ABOUT THE SIERRA: Bio-cultural RESEARCH:
Field Notes: Cerro Mohinora

by Andrew Miller - February, 2003

The mountaintop of Mohinora has been proposed by the municipio of Guadalupe y Calvo as a natural protected area. Protection of the peak amounts to protection for Arroyo el Soldado (Soldier Creek), the source of the municipal seat’s drinking water. The peak is also embroiled in a land tenure conflict between a private landowner and a nearby ejido of Tulé - Portugal. Setting the land aside as a protected area is seen as a viable solution to the battle over who will have the right to harvest what remains of the great pines on the northern slopes of the mountain. Thus far the ejido is in agreement with the plan. The absentee landowner treats the mountain as assets to be liquidated and is less agreeable. Our February visit was intended to document wintering birds and neotropical migrants of the peak that had thus far been unrepresented in the surveys completed by the Universidad Autónoma de Chihuahua.

There were hummingbirds (Broad-tailed Hummingbirds, Selasphorus platycercus, and Blue-throated Hummingbirds, Lampornis clamencia) at Chihuahua’s highest point, even in the dead of winter with night temperatures dropping below freezing and snow several inches deep on open ground on the northern slopes. What flowers? Do they subsist on small insects? There was also an incredible abundance of woodpeckers. Migrant Red-naped and Williamson’s Sapsuckers (Spherapicus nuchalis and S. thyroides) are migrants that have been identified as being of management concern in the United States because of perceived declines in their abundance. By far the most abundant woodpeckers were Acorns (Melanerpes formicivorus). Family groups of up to twelve individuals guard grainery snags where they have stored acorns in drilled holes against Stellar’s Jays and other woodpeckers.

Bark Beetles and Pines

Beetles had recently killed a large number of pines on the slopes making nesting trees available in great numbers. Bark beetles are always present, even in healthy forests, but years of drought and mild winters can create conditions where beetle populations reach outbreak levels. If the winter is warm, beetles begin to breed early and their numbers have a chance to grow. If the winter and spring are dry, the trees are drought-stressed and cannot muster the sap necessary to “pitch out” the beetles that bore through their outer bark to eat cambium, the red tissue between the protective bark and the inner wood that acts as the pine’s circulatory system. Once inside a drought-stressed tree, female beetles advertise the tree’s susceptibility with pheromones, attracting mates. In this way beetles focus their attention on trees that are unable to withstand their attack.

Remove the bark of beetle-killed tree and you will see a fine lacework of tunnels radiating out from a single inch of tunnel egg gallery like the legs of a strange prehistoric sea creature. The female beetle creates these egg galleries, once she has met a mate inside the pine’s inner bark. The small egg chambers are the starting point for the meanderings of a new generation of bark beetles. The tunnels grow in width as they radiate out as the feeding beetle grows. The path behind is filled with a fine dust of chewed cambium. After several weeks, the beetles reach breeding size. They bore out through the bark, scent the air with pheromones to orient them to drought-weakened trees where beetles have overwhelmed a tree’s resistance, and take flight. They are not great distance fliers, but they are very specific as to which trees they settle in. Trees struck by lightning are often targets. But when beetle populations explode, their numbers can reach levels where even healthy trees cannot muster the sap to keep beetles out. This is what entomologists call an outbreak, where even healthy trees succumb to bark beetles.

It is great fortune that there are so many woodpeckers during the winter months at Mohinora, as they will have a great role to play in reducing the numbers of bark beetles. During the summer, rapidly reproducing beetle populations are beyond the power of woodpeckers to control. But during winter, their numbers are reduced by harsh temperatures. And they are not breeding. Kris Covert at Northern Arizona University found that in winter, Hairy Woodpeckers can reduce the number of bark beetles found under the bark of dead trees by up to a third. Eaten beetles are not around to reproduce, so the threat of beetle outbreak is reduced for the following spring and summer by winter woodpecker predation.

What will become of island mountain peak habitats like Cerro Mohinora with the increase in global warming? As temperatures increase, the lower limit of the high altitude forest will gradually creep upwards. Eventually the heat and drying may be enough to lift the conditions necessary to maintain such a forest right off the top of the mountain. But the changes in climate may bring the end before it ever comes to that. Rain patterns are changing unpredictably. Rains during the winter months are becoming less and less dependable, leaving pines more susceptible to beetles earlier in the spring and giving beetle populations a headstart in building to outbreak levels. As conditions change beyond the range of natural variability, imbalances may allow beetle populations to reach outbreak levels far more frequently and with more devastating effect.

The Arrival of the Parrots

One evening Mauro and I returned from Guadalupe y Calvo where we had delivered a talk to the local science and technology school of sixty or so students to find Dane and Fiona in an uproar in our camp. At sunset that day they had been treated to one of the greatest thrills of the season. The parrots had arrived.

Dane tells us that while they stood warming themselves around the fire in the growing darkness, they became aware of a growing wave of sound from the valley to the southeast. They stood in the camp clearing and listened with growing excitement as the sound increased in volume from down Arroyo el Soldado. A flanx of Thick-billed Parrots flew into view, wheeling and diving in pairs as they came. More than one hundred animals filled the air with raucous cackling and made the valley seem poised, immobile, and driven to silence. Ah-ha-ha-ha-ha! They were going to roost in the trees above the camp.
In A Sand County Almanac, Aldo Leopold describes the Guacamaya as the “noumenon” of the Sierra Madre Occidental. They are the spirit of the place, its totem animal, animating and giving it dimensions as no other creature can. The landscape with them in it is animated by the magic of evolution. How could tropical birds be here (at the cold top of a piney mountain!) in such uproarious numbers? Like the gobbling of turkey in the southeastern woodlands or the howling of a wolf in the deep woods of northern Minnesota, they embody an ecosystem that is whole. Complete. Parrots are a tropical family but the “snow parrots,” as they have been called, once ranged into southern Arizona and New Mexico. Black and white photos from the turn of the Twentieth Century show gold miners in the Chiricahua Mountains in southeast Arizona holding parrots for the cook pots. Hunting and logging combined to end the parrot’s presence in the United States. They are entirely dependent on big pine forests for the pine seeds that are their nearly exclusive food and for nest cavities. Javier Cruz of Pronatura has seen them raiding bees’ nests but whether for honey or for larvae is unknown. Acorns are also a minor part of their diet. These forests are today on the verge of disappearing and the parrot along with them. No one knows how many Thick-billeds still exist. Numbers range to about five thousand individuals. When they are gone, no one who has not heard them will notice how the Sierra bereft of their laughter is diminished, silent and sad. They are the owners of the Sierra.

In the dark that night we could hear parrots leaving—a chorus of cackling in the dark. At dawn, just as the light began to creep over the horizon, the last group left. The hilarious flock gathered as pairs joined the gyring chaos of laughing and swooping birds in the half light. They left almost as a unit, their calls growing fainter as the flock departed for unknown parts. The forest seemed to resume its normal, steady, sedate life. But it held the potential for exuberant parrots like a secret smile.

Parrot–Fish in the Predawn Forest

Dane told us later how the sound of them gathering for their final salute to the mountain penetrated his dreams. He dreamed that a group of biologists had arrived to find the last of the parrots – to attempt a desperate rescue. While he protested, they spread out across the mountain to desperately search for near-to-lost parrots. He turned and walked to the stream that ran close to the camp. There he pulled out a green-beaked fish from the water. As he held it in his hand, it grew feathers and became the rare bird people were seeking on the slopes above. He let it go and pulled another out of the water. They continued to transform and circle him until there was a swarm of cackling birds all around him (that he was hearing in his dreaming mind). Parrot fish in the predawn forest. How can dreams capture so much mystery?

The Mexican Golden Trout

May 18, 2003. It was amazing how easy it was to find the Mexican Golden Trout (Oncorhynchus chrysogaster). It is Mexico’s only native salmonid and is listed as threatened by the Norma Ecológico, the law that established conservation status. We had heard from foresters at City Hall that it could be found in the Arroyo Macheras. In February, Jorge Valles, the young forestry technician who was recording the productivity of Englemann Spruce on Mohinora, had pointed out the turn to Casa Quemada (Burnt House), the community which straddles the valley where the arroyo runs.

It was May before we had a chance to visit. The rains had begun, so Casa Quemada was green with grass and ten-inch-high corn that grew in the fields surrounding the four or so houses scattered through the valley. The stream looked really good. Despite the rain and the surrounding fields, the water was mostly clear. The banks appeared stable and chiguite (Salix bonplandia) grew plentifully. There was a lot of woody material such as downed trees in the stream, making pools and hiding places that trout love. It looked perfect. Now just to find the buggers.

As we poked along the stream, taking note of Leopard Frogs (pale dorsal lines along the back) and wondering how best to conduct our search, a portly old man in a yellow shirt who had watched us from his yard by the log gate to the valley, came up to talk. He asked what we were doing. We told him we were looking for trout. “Ah sí. Nosotros les llamamos sardinas pero, sí, son truchas.” (“Ah yes. We call them sardines, but, yes, they are trout.”)
His name was Lucío Rivas Gutiérrez and he was a Tepehuan. We asked if he knew where we could see some. “Well…anywhere. There are lots of them.” We told him that we were interested in seeing some because they were rare and we had heard there weren’t many. “Yeah, people abuse them. They put lime in the water which kills many and others come and fish and take the biggest ones.” I suggested that if he knew where to get some we would be willing to pay a small fee if he let us see them. “What do you want—to take some?” No, we really just wanted to see some, take some pictures, to know them. He invited us to come back the following day and he would show us some.
When we arrived at the appointed hour of noon, we returned to find Lucío in his yard beside a great log that had had a notch removed from its length to make a water trough for his animals. We crossed the fence and came to greet him. No sooner had I asked him if he had any luck finding some trout when I noticed a cluster of medium-sized trout bunched into a corner of the canoa. Seven Mexican Golden Trout from ten to sixteen centimeters long. He had caught them with a hook and worms that morning and brought them home in an empty lard pail.

After we had chased them from one end of the trough to the other, attempting to corral them into the bucket, Lucío, amused told us to stand back. He stuck his hand into the trough and slowly and smoothly brought it up under one of the fish. “If you are good with your hands it is easier.” While Lucio slowly caught the fish at his end of the trough, I tried with one on my end. Moving slowly, my fingers brushed the belly of the little trout and it didn’t move until I had brought it out of the water.

Holding it in my hand, I was stunned to see what a beauty it was. Orange, almost red belly, fading to gold along the flanks. The tips of its pectoral and dorsal fins were white. I held the flipping, wiggling fish in my hand. Endangered. I held an endangered species in my hand. Guadalupe y Calvo is the center of their range; the municipio encompasses easily ten percent of the creature’s entire range on the planet. I was charmed immediately.
They require cold, oxygen-rich water. Even the brief time we held them out of the water to take photos and measurements caused them to float, near exhaustion. As we moved them gently back and forth in the trough to increase the flow of water and dissolved oxygen across their gills, the little fish recovered and swam back to their small school in the corner.

The trout are most endangered by the introduction of nonnative trout from the United States that have become popular in trout-farming projects throughout the Sierra in the last twenty years. The nonnatives are aggressive predators and their numbers, which far exceed those of the local populations which are subject to the limitations of food and stream conditions, are quickly swamped by the aliens. Other sources of endangerment include degradation of water quality from logging, contamination from agrochemicals, and overfishing using lime and natural plant piscicides. The soils of the Sierra dry out quickly when the trees are removed. Unprotected soils are washed into streams by the monsoon rains, silting over the gravel beds which the trout use for laying their eggs. With the protective shade of streamside trees removed, streams warm beyond the trout’s narrow tolerance (cold water holds more dissolved oxygen than warm water).

Pesticides and fertilizers, while not economically feasible for subsistence corn farmers, are widely used to protect and improve commercial crops, marijuana and opium. In this economically underdeveloped region of the Sierra, drugs are the bread-and-butter of many families. Remote arroyos with permanent water are choice cultivation sites. We looked to the head of the valley where Lucío said we would probably find more, larger fish. He didn’t think it necessary to explore farther upstream. There would be plantations there as well.

In talking to Lucío, we learned that Casa Quemada was the site of a land conflict where several local interests, or caciques, were embroiled in the fight to determine who would have the right to remove the trees. It is the sad reality of the Sierra that the best preserved places that remain are locked in agrarian battles to determine who will be allowed to take advantage of their rich resources. Use it till it’s gone, then take the money and buy an airplane to fly out drugs, buy big trucks, buy influence to consolidate power over local, less aggressive community members. Indian communities are left behind in this struggle for the top because of social constraints on ambition, lack of political savvy and lack of Spanish-language skills that leave local government machinations less open to them. The trout stream in Casa Quemada existed because of the fight over who (not if) should cut the trees.

June 24, 2003—Día de San Juan. It is so hard to prepare for the Sierra after the mesquite and heat-filled desert valley of Chihuahua. Sheetless nights of sweating with hot breezes barely moving the drapes in the open windows of our apartment – the Casa de Big Brother (a reality TV show of people sharing a big house and the inevitable intrigues and romances. No romance here, but no privacy either, what with four to eight staff members and a constant flow of visitors from the Sierra filling mattresses, kitchen and any open floor space.) For the last weeks, a high haze of clouds hint at rain and relief but bring nothing, only adding to the sense of oppressive heat. Packing for our three-week trip, I thought to pack light and leave the fleece. It is over one hundred degrees here. How could it be that I’d want it in the Sierra? But arriving tonight in the dark to Guadelupe y Calvo, with the moist mountain smells of woods and cooking and heating fires in the valley, I am glad, so glad, I brought it. I have returned to my other life in Chihuahua: the pine trees and Indian communities of the Sierra.

Three nights at Cerro Mohinora, the tallest point in Chihuahua, ceiling of the Sierra, 3,525 meters above sea level. The top is covered with mixed conifer forest. Douglas fir, Englemann spruce, Aspen, Picea religiosa (?). It is one of two places in Mexico where you can encounter Englemann spruce (the other is in the Sierra Madre Oriental in Coahuila). There are over six hundred individuals, all numbered and monitored as part of an endangered species monitoring program. It is actually suggested by some that the Englemann is not, in fact, a different species. When ice covered the American Rockies, pines and much of the familiar vegetation of America was pushed to lower elevations in the northern latitudes and south into the Sierra Madre Occidental in Mexico.

Migrating Trees

How many thousands of years does it take for trees to migrate? Warming of the continent at the end of the ice age allowed the spruce and the rest of the pines to return to northern latitudes but left small islands of trees, refugia, at the highest elevations. The forest is so unlike the rest of the Sierra that I know something like this must have happened. The trees are great, fat in the deep moist soil. The forest is mossy, dark and shady, full of slowly rotting trunks. Unlike the rest of the Sierra, fires do not burn here regularly.

It is a forest of moisture, ferns, and bright red paintbrushes, penstamon and native honeysuckle. The steep streams are home to American Dippers (I prefer their other name, ouzles – more evocative, in a Lewis Carroll sort of way), bobbing and diving from rocks beneath the fast water for larvae, Fringe-gilled Tiger Salamanders, and native trout. It is an isolated inland mountain island, rising above the drier ponderosa and oak forests of the rest of the Sierra. It is an amazing encapsulated system, containing species that are not to be found in the comparitively open dry ponderosa–oak forests that stretch away north to the American border and south to Michoacán.

From the bare talus field peak of the mountain you can look north and south along the piney spine of western Mexico. The Continental Divide. To the south lies the forested mountains of Durango, to the west runs the Río Culiacán into Sinaloa reaching the Sea of Cortez. It seems you ought to be able to see the ocean. You can almost feel it just below the horizon, even though it lies far, far away to the west. To the north and east, the Sierra of Chihuahua seems like a plain of trees seen from the lofty peak.

One morning Mauro and David received a shocking view of a southern flying squirrel (Glaucomys volans) among the mossy trunks of the upper slopes. According to the gringo mammal guides, flying squirrels do not occur in Mexico at all. It is also described as being almost entirely nocturnal. Had they not watched it eating pine seeds for over fifteen minutes, I would have doubted their sighting. David tells me that the southern flying squirrel has been documented by William J. Sheldack in Las Tuxtlas Biosphere Reserve in the state of Veracruz. Veracruz on the Atlantic coast south of Mexico City is over one thousand miles from the nearest recognized population.

Endangered Ecosystem

The language barrier and the bias towards gringo science keep so much knowledge out of circulation. North American science has skipped northern Mexico to embrace studies of the tropics which are perceived as being of greater priority – land of greater discoveries in need of more rapid protection. But less than one percent of the pine–oak and mixed conifer forests of the Sierra Madre Occidental remains in its original unharvested state. It is one of the most endangered ecosystems in the world.

As far as Audubon and Peterson’s guides are concerned, the southernmost extension G. volans falls several thousand miles to the north in East Texas. No one bothered to tell the squirrels themselves who have lived on Mohinora in secluded ignorance of their violation of accepted knowledge since the last ice age. Perhaps there is need to revise the species taxonomy. Perhaps the Mohinora squirrels deserve status as a subspecies – or perhaps species. Physical and perhaps genetic descriptions will determine the issue, but await money and interest that is not currently available to temperate research. What other range extensions await discovery in places so near but so far from biological enquiry?

Birds of Note:

Red Warbler (Ergaticus ruber). Solid red warbler with a patch of white behind the eye. In Cerro Mohinora it is at the northernmost extension of its range. The Barranca Sinforosa could be an effective barrier to it beyond that. Though the people of Pino Gordo tell me that it does exist within their lower elevation pine forests, I have yet to see it there. By now I should take it on faith that if they say it exists, it does. As so often has happened, the day I see it I will shrug and again admit that these folks know their wildlife.

Bumblebee Hummingbird (Selasphorus heliosa). At seven cm. and weighing three grams, it is the second smallest bird in world – the smallest bird in mainland North America. A green flash and a high-pitched buzz. I thought I was seeing the flight of a largish beetle. Its red throat looked black among the shady trees.

Magnificent Hummingbird (Eugenes fulgens). The largest hummingbird in North America. Green and purple iridescence.

Hermit Thrush (Catharus guttatus). Not documented as breeding in Mexico. Another range extension.