By Wendy Langhans
There’s an old saying -“Bad news travels fast.” In the mid 1350’s the Bubonic plague, which began in Asia, spread to Europe along the trade routes. The bacteria that caused it, Yersinia pestis, was spread by fleas and rats. And in the summer of 1510, the world experienced the first “recognized” influenza pandemic . It began in Asia and also spread to Africa and Europe along the trade routes. So it’s not surpising, when we think of infectious diseases, that we attribute their spread to the movement of people and animals.
But what if that’s not always true? What if animal migration can, in some cases, reduce the risk of certain infectious disease? Sounds counter-intuitive, doesn’t it?
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There’s two ways this risk reduction might work. The first way is straightforward and logical. Because it takes energy and stamina to migrate thousands of miles, a sick animal is less likely to survive the journey. In addition, there would be evolutionary pressure to produce less virulent strains of pathogens, because a kinda-sorta sick animal just might be able to make it.
The second way is more complex, and involves the parasites that live in the migrant host’s territory. Parasites have a complex life cycle, and require a host to survive. If the host has “left the building”, then the number of parasites declines. When the host returns, there are fewer parasites available to infect the host.
Recent studies  at the University of Georgia provide evidence for both types of risk reduction. They compared both the rate and virulence of protozoan infestation, (Ophryocystis elektroscirrha), in different migratory groups of Monarch butterflies. (For more information about the study, click here .)
Those butterflies that migrated the furthest distance had the lowest rates of protozoan infection. And the parasites were less virulent. Makes me wonder about the background behind another old saying - “What doesn’t kill you makes you stronger.”
Upcoming Outdoor Events:
Saturday, February 12, 1:00-3:00 PM, at Whitney Canyon. Wildlife Crossroads at Whitney Canyon. Big or small, wild animals need large ares of open land to find food, mates and homes for successful survival. Whitney and Elsmere Canyons are at the crossroads of wildlife corridors in the Santa Clarita area. Meet in the parking lot for this easy hike. 2 hrs. For directions and trail maps, click here .
Saturday, February 19, 8:00-10:00 AM, Morning Bird Hike at Towsley Canyon. With our local deciduous trees bare, now is a great time to view exposed nests and homes of our feathered friends. Beginners are welcome. Bring binoculars, easy walk. 2 hrs. For directions and trail maps, click here .
Trail Maintenance Schedule. Come join our volunteers as they help maintain our trails. Contact Steve at email@example.com  for time and place.
Wednesday mornings, January 5, 12, 19 & 26.
Saturday mornings, January 8 & 22.
You can listen to stories like this every Friday morning at 7:10 a.m. on "The SCV Outdoor Report", brought to you by your hometown radio station KHTS (AM1220) and by the Mountains Recreation and Conservation Authority.
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