Characteristics of Pocket Gophers Along an Altitudinal Transect

Tryon, Clarence Archer; Cunningham, H. N.

doi:10.2307/1378729

Cited by 9 publications

(10 citation statements)

References 8 publications

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“…Population densities of the plains pocket gopher (Geomys bursarius), the northern pocket gopher (Thomomys talpoides), and Attwater's pocket gopher (G. attwaterz) were positively related to abundance of dicots (Downhower and Hall 1966, Tryon and Cunningham 1968, Andersen and MacMahon 1981this study). Preference for dicots and avoidance of grasses by G. bursarius and T. talpoides probably reflects the high percentage of dicots (X = 69%, range: 38-95%) in their habitat (Ward and Keith 1962, Downbower and Hall 1966, Tryon and Cunningham 1968, Andersen and MacMahon 1981. Both G. bursarius and T. talpoides live in high altitude and/or high latitude areas.…”

Section: Pocket Gopher Density and Dietary Resourcesmentioning

confidence: 79%

“…Pocket gophers feed while burrowing. Although burrowing is an energetically expensive mode of travel (360 to 3400 times as great as terrestrial travel; Vleck 1981), pocket gophers feed selectively (Tryon and Cunningham 1968, Andersen and MacMahon 1981, Gettinger 1984a, Williams and Cameron 1986b. We hypothesize and Andersen (1987) suggests that pocket gophers encounter dietary resources as a result of movement patterns rather than in response to sensory stimuli.…”

Section: Demographic Variationmentioning

confidence: 87%

“…Little is known about demographic variation among populations offossorial herbivores or the responses by such populations to naturally occurring variation in their resource plants. Hansen and Bear (1964), Tryon and Cunningham (1968), and Andersen and Mac- Mahon (1981) reported variation in density, but no variation in other traits examined, such as body mass or litter size. Andersen and MacMahon (1981) studied populations of Thomomys ta/poides in four habitats, but obtained sufficient demographic data from populations in just one habitat.…”

Section: Discussionmentioning

confidence: 98%

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Intraspecific Response to Variation in Food Resources by Attwater's Pocket Gopher

Williams¹,

Cameron²

1990

Ecology

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We examined the effect of variation in availability of dietary resources on demographic variation among seven populations of Attwater's pocket gopher. Pocket gophers were live—trapped to assess demographic parameters, and additional individuals were used to determine detailed reproductive information and dietary habits. Attwater's pocket gopher exhibited variation in population density, ovulation rate, pre—implantation mortality, proportional loss of young, and total recruitment, but not in litter size, sex ratio, or age structure among the seven populations. Dietary analyses revealed that annual dicots were avoided in a habitat where their proportional occurrence was high, but the preferred dietary item (perennial dicots) was consumed in proportion to its occurrence. Population density (carrying capacity) was limited by availability of resources, primarily availability and dispersion of preferred perennial dicots. Predictability of density of pocket gophers by dietary resources was low, °12%, compared to that of terrestrial herbivores. Low population density was associated with low total recruitment, low survival of young, and longer movement by individuals through the habitat. We propose an hypothesis for regultion of population density. As availability of perennial dicots decreases, pocket gophers move greater distances to obtain this resource. Increased movement increases the probability of aggressive, intraspecific encounters. These encounters increase aggression levels in the populations, result in greater loss of young through dispersal or mortality, and generally decrease recruitment. Loss of individuals decreases population density to a level set by availability of resources and level of aggression decreases.

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Section: Pocket Gopher Density and Dietary Resourcesmentioning

confidence: 79%

Section: Demographic Variationmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 98%

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Intraspecific Response to Variation in Food Resources by Attwater's Pocket Gopher

Williams¹,

Cameron²

1990

Ecology

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“…Early work that considered the energetics of burrowing comprised either speculative accounts that featured no direct measurements (Grinnell, 1923;Tryon and Cunningham, 1968;Vaughan, 1974), or considered only basal metabolism and thermoregulatory costs (McNab, 1966). The first studies of burrowing energetics were conducted by Seymour (1973), who measured the metabolic rates of burrowing spadefoot toads (Spea multiplicata; prev.…”

Section: Introductionmentioning

confidence: 99%

Morphology and burrowing energetics of semi-fossorial skinks (Liopholis)

Alton

Clemente

et al. 2015

Journal of Experimental Biology

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Burrowing is an important form of locomotion in reptiles, but no study has examined the energetic cost of burrowing for reptiles. This is significant because burrowing is the most energetically expensive mode of locomotion undertaken by animals and many burrowing species therefore show specialisations for their subterranean lifestyle. We examined the effect of temperature and substrate characteristics (coarse sand or fine sand) on the net energetic cost of burrowing (NCOB) and burrowing rate in two species of the Egernia group of skinks (Liopholis striata and Liopholis inornata) compared with other burrowing animals. We further tested for morphological specialisations among burrowing species by comparing the relationship between body shape and retreat preference in Egernia group skinks. For L. striata and L. inornata, NCOB is 350 times more expensive than the predicted cost of pedestrian terrestrial locomotion. Temperature had a positive effect on burrowing rate for both species, and a negative effect on NCOB for L. striata but not L. inornata. Both NCOB and burrowing rate were independent of substrate type. Burrows constructed by skinks had a smaller cross-sectional area than those constructed by mammals of comparable mass, and NCOB of skinks was lower than that of mammals of similar mass. After accounting for body size, retreat preference was significantly correlated with body shape in Egernia group skinks. Species of Egernia group skinks that use burrows for retreats have narrower bodies and shorter front limbs than other species. We conclude that the morphological specialisations of burrowing skinks allow them to construct relatively narrow burrows, thereby reducing NCOB and the total cost of constructing their burrow retreats.

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“…Northern Pocket Gopher (Thomomys talpoides) adults and juveniles are difficult to tell apart in late summer and early fall on the basis of weight. In British Columbia orchard-old field habitats, from July to September, Sullivan et al (2001) used three age classes of Northern Pocket Gophers based on body weight: juveniles (young of the year, which do not breed until the next year) < 49 g; subadults (individuals of which 50% are mature in the upper weight class) 49-60 g; and adults (≥ 50% of individuals sexually mature in the lowest weight class) ≥ 61 g. However, previous studies on the body size of Thomomys talpoides (Smith 1940;Hansen 1960;Hansen and Bear 1964;Tryon and Cunningham 1968;Hansen and Reid 1973) and Thomomys bottae, Valley Pocket Gopher, (Howard and Childs 1959;Daly and Patton 1986;Patton and Brylski 1987) showed that animal weights varied among pocket gopher populations due to habitat types, altitude, latitude, and seasons . Patton and Brylski (1987) found that growth rates and body sizes of pocket gophers inhabiting alfalfa monocultures were greater than those of pocket gophers inhabiting natural-vegetation communities.…”

mentioning

confidence: 99%

Body Weights of Adult and Juvenile Northern Pocket Gophers, <em>Thomomys talpoides</em>, in Central Alberta Alfalfa Fields

Proulx¹

2005

Can Field Nat

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In an effort to recognize adults from juveniles in late summer and early fall, carcasses of Northern Pocket Gophers (Thomomys talpoides) captured from April to October 1994 in a pure alfalfa (Medicago spp.) field in Camrose and a mixed alfalfa-orchard grass (Dactylis glomerata)-dandelion (Taraxacum spp.) field in Lacombe, in central Alberta were analyzed. Mean weights of adult males and females were significantly (P < 0.05) larger than those of juveniles with near-adult body sizes in late summer and early fall. On the basis of the limits of 95% confidence intervals for individual values in Camrose and Lacombe, live-captured males weighing < 130 g could be classified as juveniles; those that are > 180 g would be adults. Males weighing between 130 and 180 g could be either juveniles or adults. Live-captured females weighing < 110 g would likely be juveniles. With larger animals, the pubic symphysis should be used to distinguish young females from adults. Given the variability of body weight in Northern Pocket Gophers, it is suggested that criteria for aging based on weight be derived for local populations in specific habitat types. On average, Northern Pocket Gopher males and females from Camrose were significantly (P < 0.05) heavier than those of Lacombe. Animals from both fields were, on average, heavier than those previously studied in natural-vegetation communities. Differences in the food nutritional quality may explain the observed variation in body weights among populations.

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Characteristics of Pocket Gophers Along an Altitudinal Transect

Cited by 9 publications

References 8 publications

Intraspecific Response to Variation in Food Resources by Attwater's Pocket Gopher

Intraspecific Response to Variation in Food Resources by Attwater's Pocket Gopher

Morphology and burrowing energetics of semi-fossorial skinks (Liopholis)

Body Weights of Adult and Juvenile Northern Pocket Gophers, <em>Thomomys talpoides</em>, in Central Alberta Alfalfa Fields

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