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La paradoja del ingeniero intervencionista

22 de Julio del 2012 - Rolando Rodríguez Muñoz (Gijón)

Lo que determina si un espacio o paisaje es natural o no es la existencia de intervención humana. Por definición, los paisajes naturales son aquellos que no están manejados por el hombre. Cuando este actúa se produce una degradación en mayor o menor medida, que da lugar a un paisaje artificial. Por tanto, en lo que respecta al mantenimiento o conservación de ambos tipos de paisajes, la diferencia estriba en que los naturales no requieren manejo alguno, mientras que los artificiales necesitan de un manejo continuado. De hecho, cuando un paisaje natural es intervenido pierde su condición de natural. Del mismo modo, cuando un paisaje artificial deja de ser manejado, éste tiende a regenerarse por sí solo hasta que el abandono hace que recupere un estado más o menos similar al que tenía cuando era natural. En pocas palabras, el abandono convierte un paisaje en natural y el manejo en artificial.
Estas diferencias pueden parecer obvias, pero no siempre es así. En una entrevista publicada el pasado 9 de julio en este mismo diario el ingeniero agrónomo Asier Arrese les da la vuelta y afirma que los espacios naturales son espacios degradados y que los espacios degradados son naturales. De manera paradójica, describe la intervención del hombre como vital para la conservación y desarrollo de los espacios naturales, y afirma que sin esa intervención estos se degradan por sí solos. Por otra parte, resulta preocupante que un experto en gestión de áreas naturales, como así es presentado en la entrevista, considere los montes no intervenidos como espacios desaprovechados. O también que utilice el ejemplo del País Vasco como modelo de gestión de la naturaleza, argumentando que allí la presión sobre el terreno es mucho mayor. Sin duda la presión en los espacios naturales asturianos es menor que la ejercida en la mayor parte del País Vasco, de ahí que Asturias aún conserve osos, urogallos y lobos, que ya sólo coexisten en los bosques donde la acción del hombre es inexistente desde hace décadas. Estas tres especies desaparecieron del País Vasco hace mucho tiempo, y tan sólo el lobo ha comenzado a recolonizar las zonas colindantes con Cantabria y Burgos, donde aún existen áreas en un razonable estado de conservación natural.
Necesitamos terrenos en los que cultivar los productos que utilizamos para vivir, pero si queremos conservar nuestro patrimonio natural tenemos que dedicar una parte del territorio a esa finalidad, y eso se traduce en mantener esa parte libre de intervención. Si fuese necesario ponerle una etiqueta al tipo de aprovechamiento a que están destinados esos terrenos, podemos utilizar un término bien conocido y acuñado ya hace mucho tiempo, reserva natural.

Hummingbirds shake off downpours

Iturria: ABC Science

Wednesday, 18 July 2012 Rachel Sullivan
ABC

Their small size and high metabolic rate means they need to forage constantly, even during heavy rain (Source: Victor M Ortega /University of California, Berkeley)

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Hummingbirds can shake off the effects of heavy rain and hover in a heavy downpour thanks to shock-absorbing feathers, a new US study has found.

Going out in heavy rain is particularly challenging for small flying animals because of the relatively larger impact of raindrops and the weight of the water they carry around.
Raindrops can increase drag, affect control and manoeuvrability, and potentially cause structural damage to the wing itself.
Despite this, waiting it out isn't an option for some birds, bats and insects particularly those from humid environments.
Hummingbirds, which are among the smallest flying vertebrates, are found in neotropical cloud forest regions and lowland rainforest where heavy rains are common.
Their small size and high metabolic rate means they need to forage constantly, and they have evolved an insect-like ability to hover as they drink nectar from downwards facing flowers.
Dr Victor Ortega and Robert Dudley from the Animal Flight Lab at University of California Berkeley looked at how different rainfall intensities affect the hovering performance of Anna's hummingbird Calypte anna.
Male hummingbirds were filmed hover-feeding in the lab under a range of simulated rainfall levels. They then studied the film in slow motion to identify any kinematic (postural and movement) changes made by the birds in response to the increasing rainfall.
Their findings appear in the latest edition of the Proceedings of the Royal Society B.

Adjusting motion

"In our experiment, drops of light-to-moderate and heavy precipitation were only 0.002 per cent and 0.04 per cent of the hummingbird's body mass respectively," says Ortega. "However, these tiny drops can produce huge peak forces during the impact: 16 per cent and 38 per cent of body weight for light-to-moderate and heavy precipitation, respectively.
"Despite these enormous forces, we demonstrated that hummingbirds can deal very well in light-to-moderate precipitation, practically without cost," he says.
But when the rain intensity increased, the birds adjusted their motion to compensate for the impact of the raindrops and their wet plumage.
"During heavy rain, a hummingbird orients its body and tail horizontally, increases wing beat frequency and reduces wing beat amplitude," says Ortega.
"Surprisingly, these tiny birds can maintain flight control in heavy rain conditions with increased metabolic costs of only 9 per cent."
"Wing feathers particularly help to reduce drop impact forces because they are flexible, and due to this, part of the kinetic energy of the drop is transferred into bending."

Mosquitoes and crane flies

As yet, it is unknown whether other small animals exhibit a similar strategy for dealing with downpours.
A recent study showed that mosquitoes can survive drop impacts because their low body mass allows them to glance off the much heavier drops.
"However nobody knows how kinematics are affected during drop impacts," says Ortega, who has been recently exploring the takeoff performance of crane flies (Tipulidae) during rainfall.
"Crane flies are ten times bigger than mosquitoes and two orders of magnitude smaller than hummingbirds.
"I am sure that future research will solve these questions."

Birds' Perceptual and Maneuvering Abilities Inspire Small Unmanned Aerial Vehicles

Iturria: Science Daily

ScienceDaily (July 25, 2012) — The Office of Naval Research (ONR) is looking at birds' perceptual and maneuvering abilities as inspiration for small unmanned aerial vehicle (UAV) autonomy.

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The Office of Naval Research (ONR) is looking at birds' perceptual and maneuvering abilities as inspiration for small unmanned aerial vehicle (UAV) autonomy. (Credit: Image courtesy of Office of Naval Research)

An ONR-funded, five-year Multidisciplinary University Research Initiative (MURI) program is examining the control and behavioral processes of birds and other small animals when flying at high speeds through complex environments, such as forests or urban settings. Researchers are trying to understand why birds make particular flight path choices and how they can do so quickly at higher speeds than would be safe for current engineered air systems in these environments.
The goal is to develop and successfully demonstrate a small aircraft that can navigate obstacles in very complex and unstructured surroundings, while maintaining speeds as fast as 5 meters per second. The theoretical results being developed may also be applicable to larger UAVs for particular tasks, such as landing at difficult, unprepared sites.
"Autonomous systems technology can be a great way to deliver increased capability to the Navy and Marine Corps at an affordable price," said Marc Steinberg, a research program officer in ONR's Science of Autonomy Program. "We can provide warfighters with a lot more flexibility and enable new mission performance, from flight under a forest canopy and in urban canyons to damage control applications onboard ships. Flying animals provide evidence it is possible to build compact platforms with limited sensing that can safely move through challenging environments."
In the lab, researchers set up an artificial forest with tall pipes serving as trees at Harvard University's Concord Field Station. Birds and a Massachusetts Institute of Technology (MIT)-built UAV are wired with small digital video cameras and motion-capture technology similar to that used in Hollywood. Both are studied in parallel to compare and learn from performance as the research progresses. A goal is to move to flight in a real forest by the program's end.
The idea is not to copy the birds but to incorporate lessons about how they navigate and use dynamic obstacle avoidance methods into a system that can make real-time decisions that take into account its surroundings. For example, researchers already have discovered a theoretical speed at which the probability of a collision is high in forests with an average distribution of trees; if a UAV stays below that threshold, the probability of an accident lowers dramatically. The program also has begun to reveal the types of flight strategies used by birds in these environments.
"We want to build small-scale UAVs that can fly quickly through indoor and/or cluttered environments, but controlling these UAVs is very different than controlling a fighter jet flying up above the clouds," said Dr. Russ Tedrake, X Consortium associate professor of electrical engineering and computer science and aeronautics and astronautics at MIT and the MURI lead. "To be successful, we have to solve a number of incredibly hard problems in computer vision and nonlinear control. This long-term project lets us focus on the basic research questions that will lead to fundamental results and, ultimately, dramatic new capabilities for UAVs."
In addition to providing warfighters greater flexibility, small UAVs are more agile and easily transportable, and they're less expensive. A program goal is to be able to do this type of flight with cheap, lightweight digital video cameras as the main sensors. This would eliminate the need for other sensors typically used, such as laser-based ones that add cost and weight, and the MURI is testing feasibility.
The MURI involves researchers and engineers from MIT, Harvard University, Carnegie Mellon University, New York University and Stanford University.
To see a video of the small UAVs in flight, go to: http://www.youtube.com/watch?v=voN9CCmzxYk.

Songbirds Migrate On Strict Schedule

Iturria: Science Daily

ScienceDaily (July 25, 2012) — A new study by York University researchers finds that songbirds follow a strict annual schedule when migrating to their breeding grounds -- with some birds departing on precisely the same date each year.

This is a wood thrush in Belize. (Credit: Kevin Fraser)

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The study, published in the journal PLoS ONE, is the first to track the migration routes and timing of individual songbirds over multiple years. Researchers outfitted wood thrushes with tiny geolocator "backpacks," recording data on their movements.
Spring departure dates of birds heading from the tropics to North American breeding grounds were surprisingly consistent, with a mean difference of only three days from year to year, the study reports. Fall migration, however, was far less predictable. Males on average flew faster than females, and first-timers lagged behind those with more than one journey under their wings.
The geolocators, which are smaller than a dime, are mounted on birds' backs with thin straps looped around their legs. The devices measure light, allowing researchers to estimate latitude and longitude by recording sunrise and sunset times.
"It's quite surprising that the schedules of these birds are so consistent across the entire route, with some of them departing the tropics and arriving at breeding sites in North America on the same day in different years," says study author Kevin Fraser, a postdoctoral Fellow in York's Department of Biology, Faculty of Science & Engineering. "Much like airplanes, there are many factors that can influence birds' flight schedules, such as weather at departure and expected conditions at the other end of the journey. Amazingly, these small songbirds are highly consistent in their timing between years."
Interestingly, while their departure times are precise, songbirds' migratory routes can vary widely. "Migratory routes sometimes differed by several hundred kilometres between years, which may reflect a fine-tuning of migration in response to wind and weather conditions en route, such as during large open-water crossings like the Gulf of Mexico," he says.
As for arrival times, birds need to be early to lay their claim to prime breeding grounds -- but not too early.
"There is intense pressure for birds to get back to breeding grounds early to secure good territories, nest sites and, of course, mating opportunities. The early birds tend to do better and raise more young. However, cool weather in early spring can reduce food availability and even survival of early birds," Fraser says. He cautions that songbirds' consistent timing may come at a cost.
"The concern is that birds may not be able to flexibly adjust their schedules to meet new conditions with climate change," says Fraser. "This is a topic we're pursuing in current research."
The birds Fraser tracked were tagged in Pennsylvania and Costa Rica, at field research sites of his supervisor, York University Professor Bridget Stutchbury, who has studied the behavioural ecology of birds for decades. Her 2007 book, Silence of the Songbirds, details the threat to the species posed by climate change and habitat destruction.
"Numbers [of wood thrush] have plummeted in Canada by over fifty percent since the 1960s. When we lose the wood thrush, and other songbirds, we lose an integral part of the forest itself," Stutchbury says.

Helping Family Is Key for Social Birds

Iturria: Science Daily

ScienceDaily (July 11, 2012) — Social birds that forgo breeding to help to raise the offspring of other group members are far more likely to care for their own close relatives than for more distant kin, a new study has found.

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Babbler by a nest. (Credit: Photo by Lucy Browning)

The study, which looked at a highly social species from outback Australia, the chestnut-crowned babbler, also found that these birds work much harder to care for their brothers and sisters than the young of less-related group members.
The findings, published in the journal Proceedings of the Royal Society B, provide new insights into understanding why some individuals cooperate with each other for a common good rather than pursuing their own selfish reproductive agenda.
"Cooperation is a major evolutionary puzzle," says Dr Lucy Browning from the University of New South Wales and the University of Cambridge, who led the study and is a post-doctoral researcher at the UNSW Arid Zone Research Station, at Fowlers Gap, in far-western NSW.
"One idea is that by helping relatives with whom they share DNA, they can pass on their genes indirectly, but testing this idea in birds and mammals has proved surprisingly difficult.
"An alternative theory is that such cooperation is actually selfish because in group-living species like babblers, individuals can increase their own welfare by helping to make their group larger, irrespective of how closely related they are.
"The fact that babblers preferentially help family members makes it seem likely that promoting the success of kin is the reason they cooperate."
Babblers live in groups in which most members help to take care of young chicks in the nest, despite not being the parents themselves. But like any team activity, some individuals do the lion's share of all the work, while others do nothing at all.
"We wanted to get to the bottom of why some 'helpers' were so industrious while others were apparently so lazy," says Dr Browning. "We found that when helpers are caring for their brothers and sisters, they feed them three times more often than when they are unrelated. In other words, they are much more 'helpful' when looking after family."
The study took place between 2006 and 2008, with birds being fitted with tiny radio transponders that were detected each time an individual visited the nest in order to feed the chicks.

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Herbicidas en el parque de Ulia

Iturria: Ugatza Ornitologia Elkartea

Los compañeros de Ugatza denuncian, con toda la razón, la inexplicable aplicación de esta práctica en una zona que se pretende conservar precisamente por sus valores naturales. reproducimos íntegra su entrada.

 

A pocos días de la inauguración del Centro de Interpretación de la Naturaleza de Ulia, que pretende promocionar el conocimiento y la defensa del medio ambiente, la flora, la fauna, etc., nos encontramos con que a menos de 150 m del lugar, en pleno parque, una zona de aproximadamente 6.000 m2 ha sido tratada con herbicida. En pleno verano.

Se ha “sugerido” a los dueños de perros que no entren en la zona. Los caminos han sido cortados con vallas y el perímetro, más o menos señalizado con cinta roja y blanca. Parece que la prohibición de entrar en el área será de tres o cuatro semanas…

 

Los herbicidas pueden ser especialmente dañinos para los pájaros, reptiles y otros animales que viven en la zona, como la Ardilla roja que vuelve a ser observada en Ulia después de muchos años.

 

Desde Ugatza proponemos que si es imprescindible eliminar determinada vegetación, raíces, tocones.., se haga de forma manual o mecánica, y no utilizando productos potencialmente peligrosos.

Pedimos al departamento correspondiente del Ayuntamiento de Donostia, que explique a la ciudadanía qué objetivo tienen esas labores que se están desarrollando en Ulia, qué tipo de herbicida se ha utilizado, y su toxicidad, cuánto tiempo van a permanecer cerrados los caminos, y si al finalizar los trabajos se va a efectuar un informe sobre la situación de la fauna y flora del lugar, que se debería repetir pasado un tiempo desde la utilización del producto.

 

Además solicitamos al Ayuntamiento que se vigile estrechamente la hora de cierre y el acceso y aparcamiento de vehículos próximos a los bares y restaurantes del monte.