Tuesday, September 24, 2013

Camouflage- in Nature.

"The octopus, seeks its prey by so changing its colour as to render it like the colour of the stones adjacent to it; it does so also when alarmed."
-Aristotle.

Grasshoppers use camouflage to hide: here a brown grasshopper hides on a rock
 
A brown grasshopper hides on a rock
Camouflage is the art of not being seen, practised by predators, prey and plants. Colour might help an organism blend in with their environment - even when the organism itself cannot see in colour. Body shapes can make them appear to be some other object common in the same surroundings. Patterns might sometimes make an animal more noticeable, but they can also help disguise outline. The tiger's stripes and the giraffe's patches make them almost impossible to detect in dappled light. (www.bbc.co.uk)
 
Camouflage has been a topic of interest and research in zoology for well over a century. According to Charles Darwin's 1859 theory of natural selection, features such as camouflage evolved by providing individual animals with a reproductive advantage, enabling them to leave more offspring, on average, than other members of the same species. In his Origin of Species, Darwin wrote: When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather, and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey; and hawks are guided by eyesight to their prey, so much so, that on parts of the Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence I can see no reason to doubt that natural selection might be most effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant (Darwin).

The English zoologist Edward Bagnall Poulton studied animal coloration, especially camouflage. In his 1890 book The Colours of Animals, he classified different types such as "special protective resemblance" (where an animal looks like another object), or "general aggressive resemblance" (where a predator blends in with the background, enabling it to approach prey). His experiments showed that swallowtailed moth pupae were camouflaged to match the backgrounds on which they were reared as larvae. Poulton's "general protective resemblance" was at that time considered to be the main method of camouflage, as when Frank Evers Beddard wrote in 1892 that "tree-frequenting animals are often green in colour. Among vertebrates numerous species of parrots, iguanas, tree-frogs, and the green tree-snake are examples". Beddard did however briefly mention other methods, including the "alluring coloration" of the flower mantis and the possibility of a different mechanism in the orange tip butterfly. He wrote that "the scattered green spots upon the under surface of the wings might have been intended for a rough sketch of the small flowerets of the plant [an umbellifer], so close is their mutual resemblance." He also explained the coloration of sea fish such as the mackerel: "Among pelagic fish it is common to find the upper surface dark-coloured and the lower surface white, so that the animal is inconspicuous when seen either from above or below."

Thursday, March 28, 2013

Fig tree, barbets & other birds, insects etc.

Thanks to Sneshesh's bike! Its got a flat tyre the moment we reached this tree. He left under the shade of this tree and I saw some of the fruits moving here and there and then some fruits vanishing! 
The Coppersmith Barbet (Megalaima haemacephala), is best known for its regular, measured call (tuk, tuk, tuk etc.) that has been compared to a copper-smith striking metal with a hammer.
Forehead of a barbet resembled like the ripped fruit of a ficus tree. It is a resident found in the Indian Subcontinent and I saw a large number of this bird next to the Rishi Valley Rural Health Centre (http://www.rvrhc.blogspot.in/). They were busy feasting on ripped fruits of ficus. Wikipedia says they prefer fruits of Banyan, Peepul, and other wild figs, various drupes and berries, and the occasional insect, caught in aerial sallies!!
Conservation activities initiated by Rishy valley education center have helped these trees to bear this favorite food for barbets and other birds in the hot summer months. We never know the depth of relationship between a tree and a bird. None of the birds noticed me they were busy in maintaining the relationship (what I saw was only collecting fruits to eat the pulp and to disperse seeds). 'The Queen of Trees' one of the best documentaries in the whole nature series can tell us how inter-connected the earth is. (http://www.youtube.com/watch?v=sxJdweffxEE)
Trigona (genus) bee nest, one of the largest genus of sting-less bees found on the ficus tree.
This tree hosted many lives- trigona bees, dwarf honey bee (apis florea), rufous treepie, common myna, jungle myna, house crow, three striped palm squirrel, spiders of many kind, wasps etc. this is from my 1 hour watch of the tree, I am sure there will be more.

Friday, February 1, 2013

Love in a puff

Love in a puff or Balloon plant (Cardiospermum halicacabum), is a climbing plant commonly found in Madanapalle and NP Kunta.
Flower and unripe fruits of Cardiospermum halicacabum.
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Matured seeds in the puffed&balloon shaped bags.


Cardiospermum is a genus which are native to the American, Indian, and African tropics. The genus name is derived from the Greek words cardio, meaning "heart," and sperma, meaning "seed."

White heart-shaped mark on spherical seeds of Cardiospermum halicacabum

It is a very famous herb in Tamilnadu India, in treating rheumatoid, joint pain, skin diseases and intestinal inflammation.

Forest fires

Rings of fire are a common sight each year during February and March on the hill sides in our semi-arid area. What initially start as small fires develop, aided by the wind and dry vegetation, quickly into ‘wild fires’ that destroy everything in their path. It is one of the main causes for the decrease of fuel, fodder and NTFP resources on common lands on which rural communities are dependent.  During discussions with the community regarding the occurrence of fire, it was evident that fires have been a recurring problem for several decades. In earlier times (25 years back), fire was common in the area. However, the occurrence has increased now and fires have become very frequent.

Fire at the initial stage.(Photo- Shreerang Hegde)

Fires harm the environment in many ways:

In addition to destroying vegetation, insect, bird and animal (snakes, mongoose) life is also harmed.
Bare hill sides are not able to soak up the rain water, resulting in runoff which causes soil erosion. Fire releases greenhouse gases that contribute to global warming and changing climate.

Major causes of fire:
•    Lack of awareness regarding the damage caused to the environment by fire.
•    Our area has a prolonged dry season and grasses on the hill sides that dry up after the monsoon are an easily combustible material.
•    Setting fire to forests as a means to encourage the growth of pasture is still widespread.
•    NTFP harvesters light fire during the collection of forest products to make way with in the densely grown patches of grass and shrubs.
•    Fire also occurs due to human negligence, particularly through cigarette ends thrown.
•    Fire set on farmlands, to clear agricultural residues, sometimes spreads into the forest.
•    Villagers and shepherds believe that fire helps to escape from some diseases.
•    Burning logs left behind by people after brewing liquor in the forest.
•    Charcoal making in the forest.
•    Decline in demand for Cymbopogon grass to construct roofs of houses.
Changes in the life style- from Cybopogon grass to concrete roofed houses

How fire impacts the ecosystem and dependent communities?

•    Fire destroys vegetation and prevents regeneration of forests.
•    Frequent fires aid in the spread of fast growing invasive species (Lantana camara and Pterolobium indicum) that rapidly colonize the bare areas.
•    Fire destroys original forests resulting in highly degraded ecosystems with low levels of biodiversity and biomass (green manure, fodder, fiber, fruit, medicinal plants etc.) Fire in our dry deciduous ecosystems causes the replacement of the diverse native vegetation with a few fire resisting trees and grass.
•    Loss of various Non-Timber Forest Products (NTFPs) has a bearing on the economy of the communities that make income during the year from these forest resources.
•    In spite of the belief that burning organic matter enriches soil, the ashes which contribute to fertilization are often blown away by wind or are lost by leaching after the first rains.
•    Large patches of lands are left bare of vegetation, allowing the soil to be eroded and the underlying rock to show through.
•    These fire resisting trees (Dolichandrone atrovirens) are the only survivors because of the thickness of their bark.
•    Forest fires are an ecological disaster. In our region which experiences an intense summer followed by a rainless monsoon, the soils are prone to degradation.
•    During fire, the temperatures reached at the surface of the soil are very high. This completely destroys the humus, the soil micro-organisms and the soil structure, rendering the soil useless as a growing medium.
Large patches of lands are left bare of vegetation and the underlying rock to show through.

First shower after the fire takes of ashes and the burnt soil from the hills and the underlying rock to show through.

Saturday, January 12, 2013

NP Kunta (Nambulapulikunta)

NP Kunta (Nambulapulikunta) is in Ananthapur district of Andhara Pradesh. This mandal comes under the Kadri watershed with gentle to undulating slopes, comes under the arid to semi-arid part of the country and forms part of the Papagni river basin. People of NP Kunta predominantly dependent on rains and cultivates all crops related to dry land conditions. Here the forest land is of two types: revenue forest and reserve forest. While the reserve forest is under the control of forest department, the revenue forest land, which includes hillocks also is under the control of revenue department, and the Gram Panchayath is the custodian. 
In December 2012 I visited few villages as part of a study
Eguvatooplle, Kotireddygaripalle, Kundlapalle varipalle, Dhaniyanicheruvu Yeguvapalle, Papanagaripalle, Kotha middi, Silamvaripalle and Nagamvaripalle. The primary land-use type in the watershed is devoted to crop fields. While the visit I could see Redgram, groundnut, hyacinth bean, tomato, rice, chilly, and ladies finger, castor, sunflower, greens, jowar, and rice in NP Kunta. 
Tomato garden in Dhaniyanicheruvu
Many wild plants were in flowering after the rains in last months and the bird diversity was also high, apis florea bees were busy collecting honey from a Euphorbia trigona. Euphorbia are a cactus like family that is found in Africa and temperate zones around the world. Euphorbia is a genus of plants belonging to the family Euphorbiaceae. 
Euphorbia trigona flowers in full bloom
Euphorbia trigona produce immense amount of nectar that attract many insects to it to pollinate its flowers. Honey bees, beetles, butterflies, etc. were seen in the euphorbia flowers.
An insect collecting nectar from the Euphorbia trigona flowers
Many birds were seen in the harvested fields and grasslands. Green Bee-eater, Common Kestrel, Brahminy Starling, etc. were selected from the check list to share here. Majority of the birds belong to the insectivorous group and a large flock of Red-rumped swallow were seen scanning the air above a water body. Later, under a bridge observed a colony of nests made very carefully with fine clay from the fields.
Green bee eater, a hunter of all insects not just 'bees'
Common kestral, observes a gecko in the field with close attention
Rosy starling
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Red-rumped Swallows build quarter-sphere nests with a tunnel entrance lined with mud collected in their beak. They normally nest under cliff overhangs in their mountain homes, but will readily adapt to buildings and bridges.
Red-rumped Swallows nest under a concrete bridge near a water body.
A flock of Red-rumped swallows preening their feathers
Two young birds preen their feathers with great care
 Like all other birds these swallows also use their beaks to preen or clean and arrange their feathers. Enormous concentration and time was spent oiling and cleaning feathers, because I think feathers are bird’s most vital and beautiful tool.


Thanks to 
L. Rasingam, he identified the euphorbia plant.