CollinsLab

Gray Fox

Gray foxes, Urocyon cinereoargenteus, are omnivorous members of the canine family. Their diet ranges from mammals and birds to invertebrates, fruits, and nuts depending on the season and what is available.

As you can see from the figure above, we didn’t catch any on camera from 7 a.m. to 6 p.m. There could be many factors that explain this. Gray foxes are really good tree climbers, and we didn’t have any cameras in trees. Also, this species of fox is primarily nocturnal. We have written about their tree-climbing ability as well as their avoidance behaviors here.

Above you can see that they didn’t overlap much with coyotes in space. It almost looks as though the coyotes have pushed the gray foxes closer to developed area. Gray foxes also tend to avoid coyotes in time, only overlapping 55% of the time. This strategy is used to avoid interactions with the much larger carnivore, the coyote.

We also found that gray foxes were:

  • Present at 6 trap stations
  • Found in 96 photos (30 independent observation)
  • Nocturnal 96.67% of the time

Gray fox climbing in Statesville

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Deer

The most numerous animal we “caught” on our cameras was the white-tailed deer, Odocoileus virginianus. This species is sometimes referred to as a keystone herbivore, which means that they fulfill such an important role in an ecosystem that if they were to disappear, other populations would be altered tremendously. White-tailed deer alter the abundance of vegetation and the structure of communities.

We have previously discussed deer population research as well as data on deer vigilance around city trails. The figure below shows how our deer in Statesville deal with coyotes. It doesn’t look like the deer are avoiding coyotes in space or time. Deer were captured at every location where coyotes were captured. Also, these two species overlap in time 87% of the time. There is research that shows that eastern coyotes do sometimes kill fawns, but this figure is a pretty good indication that our deer don’t fear coyotes.

Finally, our year-long project showed that deer were:

  • Present at 32 trap stations
  • Found in 5534 photos (548 individual observations)
  • Nocturnal 58.58% of the time

Raccoons

One of the most common critters caught on our camera traps were raccoons. The graph above shows when they were most active in Statesville.

The northern, or common raccoon, Procyon lotor, is an opportunistic omnivore. This simply means that they will eat just about anything. This is one of the adaptations that allows them to be successful. They can descend trees (like in the picture below) because the joints in their hind feet have the ability to rotate 180°. They use their forelimbs to “see” in the dark. In fact, these front hands have four times as many touch receptors than the hind feet.

Raccoons are the most common primary reservoir for the rabies virus. They are also commonly infected with a roundworm which passes eggs through the raccoon feces. This roundworm is a major cause of death in certain rodents.

From our data, raccoons were:

  • Present at 22 trap stations
  • Found in 852 total photos (185 individual observations)
  • Nocturnal 95.14% of the time

You can see below that raccoons do not seem to avoid coyotes in space or in time. One reason could be that raccoons can climb trees. Another reason could be that raccoons are mean, and coyotes know it.

 

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Eastern Cottontails

From December 2016 to December 2017, we set out to understand how animals move in Statesville, NC. Motion-activated trail cameras were deployed throughout a section of the city’s greenway section. The camera traps were randomly placed in a grid location and then rotated every two weeks.

Thousands of pictures later, we discovered some interesting things about our critters.

This first post will highlight our Eastern cottontail, Sylvilagus floridanus. These rabbits are a successful group for many reasons. They spend large periods of time grooming and foraging year-around because they don’t hibernate. They are problematic for predators because of their great speed, quick moves, and extreme agility. Above all else, two characteristics stand out.

  1. High reproductive rate– Cottontails have a gestation period of twenty-eight days. Depending on their location, breeding starts in late January and could run through late August. It is possible that one female could produce more than thirty offspring per year.
  2. Coprophagy lifestyle- Eastern cottontails eat plants that are made up of cellulose, or fiber. Cellulose, though, is difficult to digest. Rabbits have no microbes to break down the cellulose nor are their guts made up of many chambers like cows. So, rabbits digest their food twice to aid the breakdown of cellulose. To do this, things get a little weird. Their first round of feces typically is greenish isn color. The rabbit will eat this usually right out of their anus. And yet we still love them.

Below, you can see when rabbits were most active in our study.

Rabbits were:

  • Present at 17 trap stations
  • Found in 287 total photos (83 individual observations)
  • Nocturnal 86.75% of the time

One of the coolest figures that students designed is shown below. In this particular illustration, we compared rabbit activity with everybody’s favorite predator, the coyote. The first figure (Camera Locations) shows where rabbits were spotted, where coyotes were spotted and where they overlapped. As you can see, rabbits overlapped a great deal with coyotes in space. The graph shows how these two species overlap in time. The answer: they overlap 78% of the time. This confirms what some of our pictures already were telling us that coyotes in Statesville eat a lot of rabbits. However, because of the rabbits high reproductive rate, there are still plenty out there.

 

 

 

 

 

Campus Ant Diversity

Post by research students (Fall 2017)

During the Fall 2017 semester, we conducted ant surveys from six grass plots and six pavement plots, both at the Statesville and Mooresville campuses of Mitchell Community College. Besides wanting to know what types of ants were living in each location, we were also interested in looking for differences among plot types and across the two campuses.

 

As you can see from figures 1 and 2 the grass plots in Statesville were different in composition from the grass plots in Mooresville. Red-imported fire ants (Solenopsis invicta) dominated Mooresville plots while thief ants (Solenopsis molesta) dominated the plots in Statesville. There are probably many reasons for this. One simple explanation may be that the Statesville campus provides a more suitable habitat space for the thief ants.

Thief ants and red-imported fire ants are closely related, belonging to the same genus. It seems that when they do interact, thief ants play the role of antagonists. These thieves can infiltrate and go undetected in a fire ant colony. They can then steal the young fire ants, destroy a small group of workers, and prey on the queens. As a red-imported fire ant, you would do well to avoid nesting in areas with a high density of thief ants. This could easily explain why we did not trap any fire ants on Statesville’s campus.

As figures 3 and 4 show, little black ants (Monomorium minimum) dominate the pavement plots on both campuses. This is no surprise when you realize that these tiny creatures can nest just about anywhere. There brooding chambers are typically shallow, reaching depths of only 5 cm. Maybe they were just the fastest to our bait stations.

 

 

Fig. 5 and 6 show how many plots we needed to use in each of the habitats to reach a maximum diversity (shown here as Simpson index). We used six replicates of each which looked to be adequate.

 

Diversity indices often take into account both how many different species there are in an area and also the number of each type of species. We used the Simpson index and then converted that into what is called true diversity, or the effective number of species. That is what is reflected on the y-axes of figures 7 and 8. What is interesting is that when we compared the grass plots and pavement plots of both campuses, there was no significant difference (Fig. 7). However, when we compared the overall diversity of the Statesville campus with the Mooresville campus (Fig. 8), there was significance (p=0.039). Statesville had a higher diversity of ants when compared with Mooresville.

You can figure out whether that’s good or bad.