From 2013 to 2015, the Ogallala Aquifer showed a decline of 10.7 million acre-feet, according to the United States Geological Survey.

This depletion of the aquifer has been a recurring issue since the initiation of significant groundwater irrigation in the 1950s. It is impacting some of the migratory birds on the Texas High Plains, including the snowy plover.

The snowy plover is a small migratory shorebird, similar to the familiar killdeer and the piping plover, said Kristen Heath, a graduate research assistant in the Department of Natural Resources Management in the College of Agricultural Sciences and Natural Resources at Texas Tech University.

Water crisis

Heath said snowy plovers can be seen during the breeding season and during migration in saline lakes (salinas) and salt flats in eastern New Mexico and the Texas High Plains, including Lynn, Terry and Bailey counties. These regional saline lakes have provided fresh water for millennia to indigenous peoples, migratory birds, and other wildlife from artesian springs fed by the Ogallala Aquifer, but the lakes are drying up. The basin of these saline lakes is also the top of the Ogallala Aquifer – and as water levels continue to decline, spring flow declines, and the basins dry out.

"There are 40 saline lakes in this region, and less than 10 have active springs," said Heath. "So the water crisis that people are having in this region is affecting snowy plovers too."

Research

Heath said her research focuses on the movement and connectivity of the snowy plovers throughout the High Plains region during the breeding season and to locations on the Gulf Coast and Mexico during migration and winter. She is looking into where birds are migrating, when they are migrating, and who is migrating—males, females or juveniles.

Her study areas include National Wildlife Refuges (NWR) in Oklahoma (Salt Plains NWR), Texas (Muleshoe NWR), and New Mexico (Bitter Lake NWR), as well as privately owned saline lakes in Texas. They track the birds using the Motus Wildlife System, which is a series of automated telemetry towers that track transmitters attached to captured snowy plovers.

The birds are humanely captured, Heath said, and avian nanotags are attached to the bids with a leg-loop harness that is worn like a backpack. The nanotag weighs less than a gram and lasts about six months. Then, it is either removed or falls off on its own.

Heath is not the first to do research on snowy plovers at Texas Tech. Warren Conway, the Bricker Endowed Chair in Wildlife Management and professor in the Department of Natural Resources Management, said he and his students, and collaborators from the U.S. Fish and Wildlife Service; Texas Parks and Wildlife Department, and the U.S. Geological Survey Cooperative Wildlife Research Units in Texas and Kansas have conducted various forms of research on the bird for the last 20 years.

Connecting the dots

Conway said the research was started while he was earning his doctorate at Texas Tech, and Heath's work will play a part in connecting much of the previous research. Conway said throughout the time they have been studying snowy plovers they have captured, marked and banded almost 1,500 birds in Texas, New Mexico and Oklahoma.

Twenty years ago, Conway said, they caught 350 snowy plovers on approximately three saline lakes in Texas, and 10 years later and saw 75 to 80 percent declines in the populations on the same lakes. This led to research on what had caused this decline.

Contamination

"These recent studies, which we finished in 2016, indicated that snowy plovers do have some arsenic and selenium levels of concern, mainly selenium levels," Conway said. "Almost 90 percent of all the birds that we captured during those years had detectable, if not chronic and problematic, levels of selenium in their blood, which is a potential cause of concern."

Conway said this is where Kristen Heath's research comes into play. Because they do not know where the snowy plovers are wintering, they do not know exactly where the birds are being exposed to the potential contaminants or if they are having survival issues of which the researchers were simply unaware.

Although they do not know exactly where the birds are picking up the contaminants, Conway said they suspect the increase of contaminants is connected to the continued declines in the Ogallala Aquifer, reductions in water quality, and cessation of those freshwater artesian springs that are crucial for maintaining suitable snowy plover breeding habitats.

Conway said both arsenic and selenium occur naturally in the aquifer, and as saline lakes fed by the aquifer dry up, these metals may become more concentrated – where the snowy plovers may then be exposed to more of the heavy metals.

"These birds are certainly an indicator of what's happening to the Ogallala," Conway said, "and frankly, in terms of dealing with those declining water tables and declining water availability, it's going to change how people on this landscape live."

Working together

Looking toward the future, Conway said they are working with various other research institutions and agencies to begin using molecular techniques to look at population stability and genetic connectivity beyond what we're seeing in the behavioral side from the Motus network tower nanotag deployments.

"All of this is leading towards what we have to work with in terms of developing strategic conservation approaches for snowy plovers," Conway said, "not just here, but range wide."

Source: Texas Tech University’s College of Agricultural Sciences and Natural Resources