MIGRATIONAL NAVIGATION SITE - LATITUDE

This web site, together with  www.3aaa3.com, is concerned with the ways in which migrating birds navigate to their destination. This site mostly deals with latitude and 3aaa3.com mostly deals with the longitude problem.

In particular the assumption is made that birds can measure time intervals to some extent. I adopted this position because I could not see birds as being able to measure an angle accurately (think sextant) and they have to measure something. Time seemed the only option.

I intend this site to be a focus for developing ideas based on time measurement to a sufficient state that they can demand critical attention.

I am looking for contributions from arithmetically literate scientists and especially from those who have not worked in this field. I think a knowlege of spherical triangles will ultimately be useful. Astronomers could, I think, contribute much.

On this site I have included :

A very   short sketch of how I see contemporary thinking about avian navigation.

I have included a   paper showing a system by which a bird might be able to determine latitude by measuring a time.

I have also included a   note describing another possibility for the determination of latitude. This method was subjected to months of observational work and ultimately failed.

Additionally, the reader will probably want to be in possession of the two computational tools which I have used to derive some of the data used both on this site and on 3aaa3.com.

One of these tools at  www.fourmilab.ch/yoursky can be called up directly via the internet. You may like to download some  notes that I have written to help you use it.

The second tool needs to be downloaded from   www.alcyone.de and be installed on your computer. There is a free trial period after which a small fee should be paid. I have included  notes to get you started.

The first tool from Fourmilab is a quick way of drawing pictures of the sky to give you an idea what a bird might be looking at. Unfortunately it isn't all that good at showing accurate times when stars might set. For this detail it's best to use the Alcyone tool, which is excellent at showing the numerical positions of stars but does not draw pictures.

On another site   www.3aaa3.com I have placed a paper on something called "Line Following". This seems to indicate a way to get round the problem of determining longitude.

As the assumption is made that birds can measure some time intervals two things follow :

(1) Protestations that "birds can't measure time" will not be welcomed here.

(2) The accuracy to which a bird would need to measure time for any proposed navigational hypothesis needs to be worked out and exhibited. While we might allow that a bird could measure time to one minute in an hour, some system that demanded a measurement of plus or minus one microsecond per elapsed day could safely be binned.

The author of the content is D.C.W. Morley

Latest revision 25 January 2011                                                            This site is owned by Tushino Ltd