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Construction Ahead: Prairie Dogs Build Diversity Across the Plains

An Interview with Dr. David J. Augustine, USDA – 

Dr. David Augustine
Dr. David Augustine

Black-tailed prairie dogs are helpful homebuilders, gardeners and gourmet meals according to recently published research in Conservation Biology. In “Associations of Grassland Bird Communities with Black-tailed Prairie Dogs in the North American Great Plains,” authors David J. Augustine and Bruce W. Baker reveal that the areas in which the iconic rodent is present also support higher densities of at least 9 other vertebrates. From black-footed ferrets and prairie rattlesnakes to burrowing owls, mountain plovers and horned larks, it seems that prairie dogs are living up to their “keystone species” moniker.

In response to the study, we contacted Dr. David Augustine to learn more about his work. David, who is a Research Ecologist with the USDA’s Agricultural Research Service (ARS) in Fort Collins, CO, studies plant-herbivore interactions, the ecology and management of semi-arid rangelands, and conservation biology. He received his MS in Wildlife Conservation from the University of Minnesota, and PhD in Biology from Syracuse University. Prior to joining ARS, Dr. Augustine worked for as a Wildlife Biologist for the Comanche and Cimarron National Grasslands in Colorado and Kansas.  His past research has examined the role of herbivory in a variety of ecosystems including savannas of East Africa, sagebrush steppe in Yellowstone National Park, and deciduous forests of eastern North America.

 

Prairie dog family dynamics on American Prairie Reserve, Montana.
Prairie dog family dynamics on American Prairie Reserve, Montana.

 

American Prairie Reserve: You’ve conducted research on grasslands far and wide, including America’s Great Plains and the savannas of East Africa. What draws you to these ecosystems? 

David Augustine: For me, the draw has always been the relationship between the herbivores and the overall ecosystem.  Grasslands are places where so much of the sunlight is eventually converted into mammalian herbivores, which allows the herbivores to both respond to and influence everything from soil microbes to bird communities. 

 

APR: We’re a little biased in our interest in the northern Great Plains, where American Prairie Reserve is located. How does this region to compare to others that you’ve studied?

David: When I first moved from Africa to the Great Plains, the lack of ungulate diversity was a bit disappointing – I went from working on a ranch in Kenya with cattle, sheep, goats, camels and 14 species of native ungulates to places that just supported cattle and pronghorn.  The APR represents one of the few places in the Great Plains where a full suite of native ungulates is being conserved in combination with livestock and a diverse suite of wildlife species of conservation concern.  This along with the sheer size of the relatively unfragmented prairie landscape in and around APR makes it truly unique.

Long-billed curlews are one of many species that benefit from the presence of prairie dogs.
Long-billed curlews are one of many species that benefit from the presence of prairie dogs.

 

APR: In the recent study on black-tailed prairie dogs and grassland birds, your results indicated that “large complexes of prairie dog colonies in the northern Great Plains contribute to a substantially more diverse bird community” than areas where prairie dogs are absent. What are some of the relationships that exist between prairie dogs and grassland birds that make this possible? Who needs the prairie dog to survive?

David: Black-tailed prairie dogs influence so many species because they affect grassland ecosystems in multiple ways.  First, they are a prey source for a large number of predators, from specialists like black-footed ferrets to snakes, swift foxes, and raptors.  Second, the burrows they dig provide underground refugia for other species, like burrowing owls and some reptiles, to escape from predators, storms, or extreme temperatures.  Third, prairie dog grazing modifies the vegetation substantially, creating vegetation that is more prostrate (low to the ground), sparse, and dominated by forbs – this can provide a unique breeding habitat for some bird species that are adapted to these conditions, like mountain plovers, killdeer and McCown’s longspurs.  And finally, the contrast between short, sparse vegetation on their colonies and the taller, denser vegetation off prairie dog colonies can be valuable to some species that benefit from having both types of vegetation near one another – examples include long-billed curlews and mourning doves.

 

APR: As explored in some of your previous research, black-tailed prairie dogs in northeastern Montana have been significantly impacted by plague (Yersinia pestis). What has been the impact of this disease on the landscape?

David: One major effect is that plague prevents colonies from occupying a large portion of the landscape.  Just when a colony or local cluster of colonies grows to a size where they are beginning to function as a major component of the landscape, we typically see a plague epizootic move through, returning the colonies back to small, isolated pockets of surviving prairie dogs.

Burrowing Owls make homes in the abandoned burrows of prairie dogs.
Burrowing Owls make homes in the abandoned burrows of prairie dogs.

 

APR: And what about the impact of plague in terms of other wildlife?

David: After a plague epizootic, all of those functions that prairie dogs perform – serving as prey, modifying vegetation, and generating belowground refugia – are soon lost.  Clearly their role as prey is gone first.  With one average growing season, the effects that prairie dogs had on vegetation structure are lost.  And even the belowground refugia begin to collapse and lose their value to other wildlife species within 2-3 years after the plague outbreak.   

 

APR: Mountain plovers were also mentioned in our last interview on the topic of rarity in nature with WWF Lead Scientist and author Eric Dinerstein. What, in your opinion, makes this species remarkable or unique?

David: For me, mountain plovers are remarkable because they are so closely tied to disturbance regimes in the Great Plains, both prairie dog colonies and recent burns.  Mountain plovers are an expression of the processes like grazing and fire that have been operating to sustain a variable landscape in this region for thousands of year.  It’s also amazing to watch how well-adapted they are to living in such sparse and prostrate vegetation.  One moment their white breast stands out like a beacon on the prairie, and then when they turn their back to you, they just disappear into the prairie.

 

APR: What are you working on now?

David: The past several years I’ve mainly studied intense or recent disturbances, like prairie dogs colonies and prescribed fire.  Now I am beginning to focus on the other side of the equation, which is the role and function of grassland lacking recent disturbance.  In particular, we are starting new large-scale experiments to examine how periodic, pulsed livestock grazing – where an area is grazed heavily but then rested from grazing for a year or more – affects grassland structure and habitat for native wildlife.  This is another part of sustaining the variable landscape that characterized prairie landscapes historically.

 

APR:  And for the hardest question – favorite prairie species?

David: That is hard.  One of my favorites has to be the long-billed curlew.  Their large size and long beak seem so incongruous with open prairie, yet when sitting on their nest, they are perfectly camouflaged as a cow pie.  Another example of the long coevolutionary relationships between grazers and birds in this region.  

 

Further reading:

Augustine, D. J., and B. W. Baker. 2013 Associations of grassland bird communities with black-tailed prairie dogs in the North American great plains. Conservation Biology, 1–11.

Augustine, D. J., and J. D. Derner. 2012. Disturbance regimes and mountain plover habitat in shortgrass steppe: large herbivore grazing does not substitute for prairie dog grazing or fire. The Journal of Wildlife Management 76(4):721–728.

Augustine, D. J., S. J. Dinsmore, M. B. Wunder, V. J. Dreitz, and F. L. Knopf.  2008.  Response of mountain plovers to plague-driven dynamics of black-tailed prairie dog colonies.  Landscape Ecology 23:689-697.   

Augustine, D. J., M. R. Matchett, T. B. Toombs, J. F. Cully, T. L. Johnson, and J. G. Sidle. 2008.  Spatiotemporal dynamics of black-tailed prairie dog colonies affected by plague. Landscape Ecology 23:255-267.

 

American Prairie Reserve (APR) is assembling a world class wildlife reserve in northern Montana, with the goal of one day creating a seamless 3.5 million acre grassland ecosystem. APR’s President Sean Gerrity is a National Geographic Fellow. Learn more about the Reserve, including progress to date and prairie dog restoration efforts, on the Reserve’s website.