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Why didn?t the chicken cross the road: NMSU researches decline of lesser prairie chickens

The lesser prairie chicken was once abundant over Kansas, Oklahoma, Texas, New Mexico and parts of Colorado; their population has declined about 90 percent. Their range has been reduced by about 80 percent. Today the total population is approximately 16,000 birds.

Man holding chicken
NMSU researchers trap and capture the lesser prairie chickens using non invasive procedures. In Milnesand, New Mexico, the prairie chicken ?capital,? Andy Lawrence is collecting data on the birds. (Photo by Andy Lawrence)

Southeastern New Mexico is home to a declining population of lesser prairie chickens where they inhabit a vast landscape of shinnery oak, native grasses and sand dunes.

New Mexico Cooperative Fish and Wildlife Research Unit Ecologist Scott Carleton is leading three research projects through New Mexico State University on various life history aspects of this species to benefit their management and conservation. He and his team of graduate and undergraduate students work with state, federal and private organizations to provide solutions in hopes of better understanding the biology of these birds in New Mexico.

His projects address the possible impacts of oil and gas development, seasonal use of the native and non-native Conservation Reserve Program grasslands in eastern New Mexico and impacts of habitat loss on federally managed lands by collecting data on seasonal habitat use, movement patterns, reproduction and survival of the lesser prairie chicken.

?We need to be conservation minded and try to balance the needs of both animals and humans, understand how the two can exist in the same place, at the same time and not be a detriment to each other,? Carleton said.

The birds were added to the U.S. Fish and Wildlife Service?s threatened species list in early 2014. As a step below the endangered species list, this allows a flexible plan of action to determine the fate of how conservation is resolved among the five affected states.

Almost all the birds in New Mexico are found within the shinnery oak ecosystem, made up of two- to three-foot-tall shinnery oak trees and mixed grasses where every spring the birds congregate on leks.

Monitoring the leks ? areas where the males perform their mating display to attract mates ? gives researchers insight on mating patterns and is the time when population declines can be detected.

?We know the population is declining when the males across the leks we are monitoring decrease or stop showing up,? Carleton said. ?The hens are there because the habitat and conditions near the lek are favorable for nesting, cover and food. The males are there because the hens are there and when you lose your hens to predation or poor reproduction year after year, eventually the males disappear.?

The males have high site fidelity and will visit the same lek year after year their entire lives until they die.

While the males perform their mating display of song and dance, the hens will basically walk through the lek and pick a mate. The hen will then leave the lek and find a location that meets her temperature and habitat needs. She will lay one egg a day for 10-12 days and will not start incubating until she has laid all her eggs, therefore, synchronizing hatching. These birds are precocial, meaning the moment they hatch they are able to walk.

?What we?ve been finding is that most, but not all birds, stay within five to six kilometers of the lek where they gather to breed each spring. Almost all of our birds follow this pattern,? Carleton said. ?It?s great from a conservation perspective because you know you need to protect habitat within this distance from the lek in every direction.?

However, some birds that disperse from these sites may travel large distances. This is how populations maintain genetic diversity across the landscape, by spreading new genes to other populations.

?We need to protect connectivity of these populations to benefit gene flow and for future expansion of these populations to new areas, new lek establishment and new populations,? Carleton said.

Part of Ph.D. student Andy Lawrence?s research is measuring genetic relatedness and connectivity between leks. If the prairie chickens are unable to maintain genetic diversity, often caused by isolation due to a loss of landscape connectivity, inbreeding will eventually cause them to die out.

?Can a highway, an energy field, or large blocks of degraded or altered habitat completely cut off two populations from intermixing? These are the questions Andy is addressing,? Carleton said.

By determining the ecological effects of expansion and development in areas where the chickens reside, Lawrence and his team are able to ask and eventually answer questions that can be beneficial for wildlife managers, land managers, and developers.

?In the end we want to provide a science-based product from our time in the field tracking birds, determining habitat use patterns, reproduction, survival and measuring habitat characteristics that we can give to the wildlife and land management agencies,? Carleton said. ?Specifically, provide management guidelines on what more, if any, these agencies do to benefit this species.?

According to the U.S. Fish and Wildlife Service website, the collective states will follow a plan established by the Western Association of Fish and Wildlife Agencies to meet a population goal of 67,000 birds range-wide.

Using radio collars and satellite GPS transmitters, researchers are able to track the movements of the birds, learning what their daily patterns are. Because they remain in a five to six kilometer radius of the leks, any small changes to the landscape, if any, can be detrimental to the population.

?These birds aren?t very structure friendly,? Carleton said. ?One of the big things that development brings are places for their predators to perch or hide. We have data showing avoidance of roads and areas where there are trees or shrubs. They will literally stop at roads and go around areas dominated by trees and shrubs. Whether it?s because the road traffic is too frequent or because trees provide perching or hiding areas for predators, we just don?t know for sure. What we do know for sure is that they avoid these locations which further limits the availability of habitat they need to survive.?

To put it into human context, imagine there is something you were incredibly fearful of that was limiting your ability to enter a certain area or space. If this barrier wasn?t there, you would have access to whatever it is you were attempting to attain or grasp. Human activities on the landscape can create these same obstacles for wildlife, limiting access to habitat they need to survive.

When Carleton?s research is completed, he and his team will be able to provide land management agencies information about the population impacts of natural and human-caused changes on the landscape to lesser prairie chicken survival, habitat use and seasonal movement patterns. His goal is to understand the life history characteristics of these birds, what impacts are negatively affecting these birds and how we can change what we are doing to benefit the species but at the same time still allow for energy development and other land management programs to progress or grow. Their goal is to provide the best data to support conservation, balancing the needs of both wildlife and humans.

The projects extends to fall 2016. During the duration of these projects, researchers will compare their data to data being collected by other researchers and agencies across the lesser prairie chicken range in Texas, Oklahoma, Colorado and Kansas. This way, NMSU can compare and contrast how this bird should be managed at local, regional and range wide scales so that they do not incorrectly take a one-size-fits-all approach.

For more information on Carleton?s research, visit http://web.nmsu.edu/~carleton/Scott_Carleton/Research.html