Permanent Water Sources Research Articles

Habitat Correlates of Jaguar Kill-Sites of Cattle in Northeastern Sonora, Mexico

Predation on cattle by the endangered jaguar (Panthera onca) can be a serious ecological and economic confl ict. We investigated habitat characteristics of kill sites of cattle in Sonora, Mexico, from 1999 to 2004 to see whether habitat management or cattle distribution could be used as effective nonlethal methods to limit predation. Kill-sites were positively associated with oak, semitropical thornscrub, and xeric thornscrub vegetation types, whereas they were negatively associated with upland mesquite. Sites of cattle kills were also positively associated with proximity to permanent water sources and roads. A model including these relationships fi t kill locations well (AUC = 0.933) and correctly classifi ed 93% of all kill-site locations. Because kill-sites were associated with specifi c habitat attributes, management practices that alter cattle distribution, such as placement of permanent water sources in uplands, herding, and fencing riparian areas characterized by frequent depredations, can be used to minimize co-occurrence of jaguars and cattle and, thus, potentially limit predation without illegal killing of jaguars. These practices could also lead to more uniform use of pastures and, consequently, higher stocking rates, resulting in increased profi tability to landowners. Managing habitat attributes that predispose cattle to predation may provide a viable alternative for maintaining both livestock enterprises and a large endangered carnivore in areas of confl ict.

Cattle landscape selectivity is influenced by ecological and management factors in a heterogeneous mountain rangeland

Few studies addressing drivers of cattle selectivity focus on the combination of ecological (biotic and abiotic) and management factors such as rotational systems, paddock sizes and paddock shapes. As a consequence, it is difficult to prioritise management practices integrating information of different driving factors. In a heterogeneous mountain rangeland in Central Argentina we established a total of 419 square study plots of 1 ha located in 18 paddocks with differing sizes, shapes and cattle grazing management. Plots were small samples of landscapes, covering all existing variability in vegetation and physiography. For each plot we estimated the annual cattle use, average seasonal cattle density, forage types and abiotic characteristics. We used general linear models to show that selectivity was mainly driven by biotic variables. Cattle selected landscapes dominated by short palatable plants, but the strength of this influence differed among paddocks. Selectivity was strongest in paddocks with low abundance of lawns dominated by short palatable plants and low annual stocking rate. As stocking rate and the availability of lawns increased, selectivity strength decreased. Abiotic variables had far less influence than biotic variables, showing that cattle tended to avoid rough landscapes with steep terrain in the wet-warm season; and to be attracted by permanent water sources during the dry-cold season. Seasonal stocking density and paddock size had no detectable influence on cattle selectivity and distribution. Paddock shape influenced distribution but not the strength of forage selectivity. We conclude that in our system, cattle selectivity is mainly driven by biotic factors, and the most effective methods of changing the consequent distribution pattern is by manipulating forage types and paddock shape. The role of stocking rate remains controversial as it was correlated with the proportion of lawns in the paddock.

New dates for earth mounds at Weipa, North Queensland, Australia

ABSTRACTThis paper reports new radiocarbon determinations for late Holocene occupation in the Weipa region of Far North Queensland, Australia. Earth mounds along the margins of small wetlands and freshwater creeks developed mainly after 2200 years ago, but are concentrated within the past 500 years. Their establishment appears to be associated with changing environmental conditions and a regional increase in the availability of permanent water sources around 2200 and 500 years ago. These results have implications for earth mound chronology and possibly climate change understanding elsewhere in Northern Australia.

A royal Maya country house: Archaeology at Bejucal, Guatemala

This article presents three years of archaeological investigations at the minor Maya center of Bejucal, Guatemala. A complete site history is presented relying on data from artifact analysis, architectural study, epigraphy, and bioarchaeology, with a goal towards identifying the site's function within the broader El Zotz polity. The authors argue that Bejucal underwent significant transformation following its establishment as a sacred hilltop site during the Late Preclassic period (400 b.c.–a.d. 250). The El Zotz royal family gradually appropriated the space, converting it into a royal country house and elite burial place. Bejucal's proximity to a large permanent water source suggests that the country house was situated within favorable hunting grounds. The research contributes to a broader discussion about the role of minor centers in regional settlement patterns, highlighting the benefit of textual data in making interpretations. The article also highlights the important role of salvage work in lowland Maya archaeology.

Hydrological modelling with TOPMODEL of Chingaza páramo, Colombia

Páramo ecosystems are located on the upper parts of the tropical mountains, below the snow line areas or in isolated areas where no glacier ecosystems occur. These ecosystems are considered important for their biodiversity, but mainly because they are permanent source of water for populations located at the upper and middle parts of the Andes. Recent studies indicate that ecosystems located at high altitudes, are more vulnerable to climate change and to changes in land use, which threatens the ecosystem services derived from them. There are very few studies in these ecosystems, within which, studies on the hydrological functioning are even scarcer, which seems to be related to their position in the top of the mountains and difficulties associated with the access to them. This implies that there is a need to create tools that allow us to study these ecosystems, overcoming the current difficulties. Hydrological TOPMODEL is used to investigate the hydrological functioning of the páramo of Chingaza, through a case study in La Chucua basin. For this, we calibrate and validate the model using two data sets of climate and the hydrology of the basin (climate and discharge from 2008 and 2009, respectively). Through the calibration procedure we obtain a high efficiency value of 0.76 model (coefficient Nash - Sutcliffe), which adequately represents the hydrological behavior of the páramo. Simulations with better adjustment between measured and predicted values of discharge, have low values of surface infiltration excess runoff, indicating high water storage capacity on the soils. This agrees with the predominance of subsurface flow in studied ecosystem, given the special characteristics of soils. Results also show the large influence of factors represented in the model (topography and soils), on water basin response to rainfall events. This is significant evidence of exceptional hydrological behavior of the páramos, mainly related to the presence of soil with high organic matter content. These results imply that TOPMODEL is a robust tool, able to represent in a precise manner the hydrological functioning of the basin La Chucua, and consequently it is expected that TOPMODEL can also represent hydrological conditions of Chingaza páramo.

YouTube as a crowd-generated water level archive

In view of the substantial costs associated with classic monitoring networks, participatory data collection methods can be deemed a promising option to obtain complementary data. An emerging trend in this field is social media mining, i.e., harvesting of pre-existing, crowd-generated data from social media. Although this approach is participatory in a broader sense, the users are mostly not aware of their participation in research.Inspired by this novel development, we demonstrate in this study that it is possible to derive a water level time series from the analysis of multiple YouTube videos. As an example, we studied the recent water level rise in Dahl Hith, a Saudi Arabian cave. To do so, we screened 16 YouTube videos of the cave for suitable reference points (e.g., cave graffiti). Then, we visually estimated the distances between these points and the water level and traced their changes over time. To bridge YouTube hiatuses, we considered own photos taken during two site visits. For the time period 2013–2014, we estimate a rise of 9.5m. The fact that this rise occurred at a somewhat constant rate of roughly 0.4m per month points towards a new and permanent water source, possibly two nearby lakes formed from treated sewage effluent. An anomaly in the rising rate is noted for autumn 2013 (1.3m per month). As this increased pace coincides with a cluster of rain events, we deem rapid groundwater recharge along preferential flow paths a likely cause. Despite the sacrifice in precision, we believe that YouTube harvesting may represent a viable option to gather historical water levels in data-scarce settings and that it could be adapted to other environments (e.g., flood extents). In certain areas, it might provide an additional tool for the monitoring toolbox, thereby possibly delivering hydrological data for water resources management.

Combined electrical resistivity tomography and magnetic resonance sounding investigation of the surface-water/groundwater interaction in the Urema Graben, Mozambique

This study focusses on the hydrogeology of Urema Graben, especially possible interactions between surface water and groundwater around Lake Urema, in Gorongosa National Park (GNP). Lake Urema is the only permanent water source for wildlife inside GNP, and there are concerns that it will disappear due to interferences in surface-water/groundwater interactions as a result of changes in the hydraulic environment. As the lake is the only permanent water source, this would be a disaster for the ecosystem of the park. The sub-surface geology in Urema Graben was investigated by 20 km of electrical resistivity tomography (ERT) and three magnetic resonance sounding (MRS) surveys. The average depth penetration was 60 and 100 m, respectively. The location of the ERT lines was decided based on general rift morphology and therefore orientated perpendicular to Urema Graben, from the transitional areas of the margins of the Barue platform in the west to the Cheringoma plateau escarpments in the east. ERT and MRS both indicate a second aquifer, where Urema Lake is a window of the first upper semi-confined aquifer, while the lower aquifer is confined by a clay layer 30–40 m thick. The location and depth of this aquifer suggest that it is probably linked to the Pungwe River which could be a main source of recharge during the dry season. If a dam or any other infra-structure is constructed in Pungwe River upstream of GNP, the groundwater level will decrease which could lead to drying out of Urema Lake.

Monitoring the Changing Pattern of Land Use in the Rangpur City Corporation Using Remote Sensing and GIS

Rangpur is one of the fastest growing cities of Bangladesh with a dense population. Being the headquarter of a division in Bangladesh, it is experiencing multi-dimensional problems such as over urbanization, traffic congestion, water logging, and solid waste disposal. Rangpur is a sheer example of having poor legislative actions, inefficient management and lack of public awareness, which leads the urbanization to an unplanned and resource consuming development. This study presents an integrated study of land use pattern in Rangpur City, Bangladesh, by using Geographical Information Systems (GIS) and Remote Sensing (RS). The data sources used in this study were Landsat Thematic Mapper (TM) and a Landsat Enhanced Thematic Mapper Plus (ETM+) images taken in 1989, 2000 and 2014, respectively. All images were geometrically and radiometrically corrected and the change detection methods were performed. Then, supervised maximum likelihood classification was used as a cross classification to detect change. The study area was classified into six categories on the basis of field study, geographical conditions, and remote sensing data. The remotely detected land use change from 1989 to 2014 shows that Rangpur is gradually changing, as planted trees, open spaces, low land and Permanent water sources have been transformed into built-up areas.

Turtles outsmart rapid environmental change: The role of cognition in navigation

Animals inhabiting changing environments show high levels of cognitive plasticity. Cognition may be a means by which animals buffer the impact of environmental change. However, studies examining the evolution of cognition seldom compare populations where change is rapid and selection pressures are strong. We investigated this phenomenon by radiotracking experienced and naïve Eastern painted turtles (Chrysemys picta) as they sought new habitats when their pond was drained. Resident adults repeatedly used specific routes to permanent water sources with exceptional precision, while adults translocated to the site did not. Naïve 1–3 y olds from both populations used the paths taken by resident adults, an ability lost by age 4. Experience did not, however, influence the timing of movement or the latency to begin navigation. This suggests that learning during a critical period may be important for how animals respond to changing environments, highlighting the importance of incorporating cognition into conservation.

A Comparison of Sign Searches, Live-Trapping, and Camera-Trapping for Detection of American Badgers (Taxidea taxus) in the Chihuahuan Desert

Abstract. In communities where they occur, American badgers (Taxidea taxus) play important ecological, economic, and conservation roles. Central to understanding of badger ecology and management are estimates of badger population status. However, few studies have compared methods of detecting badgers for population surveys. I compared searches for burrows and diggings, live-trapping, and the use of automatic cameras at scent lures, bait stations, and anthropogenic permanent and temporary wildlife water sources in the Chihuahuan Desert of southern New Mexico. Searches for confirmed badger burrows and diggings yielded 0.14–0.88 detections per kilometer of transect. Badgers were trapped in 1.6% of trap-weeks. Percentages of camera-weeks in which badgers were detected included 12.8% at scent lures, 5.6% at bait stations, 54.5% at permanent water sources, and 13.3% at temporary water sources.

Potential for water-resource infrastructure to act as refuge habitat

Permanent sources of natural water are expected to decline in Mediterranean-climate regions under future climate change. Therefore, stable water bodies that act as refuge habitats will become increasingly important to the maintenance of freshwater biodiversity. Man-made water bodies such as those associated with water-resource infrastructure could contribute to the available refuge habitat but little is known about fish, zooplankton and frog assemblages in such water bodies. We quantified the diversity and abundance of fish, zooplankton and frogs that reside within raw water storages and water reclamation plants and compared them to assemblages from nearby natural water bodies over a total of 19 water bodies.Overall, the faunal assemblages within the man-made water bodies showed similarities to the nearby natural water bodies with very few differences found among the three water body types. Diversity of available substrates and of submerged and emergent macrophytes were the habitat variables best correlated with diverse faunal assemblages. This study suggests that the faunal assemblages within raw water storages and water reclamation plants resemble those found within nearby natural water bodies and that there is therefore potential for water-resource infrastructure to act as an important refuge habitat during drought. Furthermore, small changes in the management of these storages to maximise habitat diversity could increase the value of the refuge, complementing their role in water-resource delivery.

Is it agriculture yet? Intensified maize-use at 1000 cal BC in the Soconusco and Mesoamerica

The development of food production in Mesoamerica was a complex and protracted process. We argue that while maize had been cultivated for many millennia, this cereal grain assumed a markedly more important role in the political economy of the Soconusco (and elsewhere in Mexico, Guatemala and Belize) only after 1000cal BC. Macrobotanical data from the long-occupied village of Cuauhtémoc document low-level maize production from 1900 to 1400cal BC with a significant increase during the final centuries of the site’s occupation after 1000cal BC. Botanical evidence of increased maize consumption at this time occurred with evidence for changing groundstone use, intensified exploitation of dog and deer as well as iconography linking maize with rulership. This was also when monumental architecture was first built to mark a regional hierarchy of political centers. Changes evident in the Soconusco at 1000cal BC parallel transformations in both highland and lowland regions of Mesoamerica when ceramic-using villagers expanded into new environments, farther away from the permanent water sources favored by Late Archaic and Early Formative peoples. We interpret the changes evident at 1000cal BC in terms of both proximate historical factors as well as ultimate adaptive causes to produce a fuller understanding of changing Mesoamerican food production practices.

Late Quaternary beach deposits and archaeological relicts on the coasts of Cyprus, and the possible implications of sea-level changes and tectonics on the early populations

Abstract Late Pleistocene beach deposits in 22 selected sites around Cyprus demonstrate the vertical changes in the Earth's crust in that island over the last 125 ka. The beach/shallow-marine deposits were observed on the abraded coastal cliffs at 3–22 m above the present sea-level. They overlie Pliocene marls, and some of them contain the Senegalese marine gastropods Persististrombus latus , Bursa granularis and Conus ermineus that no longer live in the Mediterranean. These are index fossils for the Marine Isotope Stage (MIS) 5e in the Mediterranean and, as such, suggest an uplift of up to 15.5 m over about the last 125 ka: that is a maximal rate of 0.12 mm a −1 . These findings are in accordance with Holocene beachrocks, abrasion platforms, wave notches and Roman/Byzantine fish tanks that retained their elevations, and thus enable the reconstruction of the coast encountered by the early colonizers. While the maximal uplift since the early Holocene has been minor and did not exceed 1.2–1.5 m, the sea-level changes have reached 40–50 m. The transition between the impermeable Pliocene marls and the porous Late Pleistocene deposits above them is the origin of freshwater springs and associated vegetation. The early colonizers seemed to recognize the potential of that essential permanent source of water and excavated wells, the earliest wells known so far. The locations of the Early Neolithic settlements (Mylouthkia and Akanthou) adjacent to visible water springs along the coastal cliffs may not be incidental. Not surprisingly, recent wells dug in the coastal Pleistocene deposits rely on the very same hydrological setting. Supplementary material: Appendices 1–4, which include tables and diagrams showing the vertical changes (m) and rates of vertical changes (mm ka −1 ), assuming that MIS5e isotope stage deposits are 122 ka old and are at elevation of 7.2 m asl, or 116 ka at 6.5 m, are available at http://www.geolsoc.org.uk/SUP18830 .

Sheep production and marketing system in southern Ethiopia: the case of Awassazuria district.

A survey was conducted in Awassazuria district of southern Ethiopia to characterize sheep production system. A structured questionnaire was used to collect data. Using purposive sampling, a total of 120 households from the district were included in the survey. Collected data were analyzed using descriptive statistics. Result indicated that Kajima neighbourhood has more (p<0.05) grazing land than the others. Communal grazing, roadside grazing, enset (false banana, Ensete ventricosum), banana leaf and private grazing land were major feed resources for sheep. Lake Awassa and tap water were permanent water sources. Watering frequency of sheep varies from once a day to once in 4 days. Sheep are primarily kept to generate income and equilibrate benefit and risk and for home consumption. The criteria used by the households for purchase and sale of sheep are physical characteristics (coat colour, horn and tail) (46.7 %), body conformation (35 %), age (10.8 %) and known local ecotype (7.5 %). The reasons of slaughter of sheep include festival (55 %), childbirth (18.3 %), wedding (12.5 %), mutton for home (9 %), circumcision (5 %) and for guest (1.7 %). Farmers fatten sheep for New Year (60 %), Easter (30.8 %), Christmas and Arefa (Eid al-Adha celebration (Feast of the Sacrifice); <10 %). The reasons for expansion of sheep flock in the future were market price, high market demand, immediate return, ease of management, equilibrium between benefits and risks and suitability for home consumption, ranked in decreasing order of importance. The sheep production in southern Ethiopia is constrained by shortage of grazing land (23.3 %), recurrent drought (17.5 %), disease and parasite (15 %), marketing (10.8 %), water shortage (9 %) and other constraints including predators and lack of input, capital and lack of extension service. The presence of diversified and environmentally adaptable sheep breeds, high demand of mutton in the Awassa town and presence of nutritious and unutilized feed resources like fish meal and poultry litter were some of the opportunities for sheep production in the area.

Spatiotemporal resource partitioning of water sources by African carnivores on Namibian commercial farmlands

AbstractInterspecific competition often occurs when sympatric carnivores compete for the same, limited resources, although the degree of competition between species pairs may vary with biotic factors such as body size, diet and population density. Avoidance of dominant competitors along the axes of space and time is a potential mechanism for reducing chances of direct encounters between species. However, when resources are essential and spatially fixed, options for spatial partitioning may be limited. We examined resource partitioning within a guild of eight carnivore species at water sources across two commercial farmlands in southwest Namibia. In this semi‐desert environment, surface water is scarce and farmers are forced to provision water for livestock through artificial means. Camera traps were used to record spatial and temporal activity patterns of carnivore species at artificial and natural permanent water sources. We found that carnivores use either spatial or temporal resource partitioning, with temporal partitioning being most frequently seen. An association was seen between difference in body mass and degree of spatial partitioning, where species pairings with larger differences in body mass showed the greatest degree of partitioning. These results show that while in arid environments water is rare and used by a number of carnivore species, resource partitioning allows a guild of carnivores, including species of conservation concern, to coexist outside of protected areas.

The fancy city life: Kuhl's pipistrelle, Pipistrellus kuhlii, benefits from urbanisation

Context Urbanisation is often regarded as a major threat to global biodiversity. Although wildlife is frequently affected by urbanisation, some species may actually benefit from it. Bats are among the commonest wild mammals in human-modified areas, and some species seem particularly well suited to exploit urban habitats where they find roosting and foraging opportunities. Aims We investigated habitat selection around roosts of synurbic Kuhl’s pipistrelles, Pipistrellus kuhlii, in Italy. Methods We measured the effects of the amount of urban habitat on bat reproductive timing and success in human-modified environments. Key results We found that P. kuhlii selects roosts surrounded by areas featuring urban habitats, especially those subject to urban development. Colonies in cities and suburbs advanced parturition time and produced more pups than those in rural areas. Permanent water sources and artificial lights in the surrounding habitats also seemed to favour the species reproductive success, particularly in developing urban areas. Conclusions Our results showed that this bat benefits from urbanisation and provided new insights on the effects of this major process on animal ecology and conservation in urban environments. Implications Although the ecological flexibility and positive response to urbanisation of P. kuhlii may help explain its recent range expansion, the role of climate change as a potential driver of this process has yet to be tested.

A late Quaternary record of vegetation and climate change from Hazards Lagoon, eastern Tasmania

A late Quaternary pollen and charcoal record from Hazards Lagoon on the east coast of Tasmania provides a continuous record of vegetation and climate change. The pollen record shows an Epacridaceae and Poaceae dominated grassland community replaced dry sclerophyll forest during the Last Glacial Maximum (LGM ∼22–18 cal ka BP). Eucalyptus and Casuarinaceae increased from the beginning of the deglacial period (∼18–12 cal ka BP) indicating early warming on the east coast of Tasmania. Abundant Myriophyllum and sedimentary characteristics indicate Hazards Lagoon was a permanent source of water throughout the LGM and until 16 cal ka BP suggesting either increased precipitation and/or decreased evaporation rates. A positive moisture balance throughout the LGM contrasts with records from the west coast of Tasmania and parts of mainland Australia. Fire was suppressed at the site until 14 cal ka BP, corresponding with reduced woody vegetation and a positive moisture balance. Dry sclerophyll forest established during the deglacial period, remaining stable throughout the Holocene. A coastal vegetation community developed in response to sea-level rise, characterised by abundant Eucalyptus pollen and increasing values of Casuarinaceae. By the mid-Holocene, the Hazards Lagoon pollen record is typical of a Tasmanian coastal site dominated by Casuarinaceae. This research highlights the need for spatially diverse studies throughout the Southern Hemisphere to identify drivers of environmental change during the late Quaternary.

Unravelling sources of solutes in groundwater of an ancient landscape in NW Australia using stable Sr, H and O isotopes

The Precambrian meta-sedimentary fractured rock aquifers of the Hamersley Basin in northwest Australia are some of the oldest water-bearing formations on the planet and host enormous iron ore deposits. Groundwater is the only permanent source of water in the basin, therefore understanding the hydrological processes that effect water quality and quantity is a pre-requisite for sustainable water management. We used a combination of major dissolved ion concentrations, including Sr and Ca, in combination with δ2H, δ18O and δ87Sr in flood water and groundwater as tracers to constrain the processes affecting groundwater chemistry. The δ87Sr composition of groundwater in three major aquifer types ranges from 11.8‰ to 40.6‰ and reflects the mineralogy of altered Precambrian dolomite (15.1‰ to 55.4‰) rather than the host iron ore formations (22.5‰ to 46.5‰ >95% iron oxides) or highly radiogenic shale bands and clay minerals (200‰ to 2322.5‰). Groundwater in the terminal Fortescue Marsh wetland of the basin has a rather constant δ87Sr signature of 36.6±1.4‰ irrespective of variations in TDS, δ18O and Sr concentration. This groundwater is considered to be mature in a geochemical sense, representing the final stage of water evolution on a basin scale. Mixing calculations utilising δ87Sr and Ca/Sr data demonstrate contributions of salts from three major sources: on average >92% from precipitation, ~7% from carbonate rocks and <1% from rocks with highly radiogenic signatures (shales and clays). These results demonstrate groundwater evolution from a recharge area to discharge area at the regional scale, but more importantly that water quality in the terminal wetland is primarily driven by rainfall chemistry in floodwaters rather than water–rock interactions in the catchment.

Spatiotemporal interactions between wild boar and cattle: implications for cross-species disease transmission.

Controlling infectious diseases at the wildlife/livestock interface is often difficult because the ecological processes driving transmission between wildlife reservoirs and sympatric livestock populations are poorly understood. Thus, assessing how animals use their environment and how this affects interspecific interactions is an important factor in determining the local risk for disease transmission and maintenance. We used data from concurrently monitored GPS-collared domestic cattle and wild boar (Sus scrofa) to assess spatiotemporal interactions and associated implications for bovine tuberculosis (TB) transmission in a complex ecological and epidemiological system, Doñana National Park (DNP, South Spain). We found that fine-scale spatial overlap of cattle and wild boar was seasonally high in some habitats. In general, spatial interactions between the two species were highest in the marsh-shrub ecotone and at permanent water sources, whereas shrub-woodlands and seasonal grass-marshlands were areas with lower predicted relative interactions. Wild boar and cattle generally used different resources during winter and spring in DNP. Conversely, limited differences in resource selection during summer and autumn, when food and water availability were limiting, resulted in negligible spatial segregation and thus probably high encounter rates. The spatial gradient in potential overlap between the two species across DNP corresponded well with the spatial variation in the observed incidence of TB in cattle and prevalence of TB in wild boar. We suggest that the marsh-shrub ecotone and permanent water sources act as important points of TB transmission in our system, particularly during summer and autumn. Targeted management actions are suggested to reduce potential interactions between cattle and wild boar in order to prevent disease transmission and design effective control strategies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-014-0122-7) contains supplementary material, which is available to authorized users.

A Mosaic of Adaptation: The Archaeological Record for Mesoamerica’s Archaic Period

Mesoamerica’s Archaic period lasted for seven millennia beginning at the end of the Younger Dryas (~8000 cal. BC). The end of this period was uneven, with the earliest ceramic-using villagers documented at 1900 cal. BC, but not until the end of the second millennium BC in the Maya lowlands. Food production progressively increased in Mesoamerica between 8000 and 1000 cal. BC but did not significantly alter a mixed foraging–horticultural adaptation. During the third and fourth millennia BC, sedentism increased around permanent sources of water with dependable aquatic resources, such as the lakes in the Basin of Mexico and the estuaries of the Gulf coast and the Soconusco region on the Pacific coast. A mosaic of different adaptations was created, with more mobile peoples inhabiting the dry highland valleys of Mexico and Guatemala and much of the Maya lowlands. I argue that the ultimate cause of both the beginning and the end of the Archaic period was a return to wet, warm, and more stable environmental conditions after the Younger Dryas and the three-century-long 2200 cal. BC “event.” Ultimate climatic causes, however, provide only a limited understanding of the past, whereas proximate causes provide a more complete picture of where, when, and how food production, sedentism, and ceramic use developed. The archaeological record provides the complex and regionally varied evidence to reconstruct the proximate processes that saw Mesoamerican peoples transform from small groups of dispersed foragers to sedentary food producers who laid the foundation on which later Mesoamerican civilizations were built.