Thursday, October 28, 2010

Story of Eggs

It is said that Shahtoosh shawls (weighing only 160 grams) are known as "ring shawls" and that they are so fine and light that they can be passed through a wedding band and are warm enough to hatch a pigeon egg. 


See http://factsanddetails.com/china.php?itemid=1040&catid=6&subcatid=38.


So, I asked my father, how much does a Shahtoosh shawl take to hatch a egg? He said, it would depend on the species of the bird!


As usual, we surfed and found interesting details at Stanford Education's web-site:

How much time different species actually spend sitting on the eggs during the incubation period is even more variable than who does the sitting. Individual bouts of incubation by many small passerines such as wrens may last less than ten minutes; an albatross, in contrast, may sit on its eggs continuously for weeks at a stretch. 


Where only one parent incubates, it usually spends about two-thirds to three-quarters of the daytime hours on the eggs, and the remainder feeding. Flycatchers and others that hunt flying insects spend only slightly over half their time on the nests. Small birds have high metabolic rates, and stoking their fast-burning fires exhausts fat reserves rapidly. They could not survive even a small part of a normal albatross incubating session.


The constancy of incubation often is genetically controlled and adapted to the habitat of the species. It may have a profound effect on the ability of different species to colonize new areas. For example, two starling species, the European Starling and the Asian Crested Myna, were both introduced into North America in the late 1800s. 


The species have very similar breeding habits, but the former has spread over virtually the entire continent; the latter has remained restricted to the vicinity of Vancouver where it was introduced. One hypothesis to explain the different successes of these two close relatives is that the myna's incubation constancy is genetically attuned to its subtropical homeland. It sits on its eggs for only about half of the day; the starling incubates for almost three-quarters of the hours of daylight. Although both lay clutches of 5 eggs, the starling successfully rears an average of 3.5 young per clutch; the myna manages to fledge an average of 2. This relatively low reproductive rate may account for the myna's limited success in Vancouver, compared with the explosive spread of the European Starling.


Since, in general, birds do not begin incubating until the clutch is complete, "incubation time" is defined as the period from the laying of the last egg of the clutch until that egg hatches (or, if individual eggs can't be identified, from the last egg laid to the first egg hatched). It is one more aspect of incubation that varies a great deal. Incubation time is roughly correlated with the weight of the egg. The eggs of small songbirds generally hatch in about 11 days; those of the Royal Albatross in about 80 days.

Source: http://www.stanford.edu/group/stanfordbirds/text/essays/Incubation_Time.html

Hope you enjoyed!

Sunday, October 3, 2010

Introduction To Binoculars

Picked up some cool facts on Binoculars -

  • Unlike a (monocular) telescope, binoculars give users a three-dimensional image.
  • A basic telescope has two magnifying glasses placed in line at a fixed distance. The front glass is the objective lens and the one near the eye is the eyepiece. As telescopes invert images, binoculars require a third element – an erecting prism to flip the image for us to enjoy a naturally magnified view of objects.
  • In a binocular 7x50 or 10x50, the first number  “7” or “10” is the magnification. Binocular comes with magnifications from 7x to 20x.
  • The last number “50” is the aperture in millimeters. Larger the number, the brighter the images will appear. 
  • Recommended size: 8x36 or 8x40 for good quality birding binoculars.
  • Binoculars are widely used by amateur astronomers; their wide field of view making them useful for comet and supernova seeking (giant binoculars) and general observation (portable binoculars).
  • Ceres, Neptune, Pallas, Titan, and the Galilean moons of Jupiter are invisible to the naked eye but can readily be seen with binoculars. Although visible unaided in pollution-free skies, Uranus and Vesta require binoculars for easy detection.
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