Pacific Coast

The subspecies composition of migratory sandhill cranes (Grus canadensis) which stage and winter along the Lower Columbia River in northwest Oregon and southwest Washington is uncertain, but may include all 3 using the Pacific Flyway: lesser (G. c. canadensis), Canadian (G. c. rowani), and greater (G. c. tabida). However, the status of rowani has been debated. During 2001-02, we captured and marked 8 cranes using a noose line trapping technique, and attached Platform Transmitter Terminals (PTTs) to 6 to ascertain locations of their breeding areas, migration corridors and winter sites. Morphometric data were collected for subspecies determination. From measurements and their summer distribution, we conclude that they are likely the intermediate rowani form. Because of their limited numbers, distinct coastal migration path, and habitat issues at breeding, staging, and wintering areas, we recommend that conservation efforts be increased and that they be managed as a unique population. ...

In this dissertation I address the timing of and interrelatedness between initial Early Formative period (2000–1500 BCE) transitions in residential mobility, subsistence, and social organization in Mesoamerica. I approach these topics using evidence from the La Consentida Archaeological Project (LCAP), a multi-season field and laboratory investigation of the site of La Consentida on the Pacific coast of Oaxaca, Mexico. Based on six radiocarbon dates (1947–1530 cal B.C.), La Consentida represents the earliest village site ever discovered in coastal Oaxaca, and likely in much of Pacific coastal Mexico. According to these dates, the site has produced some of the earliest ceramics and mounded earthen architecture known in Mesoamerica. In this dissertation, I argue on the basis of changes over time in earthen architecture, ground stone tools, and house construction that the community grew more sedentary over the course of site occupation. Based on studies of faunal remains, human dental pathologies, isotopic indicators, and food processing technology, I conclude that the community ate a broad diet but consumed more maize than did contemporaneous groups in other Early Formative period occupation areas, such as the Soconusco region of Chiapas and Guatemala. Culinary preferences may have changed at La Consentida, however, with a shift over time from consuming maize in beverage form to processing flour on stone mills that prompted increasing dental attrition. Anthropomorphic ceramic figurines from the site demonstrate a diversity of social roles, suggesting that the community was heterarchically complex from very early in its history. Obsidian sourcing and evidence of ceramic formal and decorative styles similar to those from other Formative period sites in West Mexico, the Valley of Oaxaca, and Central Mexico indicate La Consentida’s broad interaction sphere. The very early dates associated with ceramic vessel fragments from La Consentida may complicate current models for the adoption of ceramic technology in Mesoamerica by suggesting an early tradition developing along the western Pacific coast that was contemporaneous with the Soconusco region’s Barra phase (1900–1700 cal B.C.). These various lines of evidence demonstrate that La Consentida was a community in transformation during one of the most fundamental moments of socioeconomic change in the ancient Americas. Research at La Consentida is relevant to key archaeological debates concerning Archaic to Formative period transitions in settlement, subsistence, and social organization. Evidence from the site is beginning to support arguments for gradual adoption of sedentism, early consumption of significant quantities of maize, and the importance of heterarchical distinctions in the birth of Mesoamerican social complexity.

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Un crustacé nouveau pour la faune européenne et originaire du Pacifique Nord-Ouest, Hemigrapsus penicillatus, a été observé pour la première fois en 1994 à La Rochelle (France). Ce crabe qui étend rapidement son aire de distribution est présent actuellement depuis Laredo, Espagne (43°25′N, 03°20′W) jusqu'à Fromentine, France (46°53′N, 02°09′W) dans les zones abritées de la zone médiolittorale. Il est localement abondant, avec une densité atteignant 10 à 20 individus par mètre carré. Sa zone d'origine comporte des régions froides (nord du Japon, sud des côtes de Russie) aussi bien que tropicales (Taiwan, Hong-Kong), si bien qu'il va probablement coloniser en peu de temps la plupart des côtes d'Europe et d'Afrique du Nord.A crab previously unknown in the European fauna was discovered in La Rochelle (France) in 1994. This shore crab was identified as Hemigrapsus penicillatus, a North-West Pacific species. It appears to be spreading rapidly. It has now been detected from Laredo, Spain (43 °25′N, 03 °20′W) to Fromentine, France (46°53′N, 02°09′W) in sheltered areas of the mid-littoral zone. It is locally abundant, with a density of up to 10–20 individuals per square metre. In its native area, its distribution ranges from a cold (northern Japan, south of the Pacific coast of Russia) to a tropical (Taiwan, Hong-Kong) habitat. Being tolerant to both high and low temperatures (even at freezing point), it will probably colonize most of the European and North-African coasts within a short period of time.

Subduction earthquakes along the Pacific Coast of Central America generate considerable seismic risk in the region. The quantification of the hazard due to these events requires the development of appropriate ground-motion prediction equations, for which purpose a database of recordings from subduction events in the region is indispensable. This paper describes the compilation of a comprehensive database of strong ground-motion recordings obtained during subduction-zone events in Central America, focusing on the region from 8 to 14° N and 83 to 92° W, including Guatemala, El Salvador, Nicaragua and Costa Rica. More than 400 accelerograms recorded by the networks operating across Central America during the last decades have been added to data collected by NORSAR in two regional projects for the reduction of natural disasters. The final database consists of 554 triaxial ground-motion recordings from events of moment magnitudes between 5.0 and 7.7, including 22 interface and 58 intraslab-type events for the time period 1976-2006. Although the database presented in this study is not sufficiently complete in terms of magnitude-distance distribution to serve as a basis for the derivation of predictive equations for interface and intraslab events in Central America, it considerably expands the Central American subduction data compiled in previous studies and used in early ground-motion modelling studies for subduction events in this region. Additionally, the compiled database will allow the assessment of the existing predictive models for subduction-type events in terms of their applicability for the Central American region, which is essential for an adequate estimation of the hazard due to subduction earthquakes in this region.

Holocene and Pleistocene tectonic deformation of the coast in the Mexico subudction margin is recorded by geomorphic and stratigraphic markers. We document the spatial and temporal variability of active deformation on the coastal Mexican subduction margin. Pleistocene uplift rates are estimated using wave-cut platforms at ca. 0.7–0.9 m/ka on the Jalisco block coast, Rivera-North America tectonic plate boundary. We examine reported measurements from marine notches and shoreline angle elevations in conjunction with their radiocarbon ages that indicate surface uplift rates increasing during the Holocene up to ca. 3 ± 0.5 m/ka. In contrast, steady rates of uplift (ca. 0.5–1.0 m/ka) in the Pleistocene and Holocene characterize the Michoacan coastal sector, south of El Gordo graben and north of the Orozco Fracture Zone (OFZ), incorporated within the Cocos-North America plate boundary. Significantly higher rates of surface uplift (ca. 7 m/ka) across the OFZ subduction may reflect the roughness of subducting plate. Absence of preserved marine terraces on the coastal sector across El Gordo graben likely reflects slow uplift or coastal subsidence. Stratigraphic markers and their radiocarbon ages show late Holocene (ca. last 6 ka bp) coastal subsidence on the Guerrero gap sector in agreement with a landscape barren of marine terraces and with archeological evidence of coastal subsidence. Temporal and spatial variability in recent deformation rates on the Mexican Pacific coast may be due to differences in tectonic regimes and to localized processes related to subduction, such as crustal faults, subduction erosion and underplating of subducted materials under the southern Mexico continental margin.

Costa Rica, on the southern terminus of the Middle American Trench is being affected by active subduction on both, along the Pacific coast as well as on its Caribbean coast. Three main subduction segments can be recognized along the Pacific coast: 1) under northwestern Costa Rica, off Papagayo Gulf and Nicoya peninsula, the Cocos plate is subducting under the Caribbean plate; 2) under southern Costa Rica (Osa and Burica peninsulas) the Cocos plate subducts under the Panama Block and 3) in the central Pacific coast (between Nicoya and Osa peninsulas) the Cocos plate subducts under a shear zone that marks the transition between the Caribbean and the Cocos plate. Along the Caribbean coast, south of Puerto Limon, the Caribbean plate subducts under the Panama block.

Oviposition and embryonic-larval development are described for the muricacean snail Thais (Stramonita) chocolata from the Southeast Pacific coast. As with numerous other muricacean snails, this species engages in communal egg laying, with females depositing egg capsules in clusters on subtidal rocks. Each cluster of capsules contains 100–150 pedunculate, ampulliform egg capsules, with each capsule containing an average of 2,600 small (130 μm) eggs. Intracapsular development was followed using light and scanning electron microscopy to describe the successive embryonic stages of the species. Free-swimming veliger larvae of about 225 μm length were released from capsules after 49 days incubation at 13.6°C. The planktotrophic larvae were cultured in seawater aquaria by feeding with pure cultures of phytoplankton, recording growth and form of the larvae. Larvae reached competence after 4 months at 22°C, at 1,450–1,740 μm in size, and a few larvae were observed through metamorphosis and early definitive growth. The embryonic-larval development of T. chocolata coincides with the general characteristics of the ontogeny observed in other Thais species as well as of other genera of the Rapaninae such as Concholepas. This lent support to grouping these genera into a single clade. The lack of knowledge of the development of free larvae of Thais spp. means that we do not know whether these similarities also include an extensive larval phase as generally characteristic of other members of the clade. The mode of development may be useful in characterizing some clades of this family. Thus for example, the transference of some Thais to the genus Nucella (Subfamily Ocenebrinae) is supported by differences in the mode of embryonic development, which differentiates these subfamilies. Paleobiological data reported for Neogastropoda allow postulation of primitiveness in planktotrophic larval development compared to more recent developmental strategies such as direct development of different types, which characterize various clades of this family.

Feeding habits of the fishes Lutjanus peru and Lutjanus guttatus (Pisces: Lutjanidae) of Guerrero, México. Diet composition of the Pacific snapper (Lutjanus peru) 130-684 mm fork length (FL) and the spotted snapper (Lutjanus guttatus) 120-550 mm FL, was analyzed. Monthly samples were obtained from commercial landings in three regions off the coast of Guerrero, Mexico. Percentage by number (%N), percentage

This article describes a new subspecies of Prepona pylene of western Colombia: Prepona pylene timbiquiensis n. spp., due to a specimen collected by manual capture and baited Van Someren-Rydon traps, in the locality of Saija in the municipality of Timbiqui, department of Cauca. Also we examine and compare to all P. pylene subspecies found in Colombia, based on the review of specimens that are stored in various public and private collections in Colombia. Accordingly we report the synonyms recorded for P. pylene base on the reports found in the literature and the review of the type species described by Hans Fruhstorfer, Henry Walter Bates and William Hewitson deposited in the British Museum in London and the Museum of Zoology, University of Humboldt in Berlin, Germany.