Roadblocks

Three mule deer at border fence near Tucson

Even if you can move at the speed of climate change, sometimes other barriers stand in the way.  Some of these barriers are very visible like large fences stretched across continents. Fragmented terrain is another widely recognized barrier for species movement and is at the center of debates about facilitated relocation programs which purposefully moves species at risk to help them deal with climate change.  



 Some other barriers are more subtle.  Research on Canadian Lynx has discovered an invisible barrier between populations based on warming trends during winter.  Subtle changes in winter warming produces different snow conditions which in turn require different hunting techniques. Genetic data comparing populations from different snow conditions nearby show no gene flow.18   This separation of populations represents further specialization in the already highly specialized Canadian Lynx.  If the cats are unwilling to travel outside their preferred snow type to mate, it raises serious questions about the cat’s ability to respond to change.

Canadian lynx chasing a snowshoe hare

Jaguar, Margay, Jaguarundi, Ocelot.

The bobcats range is constrained by another type of invisible barrier.  The southern boundary of the bobcats range ends at the Isthmus of Tehuantepec in southern Mexico, despite large swaths of uninterrupted suitable habitat south of that point.  The cause of this unseen barrier is believed to be the abundance of the South American cats, namely the jaguar Panthera onca, the margay Leopardus wiedii, the  jaguarundi Herpailurus yagouaroundi, and the ocelot Leopardus pardalis. Analysis of the distribution overlap for all 5 cats in Mexico shows a high avoidance value for the bobcat and all 4 other species, in nearly identical amounts. It is unclear whether the avoidance displayed by bobcats is due to being out-competed by any one species or the cumulative effect of too many similar species vying for the same prey.16 One of the few threats facing bobcats is the expected northern expansion of the South American cats due to climate change combined with their extremely fast dispersal rates all cats possess.



Deer photo anonymously posted, pulled from northernjaguarproject.org
No photo credit found for lynx photo, taken from Carandang and Lim student project for the University of Manila.
Jaguar photo taken by Tom Brakefield
Margay photo from Animalgalleries.org  
Jaguarundi Photo from the Robinson Library, original credit not given.
Ocelot photo from tpwmagazine.com. Photo credit to Rolf Nussbaumer