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Streams in the southeastern USA are commonly affected by streamside disturbance. We investigated the effects of a small-scale clearing (associated with a pipeline crossing) on a third-order stream in southwestern Louisiana by sampling habitat, water chemistry, stream microbes, and benthic and wood-dwelling macroinvertebrates in fall 2002 and spring 2003. We selected 3 locations for sampling, one in a forested section of stream 100 m upstream of a clearing, one within the clearing, and one in a forested section of stream 100 m downstream from the clearing. We detected significantly higher temperature and fecal coliform counts and significantly lower dissolved oxygen, specific conductance, pool-riffle ratio, coarse woody debris, fine organic detritus, and heterotrophic plate counts in the clearing location compared to the upstream and downstream locations. Depth and current velocity did not differ significantly among sampling locations. Despite differences in stream characteristics, we detected only a single statistical difference: Bezzia (Insecta: Diptera: Ceratopogonidae) was significantly lower in density in the clearing location. We conclude that the observed differences in stream characteristics were not biologically substantial enough to noticeably alter composition of the stream macroinvertebrate community. However, multiple small-scale disturbances that increase fragmentation in a watershed would be more likely have significant negative affects on macroinvertebrate community diversity.
Although the ecology of the Gulf Coast waterdog, Necturus beyeri, has been studied in Louisiana, there is no information on eastern Texas populations. We document the seasonal activity and individual movements of this species in Smith County, Texas. Minnow traps were placed at 10-m intervals in Gilley Creek from 1996 to 1999 (20 total) and in Hill Creek in 2002–2003 (75 total) and checked once per week. Animals captured were sexed, measured, weighed, and tagged with PIT tags. Seasonal activity was determined from the number captured per month, and individual movements were based on distances moved between captures. Gulf Coast waterdogs in eastern Texas were active from October to March, generally moving only short distances. Occasionally, long distance movements were made, but these animals often returned to the initial capture site. Our results suggest that Gulf Coast waterdogs in eastern Texas behave much like those in southern Louisiana.
Male and female reproductive cycles are described for Sceloporus melanorhinus in Chamela, Jalisco, Mexico. Both males and females reached sexual maturity at 62 mm snout–vent length. Testes mass of adult males began to increase in March, reached maximum size in July, and began to decrease in August and September, reaching minimum size in October and November. Testes size was associated with increasing photoperiod, but not with temperature or precipitation. Enlarged vitellogenic follicles first appeared in May, and oviductal eggs were found from June to September. Vitellogenesis, follicular growth, and egg production were correlated with increasing photoperiod, temperature, and precipitation. Females produced a single clutch during the reproductive season. Mean clutch size based on oviductal eggs was 7.7 (range = 5 to 9). Clutch size was not correlated with female snout–vent length.
We studied the reproductive cycles of 350 male and female Sceloporus variabilis from coastal areas of the Gulf of Mexico, Mexico, that exhibited continuous reproduction. Males reached sexual maturity at 45 mm snout–vent length (SVL), whereas females reached sexual maturity at 44 mm SVL. Testicular mass varied among months. Testes began to increase in size during April, with maximum sizes reached from May to July. Maximal testicular growth was positively correlated with increasing temperature and photoperiod, but not with precipitation. Females contained vitellogenic follicles and oviductal eggs throughout the year, although maximal egg production occurred from June to January. Forty-two females (40%) had vitellogenic follicles and oviductal eggs simultaneously. Mean clutch size, based on vitellogenic follicles, was similar (mean = 3.7 ± 0.17 SE) to that observed by counting oviductal eggs (mean = 3.7 ± 0.10 SE). Females with a SVL ≥ 51.5 mm ± 0.91 SE had at least 2 clutches. Clutch size was correlated with female SVL. Differences in reproduction found in this study compared with other populations of the same species might be explained by environmental differences at the study sites.
We counted birds monthly from October through April of 1999–2000 and 2000–2001 on regularly grazed and rested (since 1973) semiarid grassland of central New Mexico. Horned larks (Eremophila alpestris) and chestnut-collared longspurs (Calcarius ornatus) accounted for 66% and 10% of all birds detected, respectively. We examined variation in counts of these species relative to grazing history, site, and vegetation characteristics. We used an information-theoretic approach to evaluate a set of 11 candidate models to determine which best described the variation in abundance of horned larks and chestnut-collared longspurs. There was little agreement between models for the 2 species or the 2 years. While grazing was a factor in the most likely models of abundance in the 1999–2000 sampling season for both bird species, this factor was not an important variable in explaining abundance in 2000–2001. These results suggest that abundance of horned larks and chestnut-collared longspurs are not as closely tied to grazing use during the non-breeding season in the semiarid grasslands of the northern Chihuahuan Desert, which contrasts with literature from breeding sites in the shortgrass prairie.
The golden-cheeked warbler (Dendroica chrysoparia) is a federally endangered, Neotropical migrant songbird that breeds exclusively in central Texas. Previous studies have identified habitat characteristics associated with the warbler, but a predictive model incorporating data collected over the entire breeding range is lacking. Using logistic regression, we constructed models at 2 scales based on vegetational and topographical data from individual survey points (local-scale) and potential habitat patches (landscape-scale). Models identified similar characteristics important in predicting golden-cheeked warbler occupancy, despite a difference in scale. The models suggested that warbler occupancy was positively associated with steep slopes, forest interior, Ashe juniper (Juniperus ashei) canopy cover, a tall canopy, and proximity to protected lands.
We monitored nest success of mountain plovers (Charadrius montanus) relative to distance from the nearest anthropogenic edges, such as fence lines, roads, and perimeters of crop fields, in 2003 and 2004. We located and observed 163 mountain plover nests in eastern Colorado (USA). At least one egg hatched in 81 of 163 nests. Successful nests occurred at a mean distance of 93.94 m ± 8.87 SE, whereas unsuccessful nests were located 84.39 m ± 8.95 SE from the nearest edge. Based on our model selection criteria (AICc), nests farther from edges were not necessarily more successful than those closer to edges. The logistic regression coefficient for edge effects (0.13 ± 0.12 SE) suggests that nests farther from edges are more successful. However, the standard error for the edge coefficient was large and the 95% confidence interval (−0.08, 0.35) encompassed zero, suggesting nest success was independent of distance from an anthropomorphic edge. We conclude that phenomena determining nest success of mountain plovers cannot be attributed to the single factor of anthropogenic edges in this fragmented landscape.
We explored habitat use in terms of vegetation structure and potential forage availability for mountain plovers (Charadrius montanus) in Park County, Colorado. We quantified the percentage cover of bare ground, percentage cover of shrubs (Chrysothamnus viscidiflorus), linear distance to nearest shrub, arthropod biomass, and grasshopper density for 102 plots of 1,963 m2, 51 of which were occupied by plovers and 51 of which were selected randomly within previously-classified potential habitat. We modeled the probability of habitat use by plovers based on these measurements. We further subdivided the occupied plots to model probability of habitat use by adults with broods as compared with use by pre-nesting and post-nesting adults. Percentage of bare ground and probability of habitat use for adults with broods were related inversely, but not so for adults without broods. Grasshopper density was positively related to probability of habitat use by adults without broods, whereas proximity to nearest shrub was negatively related. We propose that habitat use by plovers in South Park is influenced by the amount of available shrub-grassland edge habitat and the availability of forage.
The cave swallow (Petrochelidon fulva) was first discovered breeding in caves and sinkholes in Texas in 1915. Within the last 50 years, it has colonized new breeding sites in western and southern Texas, and colonization has been attributed to the presence of highway culverts and bridges. We examined published observations and breeding bird survey (BBS) data, and surveyed selected culverts in western and southeastern Texas to determine the rate and extent of colonization by cave swallows. From 1957 to 1999, the breeding range of the cave swallow increased by approximately 898%, with an average annual rate of increase of 6% per year. Based on BBS data, cave swallow populations are increasing 10.8% per year, and our survey indicated that cave swallows occupied >90% of the culverts surveyed in western Texas. Range expansion is likely to continue, and additional data are needed to determine how an expanding cave swallow population might affect local barn swallow populations.
Although the San Joaquin kit fox (Vulpes macrotis mutica) has been a federally protected subspecies since 1967, current information on its status throughout much of its historical range is lacking. Since 1983, only 5 surveys have been conducted, and a recent recovery plan emphasized the need for better information on the status of this subspecies. Between 2001 and 2003, we attempted to obtain new information on this kit fox on specific public and private properties in 8 counties in the San Joaquin Valley, California, where knowledge of its current status was limited or poorly understood. We used a trained detection-dog to survey for kit fox, red fox (V. vulpes), and gray fox (Urocyon cinereoargenteus) scats on selected properties, followed by species identification based on genetic analysis of DNA extracted from all scats collected. Despite extensive survey efforts (539 km), kit fox was only detected in Merced County, in the area of Santa Nella, where a small kit fox population was previously documented. Red fox scats were located in Alameda, San Joaquin, and Merced counties, and gray fox scats were located in Fresno County. Our results suggest that if kit foxes are present on the properties surveyed, they either occur at extremely low densities, rendering detection difficult, or only occur intermittently in these areas. In striking contrast, our previous surveys conducted with the same method in the southern part of the range found large numbers of kit fox scats in various areas, particularly in Kern and San Luis Obispo counties. We recommend that future conservation plans focus on preserving additional habitat in areas where kit foxes are relatively abundant, specifically western Kern County and the Ciervo-Panoche region.
We found that the number of doe pronghorn (Antilocapra americana) seen on summer surveys in 3 areas in the Southwest was related to midsummer drought indices, and that annual variations in doe mortality might be more important in determining population levels in dry years than fawn recruitment. If carrying capacity is indeed limited by a lack of nutritious forage during dry years, pronghorn managers might want to consider reducing interspecific and intraspecific competition during such periods and forgoing predator control and translocation efforts.
Jim I. Mead, Arturo Baez, Sandra L. Swift, Mary C. Carpenter, Marci Hollenshead, Nicholas J. Czaplewski, David W. Steadman, Bright Jordon, Arroyo-Cabrales Joaquin
We recovered Pleistocene fossils from a lava-dammed river deposit along the Río de Moctezuma in northeastern Sonora, at 29°41′N, 109°39′W, and 605 m elevation. Today the region is semiarid, with a foothills thornscrub community. The impoundment that resulted from the lava dam produced a short-lived marsh with an adjacent savanna. The extraordinary fauna is both diverse and rich, and includes ostracods, mollusks, fish, amphibians, turtles, a crocodilian, snakes, lizards, birds, and mammals, many with tropical affinities today. Most of the animals are either extralimital to the setting today or extinct. The recovery of Bison dictates a Rancholabrean Land Mammal Age for the fauna; a preliminary 40Ar/39Ar age suggests that the deposit is between 570,000 and 310,000 years old. The occurrence of cf. Crocodylus acutus (a crocodilian; generic assignment uncertain) and Pampatherium, the giant armadillo, is unique in the northern interior Sonora setting. We speculate that a well-developed riparian corridor along the Río Yaqui, from the Gulf of California to the mountain-valley setting at Térapa, permitted the animals with tropical affinities to extend 350 km inland.
Education of residents living on the urban-wildland interface can promote conservation of surrounding natural areas. An educational brochure, Living Close to Nature, was designed specifically for and issued to 5,000 residents living on the borders of the Nature Reserve of Orange County, California. A questionnaire was then issued to residents to test the effectiveness of the brochure and to produce baseline data on the attitudes, knowledge, and perceptions of these residents. We tested whether responses differed between: 1) respondents issued a brochure versus those who were not, and 2) respondents who recalled receiving the brochure versus those who did not. Contrary to expectations, results revealed few statistically significant differences in responses between respondents who were issued the brochure and those who were not. In fact, only 21% of the residents issued a brochure remembered receiving it. Although some statistical differences existed between respondents who recalled receiving the brochure and those who did not, these differences were small. Results suggest that it is essential to incorporate evaluations of educational materials to determine whether information is presented effectively and to tailor future educational efforts accordingly.
Dendrocoelopsis americana is reported for the first time in Missouri. Sphalloplana evaginata is reported from central Missouri and extends the range of this species by 280 km.
The invasive terrestrial planarian Bipalium kewense is found worldwide in tropical and warm temperate zones. The rate of spread and ecological impact of the flatworm will depend in part on its reproductive strategies. Members of this species reproduce primarily by fission of posterior body fragments. Herein we report, for only the second time in over 120 years of international study, the production of a fertile egg capsule by B. kewense. The capsule was produced by a flatworm from Texas, hatched in 21 days, and it contained 7 juveniles. Although the capsule structure, incubation period, and litter size were similar to those characteristic of the sexual species, B. adventitium, the B. kewense capsule was larger (112 mg) and produced larger offspring.
I report on specimens that represent the first records of 7 cicada species in 5 genera found in Mexico. This is the first report of a Beameria species in Mexico.
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 a threat to the recruitment success of this and other imperiled native fish.
The Colorado pikeminnow (Ptychocheilus lucius) is a federally endangered fish, which was once abundant and widespread in the Colorado River basin. During exotic fish removal sampling in the spring of 2003, 2004, and 2005, 2 Colorado pikeminnow were collected upstream of critical habitat in the Yampa River, Colorado. Collection of these specimens might be an artifact of low historical sampling effort, but they do serve to document potential habitat use of Colorado pikeminnow outside of critical habitat.
We placed 72 plasticine replicas of large and small snakes near a California ground squirrel (Spermophilus beecheyi) colony in San Diego County, California. Ground squirrels aggressively confronted both large and small replica snakes. Ground squirrels were more aggressive when attacking small replicas relative to large. Ground squirrels bit the smaller replicas a greater number of times, concentrating their attacks near the head of the replica. Large replicas were attacked more frequently near the tail. From the results we conclude: 1) California ground squirrels recognize increased risk of attacking larger versus smaller snakes, and 2) use of plasticine replicas is an effective method to investigate antipredator behavior of prey.
We report the collection of 4 specimens that extend the range of the least shrew (Cryptotis parva) in Colorado. The 2 collection locations are approximately 240 km and 290 km from previously collected specimens documented from the Cimarron River watershed in southeastern Colorado and approximately 300 km from those documented from the Arkansas River watershed in Kansas. These 4 specimens are the first individuals reported from the Arkansas River watershed in Colorado.
New distributional mammal records are reported for Yaxchilán, Chiapas, Mexico, and Belize. Nicéforo's large-eared bat Trinycteris nicefori (Chiroptera, Phyllostomidae) is documented for the first time for Mexico, providing the northwesternmost locality for the species. A new Belizean locality also is reported and constitutes the northernmost record. The dark Mexican shrew Cryptotis griseoventris (Soricomorpha, Soricidae) has been reported previously from the highlands from Chiapas, in coniferous forest at elevations above 2,100 m; its presence in the lowland Selva Lacandona (below 90 m) is surprising and raises questions about its specific identify. Further studies are warranted.
We obtained dejection and expulsion rates for use as correction factors in studies of diet and relative abundance of coyotes (Canis latrans). Feeding tests were performed at the Zacango Zoo, Calimaya, Mexico. We tested 3 treatments with different categories of biomass (10 to 80 g, 100 to 700 g, and 1,000 to 4,500 g). Dejection rates averaged 0.79 ± 0.22 SD excrements/g of biomass, with no significant difference among treatments. Expulsion rates significantly differed, with 1.33 scats produced/g of biomass for the first category (10 to 80 g), 4.69 scats/g of biomass for the second category, and 6.91 scats/g of biomass for the third. We compared these values with those from other studies performed with wolf (Canis lupus) and lynx (Lynx pardinus).
Morphological abnormalities can be associated with inbreeding depression or heritability in natural populations. We explored a genetic basis for antler and pedicle deformities documented in a population of reintroduced elk (Cervus elaphus) on the Hualapai Indian Reservation in northwestern Arizona. We used 12 microsatellite loci to compare individual multi-locus heterozygosity (IH) and internal relatedness (IR) between bull elk with antler malformations (n = 23) and individuals with normal antler conformation (n = 17). Additionally, we used 3 pairwise relatedness coefficients to determine whether males with deformed antlers were more closely related than males with normal antlers. Mean IH and mean IR were not significantly higher for the group with deformed antlers. Similarly, the relationship between antler malformations and pairwise relatedness also was not significant, suggesting that deformed males did not share the antler trait because of a closer genetic relationship. Other factors, such as nutritional or environmental characteristics, might be associated with the deformities. Further research is necessary to determine the underlying causes of the antler and pedicle malformations documented in the introduced elk herd in northern Arizona.
Historically, desert bighorn sheep occurred throughout Coahuila, Mexico, as far south as latitude 25°43′02″N. The subspecies Ovis canadensis mexicana probably was extirpated in Coahuila by 1970. We determined the historical range of desert bighorn sheep through a review of the available literature, interviews with long-term local residents, and a subjective habitat assessment. We found historical documentation of bighorn sheep in 14 mountain ranges (Sierra Alamitos, Sierra Maderas del Carmen, Sierra la Encantada, Sierra Hechiceros, Sierra del Pino, Sierra Mojada, Sierra el Rey, Sierra San Marcos y del Pino, Sierra Gavia, and Sierra la Paila), including 4 previously not recorded (Sierra el Fuste, Sierra el Almagre, Sierra de la Madera, and Sierra la Fragua). In addition, one archaeological site with remains of bighorn sheep was identified (La Candelaria Cave). The introduction of domestic livestock, particularly sheep and goats, and unregulated hunting probably were the major factors contributing to the extirpation of the subspecies in Coahuila. These factors persist in 7 areas, and we learned of the presence of aoudad (Ammotragus lervia) in 3 mountain ranges (Sierra Mojada, Sierra Hechiceros, and Sierra la Fragua).
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