Where are all the beavers on Arizona’s San Pedro River? Volunteers go looking for them – The Arizona Republic

SAN PEDRO RIVER On a cloudy December Saturday, a group of wildlife enthusiasts met on a dirtpull-off in southern Arizona to embark on a mission. Wide-eyed and unified, thecadre of researchers, advocates, professorsand studentshad volunteered to spend the day collecting data for conservation.

At thehelm was Lisa Shipek, the executive director and founder of Watershed Management Group, a Tucson-basednon-profit that organizesecology-based community events.She had convened the group nearthe San Pedro Riparian National Conservation Areawitha single goal: finding Castor canadensis, the North American beaver, or at the very least spotting signs they're in the area.

Beavers once thrived in this part of southeastern Arizona. Centuries of trapping led to a local extinction by the late 19th century. In their absence, the ecosystem services they provided vanished, too. Their penchant for building dams slowed stream flows, enhanced riparian habitatand even restored aquifers when flood plains overflowed.

(T)hey were a keystone species in our creeks and rivers," Shipek told The Republic."And then they were wiped out by trappers. And that really caused an unraveling of a lot of these creek and river systems and almost to the extent where the creeks and rivers and wetlands were unrecognizable from what they would have been with beavers.

So we, in a lot of ways, don't actually know what our creeks, rivers and wetlands should look like," she said, "because we've only really seen them without beavers.

Twenty-two years ago, the Arizona Game and Fish Department and the Bureau of Land Management, which manages46-miles of the San Pedro andBabocomari rivers,took on an ambitious project to restore beavers to this portion of their historical range.

Sixteen beavers were captured in other areas of Arizona, often where they were creating problems near airports or stock ponds, and released on stretches of the river.Protected, remoteand perennial, the San Pedro Riparian National Conservation Area was an ideal spot for the releases.

With the return of beavers, groups like WMG are hoping some of those essential services would be restored. That could offer a glimpse into a world that beavers once helped create.

Yet modern challenges have in recent years stunted the recovery conservationists initially hoped for. To understand why, Shipek and her team of volunteers are counting beavers one survey at a time to find out where theyre going and maybe even whats causing their disappearance. Collectively, the volunteers are a part of a growing assemblage of citizen scientists who are reshaping the way people collect data and learn about the natural world.

After introductions, Shipek and her husband,Catlow Shipek, who serves as the group's policy and technical director, split the search party of 20 into five separate groups along distinct, two-mile sections of the conservation area.

Some of thevolunteers are trained scientists. Others are just curious about nature and want to help. A passion for beavers inspired most of them to join the survey, but an affinity forwatersheds and ecology was palpable. Conversations buzzed with hydrology terms and tales of pastoutings.

Before setting off, group leaders guided everyone through what to look for. Beaver chews, chunks of bark eaten out of treetrunks, are a telltale sign that beavers are near. On smaller tree trunks, the chews look like spears pointing to the sky. On larger trees, they look like gaping wounds, wide and crater-like. Other signs include the tracks, slides, which are trails left by the beaver's dragging tail, along with scat, food caches, scent mounds and the motherlode: a beaver lodge, denor dam.

Using an app called Survey123, the volunteers were able tolog the location, type of observationand key information related to the sighting. The data will be used later to take inventory of how many beavers live in the area.

"We saw a great opportunity to do community-based conservation here in Tucson and southern Arizona, really making these types of practices accessible to people at their homes, at schools, and neighborhoods. This concept of watershed health doesn't have to be limited to agencies working on it. We can all play a part in this,"Shipek said. "Beavers are a keystone species. And so that means that they play a critical role in the health of our rivers."

For the past 16 years, Shipek has built partnerships to engage the community in watershed restoration efforts. The plan to conduct surveys came about last year after Shipek and her team discovered that the original population of beavers wasn't doing so well. After years of growth from 16 to well over a hundred in 2010, the population had crashed by 2019. That year, observers reported limited beaver activity, with just two or three believed to be in the area. No dens or lodges were seen in the SPRNCA that year. An interesting bright spotappeared in Mexico, where the beavers naturally dispersed.

Shipek was shocked. "We hadn't heard that,"she admitted on hearing about the population drop at a panel discussion. "This was a surprise and really a wake-up call that we need to be paying more attention to beavers on the San Pedro."

In an effort to understand why and how populations were changing, Shipek organizedthe first-ever community-wide survey along a 15-mile section of the San Pedro in Arizona and worked with partners in Mexico tosurvey the other side of the border. Watershed Management Group's built-in network of dedicated river enthusiasts positioned her to hit the ground running when it came to marshaling support for the survey.

What they found wasencouraging. The population had rebounded, if only slightly. They estimated there were between 12 and 15 beavers in Arizona following the 2020 survey, though that was still woefully under the carrying capacity of the river ecosystem, which is around120 beavers, according to Watershed Management Group.

A key part of the effort to count beavers included local river expert Mike Foster, who works with the Friends of the Huachuca Mountains and the Friends of the San Pedro River, a non-profit dedicated to protecting natural resources near Bisbee and Sierra Vista.

Foster, who moved to Arizona 38 years ago from Michigan, has been conducting informal surveys for nearly 20 years, since 2002. He and a fellow river hobbyist, Steven Anderson, had been collecting data andreporting their findings back to Marcia Radke, a biologist with the BLM who worked on the San Pedro.

To this day, Foster is involved with the surveys and was a team lead at the Saturday event. For him, it's been a joy to watch his efforts grow and expand to include the larger community.

"From a guy who used to be one of two that would do the whole thing by ourselves, it's so great to see how there's been this groundswell of people who are interested and paying attention to beavers," Foster confessed. "I'm really, really happy with what both Cochise College and Watershed Management Group are doing."

Steve Merkley, a biology professor at Cochise College, was also involved with organizing that first survey. As a professor, he was able to spur interest among students who proved to be eager helpers. In February2020, they were enlisted to join Fosters survey, covering areashe and his partner hadn't.

LikeShipek, they were on a mission to find out what happened to the original population of beavers. While Merkley is still working on collecting information to finalizehis research on why the beaver population has plummeted, some other folks have theories. Mountain lion predation, droughtand human trapping have been presented as potential causes for the decline, though there couldalso be a less sinisterreason, Merkley said.

"There is also evidence in other beaver literature that beavers go through natural boom and bust cycles. The populations will get really dense and then they will decline and then they'll build back up,"Merkley said. "So it could be a natural population cycle. Or it could be that they are moving to a more favorable location for them habitat-wise."

Beavers are native to the Southwest. They once roamed the many watersheds, cienegasand waterways that circulated through Arizonas valleys. The San Pedro River was once referred to as Beaver River because of its abundant beaver populations. Easily captured and with some densest fur in the animal kingdom, beavers were extirpated by excessive trapping and hunting by the late 1800s. To this day, there are still few regulations that manage beaver trapping in Arizona, though it isillegal to hunt them.

The declining need to kill them as furbearers has allowed some populations to recover. But the pumping and diverting of major waterways presents another problem. Beavers need clean water,and they need lots of it. As a result, some of the beavers may have migrated to the headwaters of the San Pedro, in Mexico.

Merkley offers this as an alternative explanation for the population flip, whereby populations are growing in Mexico while declining in Arizona. The water flows on the Mexican side of the river tend to be slower, widerand calmer,habitat beavers favor over the narrower and deeper banks of the upper San Pedro, which are prone to flash floods and torrents during the monsoon.

No matter where they are, as a keystone species, beavers have a profound impact on their environments. Their reputation as ecosystem engineers is well known and backed up by the way they alter a place.They tear into trees, slowing water and creating habitat, often times improving what's there for wildlife.

"When they dam up water in a stream, it slows the flow, which provides habitat for lots of organisms that depend on a slower flowing river,"Merkley said. "And also for the hydrology, it allows more of the water to return to the aquifer. And so it's really good, not only for plant life, but also for the longevity of the river."

By early morning of the survey, each group was dispatched to their respective stretchesof the river. Each team focused on two main areas, the actual river or the river's banks. One could either get soaked or fight through tangles of 12-foot-highphragmites, a reed species that thrives in wetlands.

"There are two big ones," exclaimed Shipek from across the river while pointing to two massive beaver chews on the opposite side of the bank. Mark Briggs, a stream restoration ecologist, who was in Shipek'sgroup and wading through waist-high water at the time, took the first recording, logging thesize, recencyand approximation to any other would-be beaver activity.

The chews were huge and their bright yellow coloring indicated they were recent. Each team member was alert and keen. Several other chews were discovered soon after as participants trudged through deep water and fought through willows andthickets of cottonwoods on the bank.

Briggs and his partner, Brooke Bushman, had tag-teamed the river portion of the tracking expedition whileShipek traipsed up on the bank. Midway through the hike, Bushman, a green stormwater infrastructure maintenance program manager with the city of Tucson,had switched from that water to the bank.

An accidental fall led to the next major breakthrough of the day. Bushman had slipped through one of the vent holes of a beaver den.

"My foot fell in and I felt this neat wafting up of cold, really like, refreshing air, that was imbued with the strong aroma of fresh cut willow and smelled like a good, clean whiskey,"Bushman said.

Their discovery was one of the highlights of the day. "We found it," Shipek hollered from across the river, referring to an actual den. Both she and Bushman examined the lodge, took photosand logged their finding into the tracking app.

Unlike a dam, which stretches across water, this den was tucked intothe muddy bank. It was thick withoverhanging roots, carpetedwith wood chips, dark and narrow. Shipek stopped to make a video.

"We have stumbled upon a bank lodge after about a quarter-mile of seeing a lot of evidence of fresh beaver chews," Shipek explained, talking to the camera. "And it looks like the bank eroded here. We're right next to the river. There's definitely a cache of food. These bank lodges can go pretty far back."

Pointing the camera into the den, she continued, "so you can see back into maybe one of the ends where there's a cache of wood. We did step into the vent hole above it. And now we're going to go check out because we think there's a dam and maybe another lodge just down the creek. Pretty cool!"

As the daycame to a close, most of the groups were meeting back on the dirt pull-off, soaked and dirty, but excited about all the information they hadcollected. Their efforts will produce valuableinformation that can be used not only to assess the health of the river, but to find out how many beavers are in the area, where they're goingand how fast they're disbursing.

While there were no live beaver sightings on the outing, their presence was clear. Shipeks group alone found over 20 signs that suggest beavers live in the SPRNCA, including chews, slidesand a den.

It will take months to compile all the data.In addition to the December survey, there was also a November survey in other parts of the SPRNCA as well as along the San Pedro and tributaries in Mexico. In total, volunteers covered 40 miles of river in Arizona and 25 miles in Mexico. Pronatura and Naturalia, two NGO partners, helped with the latter survey. The results of all three are expected sometime in the spring.

This information will be vital when looking at future releases, something Shipek hopes will occur in otherareas of southeastern Arizona. Tributaries of the Santa Cruz River, like Cienega Creek, are ripe for reintroduction and one of her goals is to mirror the efforts on the San Pedro there.

"We see beavers as one of the best restoration solutions for our watersheds, including the Santa Cruz and San Pedro watersheds. So we're investing a lot of our resources into better understanding what's going on,"Shipek said. "This survey is kind of a fundamental piece, so we're planning to do this survey annually and making it a bi-national affair because these are bi-national watersheds. We have so many hopes and dreams. We're really just at the beginning in a lot of ways."

Lindsey Botts is an environmental reporter for The Arizona Republic/azcentral. Follow his reporting on Twitter at @lkbottsand Lkbotts on Instagram.Tell him about stories at lindsey.botts@azcentral.com

Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team atenvironment.azcentral.comand@azcenvironment onFacebook,TwitterandInstagram.

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Where are all the beavers on Arizona's San Pedro River? Volunteers go looking for them - The Arizona Republic