KCRL alum Dr. Hsiang Ling Chen’s recent publication in Biological Conservation demonstrates that even low traffic, narrow roads can act as barriers to small mammal movements due to gap avoidance behavior. Dr. Chen’s research has important implications for the conservation and management of forest dependent small mammal species faced with fragmentation and disturbance.
Check it out:
Chen, H. L. and J. L. Koprowski. 2016. Barrier effects of roads on an endangered forest obligate: influences of traffic, road edges, and gaps. Biological Conservation 199:33-40.
UA Conservation Research Lab News 
Are Abert squirrels more aggressive overall than red squirrels? Our local Aberts in Flagstaff are frequently run over on our forest roads. Although they are on alert as they approach the road they are very quick to dart out in front of traffic.
Hi Maril,
Thanks for the comment and good question! Red squirrels are actually more aggressive and tenacious compared to Abert’s squirrels – our research group has observed many behavioral interactions between the two species and in almost every instance, red squirrels are the aggressors and chase Abert’s squirrels away. The appearance of Abert’s squirrels next to roads and frequent road-related mortalities are common observations, and the tendency for Abert’s squirrels to dart out in front of cars seems puzzling for sure. That Abert’s squirrels are observed near roads more than red squirrels may be related to their preference for more open forest and use of forest openings (canopy gaps) compared to red squirrels. Because Abert’s squirrels prefer more open forest, they don’t appear to associate roads as risky places, whereas red squirrels avoid canopy gaps and appear to also consider roads as dangerous canopy gaps. The tendency for Abert’s squirrels to bolt and jump in front of cars may be related to their predator avoidance strategies. When pursued by a predator, Abert’s squirrels dart in different directions to evade and confuse the predator, and when in the grips of a predator, Abert’s squirrels will often remain very still and then suddenly jump straight in the air, giving them the element of surprise and hopefully an opportunity to escape. Cars are a very recent addition to the landscape, evolutionarily speaking, and unlike any predator Abert’s squirrels have co-evolved with. The usual anti-predator tactics that Abert’s squirrels employ with avian and mammalian predators don’t work very well (or at all!) with cars, but there hasn’t been sufficient time for Abert’s squirrels to develop a fixed anti-predator behavioral response specific to cars.