The Diet that Kills?

Chicken cross the road-M
 Photo by Mark Godfrey,!i=1375222865&k=chc4NQ4&lb=1&s=A )

We have all heard about how junk food can cause obesity and diabetes, which in turn can cause us to die. But, did you know simply eating vegetables could kill too?

Well, this isn’t necessarily true for humans, but this is the case for animals. Researchers at the University of California have found evidence that diet may play a role in making an animal more vulnerable to vehicle-collision mortality.

As human populations increase, the number of roads and the amount of traffic increases as well. So what happens when we have more traffic and more roads? More and more animals die! The poor Grim Reaper is overwhelmed!

To find out if diet really does affect vehicle collision mortality for animals, the Ecology and Evolutionary Biology team at the University of California gathered data focusing on recent road kill studies on mammals and birds. They collected data from 10 studies that included 80 mammal species and 99 bird species.

In looking at the effects of diet, they also tested the effects of 10 others factors.  They looked at body mass because larger mammals may be killed more often on roads. They looked at whether the species scavenge food due to the fact that scavengers are attracted to carcasses and thus when they are feeding on the mammals they can get hit by a vehicle as well. To avoid becoming too verbose, here is a list of the other things they looked at:

  • initiation distance
  • maximum sprint speed
  • time of activity
  • brain mass
  •  longevity
  • length of maternal care
  • sociality
  • sexual dimorphism.

So what did the data tell us? Well, after looking at 8028 individual records of mammalian road kill over a span of 3,972,437 kilometers, they were able to conclude that diet did explain a significant amount of variance.  Carnivores (Meat-lovers) had the lowest rate of road kill while omnivores (Everything-lovers) had a relatively high rate of road kill.

You might be wondering, why do the poor omnivores die from vehicle collisions more often than the meat-lovers? This is a tricky question because a lot of hypotheses have been proposed.  This can be attributed to how fast omnivores are, how they move, and/or where the food is.

You know when you’re driving on the highway from, let’s say Dallas to Chicago, and you look around to only find trees, shrubs, and more trees? Well, the omnivores are attracted to this, so they are more likely to cross the road more frequently than carnivores.  Carnivores don’t get as excited as omnivores about plants so they don’t hang around the roads as much.

Now that we know diet can kill, we should focus on the solutions that can help guide them away from the road.  For example, we can remove the seeds, grass, and fruits from the roadside! But that sounds like too much work, doesn’t it? Hmm…we could put fences around the roads to prevent them from passing? Hmm…a lot of work but it could work!

As you can see, it’s difficult to think of the perfect solution, but we gotta keep trying! Conserve biodiversity and our planet!

New-Picture-3(Photo by First Worlds People,


Blumstein, D. T., & Cook, T. C. (2013). The omnivore’s dilemma: Diet explains variation in vulnerability to vehicle collision mortality. Biological Conservation,167, 310-315. Retrieved from

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