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Native fishes of the Upper Colorado River Basin have experienced substantial declines in abundance and distribution, and are extirpated from most of Wyoming. Muddy Creek, in south-central Wyoming (Little Snake River watershed), contains sympatric populations of native roundtail chub (Gila robusta), bluehead sucker, (Catostomus discobolus), and flannelmouth sucker (C. latipinnis), and represents an area of high conservation concern because it is the only area known to have sympatric populations of all 3 species in Wyoming. However, introduced creek chub (Semotilus atromaculatus) are abundant and might have a negative influence on native fishes. We assessed summer food habits of roundtail chub and creek chub to provide...
ABSTRACT-Spawninagn d movementso f the razorbacks ucker,X yrauchent exanus,w ere evaluated by radiotelemetry( n = 17 fish) and captureo f 230 adults (105 recaptures)i n the Green and Yampa rivers, 1987 to 1989. Ripe fish (n = 194) were captured in riffles with cobble, gravel, and sand substratesf romm id-Aprilt o early June. Recapturedm alesw ere ripe from2 to 28 days and recaptured females from 2 to 15 days. Razorback suckers spawned during ascending and highest spring flows at water temperatureso f about 14'C (range of 9 to 17?C).S pawning migrationso f 30 to 106 km were detectedi n 17 razorbacks uckers,b ut movementsw ere more limitedo r undetectedi n other individuals. Floodedl owlandsa nd lower portionso f...
Geographic variation in 17 cranial characters of 138 specimens of Idionycteris phyllotis was examined by use of univariate and multivariate techniques. Larger individuals occur in the central portion of the range (New Mexico and southern Arizona) Published in The Southwestern Naturalist, volume 19, issue 1, on pages 114 - 115, in 1974.
Used first paragraph of the introduction: Rock pools, or potholes, are depressions in bedrock that are not in active drainages. Precipitation collects in these basins creating small, ephemeral aquatic environments with fauna unique to temporary aquatic systems. Few studies have been made of pothole ecology on the Colorado Plateau (Romney, 1971; Findley, 1975; Dodson, 1987). Observations and studies of ecological interactions are needed to determine factors that influence ecosystem functioning and community structure of potholes. Here I report on two unusual predation events involving dipteran larvae feeding on two species of fairy shrimp. Published in The Southwestern Naturalist, volume 39, issue 2, on pages 206...
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We studied 403 colonies of black-tailed prairie dogs (Cynomys ludovicianus) in a 28,927-km2, 12-county area of the southern High Plains, and we examined the distribution, area of colonies, size of populations, and association of these colonies with playa lakes. We used visual counts and estimated size of populations based on modeling of the proportion of a population of prairie dogs above ground at the times of surveys. Colonies in the southern High Plains were small (median = 8.8 ha), with generally small populations (median = 68), and average densities of 14 � 22 prairie dogs/ha. Colonies were closer to playa lakes than would be expected by chance (P < 0.001), with 40% of colonies built in the basin, slopes, or...
ABSTRACT-In the Gila River drainage of southwestern New Mexico, roundtail chub (Gila robusta) were historically widespread and relatively common in mainstream and larger tributary habitats. Natural and human-induced habitat alterations and establishment of non-native predator fishes are believed to be the primary reasons for the current reduced range and abundance of this species. Roundtail chub has been extirpated from the San Francisco River, a major tributary of the Gila River. It persists mainly in reaches of the Gila River drainage that are free of non-native predators or where natural flow regimes and periodic flooding might act to suppress introduced predator populations and maintain habitat variability....
Vegetation plays a critical role in lizard activities such as thermoregulation. Less understood is the influence of vegetation structure on lizard mobility. This study examined the influence of cheatgrass (Bromus tectorum) patches on: 1) distribution patterns of the desert horned lizard (Phrynosoma platyrhinos) using transect surveys along an elevational gradient, and 2) sprint performance of adult and juvenile P. platyrhinos using raceways established under field conditions. There was a significant negative association between cheatgrass cover and lizard scat abundance across the study gradient, suggesting horned lizards might avoid areas with higher cheatgrass cover. Adult and juvenile sprint performance were...
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ABSTRACT-Zuni bluehead sucker, Catostomus discobolus yarrowi, is endemic to the Little Colorado River drainage of west-central New Mexico and east-central Arizona. The extent of its historical distribution is uncertain, but included several tributaries of the Little Colorado River upstream of Grand Falls, Arizona; origin of the taxon is ambiguous and contributes to poor definition of its former distribution. Fish eradication efforts in the 1960s eliminated the subspecies from portions of the Zuni River drainage in New Mexico. Surveys in New Mexico during 1990 through 1993 found it in about 15 km of Rio Nutria headwaters. Zuni bluehead sucker persists where habitat degradation (channel incision and sedimentation)...
Late winter food habits, diel feeding chronologies, and resource partitioning are documented for two cyprinids, the Virgin River spinedace (Lepidomeda mollispinis mollispinisa, threatened endemic) and the widely distributed speckled dace (Rhinichthys osculus), in Beaver Dam Wash, a stream of the eastern Mojave Desert. Adults of both species were primarily insectivorous; larvae of the stratiomyid Euparyphus and larvae of Hydropsyche were consistently among the most important food items in the stomachs of both fish species. Adult ephemeropterans and trichopterans were also important in the stomachs of L. mollispinis, where as ephemeropteran nymphs and ostracods were important in the diet of R. osculus. The percentage...
Bullfrog tadpoles (Rana catesbeiana) and red swamp crayfish (Procambarus clarkii) are widespread introduced taxa that are problematic throughout the western United States. Their impact on native amphibians and crustaceans is well documented, but less is known regarding their influence on native fishes. Predator-prey tank tests showed both species consumed eggs and larvae of the endangered razorback sucker (Xyrauchen texanus) in a laboratory setting. Tadpoles consumed 2.2 razorback sucker eggs/d and 1.4 razorback sucker larvae/d, while crayfish ate 6.0 eggs/d and 3.5 larvae/d. Relatively high densities of bullfrog tadpoles and crayfish in razorback sucker spawning areas suggest that these nonnative taxa might pose...
Geographic variation in 17 cranial characters of 138 specimens of Idionycteris phyllotis was examined by use of univariate and multivariate techniques. Larger individuals occur in the central portion of the range (New Mexico and southern Arizona) Published in The Southwestern Naturalist, volume 19, issue 1, on pages 114 - 115, in 1974.
Minckley (1991) hypothesized that introduced nonnative fishes, enhanced by river alterations, are primarily responsible for the demise of native fish species in the Colorado River system. Negative interactions with nonnative competitors and predators may impact all life stages of virtually all native fishes of the system. Predation by nonnative fishes on young Colorado squawfish (Ptychocheilus lucius) and razorback sucker (Xyrauchen texanus) is hypothesized as one reason for the decline of these two endangered species endemic to larger rivers of the Colorado River Basin (Kaeding and Osmundson, 1988; Marsh and Langhorst, 1988; Lanigan and Tyus, 1989; Marsh and Minckley, 1989). Early life stages of Colorado squawfish,...
We report new records of collared peccary (Pecari tajacu) in New Mexico that document its continued northward expansion in the United States, in general, and in northwestern New Mexico, in particular. These records might represent the northernmost extent of its range in the Southwest. Collared peccaries in New Mexico typically occur in desert, rocky, and brushy foothill regions and riparian communities. On the Zuni Indian Reservation, animals were observed at elevations up to 2,335 m in piñon-juniper and ponderosa pine habitats. Climate might play an important role in range expansion and contraction as collared peccaries might migrate north during years of drought or mild winters in search of food or new habitat....
-Effects of the east-west oriented Uinta Mountains and adjacent Uinta and Bridger basins on the distribution and taxonomy of the mammals of northeastern Utah are examined. Of the 94 species of mammals in the Uinta Mountains Region, 68 (72.3%) are affected by the Uintas in one or more of the following ways: 1) species boundary coincides with the Uintas (21 species); 2) subspecies boundaries fall within or coincide with the Uintas (12 species); 3) excluded from the Uintas but occur to the north and south or to the west (eight species); 4) boreo-monane species excluded from the adjacent Bridger and Uinta basins (22 species); and 5) use the Green River, which forms the eastern boundary of the Uintas, as a dispersal...
ABSTRACT-Larvoafe Colorado squawfish (Ptychocheilus lucius) acclimated to 22?C were subjectedt o water temperatured ecreaseso f 5, 10, or 15?Cw ithin 5 min or within 240 to 300 min. Most mortality due to shock occurred in the first 48 h. The 15?C shock in 5 min caused significant mortality of 14-day-old larvae but did not affect 40-day-olds. In addition to causing this direct mortality,s hocks of 10 or 15?Ci n 5 min caused behavioralc hanges in 14-day-oldst hat could result in indirect mortality of wild fish. Published in The Southwestern Naturalist, volume 33, issue 2, on pages 193 - 197, in 1988.
Seventeen middens of the bushy-tailed packrat (Neotoma cinerea), ranging in age from 3450 ± 40 to 160 ± 50 radiocarbon years before present (B.P.), were collected in 1996 from the Upper Gunnison Basin, Colorado. Eight of these subfossil middens contained plant remains from species that no longer occur near the locations of the middens. Radiocarbon dates on conifer remains indicated shifts in forest communities in the late Holocene at 3320, 560, and 240 B.P. Past climates were cooler than today at 3320 B.P., when mixed lodgepole (Pinus contorta) and ponderosa pine (P. ponderosa) forest expanded to lower elevations in the basin. Conditions became warmer between 1500 to 950 B.P., with additional cooling from 660...
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ABSTRACT.-A total of 31 Colorado squawfish, Ptychocheilus lucius, were collected from the Green River in 1980 and the Green, White and Yampa rivers in 1981. The fish were surgically implanted with radiotransmitter modules and their movement monitored for up to five months each year. Two movement patterns were linked to fish maturity: mature fish were highly mobile; immature fish were sedentary. A spawning migration of up to 205 km one-way was documented in 1981. Fish migrated upstream and downstream to reach a common spawning ground in the lower Yampa River canyon. Diel studies indicated no diel rhythm in movement existed until after spawning, when the fish were more active from 0800-1200 h. Colorado squawfish were...
The boreal toad (Bufo boreas) is an endangered species in Colorado and is considered a candidate species for federal listing by the United States Fish and Wildlife Service. Boreal toads are absent from many areas of suitable habitat in the Southern Rocky Mountains of Colorado presumably due to a combination of causes. We moved boreal toads from existing populations and from captive rearing facilities to habitat which was historically, but is not currently, occupied by toads to experimentally examine methods of repatriation for this species. Repatriation is defined as the release of individuals into areas currently or historically occupied by that species (Dodd and Seigel, 1991). This effort was in response to one...
The Colorado squawfish (Ptychocheilus lucius), the largest cyprinid native to North America, is endemic to the Colorado River basin and historically was widely distributed in the Colorado River and its major tributaries. Following major water developments on the Colorado River system, this species declined and is now listed by the U.S. Fish and Wildlife Service as endangered( U.S. Fish WildlifeS ervice,F ederalR egister3 9:1175,1 974). Historically the Colorado squawfish has preyed on soft-rayed fishes. Early in this century the channel catfish (Ictalurus punctatus) was established in the Colorado River system as a sport fish. Since that time, therew ere undocumentedr eportso f Colorados quawfishf ound deadw ith...
The long-eared owl (Asio otus) is a widespread Holarctic species occurring as far south as central Mexico in winter (A.O.U., 1983). Although localized, long-eared owl populations occupy portions of Arizona and New Mexico (Hubbard, 1978; Monson and Phillips, 1981). The only previous report of long-eared owl food habits from the southwestern United States is from Arizona (the same data were reported by Lange and Mikita, 1959; Stophlet, 1959). Most dietary information for long-eared owls has come from areas where voles (Microtus spp.) dominate the diet (Marti, 1976; Nilsson, 1981; Marks, 1984). Here, we report the foods of wintering long-eared owls from an area in northwestern New Mexico where Microtus do not occur....
map background search result map search result map Distribution and notes on the biology of Zuni bluehead sucker, Catostomus discobolus yarrowi, in New Mexico Migration, movements and habitat preferences of Colorado squawfish, Ptychocheilus lucius, in the Green, White and Yampa rivers, Colorado and Utah Association of Black-Tailed Prairie Dogs (Cynomys ludovicianus) with Playa Lakes and a New Approach to Estimating Size of Populations Association of Black-Tailed Prairie Dogs (Cynomys ludovicianus) with Playa Lakes and a New Approach to Estimating Size of Populations Distribution and notes on the biology of Zuni bluehead sucker, Catostomus discobolus yarrowi, in New Mexico Migration, movements and habitat preferences of Colorado squawfish, Ptychocheilus lucius, in the Green, White and Yampa rivers, Colorado and Utah