Geomagnetic Storms and Hummingbird Migration

Aug 6, 2011
John Blatchford

Female Ruby-throated Hummingbird - Tim Ross - Public Domain

NOAA warns of magnetic disturbance in the peak period of Ruby-throated Hummingbird migration. A 'Hummingbird Festival' might show if navigation is affected.

Many birds migrate at night and use the earth's magnetic field to help find their way. Solar flares cause geomagnetic storms on earth, and these may affect how effectively migrating birds navigate.

Solar Activity, Sunspots, Solar Flares, and Geomagnetic Storms

Solar Activity - Solanki, Usoskin et al. (Nature 2004) state that: 'the level of solar activity during the past 70 years is exceptional, and the previous period of equally high activity occurred more than 8,000 years ago'. This means that as well as giving the earth brighter sunshine, the sunspots, solar flares, and geomagnetic storms are becoming more powerful:

Sunspots - it seems that the number of sunspots correlates with solar intensity. Over the last decades the Sun has had a markedly high average level of sunspot activity.

Solar Flares - there appears to be an 11 year cycle for solar flares, which are associated with sunspots. Solar flares eject clouds of electrons, ions, and atoms into space. These clouds typically reach the earth a day or two after the event. Earth events include geomagnetic storms.

Geomagnetic Storms disrupt the Earth's magnetosphere, and (among the many effects) affect the Earth's magnetic field.

NOAA Geomagnetic Storm Warnings

Space Weather Alerts issued by NOAA in August 2011 predicted several geomagnetic storms, the worst on August 5, at ''Scale G3 or greater' (strong to Extreme).

This scale states that, for G1: 'migratory animals are affected at this and higher levels'. So a G3 could certainly be expected to cause migrating birds to make errors.

Ruby-throated Hummingbird Migration

A 'Hummingbird Festival' takes place in Lemont (Illinois) 5-7 August 2011, to coincide with the peak of the Ruby-throated Hummingbird migration there. In addition to watching the migration some birds will be caught and ringed (banded).

These activities will take place during the daylight, then at night many of the birds will continue their migration south. They will use the Earth's magnetic field to help them on their way.

Migration and Solar Activity

Birds and many other animals are known to use the Earth's magnetic field to orientate. Birds for example at night, and whales out at sea.

It is also known that disruptions to this magnetic field occur from time to time, but the effect these have on animal migration is a matter of conjecture.

Maybe the birds ringed (banded) during the 'Hummingbird Festival' will provide some clues. Will their routes south be any different this year?

If it turns out that the geomagnetic storms of August 2011 have a deleterious effect on successful migration of the hummingbirds there might be serious consequences for many other migratory animals in the future.

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