind for the day. On my way out I watched from behind some cottonwood saplings on the berm overlooking the colony and the terns returned to the nest within a few minutes. It’s overcast now, nearly calm, cool with a bit of humidity in the air. Chance of rain tomorrow…

A mother least tern and her chick on their nest.

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