12 May 2014

How animals beat the heat

There's always thirst-quenching food around to tackle the summer heat. And, this squirrel seems to have found it!

  • Wild animals are wired to handle the heat
    PAUL NORONHA Wild animals are wired to handle the heat
  • There's always thirst-quenching food around to tackle the summer heat. And, this squirrel seems to have found it!

Summer is here. How do insects, birds and animals in the wild deal with soaring temperatures? Akila Kannadasan finds out that the trick lies in effortless adaptation

This summer, Urigam, Asokan, and Giri, the elephants of Arignar Anna Zoological Park, Vandalur, will be given special treatment to beat the heat. At 3 p.m. every day, they will be given shower baths to cool off. In the wild, the elephant knows how to deal with the heat. So does the little red ant. The hyena has his own plans. Every inhabitant of the forest has his / her way of handling the summer heat.
So, what exactly happens inside a forest during the summer? Everything, from the blades of grass by the brush, to the neighbourhood waterhole, wears a new look for the season. The inhabitants too, undergo changes in their lifestyle. Animals have been dealing with dry spells and droughts since time immemorial. But what’s fascinating is how they do so.
“Red ants burrow deep into the soil to escape the heat,” says naturalist ‘Poochi’ Venkat. “Most insects that come out for nectar, wind up early.” Insects however, prefer humid to dry weather. But they cannot afford to expose their wings too much in the heat. Venkat says that the wings have to be well-moisturised in order to be supple.
Insects alter their comings and goings as per the weather. When the day is hot, they “retire earlier than usual”. For instance, an insect that usually floats by lazily till late in the day, will probably come out early and go home by 8.30 a.m. to escape the heat. Some insects such as the beetle and leaf spider dare not come out when the sun is out, adds Venkat.
Animals too change their activity patterns during the summer, says biologist R. Arumugam. “They restrict their activity to early mornings and late evenings,” he says.
Birds try not to spend too much time in the heat, says P. Pramod of Salim Ali Centre for Ornithology and Natural History. Since birds are warm-blooded, they react to heat much like humans. “During summer, migratory birds fly back to the Himalayas and Siberia. Resident birds will be relatively less active during the peak hours of the day,” he adds.
Wildlife conservation filmmaker Shekar Dattatri feels that “animals that have evolved in the tropics are well able to withstand summer temperatures”. Tigers, for instance, “often soak themselves in a river or waterhole for sometime and then lie in the shade during the hottest part of the day. They may also seek shelter in a cave or a thicket.” While tigers “prefer hunting at night, early morning or late evening,” Dattatri says that he has seen, on occasion, tigers “hunt during the middle of a hot summer day” when necessary. The animals might also hunt about water sources during the dry season, he adds. For, they know that herbivores will be drawn to water.
Dattatri says that “most animals get sufficient moisture from the food they eat and do not need copious quantities of water”. But elephants, however, “require nearly 100 litres of water each, a day”. “Generally, with the advent of the dry season, elephants move away from dry areas and into areas where there are reliable sources of food and water, such as streams, rivers, lakes and even reservoirs. Most forests have some perennial sources of water, which provide for animals.”
Elephants have a unique way of warding off heat. Dattatri explains that they “regulate their body temperature by fanning their large ears, which have a network of blood vessels. The flapping cools the blood passing through the ears and thus cools the body. In effect, the ears of elephants act like radiators. Elephants also love to bathe in water or splash themselves with water with their trunks, and this is another way they keep cool.”
The Forest Department is augmenting water resources in forest areas for the dry season. For 2013-2014, Department records suggest that the Tamil Nadu government has sanctioned Rs. 2.81 crore to install motors energised by solar power that will supply water in forest areas. Thirty such systems have already been installed. Waterholes are also being replenished during the summer. Dattatri believes that this practice “is a matter of some debate. Many leading ecologists feel that this is misplaced compassion and should not be done indiscriminately or as a matter of routine”.
Perhaps humans tend to think animals suffer the heat the same way they do? “People tend to compare themselves with animals. But the eco-system is different,” says a Forest Department official. “A deer can quench its thirst by eating a stem or a leaf. Another animal can do so by debarking a tree…” Animals know how to take care of themselves, he feels. They have been wired to do so.
* Summer plans at Arignar Anna Zoological Park, Vandalur
* Sprinkler facilities to be introduced at zebra, giraffe, and ostrich enclosures
* Wet gunny bags to be suspended around bird enclosures; these will be periodically moisturised
* Shower facilities to be provided for birds
* Watermelon, tender coconuts, and cucumber to be included in the diets of birds and animals

15 Indian bird species among globally endangered

The Great Indian Bustard is among the Indian bird species that are globally endangered. File Photo.
The Hindu The Great Indian Bustard is among the Indian bird species that are globally endangered. 

A study says Bengal Florican, Lesser Florican, Great Indian Bustard, Sociable Lapwing and Jerdon’s Courser are birds that are under threat due to destruction of their habitat of grasslands and scrub forests

Fifteen Indian bird species are part of a list of avians which are evolutionarily distinct and globally endangered. The Zoological Society of London (ZSL) and Yale University has come out with a study of 100 Evolutionarily Distinct and Globally Endangered (EDGE) species worldwide.
The study says Bengal Florican, Lesser Florican, Great Indian Bustard, Sociable Lapwing and Jerdon’s Courser are birds that are under threat due to the destruction of their habitat of grasslands and scrub forests. The survival of Spoon-billed Sandpiper, Siberian Crane and White-bellied Heron greatly depend on the existence of their wetland habitat.
Forest Owlet’s survival is impossible if its habitat of deciduous forests in central India is destroyed, the study said. Officials of the Bombay Natural History Society (BNHS), which works on the conservation of 12 of these threatened birds, said these species were threatened by human factors such as uncontrolled urbanisation, unsustainable industrialisation and rampant use of chemicals in agriculture.
“Comprehensive conservation action based on in-depth field research is required to save these species from going extinct. Today these habitats are facing some of the most severe human pressure which endangers the survival of the avian population found there,” BNHS director Asad Rahmani said.
Habitats such as grasslands and wetlands and the species inhabiting them have long been neglected in the conservation process in India, he added. Bittu Sahgal, editor, Sanctuary Asia, said birds such as the Bengal Florican, Great Indian Bustard, and Jerdon’s Courser are as vital to the health of grasslands as the tiger is to the forests in which it is found.
“India has displayed little regard for its grasslands these past decades and it is about time the nation stopped treating these life-saving ecosystems as wastelands”, Mr. Sahgal, also an environmental activist said.
What makes stainless steel non-magnetic whereas ordinary steel and iron are magnetic?
Greater Noida, Uttar Pradesh
We have to first understand how magnetic fields are generated around magnetic metals to answer this question. We know that within each atom, electrons spin on their axis that, in turn, causes magnetic field around them. Some electrons spin clockwise, some counter-clockwise. Generally they are paired so that the magnetic fields are cancelled. Iron which is a magnetic substance has three unpaired electrons. Each electron generates a magnetic field of its own.
If all the fields pull in the same direction then you have a magnet. In other words, the magnetic fields are aligned in a magnet. In the case of stainless steel, there are several types of them. In general they are made of iron (Fe), carbon (C), and about 10 per cent chromium (Cr). Some contain Nickel (Ni).
But other metals are added to obtain different properties. As stainless steel contains iron, a magnetic metal, one it would seem that it would be magnetic. However, when nickel (Ni) is added to stainless steel the result is a non-magnetic form of stainless steel, called austenitic stainless steel. At the atomic level, all the iron atoms act as mini magnets that are aligned in the same direction.
The net effect of this is that collectively the magnetic properties of all the iron atoms add up to produce the overall magnetisation of the material. This is known as ferromagnetism. But the addition of other elements to iron changes the properties. For instance, when chromium and nickel are added, the arrangement of atoms changes completely and this, in turn, affects the magnetic properties of iron. The nickel and chromium that are added to iron tend to cancel the magnetic fields and the net outcome is that stainless steel becomes a non-magnetic substance.