New Method for Counting Birds Developed

It was fascinating to read about this new acoustic technique developed by , Deanna Dawson of the US Geological Survey and Murray Efford of the University of Otago, New Zealand, for counting birds. The acoustic technique gives a more accurate estimate of bird numbers than using nets to capture birds.

Deanna has worked out a way of using recordings of birdsong to accurately measure the size of bird populations. The technique involves innovative combination of sound recording with spatially explicit capture-recapture (SECR). Sound spreading through a forest or other habitat leaves a ‘footprint' and the size of the footprint depends on how quickly the sound attenuates.

The new technique can also be used to measure hard-to-reach populations of marine mammals, such as whales and dolphins.

The findings have been published in the latest issue of the British Ecological Society's Journal of Applied Ecology.

Back in Kochi

Hi,
I am back in Kochi after attending the 5th World conference on Mountain ungulates. The conference was a revelation. The present status of mountain ungulates worldwide was discussed threadbare by the leading lights of conservation. I stand benefited immensely from the proceedings of this wonderfully organized conference. Hats off to the organizers.

Fascinating Mating Habits of Seahorses

Did you know that Seahorses are the only species in which males truly become pregnant?

The other day I read a fascinating piece on the mating habits of Seahorses in Guardian UK.
Seahorses inhabit a wide stretch of the oceans. It is a misconception that they are restricted to warm azure waters of equatorial shores.

As mating prelude Seahorses greet each other with a nose-to-nose caress. Then they wrap their tails around a single blade of grass and begin a seductive dance, spiraling round and round each other. The first time a seahorse couple meets, this gentle courtship carries on for hours, days even. Then a short hollow tube emerges from the female, which she pushes into an opening in her partner's belly and the female shoots an egg-laden liquid into the male. The male then sways and wiggles his body, settling the eggs into position where they will remain for the next few weeks, growing in a protected internal pond.

So what makes them the male of the species if they get pregnant?" The simple answer is sperm.

If you want to read the full story click here

Pesticides: Easier Detection of Pollution and Impact in Rivers Made Possible

Researchers from the Helmholtz Centre for Environmental Research (UFZ) have developed a tool that can easily estimate the harmful effect of pesticides on living organisms in rivers and on water quality. This can be done in minutes.

Pesticides cause characteristic changes to the composition of the life community that is affected. What is required is to find out which living creatures, e.g. insects and crabs, are found at a certain point along the river and in what numbers. The scientists have now set up a Web application where this data can be entered and evaluated to show immediately the level of pollution.

Regional data is currently available for Germany, France, Finland and Western Siberia, but the system has also been tested in the UK and in Australia. There is no charge for using the service. The advantage of the new tool is that in many cases, complex, expensive chemical analyses will no longer be necessary.

Journal reference:

Beketov M.A., Foit K., Schäfer R.B., Schriever C.A., Sacchi A., Capri E., Biggs J., Wells C., Liess, M. SPEAR indicates pesticide effects in streams - comparative use of species- and family-level biomonitoring data. Environmental Pollution, 157(6), June 2009

Light as an Aid for Bird Migration

Latest research on European Robins is making established facts about migration of birds on its head. Scientists have discovered that In European Robins, a visual center in the brain and light-sensing cells in the eye and not magnetic sensing cells in the beak allow the songbirds to sense which direction is north and migrate correctly.

Researchers have known that built-in biological compasses tell migrating birds which way to fly, but the details of how birds detect magnetic fields has been unclear.

Special proteins called cryptochromes in the birds’ eyes may mediate this light-dependent magnetic sensing according to the scientists. Light hitting the proteins produces a pair of free radicals, highly reactive molecules with unpaired electrons. These electrons have a property called spin which may be sensitive to Earth’s magnetic field. Signals from the free radicals may then move to nerve cells in cluster N, ultimately telling the birds where north is.

To find the location that houses the magnetic compass the scientists caught 36 migratory European robins and made sure that the birds could all orient correctly under natural and induced magnetic fields. Next, the researchers performed surgeries on the birds to deactivate one of the two systems. The team either severed the nerve that connects the beak cells to the brain, or damaged the brain cells in cluster N that receive light signals from cells in the eye.

Birds with the severed beak-to-brain nerve, called the trigeminal nerve, still oriented perfectly. On the other hand, birds with damaged cluster N regions could no longer sense and orient to magnetic fields. These robins failed to pick up both the Earth’s natural magnetic field and the artificial fields created by the researchers.

Details of the study appear in Nature dated October 29^th.