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United States Department of Agriculture

Agricultural Research Service


Location: Range Management Research

Title: Pack rats (Neotoma spp.): Keystone ecological engineers?

item Whitford, Walt
item Steinberger, Yosef

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2010
Publication Date: 6/15/2010
Publication URL:
Citation: Whitford, W.G., Steinberger, Y. 2010. Pack rats (Neotoma spp.): Keystone ecological engineers? Journal of Arid Environments. 74:1450-1455.

Interpretive Summary: Pack rats are native rodents common in desert environments. This study funded by the National Science Foundation, examined two questions regarding the roles of these rodents in these environments 1) are they ecological “engineers,” that is, are they critical species affecting the functioning of deserts (an area of ~5% of the U.S.) and 2) are they prevalent in different vegetation types within this desert? The importance of recognizing any species as a keystone “engineer” of any environment is illustrated by the list of species known to perform key functions. This list includes beavers, grizzly bears, prairie dogs and elephants. This study concluded that the white-throated woodrat and the plains woodrat perform keystone type functions in the Chihuahuan desert. Of additional importance, the study found these woodrats performing these function sin many different vegetation types from shrublands to grasslands. They are capable of exiting in a range of environments which likely makes them more resilient to natural or human factors that may cause these environments to change.

Technical Abstract: The potential role of two species of pack rats (Neotoma albigula and Neotoma micropus) as keystone ecological engineers was examined by estimating the species diversity of invertebrates living in the nest middens, and nitrogen mineralization rates in soils associated with the middens. Although pack-rat middens in tarbush (Flourensia cernua) shrublands were smaller than those in creostebush (Larrea tridentata) shrublands, they housed a higher abundance and diversity of arthropods. The Neotoma spp. middens were an important microhabitat for crickets (Gryllus sp.), wolf spiders (Lycosa spp.), and lycid beetle larvae (Lycidae) in all of the shrub habitats. There were five arthropod taxa that occupied all middens in the creosote-bush shrubland, and 12 arthropod taxa that occupied all middens in the tarbush shrubland. Soils associated with pack-rat middens had significantly higher soil organic-matter content than reference soils. Nitrogen mineralization was significantly higher in soils associated with pack-rat middens than in reference soils. Neotoma spp. create habitats with moderate microclimates that are essential for several invertebrates, thus contributing to maintenance of biodiversity. The effects of middens on soil organic matter and nitrogen mineralization create nutrient-rich patches. Neotoma spp. affect biodiversity and critical ecosystem processes, thus supporting the designation of keystone ecological engineers.

Last Modified: 07/23/2017
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