conservation.arizona.edu - keystone species

Black-tailed prairie dog (Cynomys ludovicianus) reintroduction can limit woody plant proliferation in grasslands

mmerrick — Fri, 17 Jul 2020 20:43:34 +0000

Authors

Sarah L. Hale

John L. Koprowski

Steven R. Archer

Tree and shrub proliferation has been widespread in grasslands worldwide, and has altered ecosystem function and wildlife habitat. Several causes have been proposed for the woody plant encroachment phenomenon. The widespread eradication of a native keystone herbivore in North American grasslands, the prairie dog (Cynomys spp.), is one potential contributing factor that has received relatively little attention. We hypothesized prairie dogs would have historically suppressed woody plants by creating “browse traps” through their systematic clipping of vegetation. We tested this hypothesis by conducting surveys and experimentally manipulating shrub accessibility via exclosures and artificial saplings on and around recently reestablished black-tailed prairie dog (Cynomys ludovicianus) colonies in southeastern Arizona, United States. Shrubs were common on the nascent colonies (mean ± SE = 132 ± 32.7 plants ha–1), but at substantially reduced densities compared to off colonies (305 ± 94.9 plants ha–1). Among branches placed on colonies to simulate “saplings” 89% were damaged within 3 days of “planting,” whereas those placed off colonies were virtually untouched. This was true for both a deciduous, N2-fixing shrub (velvet mesquite, Prosopis velutina) and an evergreen non-N2-fixing shrub (creosote bush, Larrea tridentata). Prairie dogs on newly established colonies did not extirpate woody plants over the time-frame of our study, but reduced their abundance and suppressed their growth, which would ostensibly prevent them from achieving dominance. Implications for extending the longevity of widely practiced “brush management” grassland restoration treatments are discussed in the context of perceptions of prairie dogs as rangeland pests. Prairie dogs represent an enigma in keystone conservation. Whereas the reintroduction of large or charismatic keystone species [e.g., sea otters (Enhydra lutris)] are conducted to restore critical ecological function, reintroductions of other keystone species, such as gray wolves (Canis lupus) and in our case, prairie dogs, are highly controversial. Our findings suggest reintroductions of this negatively perceived small herbivore could function as a tool to locally suppress woody plant proliferation that is widely regarded as an impediment to livestock production. Accordingly, prairie dogs could promote restoration efforts to re-establish and maintain habitat for grassland endemics while promoting biological diversity and other ecosystem services.

Additional Information

Frontiers in Ecology and Evolution

Date of publication:

2020

Topics

keystone species

browse trap

grasslands

restoration ecology

Research Categories

Behavioral Ecology Human Wildlife Conflict Natural History Threatened and Endangered Species

Hale, S. L., J. L. Koprowski, and H. Hicks. 2013. Review of black-tailed prairie dog reintroduction strategies and site selection: Arizona reintroduction. In Gottfried, Gerald J.; Ffolliott, Peter F.; Gebow, Brooke S.; Eskew, Lane G.; Collins, Loa C., com

thackerk1 — Mon, 22 Jul 2019 18:05:30 +0000

Authors

Sarah L. Hale

John L. Koprowski

Holly Hicks

The black-tailed prairie dog (Cynomys ludovicianus) was once widely distributed throughout the western United States; however, anthropogenic influences have reduced the species’ numbers to 2 percent of historical populations. Black-tailed prairie dogs are described as a keystone species in the grassland ecosystem, and provide many unique services, including burrows for other species (e.g. burrowing owls [Athene cunicularia] and rattlesnakes [Crotalus spp.]), nutrient rich soil that, in turn, provides rich vegetationfor grazers, and food for many carnivores and birds of prey. Several efforts have been made to reestablishthis species to its historical range. In southeastern Arizona, a recent reintroduction effort was built upon work of scientists that identified potential suitable areas with characteristics similar to those of existing prairie dog colonies in Mexico. Prairie dogs were first translocated to the sites in 2008, and individuals still remain on the landscape today. We compare this to other reestablishment efforts, and provide suggestions on ways to increase success of future reintroductions.

Additional Information

Review of Black-Tailed Prairie Dog Reintroduction Strategies and Site Selection: Arizona Reintroduction

Date of publication:

2013

Topics

black-tailed prairie dog

keystone species

population reduction

reintroduction

reestablishment

Ecosystem-level effects of keystone species reintroduction: a literature review

thackerk1 — Thu, 27 Jun 2019 23:42:45 +0000

Authors

Sarah L. Hale

John L. Koprowski

The keystone species concept was introduced in 1969 in reference to top‐down regulation of communities by predators, but has expanded to include myriad species at different trophic levels. Keystone species play disproportionately large, important roles in their ecosystems, but human‐wildlife conflicts often drive population declines. Population declines have resulted in the necessity of keystone species reintroduction; however, studies of such reintroductions are rare. We conducted a literature review and found only 30 peer‐reviewed journal articles that assessed reintroduced populations of keystone species, and only 11 of these assessed ecosystem‐level effects following reintroduction. Nine of 11 publications assessing ecosystem‐level effects found evidence of resumption of keystone roles; however, these publications focus on a narrow range of species. We highlight the deficit of peer‐reviewed literature on keystone species reintroductions, and draw attention to the need for assessment of ecosystem‐level effects so that the presence, extent, and rate of ecosystem restoration driven by keystone species can be better understood.

Additional Information

Restoration Ecology

Date of publication:

2018

Topics

ecosystem restoration

keystone species

reintroduction

population declines

ecosystem-level effects

Research Categories

Population Ecology Threatened and Endangered Species

Kangaroo rat foraging in proximity to a colony of reintroduced black-tailed prairie dogs

thackerk1 — Thu, 27 Jun 2019 21:57:47 +0000

Authors

Kirsten M. Fulgham

John L. Koprowski

We examined the indirect effects of reintroduced black-tailed prairie dogs (Cynomys ludovicianus) on resident kangaroo rat (Dipodomys) populations. We used the Giving-up Density theory to quantify kangaroo rat foraging on a black-tailed prairie dog colony vs. foraging near the colony edge or in the surrounding native habitat. This approach allowed us to assess the influence of black-tailed prairie dogs on kangaroo rat foraging activity. Our results showed a greater foraging preference off-colony in most seasons. Kangaroo rats visited off-colony feeding trays more frequently and collected a greater mean mass of seed as well. This indicated that kangaroo rats perceived the area off the prairie dog colony as having a lower foraging cost than the on-colony or colony edge locations. Our data suggest that from the perspective of the seed-eating kangaroo rat, the colony is not viewed as high quality habitat. Both prairie dogs and kangaroo rats have been described as keystone modifiers in grassland ecosystems. What impact the reintroduction and management of one keystone species might have on another keystone species deserves additional consideration as we attempt to restore arid grassland ecosystems.

Additional Information

The Southwestern Naturalist 61:194-202.

Date of publication:

2016

Topics

reintroduction

black-tailed prairie dog

kangaroo rat

Giving-up Density theory

foraging

keystone species

Research Categories

Behavioral Ecology Threatened and Endangered Species