martes, 7 de marzo de 2017

martes, 28 de febrero de 2017

El Cálao de Yelmo en peligro crítico de extinción. Hermosa fealdad y belleza atroz



A helmeted hornbill displays its casqued beak. Photo ©Muhammad Alzahri
  Photo ©Muhammad Alzahri, visto en mongabay



En teoría la conservación de las especies debería ser totalmente independiente de la concepción que tengamos sobre lo bonitas o emblemáticas que sean, pero lo cierto es que en asuntos de conservación, la estrella son los animales, y entre ellos los que nos parecen hermosos. Los feos no suelen protagonizar campañas de concienzación ni tienen mucho espacio en las webs de peticiones públicas. Las organizaciones de conservación se están estrujando la imaginación para hacer más atractivas esas especies de animales que no nos impactan por su belleza precisamente, y me ha llamado la atención la llevada a cabo por Arkive que ha organizado una votación para elegir el favorito entre los animales poco amados. Ha ganado el dingo, animal bello sin duda alguna, pero entre los propuestos hay muchos que claramente no lo son, y entre ellos me he fijado en el Cálao de Yelmo, un ave en gravísimo riesgo de extinción que lo tiene difícil para protagonizar la portada de un folleto de viajes. Y aún así es mucho más fácil hablar de la conservación del Cálao de Yelmo que de la del árbol sobre el que está posado, bien deben saberlo en World Land Trust, la organización que ha propuesto al Cálao a este concurso.

El Cálao de Yelmo (Rhinoplax vigil)) es  ave de aspecto peculiar, que es tanto majestuoso y ancestral como grotesco y ridículo, según en qué nos fijemos.
A los amantes de lo curioso o extravagante así como a los fanáticos de los dinosaurios, no tengo que contarles nada, el aspecto del propio animal es sus mayor baza para su conservación. Para quien no lo encuentra atractivo en absoluto este animal puede ser una buena prueba de que el valor intrínseco de un animal no debe estar vinculado a la belleza que le veamos. Pero además deberíamos cuestionarnos la belleza de nuestra atracción por los objetos que encontramos bellos, que es lo que está llevando a esta especie a la extinción, ya que se está cometiendo una atroz carnicería para sastifacer la demanda de nuevos ricos que exigen objetos que denoten lujo y estatus.

Vamos a conocer un poco mejor al Cálao de Yelmo.

Por su pico los conocereis, los Cálaos

 
Los cálaos son un grupo de unas 60 especies que pertenecen a la familia de los Bucerotinae, aves que no pasan desapercibidas por su gran pico que les da una expresión peculiar. Se les encuentra en África, Melanesia y Asia.

En general todas estas especies muestran un comportamiento similar, viven en bosques y espacios algo más abiertos, son sedentarias y diurnas, la mayoría territoriales, que vuelan en parejas o en pequeños grupos familiares, y se alimentan de frutas,insectos y pequeños animales. Son monógamos (hablando de aves reservad un 10% de escepticismo para esta palabra ya que la mayoría de los estudios suelen encontrar alrededor de un 10% de pollos que no están emparentados directamente con sus padres en muchas especies de aves "monógamas"), suelen nidificar en cavidades naturales entre las rocas o en los árboles, tales como huevos abiertos por pájaros carpinteros. Algunas especies llevan estos hábitos de nidificación a un extremo muy dramático ya que la hembra se encierra en el nido, que en este caso es siempre es un agujero en un árbol, mediante una pared construída por barro, heces y restos de comida dejando tan sólo una pequeña apertura para que el macho la alimente.

Pilai Poonswad anillando un Cálao. Esta mujer ha creado la organización The Hornbill Research Foundation para la protección de estas emblemáticas aves. Visto aquí

 En resúmen, los cálaos no están hechos para pasar desapercibidos ni para sastifacer nuestros estándares de belleza, a pesar de que algunas especies sí nos pueden parecer hermosas pero otras, como el Cálao de Yelmo, definitivamente...no.

El Cálao de Yelmo, el pájaro "dinosaurio". Singular, valioso y en peligro de extinción por su pico. Una tragedia que no es tan conocida como la de los elefantes. Vamos a acordarnos del pájaro.

Su gran cabeza y colores contrastados recuerdan a más de una reconstrucción de dinosaurios avianos.
 

Bosque primigenio en Borneo. No es posible separar la conservación animal de la conservación de su hábitat. Photo by CIFOR
s profundos reclamos del Cálao de Yelmo todavía se oyen en los bosques primigenios de la Penínsual Malaya, Sumatra y Borneo. Es un ave que no puede pasar desapercibida debido a su llamativo plumaje, con grandes plumas con un contraste acusado de bandas blancas y negras, y su peculiar parche de piel roja en cara y pecho, gran tamaño, y característico pico.
Llega a medir 1,20 metros de cabeza a cola y más de 1,8 metros de envergadura alar, los machos son ligeramente más grandes y pesados que las hembras, 3,1 kg de promedio los primeros y 2,7 kg las segundas.

Photo by Christian Goers


Lo más extraño de esta enorme ave es su protuberancia en forma de yelmo que se extiende desde la parte superior del pico hasta el mismo cráneo. A diferencia de todas las demás especies de Cálao, en el Cálao de Yelmo esta protusión es sólida, hecha a base de queratina, y su peso supone más del 11% del peso corporal del ave. Y no es que sea un mero adorno, los machos emplean esta excéntrica herramienta natural como un ariete en sus combates aéreos durante la temporada de apareamiento, y ambos sexos usan los picos como herramientas calibradas para extraer insectos de troncos en descomposición.

Photo by Nur Atiqah Binti Tahir


Durante siglos la gente ha usado el yelmo del Cálao como una especide de "marfil rojo" para tallar, cuentas y productos de lujo. Tradicionalmente los índigenas cazaban cálaos para fabricar medicinas tribales y también para comerciar con China; sin embargo los animales abatidos con este propósito eran pocos y esta caza no suponía una gran amenaza para la especie.
Pero durante los últimos cinco años la especie ha estado sometida a una terrible presión debido al incremento exponencial de la demanda de "marfil rojo". Actualmente su precio en el mercado negro en China es cinco veces superior al marfil auténtico, el de elefante, la creciente población de nuevos ricos deseosos de objetos que denoten su alto estatus espolea esta inflación de precios. Los furtivos, tan inmunes a cualquier tipo de preocupación por la conservación de las especies como lo son muchos de los compradores de este marfil rojo, han provocado tal carnicería en esta especie que su estatus ha pasado de "Casi Amenazada" a "En peligro crítico" en este año.

Un cráneo de Cálao que muestra cómo se talla el yelmo. Yo lo encuentro repulsivo,la verdad. History Museum of London. Photo: The Natural History Museum/Alamy. Fuente de la foto: http://www.audubon.org/news/rare-helmeted-hornbills-found-black-market


Muestra de piezas hechas con el dichoso "marfil rojo". Por esto estamos extinguiendo a esta especie. ¿Belleza?, intentemos recordar que detrás de estos objetos está la carnicería a la que se está sometiendo esta especie.
 

A esta caza masiva hay que añadirle la pérdida de hábitat, de hecho la demanda de aceite de palma es otra amenaza seria para esta especie.
Escribo estas líneas sobre el aceite de palma y me doy cuenta con tristeza de que me voy a tener que mirar la composición de las galletas y productos elaborados que compro.

Yelmos decomisados

Iniciativas para la conservación de esta especie

Está claro que las claves para salvar al Cálao de Yelmo están en la conservación de su hábitat y en la lucha contra el furtivismo.



Según el portavoz del World Land Trust, en la web de Arkive, ésta organización junto con Hutan trabajan localmente en Borneo para conservar el hábitat de esta especie. Además de financiar la compra de tierras para crear importantes corredores de vida salvaje, se contrata a miembros de las comunidades locales para llevar las tierras, protegerlas y fomentar el uso de prácticas tradicionales y sostenibles. 

Similares medidas propone la Rain forest Trust

https://www.rainforesttrust.org/news/helping-helmeted-hornbill/

Y ¿qué podemos hacer cada uno en nuestra casa para ayudar a esta especie?

Como todas las especies magníficas que están amenazadas de extinción, la mayor esperanza es que la gente las conozca, sea consciente de su importancia, y debo decirlo, el amor a estos animales. Seamos veganos o no, deberíamos evitar a toda costa comprar objetos elaborados a partir de piezas obtenidas de animales. Puedes pensar que por comprar un pequeño recuerdo no haces mucho daño, pero párate a reflexionar sobre cuántos animales matan para que los turistas como tú se lleven cada uno su recuerdo. Otra reflexión que es necesaria es la atrocidad que hay detrás de la belleza de muchos objetos tan exquisitamente elaborados. Y la banalidad de la búsqueda de estatus que devora cualquier especie que sea tan desgraciada de poder surtir de objetos absurdos a este mercado.

Pero también ser más conscientes de nuestro impacto como consumidores comunes y corrientes. No solemos reparar en el impacto sobre el ambiente de los productos que consumimos, y lo cierto es que las grandes marcas hacen todo lo posible para vivamos con los ojos cerrados a esta realidad. En el envase de nuestras galletas preferidas veremos dibujitos infantiles muy monos, nunca una foto del bosque primigenio que se taló para cultivar las palmas de las que se obtiene el aceite con el que se cocinan...Y sí, hacer la lista de la compra es una lata, tenemos poco tiempo y mucha gente ya quisiera poder comprar las dichosas galletas. Pero los que podemos elegir deberíamos saber la fuerza que tenemos como consumidores.

Fuentes consultadas:
https://es.wikipedia.org/wiki/Bucerotinae
https://en.wikipedia.org/wiki/Hornbill
https://www.rainforesttrust.org/news/helping-helmeted-hornbill/
http://blog.arkive.org/2017/02/vote-for-your-favourite-unloved-species-helmeted-hornbill/

jueves, 9 de febrero de 2017

How do cheetahs defend themselves?

(Generally speaking, cheetahs run).

Although adult cheetahs are skilled predators built for speed, as we all know, they are weaker than other big cats (lions and leopards) and hyenas which are their natural competitors. They can, and often do, steal their preys and also kill their cubs. Besides, as cheethahs rely on their speed to chase, they will not risk to fight to another predators.

I don't consider cheetahs top predators in this sense, they are really vulnerable to their competitors, according to some data they can lose up to 50% of their preys due to interlopers, and what is worst, up to 90% of their cubs are killed in the first weeks of life by wild dogs, lions, leopards, hyenas and eagles..
So the best defense against these threats is to avoid it. Cheetahs tend to hunt

in the mornings and  evenings, when enemies are dormant. It also eats immediately after it  downs its prey, before intruders such as lions, leopards, hyenas,  jackals, baboons and vultures arrive.
But in some cases cheetahs fight. For example, mother cheetahs defending their young and groups of male cheetahs teaming up to chase away other predators such as servals:


Here is a video of a mother cheetah confronting a wandering lioness to defend her cubs (in this case the cheetah seems to have notice the relaxed pace of the lioness and taken advantage of it, there are also some other videos of lions and lionesses kiling cheetahs, but I have preferred this one as an example of how brave can be cheethahs in some ocassions):




A great place to know about cheetahs, and their conservation:

Cheetah Conservation Fund

lunes, 6 de febrero de 2017

Do fishes have 3D vision?

Short and tricky answer, yes. It is tricky because fish are a vast number of animals, besides a paraphyletic group of animals.
Long answer that need an explanation i´ll provide you bellow is "yes, to some degree, fishes are able to have binocular vision".

Getting into a deeper view of your point, what you are looking for is binocular vision. And it is due to the superposition of the fields of vision of both eyes and the work of the brain as you say.
And you are right, the position of the eyes have a a determining role on getting this binocular or stereovision, exactly they inceed in the width or degree of the angle where this 3d vision is possible.

  • For a start, we can take a look to a typical hervibore mammal. I choose this protoptype because they live in the same enviroment that we do, and they have similar eyes to that we have:


The Mammal Eye and Vision in Mammals
Horses can see up to 215º, but have a binocular vision field of less than 90 degrees, just in front of their head. Humans have a total vision field of 180º, 140º of binocular vision.  In fact, primates have greater binocular vision field than typical carnivores. This is a great advantage if you jumping between branches and can fell down more than 40 mtrs if you don´t see clearly how far is the next branch.

  • Let´s go to the fishes. They make stereovision the way we do, overlapping the two eyes field of vision

The Earth Life Web, the Fish Eye and Sight in Fish

  • But many fishes have an extra vertically flattered head that keep their eyes quite in the side of the head. One of the ways of improving their frontal, and thus binocular vision, is to increase the their monocular field of vision.


This chart is excerpted from The Earth Life Web, the Fish Eye and Sight in Fish

                     Visual Range in Men and Fish
 Entity Horizontal Vertical Binocular
Man              154°              150°              25°  
Fish                165°             134°               12°                          (**)

This is what many of the fishes that have extra narrow compressed head  shape do. They usually have very large eyes and they are in a very front  position in their heads, allowing a major overlaping this way.


(**) You can say now, but you telled that people had 140º of binocular vision. Yes, but here are data from another source and they make a difference between horizontal and vertical vision. And data usually varies a little depending of the source.


As usual, predators have more frontal eyes to increase distance perception and prey side eyes to increase the field of vision in spite of binocular vision.

  • There are more special adaptations to improve their vision skills as water is a more challenging enviroment to this sense that is air.


  • Some of the deeper water fish have tubular eyes with big lenses and only rod cells that look upwards. These give binocular vision and great sensitivity to small light signals. This adaptation gives improved terminal vision at the expense of lateral vision. Vision in fishes.


  • And there are more tricks in the bag: Benthic

  • predators, like flatfish, have eyes arranged so they have a binocular view of what is above them as they lie on the bottom. Vision in fishes.

sábado, 4 de febrero de 2017

Do dolphins have eyelashes?

o, they don't. I'm not sure that eyelashes are totally unuseful for them, but as so many things in animals potential the existence or ausence of a character is not always totally correlated with its utility.

But they have whiskers or at least they had, dolphins are born with a few hairs around the tip of the beak -which is called the rostrum if you want to sound more technnical- , that they lose them shortly after birth, retaining only the roots under the skin. Only the Boto river dolphin  retains them which has persistent small hairs on the rostrum.

In the four pictures above you can see the stages of dolphin hair.  Figure A shows the hair root that all dolphins have buried in the skin.   Figures B and C show with arrows the hairs that stick out around the  time of birth.   Figure D shows the dark pits that each contain the hair  root below.
Source of these terrific photos and text: NATIONAL MARINE MAMMAL FOUNDATION, by Sam Ridgway. (Thank you Sam).


But...what I suspect, but I haven't been able to test is that embryos have more hair in earlier states of development and that those hairs are reabsobed before birth.

Sources:

jueves, 2 de febrero de 2017

If Cecil the lion's death is going to lead to the death of the remaining 6 cubs from another male lion in pride, why can't the national park authorities make a move to relocate the 6 cubs or the male lion? Won't it save the 6 cubs' lives? Unfollow3 Comment Share Downvote

n spite that this was the main concern in the first moments after the killing of Cecil, today it seems that the better decission is to keep his 7 cubs in their pride.
The main reasons for this may be these:
- Cecil's comrade Jericho (presumably his brother), the amle lion you ask about, got along well with Cecil. It was very probably that Jericho didn't hurt the cubs when he took over the pride, as it has happened. Also, relocating him would have left the females alone, and any rogue male could easily take over the pride. Jericho is an ally,so to speak, not an enemy for the cubs.
- Cecil's genetics. If they relocate the cubs, they had to raise them, and hence they would not be wild lions no more, avoiding to continue this good genetic pool in the wild.
- Although the risk of an alliance of rogue males taking over the pride is a fact, Jericho (probably 11 years) is doing a good job by now.
- Economy. I don't know whether there are parks with captive lions under the responsability of Zimbabwean authorities and/or conservation organizations, but the Zimbabwe is a country with low incomes that already told about that the cost of translocating these cubs is very high to them. Also, wildlife conservation doesn't interest the general media in this country, so there has not been a internal demand of soing it so.

But, so far, these cubs are ok:

These are some of the cubs, date Aug 2. Source of the image: Safaris @ African Bush Camps

If you want to trustable
information about these cubs, the best link is Wildlife Conservation Research Unit, it is the the team that monitored Cecil. In their web they report that the cubs are healthy and secure as of Aug. 18th 2015

martes, 31 de enero de 2017

Why was Oliver the chimpanzee human-like?


I learned about Oliver the chimpanzee after answering another question and I developed a kind of sympathy towards his story.
The abstract of my answer is that Oliver was a common chimpanzee that had retained some juvenile characteristics in his face that made him appear more 'human-like' and a preference for walking upright that he could have developed as a juvenile growing with his first owners, a couple that bought him when he was about two y.o. The most peculiar trait he shoed was how upright he could walk, but this type -although very excepcional- of gait has been found in some other apes like the gorilla of the video I have added. And finally, some years of abuse resulted in muscle atrophy and loss of all teeth wich contributed to making his appeareance more slender and his face more plane.
Oliver was famed as a chimpanzee with many human like traits, but in fact many studies carried out after his death showed clearly that he was a common chimpanzee without chromosomic anomalies.
A geneticist from the University of Chicago examined Oliver's chromosomes in 1996 and revealed that Oliver had forty-eight chromosomes instead of forty-seven. This disproved the earlier claim that he did not have a normal chromosome count for a chimpanzee.
Oliver's cranial morphology, ear shape, freckles and baldness fall within the range of variability exhibited by the Common Chimpanzee.
Scientists performed further studies with Oliver, the results of which were published in the American Journal of Physical Anthropology.
However a full DNA test has never been performed. Although many requests were made for access to Oliver for medical testing during his later years at Primarily Primates and again after his death in 2012, it was the policy of PP to refuse all such requests, calling those inquiries "scientific tourism."

Judging by the pictures I have seen he looked like if he had retained some juvenile characters like a somehow flatter face (aslthough that the effect was stressed by the fact that many of the photographs were taken when he was old and had his teeth removed), bald and without beard. He also had a tendence for walking upright, strinkingly upright,  and rarely was seen knucling. He was a well developed male in spite of the juvenile traits in his appeareance. Also, reading his biography -it is very interesting- it results that Oliver was purchased by a Pensilvannia laboratory when he was about 30 years old, and that he spent nine years in a small cage what resulted in his muscles atrophying, which could give him the slender look he exhibits in the pics, apart from horrible mental and phisycal suffering. Oliver, with all his fame, was an abused chimp, and I congratulate that people of Primarly Primates finally took care of him and decided to maintain scientific analysis far from him for the rest of his life:
Oliver was purchased in 1989 by the Buckshire Corporation, a Pennsylvania laboratory leasing out animals for scientific and cosmetic testing. His entrance examination revealed some previous rough handling. He was never used in experiments, but for the next nine years, his home was a small cage, whose restricted size resulted in muscular atrophy to the point that Oliver's limbs trembled.
In 1996, Sharon Hursh, president of the Buckshire Corporation, after being petitioned by Primarily Primates, allowed his retirement to Buckshire's colony of 13 chimpanzees.
So, accordingly to the studies carried out, and in absence of a genetic study, it seems that Oliver was a common chimpanzee whose 'human-like' traits had been highly hyped by his owners who had exhibited him.
The peculiar -for a chimp- way of walking is also not unheared of in some few other non human apes (very few), like the gorilla of this video: