CamTraps

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

Advertisements

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.

 

M2E1L0-0R336B386

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.

 

 

 

 

 

Huggin’ Trees by Design

By Tim Ross (Own work) [Public domain], via Wikimedia Commons

By Tim Ross (Own work) [Public domain], via Wikimedia Commons

How do you survive if you’re not the most dominant canine in an area? If you have to share space and potential food with your faster and sometimes much larger cousin, how do you and your kin thrive day in and day out? These are questions the gray fox, Urocyon cinereoargenteus, must answer.

The common gray fox is a crepuscular and nocturnal canid whose home range averages around 1.5 square miles. This range contracts during the spring when they mate and have pups and then expands during the fall while they search for food. Their diet, like both red foxes and coyotes, consists of small mammals and even birds. Unlike other canids, the gray fox’s digestive system is better equipped to handle much more fruit.

In many parts of the southeast, including Statesville, gray foxes live with both red foxes and coyotes. Not much is known about how red foxes and gray foxes divide habitat in areas where they overlap. What is known is that red foxes seem to prefer more open terrain while gray foxes stick to the woods. it’s certainly possible that these two species use time-share strategies to avoid interactions.

Having to share space and resources with coyotes, however, could cause major, or fatal, problems for the foxes. Coyotes have been implicated in the decrease of red fox populations in certain areas (Cypher 1993). However, gray fox populations do not seem to be impacted as much by the larger coyote. Our small data set from greenway patches seem to support the idea that gray foxes tolerate coyotes better than red foxes. The following shows the number of pictures of each species we have collected from two camera traps from August to December during both 2015 and 2016:

                               Camera A             Camera B
Coyotes             25                         10
Gray fox            24                           2
Red fox                1                           2

Is the explanation just that the diets of gray foxes and coyotes are different or is it that gray foxes avoid coyotes spatially and/or temporally?

Both Cypher (1993) and Neale and Sacks (2001) found that there was actually a high dietary overlap among coyotes and gray foxes year-round. The implication is that this means, more than likely, that there is interspecific competition when they live in the same area. Neale and Sacks (2001) also used scat analyses to determine that gray foxes did not avoid coyotes in space. Our data (Figure 1) suggest that gray foxes don’t avoid coyotes in a temporal (time) dimension either.

rplot

Figure 1. Gray fox versus Coyote

The answer to how gray foxes avoid coyotes seems to be found in their evolutionary past. Gray foxes were the first canid to diverge from the rest of the canid family. They are a primitive species that branched off from the rest of the canids around ten million years ago (Lindblad-Toh et al. 2005). As a matter of fact, there is scientific support that states that the gray fox should not even be considered a canine or a vulpine (red fox). The gray fox is what geneticists call a basal canid, meaning it represents an ancient lineage.

Gray fox climbing in Statesville

Gray fox climbing in Statesville

As a result of this ancient lineage, the gray fox has many unique characteristics. Some features are only shared with another ancient species, the raccoon dog (Nyctereutes procyonoides). Gray foxes have hooked claws and the ability to rotate their forearms. This, coupled with the fact that they have the shortest leg-to-body ratio of any wild canid, allows them to easily hug tree trunks or branches and climb. Ecologically, they are more like cats. When pursued, gray foxes are not really interested in running. They would rather scamper up a tree. It’s this ability that helps them minimize conflict with coyotes.

Next time you are out in the forest, take the time to look up into the trees. You may get a peek at one of these cat-like dogs.

Gray fox foraging

Gray fox foraging


Cypher, B. L. 1993. Food Item Use by Three Sympatric Canids in Southern Illinois. Transactions of the Illinois State Academy of Science, 86: 139-144.

Lindblad-Toh et al. 2005. genome sequence, comparative analysis, and haplotype structure of the domestic dog. Nature, 438: 803-819.

Neale, J. C. C. and Sacks, B. N. 2001. Food habits and space use of gray foxes in relation to sympatric coyotes and bobcats. Canadian Journal of Zoology, 79:1794-1800.