Navigational Methods in Birds

Updates on : The Tushino Ltd ALFIC system

BACKGROUND

Since the first publication of the ALFIC system in July 2018 some progress has been made in filling in some of the perceived difficulties.

These were :

(1) Many birds migrated at night when there would be no solar generated ozone for the birds to use as a check on their eastings.

(2) It was unclear how a small bird flying over the ocean from one landmass to another could keep track of its easting

(3) It was unclear how a pelagic bird such as an albatross could locate its small and remote breeding island

(4) It was unclear how a coastal nesting bird such as a Manx Shearwater could fly out far to sea, feed, and then fly back directly to its nest often in the dark and in poor weather

(5)There has been uncertainty about just what properties a bird could, or should, derive from its magnetic sense.

UPDATED ANALYSIS

Although it may not seem so, and although we could not see it ourselves for a long time, items (1) and (2) need no further development. So long as the assumptions of the ALFIC system are accepted, (1) and (2) follow directly.

Items (3) and (4) are unsolved. We believe at the moment that either (A) Ozone is formed over the remote ocean, or (B) There is some completely other chemical whose concentration depends on "diurnal time" if I can use a phrase.

We have struggled to find suitable data but have not been successful.

We are in the process of asking academic specialists for advice.

EXCLUSIONS

A correspondent has asked us whether any methods under consideration for pelagic birds could be relevant to the homing of turtles and the mysterious beaching of whales.

For now, at least, we have declined to comment. Birds are a hard enough problem for now and in any case, the matter is likely to fall under items (3) or (4) neither of which we understand.

ITEM (5) AVIAN MAGNETOMETERS

Very many papers on avian navigation refer to the birds magnetic sense and we have been considering the matter carefully.

The first thing to say is that we are not at all concerned with how the detection of the field is managed. It is of no consequence to us whether the birds rely on magnetite particles in the beak, cryptochromes in the left eye or woogles in the boogle. What is important for the present purpose is what the bird measures and how accurately it can measure the said quantities.

At the moment we believe that a bird can measure the total magnetic field, F, but not more accurately than to about 100 nT. (See P56 in the book)

We also believe that birds can see the inclination of the magnetic field to the horizontal and, by implication, the direction of travel, but to nothing like the accuracy of F. Perhaps the error might be of the order of plus or minus five degrees of arc.