We have learned a great deal about animal movement and activity patterns from collecting and analyzing pictures in Statesville’s green patches and neighborhoods.
If you look at Figure 1, time (24-hour) is displayed on the x-axis while activity level is displayed on the y-axis. Activity level is simply the number of detections (pictures) within a particular hour divided by the total number of detections. Figure 1 shows us that coyotes in Statesville are primarily nocturnal. In fact, our data for the past six years show that coyotes are 76.5% nocturnal. In some of our neighborhood plots, that percentage gets as high as 88.9%. This is calculated by dividing the total number of night coyote pictures by the total number of coyote pictures. Night is defined at the time right after sunset to the time right before sunset. Of course, this time frame varies throughout the year, but we have data analysis software that will calculate this for us.
Figure 2 shows coyote activity patterns alongside two other urban carnivores that we have in Statesville, the red fox and grey fox. There may be some slight differences that we could tease out between the three species, but for the most part, they all follow the same nocturnal pattern.
While it’s hard to gather accurate population counts with camera traps, there are analyses that will give us an idea of how abundant coyotes are in Statesville compared to other urban animals.
We looked at and analyzed one particular data set from this past spring. We placed one group of cameras in green spaces that bordered rural areas and another group of cameras in several neighborhood corridors, all within Statesville city limits.
Statesville Green Space
The green space area covered approximately 175 acres. The cameras ran continuously for 126 nights. Coyote pictures made up 1.5% of the total pictures taken. In comparison, raccoons and opossums combined for 49.4% of the total pictures taken. Over the 126 days we recorded 9 independent sightings of coyotes (87 independent sightings for raccoons). As part of our protocol, a sighting was considered independent if two photos with the same sighting were taken at least thirty minutes apart. So, the coyote that hangs around a certain camera for 2-3 hours only counts as 1 independent sighting.
We also analyzed the abundance index of each animal that we captured in this area. This index takes into account the number of independent sightings for a species and the total number of nights (in this case 126). The calculation is as follows:
# of independent sightings/# nights x 100
The abundance index for coyotes was 7.1. For raccoons, it was 69.0. Figure 1 shows the indices for the rest of the animals captured.
Statesville Neighborhood Corridors
Our neighborhood cameras were placed in natural corridors, which are areas in backyards (between houses) where you can see animal trails. These data are important because it lets us know what animals are moving through yards. The downside, however, is that the abundance index for each species and number of detections get inflated because these are trails animals use a lot.
These cameras ran for 78 nights. Coyotes comprised 15% of the total pictures taken. Raccoons and opossums combined for 54%. The abundance index for coyotes was 60.3 (again, the corridor factor inflated this). The index for raccoons was 105.1. Figure 2 shows the rest of the animals captured in neighborhoods.
Relatively speaking, coyotes are not the most abundant urban animal we have in Statesville.
We don’t know for sure the percentage of certain species that make up the diet of Statesville’s coyotes. We have pictures with coyotes walking by with rabbits in their mouths. Students will be using a protocol this year to study scat. Even though we don’t know about the specific coyotes in Statesville, we do know what coyotes eat from other studies.
Coyotes are not just hanging around harassing dogs and cats. They are not sitting and waiting on cats to cross a trail so that they can scoop them up. If cats were #1 on their list of prey, we would not have any more domestic/feral cats in Statesville. In most studies, cats only make up 1-2% or less of the diet of urban coyotes (MacCracken 1982, McClure et al. 1995, and Bollin-Booth 2007). Coyotes are actively engaged in the ecosystem as urban predators. They are influencing ecosystems by mostly eating small rodents and rabbits. They have been also known to scavenge deer carcasses. On occasion, they may be able to bring down deer. None of these are bad for the ecosystem since we do not currently have a rodent, rabbit, or deer shortage in Iredell county.
Coyotes are not only directly influencing the movement patterns of their prey, they are also influencing competitors. We have been able to analyze our camera trap data in such a way to look at the overlap of activity between two species. Figure 5 shows the activity pattern of coyotes compared with squirrels. Squirrel activity peaks between 9-10am, and then again around 5pm. Both are these times are when coyote activity is decreasing. Squirrel are not active at night when coyotes are. This is smart if you’re a squirrel.
What if you’re a deer? Figure 6 shows coyote/deer overlap. Deer activity seems to peak between 7-8am, but then again around 8pm when coyote activity is high. This may indicate that, in Iredell county, coyotes are not a threat to deer. Deer activity stays higher than coyotes during the day, but slightly lower than coyotes through the night.
Figure 7 shows coyote/rabbit overlap using a large dataset. You can see that rabbit activity is the greatest in the morning, just a little earlier than squirrels. However, when we break down our data into green spaces versus back yards, we see a different pattern. Figures 8 and 9 show coyote/rabbit overlap in green spaces and back yards, respectively. “Dhat1” measures overlap on a scale from 0-1, with 0 being no overlap in activity and 1 being 100% overlap in activity. There’s a higher overlap in green spaces. Also, the back yard rabbits seem to like to be out right after midnight. Maybe coyotes are influencing the behavior of rabbits in Statesville.
What about other animals that aren’t prey? Figures 10 and 11 show the overlap between coyotes/raccoons and coyotes/cats, respectively. Raccoons look to be even less active during the day than coyotes and more active during the night. Cats, on the other hand, are all over the place. Their activity peaks around 7pm, right before coyote activity during the night peaks.
Coyotes are carnivores. Coyotes are active. Coyotes are clever and curious. However, for the most part, they want nothing to do with you or your pets.
We should be careful when we speculate. For example, it is hard to determine whether domestic/feral cats disappeared because of coyotes or for another reason. Just because a pet disappears does not mean that coyotes “got” it. Blaming coyotes for everything only increases the fear factor.
One way we can better understand how (or if) coyotes are influencing other animals is to look at how other species use habitats with a coyote presence compared with how they use habitats with no coyote presence. This “intensity” is measured by the # of detections/total # of detection days (duration). Figure 12 shows us what we would expect. Squirrels are not detected as much in areas where coyotes are present. Again, this is good for the squirrel. Figure 13 shows us the same pattern with deer. Maybe this is just coincidence or maybe it means that deer simply don’t stay in coyote-occupied habitats too long. Figure 14 seems to show us something unexpected. It looks like, at least in Iredell county, that raccoons thrive in the presence of coyotes. It doesn’t look like they are impacted at all. Finally, figure 15 shows us domestic/feral cats and dogs decrease activity in habitats that are occupied by coyotes.
Coyotes may influence how intensely certain species use certain habitats. Coyotes probably play a part in influencing the activity of certain species. However, this does not mean they coyotes are responsible for the disappearance of all pets.
Is it fair to call coyotes “non-native” or “invasive”? To properly answer this question, we need to explore the issue and find out where they came from, how they got here, and why they came. Also, it doesn’t hurt to delve into the latest research on canine genetics. It does no good to speculate or simply rattle off stories that you have heard from sources that were probably not reliable.
Let’s debunk some myths. We do know is that coyotes were not introduced into NC by state officials because they had made a deal with insurance companies. This story states that NC officials released them to help control the deer population because there were too many automobile accidents. It’s simply not true.
In 2008, Iredell County Animal Services and Control sent out a publication that says at one point in the past, foxes were in so much demand for hunting that someone transported coyotes from Virginia into Iredell County to replace them. Hurricane Hugo, which came through the county in 1989, supposedly demolished the coyote pens, and they all escaped into the wild. These coyotes then reproduced and created the current problem. Some people believe that these hunters were solely responsible for bringing coyotes to NC. This is also not entirely true.
The most probable way coyotes infiltrated Iredell county is by a natural process we call migration. Hunters bringing coyotes to Iredell county in the 1980’s may have helped them spread faster into the area, but coyotes expanded into the area naturally by moving into a territory that was once occupied by wolves.
As you can see in the illustration, coyotes have recolonized North America over the last 100 years. There is no doubt that our eastern coyote here in Statesville is a hybrid. What’s remarkable is the evolutionary story this creature has to tell. Studies show that the eastern coyote is actually a mixture of 3 species: coyote, dog, and wolf. Here’s the breakdown by genes:
Genome of coyotes in the Northeast 60%-84% coyote, 8-25% wolf, and 8%-11% dog
Genome of coyotes in Virginia 85% coyote, 2% wolf, and 13% dog
Genome of coyotes in the Deep South 91% coyote, 4% wolf, and 5% dog
As you can see, this mixture changes as you move south along the eastern region of the U.S. Even though coyotes show evidence of hybridization, most researchers do not think they are still naturally mating with dogs or wolves. We have no wolves here in North Carolina, except for the tiny population of red wolves along the coast. Even those red wolves show a mixture of gray wolf and coyote genes.
By most accounts, coyotes are described as “non-native” and “invasive.” Those are two words that may not be suitable in this case. Should we refer to a species as non-native if it came into an area naturally? To call a species invasive, you would need to show that it is negatively impacting the ecosystem. Are coyotes doing this? It seems that they are simply occupying a niche that was left open when the wolves that once roamed NC disappeared.