A day with a field researcher in a vulnerable riparian ecosystem

Ariana La Porte searching for Gray Hawk nests
Ariana La Porte searching for Gray Hawk nests. Photo by Cali Nash/Arizona Sonora News Service

After miles of off-roading and a quarter mile of hiking around a small, rocky river, Ariana La Porte spots it.

She fixes her black binoculars to her eyes, moving around the sequoia but never drifting her gaze from the nest. She sees a bundle of twigs and branches swathed together, with green vegetation on the outskirts and down-like feathers poking out the top, a sure sign the nest is inhabited.

She begins to whistle like a gray hawk in hopes of drawing out a response. Minutes pass and a male bird mimics her call.

“This is a textbook example of how to locate a nest,” she says excitedly, a little shocked at her good fortune. As she finishes marking the location of the nest—somewhere near Sonoita—and its other features in her notebook, a female bird begins to cry shrewdly. La Porte immediately heads out, knowing that the female, who is brooding her eggs, wouldn’t call out unless she felt threatened by another’s presence.

La Porte is the project lead for the Arizona Gray Hawk Project. She explores the lifestyle changes of gray hawks in the San Pedro River and sky islands further north as part of her master’s thesis research about wildlife conservation.

There isn’t much documented information known about gray hawks, but La Porte is changing that. In response to an expanding gray hawk population and ecological changes at the San Pedro River, the birds’ traditional home in Arizona, the gray hawks have migrated north. By studying these birds, La Porte hopes to find out how successfully the species is surviving in new environments compared to at the river.

Decked out in cargo pants ripped from previous thorn encounters, with binoculars hanging around her neck, La Porte is ready to go bird watching. She says that much of her field research is spent hiking through Arizona’s wilderness, searching the tops of sycamore, white oak and cottonwood trees for gray hawk nests.

It’s a goose hunt of sorts, she admits. Even so, La Porte doesn’t wander about aimlessly, hoping to stumble upon treasure. She seeks out reliable bird watchers and posts on list serves for tip-offs of gray hawk sightings, then uses aerial Google maps and GPS to locate potential hotspots.

What she does when she finds the nests depends on what part of the season she’s in. At the beginning of last summer, La Porte had just finished setting up cameras in 15 different bird nests to observe gray hawks in various ecosystems. She used the footage to study what gray hawks eat, how often they eat and how many chicks they hatch and raise.

At the end of last summer, when she was climbing trees to take down the cameras, she fell and broke her back. She’s since recovered, and is now focused on locating new nests ­­for one more breeding season, where she’ll repeat the process of camera set-up and retrieval. She’ll use her findings to make management recommendations to the Bureau of Land Management, Forest Service and Fort Huachuca, the landowners in the study area.

La Porte says her data will give scientists a baseline status of the gray hawk population so that any changes in the future, particularly as the result of climate change, can be compared to the current statistics.

Gray hawks are “a really important part of the riparian ecosystem in this area”—namely the San Pedro River and sky islands—“and so if that goes away” due to climate factors, “so will they,” La Porte says.

Awareness about the importance of the San Pedro River and sky islands matters, she said.. Historically these riparian ecosystems have constituted about 1 percent of the U.S, but they are responsible for much of its biodiversity, especially in the Southwest,  La Porte says. According to the Center of Biodiversity, about 45 percent of all the birds in North America rely on the river at some point in their lives, and this dependency is increasing.

As a top predator in these environments, gray hawks rely on a complex chain of plants and animals to survive. The health and survival of gray hawks is a strong indicator of the health and survival of the entire ecosystem. By protecting a species like the gray hawk, “you end up protecting its habitat and then everything else that lives in the habitat,” La Porte says.

What makes the San Pedro River so special is that as the last undammed river in the Southwest, it’s a “living laboratory,” according to La Porte. Because the average person has limited access to the river, the area is relatively undisturbed, making it perfect for studies.

This river, like most environments, is threatened by human development.

On a day-to-day basis, unsustainable groundwater pumping threatens to destroy the water levels crucial to so many species, like the gray hawks.

Full slideshow below.

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Cali Nash is a reporter for Arizona Sonora News, a service from the School of Journalism with the University of Arizona. Contact her at cnash@email.arizona.edu.


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