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We recorded 156 taxa of legumes, comprising 50 genera, 152 species, and 34 infra-specific taxa, in the southern part of state of Nuevo León. Genera with the highest numbers of species were Dalea (19), Desmodium (12), Acacia (10), Astragalus (10), Phaseolus (8), Mimosa (8), Lupinus (7), and Senna (6). The growth forms were herbaceous species (49% of species), shrubby species (33%), twining and climbing species (16%), and arboreal species (2%). The highest numbers of taxa were in oak-pine forest (95), coniferous forest (excluding Pinus cembroides) (93), oak forest (59), and Pinus cembroides forest (56). Based on legume distribution in different plant communities, 3 distributional patterns were recognized: 1) shrublands and halophytic grasslands; 2) oak, oak-pine, coniferous (other than Pinus cembroides), and Pinus cemborides forests and piedmont scrub; and 3) subalpine prairie.
We studied the seed dispersal process of a population of Bursera fagaroides (Burseraceae) on the coast of the Gulf of Mexico by considering 1) all phases of the dispersal process (i.e., fruit removal, effect of seed passage through digestive tract, seed deposition, removal of seeds from the ground, germination, growth and survival of seedlings and adults, and seed set); 2) plant and animal components and their interaction; and 3) spatial variation in these components using different subpopulations. Hill aspect and surrounding microenvironment or habitat affected individuals of B. fagaroides, and this effect depended on life stage (seed, seedling, or adult). Seed germination was greater in moderately-shaded areas (below the perennial plant species Coccoloba barbadensis) than in relatively open sites (below B. fagaroides or on bare sand); seedlings grew less on sites in bright sunlight; adult individuals were not detected in highly-shaded places; and females inhabiting open sites (grassland) had more removed seeds than those of shaded areas (shrubland and dry forest). Vireo griseus and Dumetella carolinensis, the only species consuming fruits of B. fagaroides during our study, differed in their effect on seeds: seeds ingested by V. griseus did not germinate, whereas 17% of seeds ingested by D. carolinensis germinated. Additionally, even though both bird species preferred the tropical dry forest, their foraging behavior differed. Vireo griseus was mostly found at mid-canopy height in tree-dominated sites, and D. carolinensis used the understory of shrubby areas; B. fagaroides does not inhabit tree-dominated sites. Our results indicated that there was no “best” place for a seed to land. What is suitable for a seed might not be optimal for a fruiting plant. Thus, patterns of seed dispersal are almost certainly altered by processes that happen long after seed deposition.
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 information on the ecology of each species and obtain insight on potential trophic overlap. Roundtail chub and creek chub seemed to be opportunistic generalists that consumed a diverse array of food items. Stomach contents of both species were dominated by plant material, aquatic and terrestrial insects, and fishes, but also included gastropods and mussels. Stomach contents were similar between species, indicating high trophic overlap. No length-related patterns in diet were observed for either species. These results suggest that creek chubs have the potential to adversely influence the roundtail chub population through competition for food and the native fish assemblage through predation.
Reliable estimates of extinction time for small populations of threatened and endangered species based on long-term field surveys provide crucial information for species conservation. We estimated population parameters and extinction times for Coachella Valley fringe-toed lizard (Uma inornata), which is listed as a federally threatened species and a California state endangered species. We used field survey data from 2 transects (TPP1 and TPP2) at Thousand Palms Preserve, California, from 1986 to 2003. We also used data from another subpopulation (TPP3) of this species 6 km from TPP1 and TPP2, where this species became extinct in 2001, to estimate uncertainty of extinction time. Our results indicated that the difference between modeled extinction time and the real extinction time of the subpopulation on TPP3 was about 2 y. The extinction times for U. inornata at TPP1 and TPP2 would be about 23 to 50 y. The extinction time estimate has good relationship with the habitat area; thus, in larger effective habitat area, there will be an increase in the estimated time to extinction. Assuming all available habitats have population connectivity, the estimated extinction time would be about 78 y. There was a trend toward a decrease in the mean reproductive productivity of the lizard during the study. Although there were cycles in population dynamics, the population density trajectories on phase diagram became close to 0. For fragmented sand-dune habitats <100 to 200 ha, the persistence of subpopulations of U. inornata is doubtful. The main cause for the decrease of this subpopulation might be the shortage of food resources during the frequent, severe droughts.
Little is known about the ecology of the alligator snapping turtle, Macrochelys temminckii, particularly demography and behavior. To learn more about the species in Oklahoma, we conducted a telemetry project on 2 small streams at Sequoyah National Wildlife Refuge, an 8,417.5-ha refuge located in east-central Oklahoma. Between June 1999 and August 2000, we fitted 19 M. temminckii with ultrasonic telemetry tags and studied turtle movements and microhabitat use. Turtles were checked 2 to 3 times weekly in summer and sporadically in winter. Several microhabitat variables were measured at each turtle location and a random location to help quantify microhabitat use vs. availability. We recorded 147 turtle locations. Turtles were always associated with submerged cover with a high percentage of overhead canopy cover. Turtles used deeper depths in late summer (but not deeper depths than random locations) and deeper depths in midwinter (and deeper depths than random locations) than in early summer. They used shallower depths than random locations in early summer. This seasonal shift in depth use might be thermoregulatory, although evidence for this is indirect. The mean linear home range for all turtles was 777.8 m. Females had larger home ranges than males, and juveniles had larger home ranges than adults, although the latter was not statistically significant. Macrochelys temminckii used submerged structures as a core site, and stayed at each core site for an average of 12.3 d.
Innate avoidance responses by potential predators to color patterns of snakes have been reported. Predation that is nonrandom with respect to the phenotype of the prey species is a well-characterized mechanism of natural selection, the driving force of adaptive evolution. Using both model and live snakes, we investigated the responses of 11 naïve roadrunners, Geococcyx californianus, to 3 sympatric species of venomous and nonvenomous snake (Micruroides euryxanthus, Pituophis catenifer, and Crotalus atrox). Neither model nor live coral snakes elicited overt avoidance responses from the birds. Models elicited fewer pecks than moving live snakes. A gopher snake and a rattlesnake also failed to elicit overt avoidance behaviors. However, in contrast to the coral snakes, both snakes elicited a significantly higher number of leaps and wing flips, behaviors used by roadrunners when subduing dangerous prey. We conclude that roadrunners have no overt innate reactive behaviors to color patterns of coral snakes. Roadrunners do display such behaviors to rattlesnakes and gopher snakes as if both were dangerous prey, suggesting either Batesian or Mullerian mimicry.
We measured reproductive success of 52 Chihuahuan raven (Corvus cryptoleucus) nests in the southern High Plains of Texas in 1999. Egg laying was initiated between 12 April and 21 June. We observed 5.2 ± 0.2 eggs (mean ± SE) per nest, 3.3 ± 0.3 hatched chicks per nest, and 2.6 ± 0.2 fledged chicks per nest. Incorporating “days at risk,” we estimated reproductive success was 36.5 ± 0.5%, and reproductive output was 1.9 fledged chicks per nesting female. Average distance from each nest to its nearest neighbor nest was 851 ± 168 m (minimum = 233 m, maximum = 8,465 m). Nest success was unrelated to nearest neighbor distance or nest height, but was correlated with clutch initiation date. The likelihood of nest failure increased by 0.9% with each passing day.
We examined patterns of habitat use within a community of bats along the Provo River in Heber Valley, Utah. The landscape was divided into 5 habitat categories: riparian forest, wetland, agricultural field, edge, and a habitat restoration site. We used Anabat II bat detectors to record the number of echolocation calls per night within each habitat type as an index of bat activity. Echolocation calls were classified into foraging guilds based on acoustic traits, and we analyzed activity by entire community and by the 4 guilds related to habitat type and environmental variables. Activity was not significantly related to moon phase, average temperature, or day of the season. Activity by the entire bat community was significantly higher in riparian forest and edge habitats compared to other habitat types. Activity of the “high” Myotis guild was significantly greater in the riparian forest, edge habitats, and in the restored habitat site. Similarly, activity by the “low” Myotis guild was significantly higher in riparian forest and edge habitats. In contrast to the Myotis guilds, activity of molossids was significantly higher in agricultural fields compared to other habitats. Activity by the “low” Eptesicus guild did not vary significantly among habitats.
Direct mortality of forest wildlife due to fire is rarely documented. In June and July 2004, the Nuttall Complex Fire burned 11,898 ha in the Pinaleño Mountains, southeastern Arizona. Portions of these mountains serve as the only habitat of endangered Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis). Survival of radio-collared red squirrels over a period that included the fire was lower in areas that were burned than on unburned areas; however, the majority of squirrels on our study areas survived the fire. Distance of nests from middens did not differ between pre-fire and post-fire periods for animals in burned or unburned areas, indicating that squirrels did not abandon middens immediately after surviving the effects of fire.
Cavity nests are rarely used by Abert's squirrels (Sciurus aberti) in ponderosa pine (Pinus ponderosa) forests. Introduced Abert's squirrels in the Pinaleño Mountains of Arizona, however, exhibit occasional use of cavity nests (ca. 10%). We examined characteristics of cavity nest sites in this introduced population. Cavity nests were located at two-thirds of the tree height and were found mainly in both dead and live aspen (Populus tremuloides). Aspen cavity trees were larger than aspen random trees. Aspen cavity sites had more large snags and less ponderosa pine and were less steep than aspen random sites. Abert's squirrels possibly use cavities in large aspen trees because thick trunks and older trees might allow larger cavities to form, might provide greater thermal and wind protection, or both. The greater use of cavity nests by the Abert's squirrels in our study could be due to the higher frequency of cavity-forming aspens or harsher winter conditions in mixed-conifer forests of the Pinaleño Mountains than in ponderosa pine forests where Abert's squirrels typically occur or both.
Spool-and-line tracking is an innovative and inexpensive way to record the movements of small mammals in a variety of habitats, and could have important applications for conservation related studies. However, the potential negative effects of the method have not been investigated. We document the effects of spool-and-line tracking on short-term change in body mass, recapture, and survival probability of banner-tailed kangaroo rats, Dipodomys spectabilis, in southeastern Arizona. We attached spools to D. spectabilis adults of both sexes during 3 y of varying environmental conditions, with total sample sizes of 90 experimental and 81 control animals. We did not attach spools to females in late pregnancy, and, to avoid entanglement, we did not attach spools to kangaroo rats located within 25 m of each other on the same night. We found no significant negative effects of spool attachment on body mass, survival, or recapture probability in either sex in any year.
Morphometric variables were analyzed for 119 specimens from 28 localities in New Mexico and Texas to determine whether they can be used to distinguish between individuals of known identity of Perognathus flavus and P. merriami. Multivariate analysis of variance suggested that morphological characters from individuals of these 2 species differed significantly. Discriminant functions analysis produced 5 cranial and 2 external characters (bullar length, mastoid breadth, interorbital breadth, interparietal breadth, interparietal length, tail length, and hind foot length) that differed significantly in these 2 species. A subsequent classification analysis of 55 specimens from 21 localities was performed to test the utility of these characters in identifying unknown individuals, and 87% of the individuals were identified correctly.
Robert D. Bradley, J. Delton Hanson, Brian R. Amman, B. Dnate' Baxter, Darin S. Carroll, Nevin D. Durish, Michelle L. Haynie, Mariko Kageyama, Lisa K. Longhofer, Francisca M. Mendez-Harclerode, Serena A. Reeder, John R. Suchecki, Donald C. Ruthven III, Maria N. B. Cajimat, Ciro Milazzo Jr., Mary L. Milazzo, Charles F. Fulhorst
Below normal precipitation during June 2001 through June 2002 was recorded at Chaparral Wildlife Management Area, near Catarina, Texas. This drought was followed by a 13-mo period (July 2002 through July 2003) of above average precipitation, providing an opportunity to examine the response of 5 species of rodents to drought conditions. Comparison of the number of unique individuals captured during the drought to the post-drought revealed a significant increase in the total number of individuals (approximately 500%) and in the number of individuals per species. A 3-mo lag time was observed between the end of the drought and the onset of population recovery. Although an increase in population size was anticipated as precipitation patterns returned to normal, the magnitude and rapidity of the recovery exceeded predictions and documented the resilience of rodents to adverse climatic conditions.
The range of the single-site endemic cave crayfish, Cambarus tartarus, is expanded to an additional cave system (Long's Cave), but is still restricted to the Spavinaw Creek watershed within Delaware County, Oklahoma. Censuses of these 2 populations in 2001 and 2004 produced record high counts: 17 individuals in January-Stansbury Cave and 63 in Long's Cave. January-Stansbury Cave, with at least 52 species of animals, is the most species-rich subterranean habitat in Oklahoma to date. Conservation activities are summarized. Cambarus tartarus remains extremely vulnerable to degraded habitat quality, and further protection is recommended.
We provide complete, updated data on the status of the endangered black-capped vireo (Vireo atricapilla) and its habitat on Fort Hood Military Reservation, Texas. We searched 74,880 ha of Fort Hood during spring and summer 2002 and 2003, noting the locations of potential habitat patches and vireos. We mapped 6,971 ha of potential habitat, 90% of which was occupied. Such high occupancy suggests that vireos have colonized most of the available vireo habitat on Fort Hood. We detected 1,846 male vireos. The area of occupied habitat and number of male vireos both exceed goals set in the Endangered Species Management Plan for Fort Hood. Assuming that half of the male vireos had mates, Fort Hood alone would exceed the previously published recovery goal of 750 breeding pairs for the Lampasas Cut Plains set in the recovery plan for the black-capped vireo.
Habitat preferences were determined for a guild of surface-diving waterbirds wintering in Redfish Bay, Texas: common loon (Gavia immer), eared grebe (Podiceps nigricollis), pied-billed grebe (Podilymbus podiceps), double-crested cormorant (Phalacrocorax auritus), red-breasted merganser (Mergus serrator), and American coot (Fulica americana). American white pelican (Pelecanus erythrorhynchos) also was included because it occupies habitats similar to those of the surface divers. Between November 2001 and April 2002, the locations of 4,232 surface divers and American white pelicans using aquatic habitats in Redfish Bay were recorded and entered into a GIS that included a National Wetlands Inventory layer. Bird habitat preferences-avoidances were determined using a test based on Bonferroni's inequality. American coots, American white pelicans, and pied-billed grebes preferred shallower estuarine subtidal seagrass beds, whereas common loons, double-crested cormorants, and eared grebes preferred deeper estuarine subtidal unconsolidated bay bottom. Red-breasted mergansers showed no habitat preferences.
We identified 13 specimens of Preble's shrew (Sorex preblei) and 5 specimens of the Inyo shrew (Sorex tenellus) from Lassen Volcanic National Park (LVNP), California. These records represent the first captures of either species from LVNP and substantially extend the ranges of both. This is the first recorded instance of these 2 species occurring in sympatry.
We examined a specimen of Neotoma nelsoni collected in the Mexican state of Puebla, which represents the third known record for the species and the first one for the state. The distribution of the species is restricted to the eastern slopes of the volcanoes Pico de Orizaba and Cofre de Perote, mainly within the cloud forest. The specimen of N. nelsoni has external and cranial characteristics that are different from other species of the genus. The distribution of the species is small, the sizes of populations are small, and the populations exist in geographic isolation. None are located within legally protected areas, which presents problems for the conservation of the species.
We obtained new records of the Tehuantepec jackrabbit, Lepus flavigularis, in the state of Oaxaca, México. The records represent 3 new populations of L. flavigularis in the southern part of the Isthmus of Tehuantepec. The total area where the new records of L. flavigularis occurred is 67 km2. It is necessary to conduct additional studies to obtain details of the actual distribution of the endangered L. flavigularis and recommend actions for its conservation.
We observed an attack by a bobcat (Lynx rufus) on a cottontail rabbit (Sylvilagus) that involved stealthy approach by the cat for >1 h, followed by a 12.3-s chase covering 116.0 m for the cat and 128.4 m for the rabbit. During the chase, the route of the cat from starting point to kill site was more direct than the semicircular route of the rabbit. Stride lengths for the cat and total distance covered by the chase were longer than those previously reported for bobcats.
Coyotes (Canis latrans) are common in urban areas throughout North America. However, their urban diets have been studied rarely, possibly because tools to discriminate coyote feces (i.e., scats) from those of domestic dogs have not been available. We used molecular techniques to discriminate between scats from coyotes and domestic dogs. Our objective was to assess field accuracy in identifying coyote scat from dog scat. We collected and analyzed 34 scats (classified as coyote scat) via DNA analysis to determine whether they were deposited by coyotes. Ten scats classified in the field as coyote were from domestic dogs. We could not distinguish between coyote and dog scats in Tucson simply by observing scats. The role that available food items play in feeding strategies of coyotes needs to be examined thoroughly to fully understand their ecology and relationships to dogs and humans in urban areas. DNA analysis used for scat identification provides a mechanism to distinguish canid scats.
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