Rodrigo Medellin, Mexico’s Bat Man

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Feb 192015
 

Rodrigo Medellin, a Mexican expert on bats (Mexico’s Bat Man) was the winner of the 2012 Whitley Fund for Nature Gold Award for his on-going work to study, raise awareness and highlight the importance of Latin America’s bats. The award reflects Medellin’s outstanding contribution to nature conservation.

This short video narrated by Sir David Attenborough, summarizes Medellin’s work:

Medellin, an ecology professor who, among many other achievements, has found bat species previously thought extinct, was the subject of an episode in the 2014-2015 season of the BBC series Natural World. The documentary won the 2014 Panda Award for Best People and Nature Film.

As a child, Mexico’s Bat Man kept vampire bats in his bathroom and some of his own blood “in the fridge so that I could feed them every night”.

Little friend: Rodrigo with one of the Lesser Long Nosed Bats his hard work has helped to conserve

Rodrigo with a lesser long nosed bats Credit: Amy Cooper, BBC2.

Bats are more important to ecology, and Mexico’s economy, than you might think. For instance, the lesser long-nosed bat is the main pollinator of the agave plants from which tequila is produced. Medellin’s research has involved tracking and understanding the extraordinary migrations undertaken by bats such as the lesser long-nosed bat, which pollinates the agaves during its annual migration. (Worldwide, bats also propagate at least 500 other economically important night-flowering species).

The bats’ journey covers 1500 kilometers (almost 1000 miles) from southern Mexico to the Sonoran Desert straddling the Mexico-USA border, via the so-called ‘Nectar Corridor’, the coastal lowlands between the Western Sierra Madre and the Pacific Ocean. Indeed, in the desert region, the lesser long-nosed bat is responsible for pollinating the distinctive saguaro cactus (which is incapable of self-fertilization), the key to the whole Sonoran ecosystem.

Elsewhere, bats can be a tourist attraction, as at Bracken Cave, Texas, home to an estimated 20 million Mexican free-tailed bats. in addition, fruit-eating bats help stimulate the regrowth of rainforests, by distributing five times more seeds per square meter than birds.

Medellin has devoted his life to ensuring the conservation of bats in Mexico and, fortunately for all tequila lovers, appears to have been successful. Because of his work, the Tequila Bat is now off the endangered species list. Over the past three decades, Medellin has campaigned tirelessly for people to appreciate the value and beauty of bats, creating a network of bat-friendly ‘safe caves’, and pioneering conservation techniques that are now being copied around the world.

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Are Monarch Butterflies in danger of extinction?

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Oct 182014
 

As a species, monarchs are native to North America, but subsequently island-hopped their way around the world—across the Pacific to Hawaii, Tonga, Samoa, Australia and New Zealand, and across the Atlantic to Europe. In parts of Mexico, particularly in the area around Lake Chapala, there is a healthy population of non-migrating monarch butterflies; these butterflies can count on year-round access to milkweed plants on which to lay their eggs. As a result, it is reasonable to conclude that the species itself is in no danger of extinction.

However, what may be “endangered” is the annual migration of Monarch Butterflies to and from Mexico. This annual migration is categorized as an “endangered phenomenon” by the International Union for Conservation of Nature. Threats to the migration come from climatic change and extremes, as well as from the impacts of human activity. In some years, unusually cold snaps and hailstorms have caused the premature death of millions of butterflies, though, as yet, this has had little if any discernible effect on total monarch numbers. Human activity has greatly reduced the area of the monarchs’ natural overwintering habitats, in both California, for real estate developments, and in Michoacán, due to forest clearance for timber and agriculture. Farming activities in the US have also resulted in the loss of milkweed along the Monarchs’ migratory pathways. This loss may have far more serious consequences on the long-term viability of the annual migration. Without milkweed, the female Monarchs are unable to lay their eggs on a suitable host plant, and the Monarch caterpillars will never acquire their chemical defenses against predation.

The numbers of Monarchs overwintering in Mexico have varied greatly from one year to the next. The graph below, reproduced widely in the press, has been used as evidence that the numbers of migrating Monarchs are in sharp decline. A note of caution is needed, though, since the estimates of numbers used for the graph are based on the area of trees occupied by the butterflies, and not on a direct count (which is clearly impractical!)

Monarch-Trends-1994-2013

The challenge for researchers is to be certain that the density and architecture of trees is similar from one year to the next. If the trees are less densely grouped, for example, one year than the next, in the particular areas occupied by the butterflies, then the area the butterflies need will be correspondingly larger. The lower area in recent years could be at least partially explained by a higher tree density in the overwintering areas, allowing the same number of butterflies to co-exist in closer proximity to each other.

This is not to say that there is not cause for concern. According to the National University (UNAM)’s Environmental Geography Research Center, at current rates of deforestation, the area of overwintering sites for the Monarch butterflies could be reduced by 75% in the next 18 years, leaving just 12,000 ha of suitable habitat. The protected area, established in 2000, covers 560 square kilometers (56,000 ha. or 216 sq. mi) but includes land cleared for pasture, settlement and cultivation. Researcher José López García claims the reserve is losing 3% of its forest each year. He blames clearance and changes of land use more than illegal logging. The rate of forest clearance has been exacerbated by a rapid rise in the population of the El Rosario ejido. El Rosario is the gateway to the most-visited part of the reserve, attracting thousands of tourists annually. The ejido’s population rose by an average of 5.65%/year between 2005 and 2010.

What is Mexico doing about this?

The Mexican conservation strategies for the butterflies are designed to protect their overwintering habitat and provide alternative sources of revenue and employment for local campesinos who depend on the land and forest for their livelihood. After some doubtful years in the early 1980s, there is now a system of formally protected monarch butterfly reserves, and concerted conservation efforts to prevent further destruction of the monarchs’ unique overwintering habitat.

The modest entrance fees to Monarch Butterfly reserves help fund development projects in the local communities. There is a strict code of conduct for tourists to prevent noise, littering and straying from the well-marked paths.

While the new rules have undoubtedly had some success, it is still preferable to visit, if at all possible, during the week and not at the weekend when the reserves are at their crazily busiest.

On a quiet day,pausing to catch your breath in the peace of the forest as you climb the trail, you will then be just as surprised as I first was when you realize that the gentle swishing sound you can hear around you is not the sound of the wind blowing through the tree limbs but the sound caused by millions of tiny wings beating as the butterflies flutter about in the sky.

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Oct 112014
 

Most monarch butterflies never migrate, but one generation of the North American monarch population undertakes an annual, long distance migration, a journey without parallel in the insect world. Every winter, some one hundred million monarch butterflies fly south into Mexico from the U.S. and Canada. They congregate and spend the winter in a dozen localities high in the temperate pine and fir forests of the states of México and Michoacán.

Where do the Monarchs overwinter?

The exact sites where the butterflies overwinter were only found in the mid 1970s after a search of nearly forty years. Scientists are still unable to explain all the details of this enigmatic annual migration, but their unexpectedly sophisticated navigational ability seems to rely on an incredible innate accuracy in pinpointing their position by using their eyes and antennas to measure the angles of the sun’s rays, compensating for time of day, and ensuring they continue to fly in a southerly direction towards the state boundary separating Michoacán from the State of México.

How fast can they fly?

The tagging of butterflies has proven that they make the 2500 kilometer trip each way at an impressive average speed of 20 km/h, with maximum speeds of up to 40 km/h (25 mph). Monarchs don’t fly at night, partly because they need daylight to navigate and partly because they fly best when sunlight has warmed their wings, like miniature solar panels, raising their body temperatures some 10 to 15 degrees Celsius above ambient air temperatures.

The butterflies are energy-efficient flyers, making regular nectar stops along the way to refuel. One third of their dry body weight is energy-giving fat but far from losing weight on their exhausting journey south, they actually appear to gain it! There are still many mysteries about the monarchs but they certainly provide one of the most amazing natural spectacles to be seen anywhere on earth. Millions of orange butterflies, with black and white-spotted wings, whether flying overhead or, as on cooler days, clinging apparently lifeless to the grey-green fir trees in such numbers that the trees appear to be in blossom, are an absolutely unforgettable sight.

Based on original map design created by Paul Mirocha (paulmirocha.com) for Monarch Watch.

Based on original map design created by Paul Mirocha (paulmirocha.com) for Monarch Watch.

The journey south

In September and October, as temperatures in the U.S. and Canada fall, and food supplies become scarce, the monarchs fly south in small groups. Some of these groups fly only as far as Florida or western California where they spend their winters in milder conditions. But many of the small groups from east of the Continental Divide eventually coalesce and fly much further south, as far as Mexico, arriving en masse in the state of Michoacán towards the end of November.

This migratory group is comprised of as many as 120 million individuals and spends the winter in semi-dormancy, on the pine and oyamel (sacred fir, Abies religiosa) trees found at elevation of about 3050 meters (10,000 feet) along Mexico’s central Volcanic Axis. Until spring comes, in March or April, these butterflies cling to the branches and trunks of the trees, enjoying temperatures between 10 and 16 degrees Celsius, protected from cold northerly winds. Their metabolism slows down in these low temperature, low oxygen conditions and they exhibit movement only on warm, sunny, days.

The generation that flies into Mexico does not mature sexually until the following spring. In February and March, the best months to see them, early spring sunlight begins to penetrate the groves of fir trees, temperatures begin to rise and the forest floor slowly comes alive with new plant growth. The butterflies, having successfully overwintered the worst weather, unfurl their wings and flutter about in search of food and water. As they regain their strength, so they become sexually mature and the mating process starts.

The journey north

After mating, the butterflies begin to leave the reserves, flying back towards the north. Five days later, in northern Mexico and the southern U.S., each female lays two to three hundred eggs on the underside of milkweed leaves. They first check (by smell and touch) that no eggs have already been laid there, and then space their eggs in such a way so as to ensure that each larva that hatches two to three days later will have an adequate supply of food. The larvae grow quickly, changing their skins five times before becoming pupae. After a further two weeks, butterflies emerge, and fly northwards. Each generation of monarchs probably acquires a different chemical “blueprint”, based on the exact species of milkweed it eats, giving it the information it needs to know where to fly. Eventually, by April, the northernmost butterflies reach Canada.

No individual butterfly completes the entire 5000 kilometer round trip. Most of those that fly south die soon after mating in spring (with males often dying in the reserves and never starting their homeward trip), while those who head north cannot hope to survive long into the summer, when normal reproductive cycles, each lasting from four to six weeks, are reestablished.

The last generation of each summer, perhaps prompted by shorter days, soon departs on the next wave of mass migration to Mexico. Those from furthest north will cross the Great Lakes on their return in a single day’s flight, an impressive feat in its own right. They have been spotted flying south at heights up to 1500 meters and exploit thermals to gain height and save energy.

Where to see Monarch Butterflies

Several monarch reserves are open to the public each year. Each has its own distinctive character. Two of the most important reserves are close to the town of Angangueo. Sierra Chincua, north of the town, is the site where the first Canadian-tagged monarch was found in the mid 1970s. This is also where I first saw the butterflies, in 1980, while looking for a potential site for geography fieldwork. It was a serendipitous discovery, and led to me being mistaken for a BBC reporter, but that’s another story!

Angangueo. Sketch by Mark Eager; all rights reserved.

Angangueo. Sketch by Mark Eager; all rights reserved.

The most accessible reserve open to the public is El Rosario, south of Angangueo, where there are dozens of souvenir stalls and rustic snack stands—don’t miss sampling the delicious hand-made blue-corn tortillas. The narrow trails in the sanctuary, with information boards at regular intervals, wind steeply several hundred meters uphill, reaching a maximum altitude of 3050 meters. This altitude can cause some shortage of breath and air temperatures are generally low, so be sure to bring a sweater.

El Rosario can be reached from either Angangueo (steeper but more direct approach) or Ocampo. Anyone driving their own vehicle to El Rosario is advised to use the route via San Felipe (on Highway 15) and then Ocampo. From Ocampo any vehicle with adequate ground clearance, including the local taxis, can negotiate the fourteen kilometers to the monarch sanctuary parking lot.

The San Felipe-Ocampo junction on Highway 15 is marked by a line of fruit and soft-drink stalls, many of which in season sell delicious granadas (pomegranates). Also at this junction is an interesting sixteenth century church which, until as recently as 1995, had tombstones in its atrium, unusual in Mexico. Normally, the Spanish buried their dead as far away from the churchyard as possible, presumably to avoid the risk of disease.

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This post is based on chapter 36 of my “Western Mexico: A Traveler’s Treasury” (link is to Amazon’s “Look Inside” feature), also available as either a Kindle edition or Kobo ebook.

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Ecocide in Lake Cajititlan, Jalisco: massive fish death

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Sep 062014
 

Hundreds of thousands of dead fish have washed up on the shores of Lake Cajititlán in Jalisco in the past ten days.

Lake Cajititlán is about 9 kilometers (5.6 miles) long and 2 km wide. It is mid-way between the city of Guadalajara and Lake Chapala, Mexico’s largest natural lake. Fortunately, Lake Cajititlán does not have an outlet, so water and fish from the lake can not enter other nearby streams or lakes.

Map of Lake Chapala, Jalisco, Mexico

Map of Lake Chapala, Jalisco, Mexico. Credit: Tony Burton; all rights reserved.

According to government officials, about 3 million dead popoche chub (Algansea popoche) with a combined weight of 82 metric tons were removed from Lake Cajititlán in the latest ecocide.

Initial reports contained conflicting versions of events, with local fishermen claiming far higher losses than government officials. The currently accepted figure of 82 metric tons suggests that the fishermen’s estimate was far closer to reality than the early “official” figures.

cajititlan-ecocide

(AFP Photo / Hector Guerrero)

Local authorities at first tried to persuade residents that the die-off was part of a “natural cycle”. However, this idea was quickly dispelled by state and federal agencies who are continuing investigations to establish the precise causes of the ecocide. Their preliminary technical studies have confirmed that the die-off of fish was due to contaminated water with dissolved oxygen levels well below the limits for a healthy fish population. The contamination appears to originate from raw sewage entering the lake and the inefficient operation of the existing sewage treatment plants.

Low oxygen levels could also result from seasonal rainy season runoff washing excess fertilizers into the lake, increasing the water’s nitrogen and phosphorus loads, promoting eutrophication.

State authorities have issued an environmental emergency alert for the lake, but have consistently maintained that the event has not endangered the health of local residents.

This is the fourth fish kill affecting Lake Cajititlán in 2014. This latest ecocide is only one of several ecological disasters that have befallen Mexico in recent weeks.

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Tracking the migratory routes of Mexico’s sea turtles

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Jun 302014
 

The Wildlife Protection and Conservation Program at the CIIDIR Sinaloa campus of Instituto Politécnico Nacional (National Polytechnic Institute), has developed a series of research projects focusing on sea turtle conservation in northwest Mexico. For one of their projects, researchers released (on the Playa Las Glorias beach in the city of Guasave) three sea turtles who can now be tracked using satellite tracking devices affixed to their shells. The main purpose is to allow researchers to determine the sea turtles’ migration routes.

leatherback-turtle

These three Loggerhead sea turtles (Caretta caretta) now carry transmitters that are connected to the ARGOS satellite system. This should enable their location to be closely tracked for at least a year. The migration of these three sub-adult Loggerhead turtles – named Umi, Baawe and La Hija del Señor – can be followed via the Seaturtle.org website:

These sea turtles nest in Japan, but then migrate to the coasts of Hawaii and Mexico to feed and develop. Experts say that they will only migrate back to Japan once they have reached sexual maturity.

This research is only one of many that involves tracking sea turtles. Off the Gulf Coast of Mexico , a longer-established study has sought to determine the movements of Kemp’s Ridley turtles (Lepidochelys kempii), many of which nest in Tecolutla, Veracruz. These turtles nest an average of 2.5-3.0 times per season, and tracking their movements should help predict where and when the turtles might nest, helping conservationists identify and protect nesting sites.

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Common errors of Mexican geography #2: confusing the Sierra Madre with the Volcanic Axis

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Jun 192014
 

Describing somewhere in Mexico as being “located in the Sierra Madre mountains” may conjure up images of high, possibly snow-capped peaks and rugged scenery, but does very little to pin down the location. Mexico has several Sierras Madre (literal translation: Mother Ranges). The three main Sierra Madre regions in Mexico are the Western Sierra Madre, Eastern Sierra Madre and Southern Sierra Madre (see map).

The Western Sierra Madre (Sierra Madre Occidental) is the youngest, highest and most viciously dissected of the three. This region includes the scenically amazing Copper Canyon region we have described in many previous posts, including:

Location of Volcanic Axis and Monarch Butterfly reserves

Location of Volcanic Axis and Monarch Butterfly reserves. Basemap: Figure 3.1 of Geo-Mexico; all rights reserved.

The Western Sierra Madre extends only as far south as the states of Nayarit and Jalisco.

Its counterpart on the eastern side of the country is the Eastern Sierra Madre (Sierra Madre Oriental) which is older, lower and less rugged. Between these two major mountain ranges are mid-elevation basins and plains.

At the southern end of both the Western Sierra Madre and the Eastern Sierra Madre is the Volcanic Axis.

The Southern Sierra Madre (Sierra Madre del Sur) lies south of the Volcanic Axis, largely in the state of Oaxaca.

The details of Mexico’s physiographic regions are complex, but the basic relief pattern of these three Sierra Madre regions, separated by the Volcanic Axis and mid-elevation basins and plains, is fairly simple. It is therefore disappointing when we read references to the Sierra Madre regions that are geographically inaccurate.

The Monarch Butterfly reserves, for instance, are regularly described as being in the Sierra Madre, or the Western Sierra Madre, even though they are located hundreds of kilometers away from the Western Sierra Madre, on the southern edge of the Volcanic Axis (see map). In the original National Geographic article about the “discovery” of the Monarch Butterflies’ overwintering sites (August 1976), the location of the butterflies was deliberately left vague (to prevent human-induced disruption of the sites), so that article can readily be excused for mislocating the sites as being in “Mexico’s Sierra Madre”. (The tiny map that accompanied that article also shifted the Monarch’s wintering areas well away from their real position.)

Despite the efforts of the National Geographic, it was not long before journalists published articles giving the precise locations of the sites, and visitors started to flock to see this marvel of nature. The establishment of reserves has now brought a measure of sanity and control to access and most visitors now behave respectfully.

One of the latest in the long line of journals and magazines to erroneously refer to the site of the Monarch reserves as “in the remote Sierra Madre mountains” (but lacking the original excuse of the National Geographic) is the Canadian Geographic in its December 2013 Annual Wildlife Issue. The general tone of the article is helpful, and it rightly emphasizes the need to protect habitat along the entire migration route between Canada and Mexico, so why mar the overall quality by making such a basic error of Mexican geography? Let’s help educate readers by making it clear that the Monarch Butterfly reserves are not in any Sierra Madre, but are in the Volcanic Axis!

How similar are Mexico’s two major deserts, the Sonoran Desert and the Chihuahuan Desert?

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May 292014
 

There are four desert areas in North America. Two of these areas (Great Basin and Mojave) are in the USA. The other two (the Sonoran Desert and the Chihuahuan Desert) are almost entirely in Mexico, but extend northwards across the border. The Sonoran Desert includes most of the Baja California Peninsula, together with the western part of the state of Sonora. The Chihuahuan desert is the northern section of the Central Plateau, including the northern parts of the states of Chihuahua.

The Chihuahuan Desert has been intensively studied by scientists interested in the possibility of life on Mars – see this New York Times article: Learning About Life on Mars, via a Detour to Mexico.

In a previous post – Why is northern Mexico a desert region? , we saw how the combination of the descending air of the Hadley Cell, which results in surface high pressure, and the effects of rain shadows resulting from neighboring mountain ranges contribute to the low annual rainfall total characteristic of both Mexico’s desert areas.

deserts-colorWhile these two deserts both experience an arid climate, they also have many differences.

Area

The Sonoran Desert has an area of about 311,000 square kilometers (120,000 sq mi). The Chihuahuan Desert has an area of about 362,000 square kilometers (139,769 sq mi).

Elevation

The Sonoran Desert is lower in elevation that the Chihuahuan Desert, with some parts (in the USA) lying below sea level. The Chihuahuan Desert varies in elevation from 600–1675 m (1969–5495 ft).

Summer temperatures

The Sonoran Desert tends to have higher summer temperatures than the Chihuahuan Desert, though even in the Chihuahuan Desert, daytime temperatures in summer are usually between 35 and 40̊C (95-104̊F).

Seasonal rainfall patterns

The ratio of winter to summer rainfall decreases from west to east. Most of the Sonoran Desert (to the west) has a bimodal rainfall regime with spring and summer peaks. On the other hand, most of the limited rain that falls in the Chihuahuan Desert comes in late summer.

The Chihuahuan Desert has a mean annual precipitation of 235 mm (9.3 in), though annual totals vary from 150 to 400 mm (6–16 in).

Vegetation, fauna and biodiversity

These seasonal rainfall differences result in significant differences in the vegetation of the two areas.

The bimodal precipitation in the Sonoran Desert provides two flowering seasons each year. Some plants bloom in spring, following winter rains, while others flower in late summer, following summer rains. Typical plants in the Sonoran Desert include columnar cacti (Cereus spp.) such as sahuaro, organ pipe, and cardon, as well as many other types of cacti, including barrels (Echinocereus), chollas (Opuntia spp.) and prickly pear (Opuntia spp.). Other succulent plants are also common.

More than 60 mammal species, 350 bird species, 20 amphibian species, 100 reptile species, 30 native fish species, 1000 native bee species, and 2000 native plant species have been recorded in the Sonoran Desert. The Sonoran Desert includes the Colorado River Delta, which was once an ecological hotspot within the desert, fueled by the fresh water brought by the river, though this flow has become negligible in recent years. See, for example, Will the mighty Colorado River ever reach its delta?

The vegetation of the Chihuahuan Desert is dominated by grasslands and shrubs, both evergreen and deciduous. Common species include tarbush (Flourensia ternua), whitethorn acacia (Acacia constrictor) and creosote bush (Larrea tridentata). The Chihuahuan desert has small cacti; succulent agaves (Agave spp.) and yuccas. Plants bloom in late summer, following the summer rains.

The Chihuahuan Desert is home to about 350 of the world’s 1500 known species of cactus, and includes the fascinating area of Cuatro Ciénegas, which has an unusually high number of endemic plant species and is one of the world’s richest hotspots for locally endemic cacti.

The Chihuahuan Desert is considered to be one of the three most biologically rich and diverse desert ecoregions in the world, rivaled only by the Great Sandy Tanmi Desert of Australia and the Namib-Karoo of southern Africa. However, settlements and grazing have heavily degraded the natural vegetation of some parts of the Chihuahuan Desert.

he Chihuahuan Desert has about 3500 plant species, including up to 1000 species (29%) that are endemic. The high rate of endemism (true for cacti, butterflies, spiders, scorpions, ants, lizards and snakes) is due to a combination of the isolating effects of the basin and range topography, climate changes over the past 10,000 years, and the colonization of seemingly inhospitable habitats by adaptive species. See here for more details of the flora and fauna of the Chihuahua Desert.

Landforms

This basin and range landscape of the Sonoran Desert trends north-northwest to south-south-east. Parallel faulted blocks are separated by alluvial bajadas (broad, debris-covered slopes), pediments and plains, which become wider approaching the coast. Despite being a desert area, this region exhibits many features that have resulted from water action, including wadis, salt flats, stream terraces and alluvial fans.

For a fuller description of the landforms of the Sonoran Desert, see this extract from A Natural History of the Sonoran Desert (edited by Steven J. Phillips and Patricia Wentworth Comus) published by the Arizona-Sonora Desert Museum.

The Sonoran Desert includes the subregion of the Sierra of Pinacate (part of El Pinacate and Gran Desierto de Altar Biosphere Reserve) with its distinctive volcanic cones, craters and lava flows. For more details, see The landforms of the El Pinacate and Gran Desierto de Altar Biosphere Reserve.

The landforms of the Chihuahuan Desert have been molded by tectonic uplift and erosion. Steep-sided but low hills are separated by wide bajadas from former lake beds and alluvial plains, occupying inland basins known as bolsons. Many parts form closed, interior basins with no external drainage. South of Ciudad Juárez, at Samalayuca, is one of Mexico’s most extensive areas of sand dunes. This is one of the most arid parts of the country, with high levels of salinization.

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Mexico presides over Convention for Protection of Sea Turtles

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Jul 122013
 

Mexico is home to six of the world’s seven species of marine turtles, all of which are on the international Red List of endangered or critically endangered species. Participants at last month’s meeting of the Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC), have elected Mexico to preside over the organization for the 2013-2015 period.

Luis Fueyo Mac Donald, the Commissioner of Mexico’s National Protected Natural Areas, says that Mexico will lead the efforts to promote the recovery of sea turtle populations in the Pacific Ocean, a priority because the marine animals are seriously threatened. The intention is to raise public awareness about the turtles’ plight and expand regional cooperation to protect turtle nesting and feeding grounds, as well as migration routes.

Selected marine turtle nesting beaches in Mexico.

Selected marine turtle nesting beaches in Mexico.

The next formal meeting of the IAC members will be held in Mexico in 2015.

In related news, the Central America Fisheries and Aquaculture Organization (Ospesca) has announced that new regulations are now in place to protect sea turtles in Central America and the Dominican Republic. The regulations should greatly reduce the numbers of turtles caught in shrimp nets, which now have to be fitted with Turtle Excluder Devices (TEDs). TEDs are metal grids of bars attached to shrimp trawling nets; they have openings designed to allow larger animals, such as sea turtles, to escape, while keeping shrimp inside.

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Mexico’s geomorphosites: El Sótano de las Golondrinas (Cave of the Swallows)

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Apr 112013
 

El Sótano de las Golondrinas, in the municipality of Aquismón in the state of San Luis Potosí, is a massive limestone sinkhole (pit cave), one of the largest known in the world. In terms of depth, it is thought to be the second deepest sinkhole in Mexico and is probably in the world’s top 20.

The depth of sinkholes can be difficult to determine. For example, in the case of El Sótano de las Golondrinas, its surface opening is about 50 meters by 60 meters (160 by 200 ft) in size, but is on a slope. The depth on the high side is about 376 meters (1220 ft); the depth on the low side is about 330 meters (1090 ft).

sotano-de-las-golon

Below the surface (see profile) the sinkhole is roughly bottle-shaped. The floor of the sinkhole is about 300 x 135 meters (990 by 440 ft) in area. However, the sinkhole is believed to have formed from the collapse of the roof of an underground cave. As a result, the floor of the sinkhole is not solid rock but rubble that presumably came from the walls and former roof. A shaft on one side extends down at least another 100 m, suggesting that the true floor of the original cave lies at least that far beneath the current rubble-strewn floor.

US photographer Amy Hinkle shot some spectacular images earlier this year in this cave.  The accompanying article highlights the “secret garden” that “nestles 300 meters beneath the surface of the earth”.

The cave’s name (literally “basement of the swallows”) derives from the thousands of white-collared swifts that inhabit the overhanging walls of its interior. They spiral out of the cave every morning over a period of 25-30 minutes and return to their cave homes close to sunset. Large numbers of green parakeets also live in the cave.

The floor of the sinkhole is home to a rich plant life, as well as a diverse selection of  fungi, millipedes, insects, snakes, and scorpions.

The original cave is thought to have been formed by a lengthy period of water erosion along a major fault line in the lower Cretaceous limestone in the Sierra Huasteca (part of Mexico’s Eastern Sierra Madre). Over time, the cave became larger as a consequence of both the water erosion and due to mass movements (landslides, rockfalls) on its walls. Eventually, the size of the cave was so large that its walls could no longer support its roof which then collapsed into the cave, leaving the open air sinkhole seen today. Following heavy rain, short-lived waterfalls cascade down the sides of the sinkhole.

The first documented exploration of El Sótano de las Golondrinas was apparently in 1966. Since that time, the cave has become a popular destination for various adventure sports including rappelling, abseiling and base jumping (no longer allowed).

There are several other very deep sinkholes in the same general area, including Hoya de las Guasguas (with a 202 m deep entrance shaft) and Sótano del Barro (402 m in depth).

Some ornithological studies have found that the bird population of El Sótano de las Golondrinas is decreasing, perhaps due to the disturbance caused by the increasing number of human visitors. To limit disturbance, access and activities are more tightly controlled. For instance, descents into the cave are now strictly limited to daylight hours when the birds are absent, and a no-fly zone has been established around the cave, primarily to avoid helicopter disturbance.

El Sótano de las Golondrinas is yet another outstanding example of a geomorphosite in Mexico. Mexico has literally thousands of geomorphosites. Among those described in previous Geo-Mexico posts are:

References:

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Two examples of bird re-introduction programs in Mexico

 Mexico's geography in the Press  Comments Off on Two examples of bird re-introduction programs in Mexico
Dec 222012
 

Assuming that the world did not come to an end yesterday, Geo-Mexico would like to convey best wishes to everyone for the entire duration of the next Long Count Maya calendar cycle, which runs until sometime in 2406. This may allow sufficient time for some real progress to be made in environmental stewardship.

Today’s post looks at two ornithological conservation projects that have made significant advances in 2012. The first is in Maya territory in south-east Mexico, where biologists are trying to stave off the extinction of the colorful Scarlet Macaw, and extend its current range. Researchers believe that between 250 and 400 of the birds now remain in the wild, almost all of them in the area straddling the borders between Mexico, Guatemala and Belize.

Birds raised in the Xcaret Center for the breeding of macaws, located in the state of Quintana Roo, are being gradually prepared for being set free in Aluxes Park, an ecological reserve on the edge of the natural forest in Palenque, in the state of Chiapas. The plan is to release as many as 250 birds over the next five years. The natural range of the Scarlet Macaw, prior to deforestation, habitat loss and wildlife trafficking, once extended all the way along Mexico’s Gulf coast, from Tamaulipas to Campeche.

At the other end of the country, a decade-old multi-institutional project (government, academic and NGO) aims to reintroduce the California Condor into Baja California state. There are believed to be about 30 California Condors now flying free in the Sierra de San Pedro Martir, following the release of six condors there earlier this year.

California Condor

California Condor in flight. Credit: Friends of the California Condors

Specialists say the project has almost reached the point at which the birds are likely to reproduce successfully in the wild. Since 2008, 10 nesting sites have been located. Condors nest in caves making it difficult and time-consuming to locate nests, even when the birds are tagged with transmitting devices. Among the threats to the success of the program is the incidence of lead poisoning in condors resulting from them swallowing bullets left in animal carcasses killed, and then abandoned, by hunters.

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