The blue fan palm (Erythea armata) oases of the Sierra San Pedro Mártir, Baja California, Mexico, are unique not only because of their occurrence on the Pacific side of the Peninsular Range, but also because they span a steep transition from Mediterranean-type scrubland and piñon woodland to the Vizcaíno and Colorado phases of the Sonoran Desert to the south and east. Here we describe soil-water relations and community composition in 3 grazed Pacific-side palm oases along a 20-km transect from Sonoran Desert at 700 m elevation (El Rincón), to an ecotone of mixed desert scrub, coastal scrub, and mountain chaparral at 900 m (San Miguel), to chaparral and piñon-juniper woodland at 1,200 m (El Represo). Soil water was measured by using a neutron probe during an annual cycle. The palm grove at El Rincón had low soil water in the arroyo and oasis throughout the study period, although water was always present in pools both upstream and downstream. At San Miguel, pools were dry most of the time, but both the arroyo and oasis had moderate soil water, and the arroyo apparently received moisture by subsurface flow from nearby highlands. The seemingly dry oasis at El Represo had moderately high soil water, which was apparently maintained by a local seep. A total of 193 taxa were recorded, but only 30 (15.5%) were common to all 3 sites. In these communities, the Californian component diminished from 40 to 29% across the Californian-Sonoran transition, while Sonoran taxa decreased from 41 to 29% in the opposite direction. Determination of the most important species across this biome boundary revealed a strong Sonoran influence, even in the chaparral-piñon-juniper site. Erythea armata seems to be a species particularly adapted to this arid transitional region.

We examined the effects of water temperature on growth of Zizania texana (Texas wild rice), with a distribution in the wild restricted to the upper 4.9 km of the San Marcos River, Hays County, Texas. Plants were grown in tanks randomly assigned to 1 of 3 water temperature treatments: 15.5 ± 1.5, 22.5 ± 1.5, and 28.5 ± 1.5°C for 10 weeks during fall 2001. Leaf number, leaf length, and number of reproductive culms were recorded weekly for each plant. Biomass was recorded after 10 weeks. The effects of temperature, week, and their interaction were significant for leaf number and leaf length. Greatest mean leaf number occurred at week 10 for plants grown in 15.5°C water (27.5 ± 6.3); week 8 for 22.5°C water (63.2 ± 4.4); and week 9 for 28.5°C water (42.4 ± 5.5). Leaf length decreased in 15.5°C water from 37.6 ± 3.4 to 32.9 ± 3.3 cm, but increased in 22.5°C water from 41.0 ± 0.6 to 62.0 ± 2.6 cm and from 41.8 ± 0.8 to 60.3 ± 2.7 cm in 28.5°C water. Plants grown in 15.5°C water did not produce reproductive structures, and plants grown in 28.5°C water produced more culms per plant (3.3 ± 0.31) compared with plants grown in 22.5°C water (0.57 ± 1.07). Temperature influenced leaf, culm, root, and total biomass. Total biomass was less in 15.5°C water. Leaf biomass differed among all treatments. Plants in 28.5°C water allocated more biomass to reproductive organs compared with other treatments. Data from temperature recorders, placed at 4 locations downstream from the current range of Z. texana, showed that, although the mean temperature remained fairly constant among sites, the range of temperatures recorded increased with distance downstream.

African rue (Peganum harmala) is an herbaceous perennial plant native to arid and semiarid regions of northern Africa and Asian deserts that has spread to parts of the southwestern United States and northern Mexico. Despite its occurrence in many geographic regions, little is known about the biology and ecology of this invasive species. We conducted field studies on 2 populations of African rue in the northern Chihuahuan Desert to describe its vegetative and reproductive phenology. Overwintering, dormant plants in both populations commenced growth in mid March, grew through May and June, and initially senesced during June and July. Shoot development was synchronous between the 2 populations, but was not related to ambient or soil temperatures or precipitation. Onset of senescence was not related to calendar date or accumulated temperature. Flower production commenced at both sites in mid April, and fruit maturation occurred in June and July. Fruit maturation was related to calendar date and ambient temperature. In one population, senescent plants initiated new shoots in August and produced a second cohort of flowers. This renewed growth was not related to temperature, but likely triggered by midsummer precipitation. Therefore, African rue exhibits characteristic “drought evader” growth and reproduction strategies. This fundamental description of African rue phenology provides knowledge needed to manage this invasive species.

We used coarse-mesh and fine-mesh leafpacks to examine the importance of aquatic macroinvertebrates in the breakdown of floodplain tree leaf litter that seasonally entered a sand-bedded reach of the sixth-order Yampa River in semiarid Colorado. Leafpacks were positioned off the easily mobilized channel bed, mimicking litter trapped in debris piles. Organic matter (OM) loss was fastest for leaves collected from the floodplain and placed in the river in spring (k = 0.029/day) and slowest for leaves collected and placed in the river in winter (0.006/day). Macroinvertebrates were most abundant in winter and spring leaves, but seemed important to processing only in spring, when exclusion by fine mesh reduced OM loss by 25% and nitrogen loss by 65% in spring leaves. Macroinvertebrates seemed to have little role in processing of autumn, winter, or summer leaves over the 50-day to 104-day monitoring periods. Desiccation during bouts of low discharge and sediment deposition on leaves limited invertebrate processing in summer and autumn, whereas processing of winter leaves, which supported relatively large numbers of shredders, might have been restricted by ice formation and low water temperatures. These results were consistent with the concept that microbial processing dominates in higher-order rivers, but suggested that macroinvertebrate processing can be locally important in higher-order desert rivers in seasons or years with favorable discharge and water quality conditions.

We determined the diet of Chirostoma lucius from Lake Chapala and Guaracha Reservoir in central Mexico by stomach content analysis. Diet consisted primarily of juveniles of small Chirostoma species, as well as cladocerans and copepods. Seasonal change in prey showed high fish consumption in the rainy period, whereas crustacean consumption increased in the dry period. Diet varied with size, with smaller fish selecting large numbers of small zooplankton prey, whereas the largest size classes fed principally on fish. The size for the shift to piscivory was smaller in Lake Chapala (10 cm) than Guaracha Reservoir (14 cm), and the value for the pooled data of both populations was 12 cm.

We used bioenergetics models for humpback chub, Gila cypha, and rainbow trout, Oncorhynchus mykiss, to examine how warmer water temperatures in the Colorado River, Grand Canyon, Arizona, through a proposed selective withdrawal system (SWS) at Glen Canyon Dam, would affect growth, consumption, and predation rates. Consumption by the rainbow trout population was at least 10 times higher than by the smaller humpback chub population. Water temperature increases of 6°C during autumn increased growth of humpback chub and likely increased their survival by reducing the time vulnerable to predation. Water temperature increases caused by drought in 2005 did not alter humpback chub growth as much as the SWS. Increased temperatures might cause changes to the invertebrate community and the distribution and abundance of other warmwater nonnative fishes. The implications on the entire aquatic community need to be considered before any management action that includes increasing water temperatures is implemented.

Parapharyngodon grismeri n. sp. from the intestines of the central Baja California banded rock lizard, Petrosaurus repens, and the San Lucan banded rock lizard, Petrosaurus thalassinus, is described and illustrated. Parapharyngodon grismeri n. sp. is the forty-second species assigned to the genus and differs from other species in the genus in that males possess posteriorly situated lateral alae, have cloacal lip adornment, and have spicules 116–128 µm long; females possess alate eggs and a stout terminal spike. In addition to the new nematode species, gravid individuals of Oochoristica sp. (Cestoda: Linstowiidae), Spauligodon giganticus (Nematoda: Pharyngodonidae), and Strongyluris similis (Nematoda: Heterakidae) and larvae of Ascarops sp. (Nematoda: Spiruridae) and Physaloptera sp. (Nematoda: Physalopteridae) were found in P. repens, and S. giganticus, S. similis, and larvae of Physaloptera sp. were found in P. thalassinus.

We studied niche segregation among 3 syntopic lizards, Uta stejnegeri, Uma exsul, and Aspidoscelis marmorata, in the sand dunes of Viesca, Coahuila, Mexico. In 2004, we analyzed both microhabitat and substrate niches during a warm season and a cold season. Niche breadth and overlap were calculated, and a selection index was used. Each lizard species selected microhabitats that focused on a single perennial plant species and a specific range of sand compactness. Uta stejnegeri was highly associated with the perennial Suaeda nigrescens and highly compacted sand. Uma exsul was associated with sites with deep, loosely compacted sand and Larrea tridentata. Aspidoscelis marmorata was associated with the occurrence of Prosopis glandulosa and moderately compacted sand. Associations described here could help to develop a future conservation and management program for these sand dunes, where the endemic U. exsul and other species are protected.

We report the first information on seasonal abundance, sex ratio, body size, reproduction, and diet for a population of Thamnophis scalaris from the State of Mexico. Data were collected during 1992 and from 1998 to 2000 at Toluca. Thamnophis scalaris showed a bimodal peak of activity in spring-early summer and in autumn. The sex ratio of adults was significantly different from 1:1, but can be misleading because of the unknown natural history of T. scalaris. Sexual size dimorphism was only apparent in relative tail length of adults. Four litters were born from July 1 to 17. Mean litter size was 7.0 ± 1.4 snakes per litter. Male and female neonates were of similar snout-vent length (SVL) and mass at birth. The sex ratio of neonates was 1:1. Of the stomachs examined, 81% contained earthworms and 19% contained vertebrates. Vertebrates (lizards and viperine snakes) were ingested only by T. scalaris >40.0 cm SVL. This suggests an ontogenetic shift in the diet of T. scalaris. The mean vertebrate prey mass was 21.4 ± 10.0% of snake mass. No differences were found in prey type between the sexes.

The tallgrass prairie historically burned every 2 to 3 y, removing the litter layer and leaving post-burn environments inhospitable to many terrestrial species. Selection pressures, such as lack of food and shelter and increased predation, are intensified for some species over limited time periods. To quantify predation pressures on large snakes, artificial snakes were placed in recently burned and long-term unburned areas of a grassland system in northeastern Kansas. Any disturbance to the original placement of the model snake was considered a predation attempt. Statistical models were used to estimate daily survival rates of individual artificial snakes within both habitat types. A group effect (burned vs. unburned) was selected as the single top model, garnishing >93% of the support for the data. Survival estimates from this top model indicated artificial snakes in newly burned areas had significantly lower daily survival than those placed within unburned sites. Indirect evidence from destroyed artificial snakes indicated raptors were a major predator on large snakes. Overall herpetofaunal activity in burned areas was low during the first 20 d post-burn, with increasing activity throughout the rest of the season. However, activity within unburned areas was constant throughout the spring. Burning tallgrass prairie likely increases predation pressure on large snakes in the area for 1 to 2 mo following the burn due to the lack of cover against aerial predators.

Secondary pine-oak (Pinus-Quercus) forests of the Sierra Madre Occidental are a dominant forest structure in Mexico, but have received little attention from ornithologists. In 2002, we recorded breeding birds and vegetation characteristics in a second-growth pine-oak forest in southwestern Chihuahua. We categorized birds into nesting guilds and predicted their response to forest management. We recorded 1,446 individuals representing 44 species. The most abundant species were in 4 nesting guilds: generalist, secondary cavity, ground, or shrub nesters (89% of observations). We rarely recorded species listed as endangered or under special protection. Second-growth forests were open canopy, uneven aged, and dominated by small pine trees. Pines in largest size classes had been removed and there were few large pine snags. We conducted limited surveys in an old-growth pine-oak forest in 2003. Despite lower effort, we recorded twice the number of primary cavity nesters, suggesting snags were limiting in second-growth forest. Shrub nesters were higher in abundance in the second-growth forest, suggesting removal of overstory increased shrubs. Understanding species-habitat relationships is essential for long-term conservation within this species-rich ecosystem.

Through the analysis of 458 barn owl (Tyto alba) pellets collected between 1981 and 1995 on 2 islands in the northern Gulf of California, Mexico, we found significant differences in the main components of the diet of barn owls on these islands, where introduced rodents, bats, and seabirds occur. On Rasa Island, the most important prey was Rattus rattus, followed by Myotis vivesi, Oceanodroma microsoma, Mus musculus, and 4 bird species. On Partida Island, the main prey was M. vivesi, followed by O. microsoma, R. rattus, and 3 bird species. The mean number of prey per pellet was higher on Partida Island (1.08) than on Rasa Island (0.91), but the mean biomass per pellet was higher on Rasa Island (75.8 g) than on Partida Island (25.8 g). The storm-petrels O. microsoma and O. melania were taken by barn owls in proportion to their abundance on both islands. Conversely, barn owls on Rasa Island ate more R. rattus than M. musculus, possibly because of the larger size of the former. Overall, our data suggest that barn owls in the Gulf of California behave as flexible predators that take prey according to availability and profitability.

As a group, kangaroo rats (Dipodomys) are considered almost exclusively nocturnal. Diurnal activity by kangaroo rats has occasionally been noted, but the anecdotal nature of these accounts suggests it is a rare occurrence. While using video cameras and recorders to collect data on food habits at nests of ferruginous hawk (Buteo regalis) and Swainson's hawk (B. swainsoni) on and near the Rita Blanca National Grassland in 2003 and 2004, we detected numerous D. ordii. We subsequently explored possible relationships between the frequency of capture of D. ordii by these raptors and the time of day and moon phase. We recorded 54 deliveries of D. ordii to 8 of 12 ferruginous hawk nests and 8 of 14 Swainson's hawk nests. D. ordii was captured throughout the course of the day; there were no relationships between hour block of day or moon phase with the number of deliveries. Our review of other diet studies for ferruginous hawk, Swainson's hawk, Harris' hawk (Parabuteo unicinctus), and prairie falcon (Falco mexicanus) revealed kangaroo rats accounting for 1.1 to 6.6% of prey used. In contrast to the prevailing view that kangaroo rats are almost exclusively nocturnal, our data and those from other diet studies of some diurnal raptors suggest kangaroo rats might be more active during diurnal periods than previously thought. Diurnal activity by kangaroo rats might be related to local forage conditions. A more complete understanding of diurnal activity patterns by kangaroo rats will require more focused examination of their behavior in relation to vegetation and climate conditions.

Research on the distributions of 2 species of pocket gopher in Kansas, the plains pocket gopher (Geomys bursarius) and the yellow-faced pocket gopher (Cratogeomys castanops), revealed large tracts of land within their distributions that neither species occupies. We hypothesized that habitat and land-use practices in these tracts exclude pocket gophers. To test this hypothesis, we compared the relative frequencies of soil-texture and land-cover types within unoccupied tracts with those in surrounding tracts where pocket gophers occur. Our results indicated that the unoccupied tracts consisted largely of areas with fine-textured soils that are planted to crops. The crops, mainly corn, wheat, and grain sorghum, were harvested and disked annually, and even the roadside ditches adjacent to the cropland were plowed and planted. We concluded that pocket gophers are unable to inhabit these areas because land-use practices have destabilized the habitats, eliminating both refugia and dispersal corridors.

Several aspects of the pollination biology of Justicia candicans were studied in a population located in central Sonora, Mexico. The species flowered from January to April during the studied year (2003). Its flowers secreted up to 4 µL of nectar that had 41% sucrose. It is self-compatible and visited primarily by the resident hummingbird, Cynanthus latirostris, and occasionally by the common bee, Apis mellifera.

We collected data on diet of the marbled toad (Bufo marmoreus) on conserved and disturbed areas of tropical dry forest on the coast of Jalisco, Mexico, during 2000 and 2001. Although the diet of B. marmoreus consisted of 19 prey taxa, the moderately low dietary diversity measure (H′ = 1.51) reflected the dominance in the diet of only 3 groups of prey: ants, beetles, and termites. Toads in the conserved area consumed greater proportions of ants (36.7% by volume), whereas toads in disturbed forest consumed greater proportions of beetles (53.1% by volume). Diet diversity was significantly lower in the disturbed area. However, abundance, size, and weight of toads was similar in both areas, suggesting that prey availability was not affected by disturbance.

The consumption of large (>15 kg) mammals by Morelet's crocodile (Crocodylus moreletii) is poorly documented. We present field observations of necrophagy and interspecific kleptoparasitism (defined as the stealing of food from an individual by another individual) involving the consumption of domestic cattle (Bos taurus) and Baird's tapir (Tapirus bairdii) carcasses, respectively, by Morelet's crocodile in Belize. Our single observation of kleptoparasitism occurred when an adult crocodile fed upon and attempted to hijack a tapir killed by a jaguar (Panthera onca). Crocodiles gained access to the interior of carcasses by tearing through the abdominal wall (tapir) or expanding an opening made by feeding vultures (cattle); feeding then progressed to the limbs, neck, and head. Crocodiles quickly located and congregated at cattle carcasses, possibly attracted by large flocks of feeding vultures. Feeding aggregations were composed solely of adult crocodiles; juveniles and subadults were probably excluded by the presence of larger, dominant individuals. Crocodiles required 72 to 96 h to consume cattle carcasses. While our observation of kleptoparasitism is among the few yet reported for any crocodilian, we speculate that this foraging strategy is more widespread and has likely been overlooked by previous investigators, owing to the difficulty of observing feeding behavior in the wild. Collectively our observations suggest that large mammals represent an important, albeit rare and hitherto overlooked, food resource for adult C. moreletii in Belize.

We quantified the food habits of the endangered blunt-nosed leopard lizard (Gambelia sila), an endemic species of the San Joaquin Valley, California. Based on analyses of stomach contents and prey remains in scats, we determined that this species is an opportunistic predator that eats large numbers of orthopterans, coleopterans, and hymenopterans, with dipterans, hemipterans, and lizards taken in lesser numbers. These data are similar to the qualitative or unpublished data of previous studies, and also are similar to the food habits of the congeneric Gambelia wislizenii.

An annotated checklist of the type specimens in the Herpetological Collection of the Escuela Nacional de Ciencias Biológicas (ENCB, I. P. N.), Mexico, is provided, which includes 6 holotypes and 37 paratypes of 6 species and 2 subspecies: Pseudoeurycea boneti Álvarez and Martín, 1967 (holotype); Bipes caniculatus multiannulatus Álvarez, 1966 (holotype, 23 paratypes); Dipoglossus legnotus Campbell and Camarillo-R., 1992 (holotype); Sceloporus torquatus mikeprestoni Smith and Álvarez, 1976 (8 paratypes); Anolis alvarezdeltoroi Nieto-Montes de Oca, 1996 (holotype); Lepidophyma chicoasensis Álvarez and Valentín, 1988 (holotype, 3 paratypes); Lepidophyma lowei Bezy and Camarillo-R., 1997 (2 paratypes); and Lepidophyma tarascae Bezy, Webb and Álvarez, 1982 (holotype, 1 paratype).

We collected 3 specimens of the rock squirrel (Spermophilus variegatus) in San Francisco Cotahuixtla, Oaxaca, Mexico, which represent the first record of this species for this state. The new record expands the distributional range southward by 85 km.

We report 14 new mammalian records for the state of Tlaxcala, Mexico, which equals half the total number of mammalian species previously known. Tlaxcala is the smallest state of Mexico, and it is mostly devoted to growing crops and raising cattle; therefore, these results are important for conservation of local biodiversity.