Research

Campus Ant Diversity 2018

Post by research students (Fall 2018)

During the fall 2017 semester, we conducted ant surveys on both our Statesville and Mooresville campuses. Once again we surveyed ants across six grass plots and six pavement plots. However, this time we only sampled from the Statesville campus. The figures below show these comparisons.

You will notice different compositions from 2017 to 2018. Why is this? Could it be because of temperature differences? On 8/21/17, the average temperature in Statesville was 78ºF (high- 89ºF, low- 68ºF) while on 8/27/18 the average temperature was 69ºF (high-73ºF, low-66ºF). Temperature is probably not the only factor involved. Hopefully, a deeper dive into data will allow us to figure this out.

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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

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. They also do not have multi-chambered guts 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 is color. The rabbit will usually eat this right out of their anus and the food will travel through the digestive tract for round two.

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 most informative figures that we 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. They overlap 78% of the time. This confirms what some of our pictures already were telling us. Coyotes in Statesville eat a lot of rabbits. However, because of a high reproductive rate, rabbits are doing just fine.