Forage preferences in two species of prairie dog (Cynomys parvidens and Cynomus ludovicianus): implications for hibernation and facultative heterothermy

Abstract

Several laboratory studies have shown that the ingestion of dietary linoleic (18:2 o6) acid before winter can promote deep and continuous torpor, whereas excess consumption of a-linolenic acid (18:3 o3) can interfere with an animal's ability to reach and maintain low body temperatures during torpor. As mammalian heterotherms obtain linoleic and a-linolenic acid strictly from the diet, diet selection has been proposed as a mechanism that allows hibernators to ingest levels of linoleic and a-linolenic acid that promote favorable torpor patterns. Here diet, dietary nutrient content and patterns of forage preference of a representative hibernator, the Utah prairie dog Cynomys parvidens, and a facultative heterotherm, the black-tailed prairie dog Cynomys ludovicianus, were examined under natural field conditions. Diets of black-tailed (BTPD) and Utah prairie dogs (UTPD) differed across seasons (BTPD F 26,108 = 9.59, Po0.01; UTPD F 38,80 = 3.25, Po0.01) and elevations (BTPD F 26,108 = 20.15, Po0.01; UTPD F 38,80 = 20.51, Po0.01), and forage preference indices indicate that neither species randomly selected plant species relative to their abundance on colonies in any season. Black-tailed prairie dogs did not consume or avoid consumption of plant species based on levels of total lipids, linoleic acid, a-linolenic acid or nitrogen. Considering only the plants consumed, black-tailed prairie dogs appeared to prefer plants with low levels of a-linolenic acid (F 1,19 = 5.81, P= 0.03), but there were no detectable relationships between preference and other nutrients. Utah prairie dogs consumed plants higher in a-linolenic acid (t= 1.98, P= 0.05) and avoided plants high in linoleic acid (t=À2.02, P= 0.04), but consumption-avoidance decisions did not appear to be related to nitrogen or total lipids. Of the plants consumed, Utah prairie dogs again preferred plants high in a-linolenic acid (F 1,17 = 4.62, P= 0.05). Levels of linoleic and a-linolenic acid were positively correlated in plants consumed by prairie dogs (BTPD Pearson r= 0.66, Po0.01; UTPD Pearson r =0.79, Po0.01), reducing the opportunity for independent selection of either lipid.

Interactions between black-tailed prairie dogs (Cynomys ludovicianus) and vegetation in habitat fragmented by urbanization

“…While it is known that prairie dogs often provide a competitive advantage to forb species (Coppock et al, 1983;Day and Detling, 1994;Detling, 1998), and it is thus conceivable that prairie dogs in this study system are enhancing the spread of this invasive exotic species, further studies are needed to confirm this relationship. In addition, prairie dogs are known to consume field bindweed (Lehmer et al, 2006), and thus may actually have potential to limit its spread.…”

Paltry past‐precipitation: Predisposing prairie dogs to plague?

“…Common soils include Edgar (loamy) and Valent (sandy) soils. Common forage for prairie dogs in the study area includes blue grama ( Bouteloua gracilis ), buffalo grass ( Buchloe dactyloides ), western wheatgrass ( Agropyron smithii ), needle and thread grass ( Stipa comata ), prickly pear cactus ( Opuntia polyacantha ), and several species of forbs (Lehmer and Van Horne , Lehmer et al ).…”

Effects of vegetation differences in relocated Utah prairie dog release sites

“…The height of the canopy layer plant was also measured to calculate average vegetation height. Because Utah prairie dogs consume a wide variety of plant species [8] and species composition varied at each site, we focused our analysis on comparing the percent cover of grasses (this included sedges and rushes), forbs, and shrubs, and comparing vegetation height at each site. We did not compare species composition between sites.…”

“…By comparing how frequently a plant was consumed versus how common it was at the site, researchers have been able to determine if a plant species was preferred or avoided by Utah prairie dogs. In a study by Lehmer [8], Utah prairie dogs preferred scarlet globemallow (Sphaeralcea coccinea) and cheatgrass (Bromus tectorum) in each season and elevation. Animals in low elevaions preferentially foraged on western wheatgrass (Elymus smithii), Indian ricegrass (Stipa hymenoides), scarlet globemallow, and needle-and-thread grass (Hesperostipa comata).…”

“…), cheatgrass, and sedges (Carex spp.). Utah prairie dogs avoided shrub species such as rubber rabbitbrush (Chrysothamnus nauseosus), Douglas rabbitbrush (Chrysothamnus viscidiflorus), and black sagebrush (Artemisia nova) [8].…”