Saved by the Little Yellow Telemetry Plane

Date: October 2007
Location: Yellowstone National Park

When tracking wildlife, it is often necessary to use an airplane to locate a radio-collared animal. I myself hate doing this. While I am fortunate enough not to feel the need to lose my lunch during the tight circles necessary for homing in on a critter, I just can't convince myself that a sudden gust of wind or a seemingly inevitable mechanical failure won't send me hurtling thousands of feet down to my death. Humans were given legs for a reason - walking, and stepping on gas pedals. I prefer transportation involving constant contact with solid ground.

To each his own, however; aerial telemetry remains an important part of wildlife biology. In Yellowstone, when I worked for six weeks studying grizzly and black bear food habits, a man named Steve contracted his services in his bright yellow telemetry plane to track our collared bears each week. Once he heard the signal, dual antennae on each wing guided him toward it, and a tight circle once immediately above the animal would confirm the location.

The collars these bears carried collected GPS locations of that bear every half hour, and during his flights Steve could download all those locations remotely, just by flying over the animal. Then my boss would project those locations onto a map, and our job as technicians was to hike in to a random sample of locations to see what the bear was doing there. Most of the time the bears were grazing on vegetation, sleeping, or digging for mushrooms, but occasionally we found prey kills.

There was rarely any danger that we would stumble upon the bears themselves; the design of the sampling protocol ensured that at least two weeks had passed between when we landed on the bear's trail, and when the bear him/herself had made it. The home ranges of bears are quite large. Though there were undoubtedly uncollared animals near us at all times, and we took all necessary precautions (e.g. carrying bear spray, shouting "HEY BEAR" or talking very loudly to each other, not hiking alone), we certainly never expected to run into our collared critters.

On one occasion, our little boat the Silvertip (which also happens to NOT meet my criteria for preferred transportation, and so has been bequeathed a special kind of loathing from me) dropped me and Justin (one of my bosses) onto a gravelly beach on the eastern shore of Yellowstone Lake. (As Yellowstone is a national park, docks are not common around the Lake. By "dropped off", I refer to the process of approaching the beach at full speed, hastily raising the prop, ramming the shore head-on while the lucky technicians leap as far off the bow as they can with all their gear, and the remaining crew pushes the boat back off the beach with long poles until the prop can be lowered again. "Picking up" was equally adventurous - and wet.)

Soon after landing on the beach, Justin used his telemetry gear to scan for the signal of the grizzly bear whose locations we were supposed to visit that day. Her signal came in loud and clear; she was still in the area, even though the locations were more than two weeks old. Because it is never smart to play hide and seek with grizzly bears, we decided to scrap the day's plans, reboard the boat, and head to some other sites. We would return to complete the task as soon as the bear had left.

A few days later, my other boss Shannon and I leapt off the boat onto the same beach for another attempt at this bear's sites. It was a sunny, warm autumn morning. She scanned for the bear, and this time the signal was very weak. We bid adieu to our comrades in the boat and headed east away from the shore.

The going was rough. Much of Yellowstone burned in 1988, and 20 years later many places were choked with thick deadfall or dense thickets of new lodgepole saplings. It made for very tricky backpacking. Though we only had to travel a kilometer or two, it took us quite a while to manuever around all the logs and clingy young trees. Resilient dead limbs reached up from fallen snags to gouge our shins at the slightest misstep. We were headed to Delusion Lake, and in this tree graveyard it seemed appropriately named.

Gradually, the logs thinned out and healthy, green trees began to appear as we moved out of the burn area. It was a relief to walk on more or less open ground again.

We were about 200 yards from the points we were to investiage, when in the distance we heard a familiar drone. As we continued to approach the locations, the drone became louder, and soon we could pick out Steve in his yellow plane away to the north and west. The closer we got to our destination, the nearer the plane seemed to be coming. At first we weren't alarmed, since there was still plenty of park lying to the east, in which one or more of our collared bears could be roaming.

Eventually we realized Steve would soon be flying right overheard. Shannon, who knew Steve well and even joined him periodically on his weekly flights to download the bear locations, thought maybe he had seen us in the sparse landscape and was doing a fly-by. Both of us smiled broadly and waved as the yellow plane roared over our heads.

Our smiles quickly faded as he turned the plane and began to circle.

Optimistic as ever, Shannon thought Steve was circling over us to say hello. We waited as Steve circled several times, our necks craning and our heads dizzy as we followed his progress. When he straightened out and continued east, Shannon quickly pulled out the telemetry receiver and antenna from her pack, just to make sure the bear wasn't close.

BEEP.       BEEP.       BEEP.

The signal came booming in. The low hills near the beach had evidently hidden the signal when we had scanned for her upon landing, but she was definitely here. The look on Shannon's face was enough to set me in motion immediately behind her as she made a beeline back the way we had come. She was even too worried to shout, the normal protocol for avoiding bears; she thought we were so close that our shouts might alarm and provoke the bear, rather than harmlessly warn it of our presence.

We hiked back through the deadfall, this time veering south toward a little stream that might provide an easier route to the beach. The hike was hard enough, but adding fear and haste made it all the more exhausting. After we had gone a few hundred yards, and the bear's signal was weak enough to assure us that we were far enough away, we stopped to rest. Slowly we picked the rest of the way back to the beach, sat on a low hill (perhaps the same one that had blocked the bear's signal), ate some lunch, and said nothing.

Faintly, we heard Steve flying in the distance, perhaps returning to Gardiner to land. After a while the boat returned and picked us up. In the end, we decided the bear was probably starting to den there near Delusion Lake, which would explain her constant presence there for multiple weeks. The field season was nearly over. Soon the bears' collars would automatically drop off and we would wrap up the field work by retrieving them, just as the first autumn snows arrived.

I still hate aerial telemetry, but on that day, I was grateful for it. Based on the strength of the radio signal, Shannon thought we had gotten within a hundred or so yards of that bear. Steve's arrival was the warning we needed, right in the nick of time.