2017 Spring

Coyote Misconceptions

The recent coyote attack in Iredell county is unfortunate and sad. Someone lost a pet in a matter of seconds. Human fear and emotions are real and for good reason. The dog was likely attacked with no warning at all.

In situations like this, comments like, “What do we expect? We have built houses in their habitat” are not helpful. It also does no good to simply say, “If I see one, I am going to just shoot it!” or to argue whether or not you can actually shoot a coyote within city limits. These comments bring little comfort to the people who have seen coyotes in their neighborhoods and are frightened. What may actually help is understanding coyote behavior and knowing what the scientific literature says about this urban carnivore.

For the past 6 years, researchers at Mitchell Community College have surveyed areas around Statesville using motion-activated trail cameras. The following picture shows where coyotes have been observed (highlighted in yellow).

Figure 1. Statesville, NC coyote habitat. Diagram is based on data collected from Mitchell Community College Trail Camera Studies.

As you can see, if there is a green patch within city limits, these animals can be successful. Individual coyotes or pairs can typically have smaller home ranges in urban environments because resources (i.e. food) are greater. Below, we have attempted to provide answers to some coyote questions by compiling data from scientific articles. We have also used some of our own camera trap data from Statesville.

1) Have coyotes just recently learned to live with people? Nope.

In a recent news article, a N.C. Wildlife Resources Commission biologist was quoted as saying coyotes are “getting used to people.” This makes it sound like the co-existence between coyotes and humans is relatively recent. It’s not. Coyotes have never been solely wilderness creatures. For the 15,000 years since humans have inhabited North America, coyotes have been living alongside us (Flores 2016). Besides, we do not ever want coyotes to get used to us to the point where they feel comfortable.

2) Are coyotes “non-native” and “invasive”? It depends on how you define “non-native.” As far as invasive goes, not by a long shot.

It is probably accurate to say that coyotes are the most persecuted animal in North America, with 500,000 of them killed every year (Flores 2016). What makes them different than any other urban animal is that they are deemed a “problem” just because of their presence. By most accounts, coyotes are described as “non-native” and “invasive.” Those are two words that may not be suitable in this case.  In 2008, Iredell County Animal Services and Control sent out this publication. It states that 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. Judging by how fast coyotes have spread into other counties throughout North Carolina, it is unclear whether this single event helped coyotes spread into the area faster than they normally would have. Even though coyotes may not have always inhabited North Carolina, red wolves once did. Since recent genetic research has shown that 80% of the red wolf genome is similar to coyotes, you could make an argument that coyotes (their genes, anyway) are native (VonHoldt 2011).

3) Are coyotes beneficial to urban ecosystems? Yes.

As is the case in Statesville, coyotes are the top predator in most urban ecosystems. Crooks and Soule (1999) showed that coyotes regulate a trophic cascade mechanism within fragmented landscapes. In the absence of coyotes, mesopredator (like raccoons or cats) populations increase. When mesopredators increase, songbirds tend to decrease, so you could make the argument that coyotes benefit native songbirds. Coyotes can also influence foxes, cats, raccoons, and skunks through direct competition. They may even influence behavior in domestic cats in urban environments (Kays et al. 2015). At our urban green patch sites, we did not catch any domestic cats. However, at our backyard sites over the same period of time, we had 22 independent captures of cats. So, maybe cats know where to go and where not to go. Through direct predation, coyotes do regulate rodent, rabbit, and in some areas, deer populations. For example, look at both Figures 2 and 3.  Coyote and rabbit activity overlap is higher in Statesville green spaces (Figure 2) than in backyards (Figure 3). You will also notice that rabbit activity peaks soon after midnight in backyards where coyotes are less dense (Figure 3). In Statesville green patches, rabbit activity peaks a little before 6 a.m. and right after 6 p.m. Are coyotes changing the behavior of rabbits in urban environments?

Figure 2. Coyote and rabbit activity overlap in urban green patches.

Figure 3. Coyote and rabbit activity overlap in urban backyards.

4) Do coyotes pose a danger to pets? Obviously, yes, but conflicts are rare.

Occasionally, coyotes do kill pets, but it is hardly a common occurrence. Contrary to popular belief, coyotes do not simply eat garbage and harass pets. It’s not the dumpsters or the small cats that attract coyotes to urban areas. Coyotes are top-level carnivores here in Statesville, and they are actively engaged as predators. Most conflicts with pets are because coyotes view small dogs and cats as competitors, not as food. In fact, this competitive response is similar to the response that coyotes show towards smaller foxes. Coyotes in urban ecosystems do not depend on pets as food (Gehrt 2007).  If they did, we would not have any pets left. 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). Our studies have shown that coyotes prefer cottontails in Statesville.

5) Are coyotes dangerous to humans in urban environments? Typically, not at all.

Coyotes have been documented attacking people. In 1981, a small child died from a coyote attack (Howell 1982). In 2009, White and Gehrt classified 142 U.S. and Canadian coyote attack reports. They categorized the attacks as follows:

Predatory- 37%

Investigative- 22%

Pet related- 6%

Defensive- 4%

Rabid- 7%

Like the recent attack in Statesville, most of the attacks occurred during pup-rearing season (May-July). “Problem” coyotes seem to be those that have become habituated to humans. Most urban coyotes avoid humans by shifting to more nocturnal activities. Our data certainly indicate this. Over 126 days, we collected 56 independent coyote captures on our cameras within city limits. Our data show that coyotes within city limits are, on average, 68% nocturnal. Four capture sites in one particular area showed that coyotes were 89% nocturnal.

Habituation could be the result of intentional or unintentional feeding of wildlife or avoiding them when they are seen. To successfully live with these predators, it is always best to yell and scream at them if you see them in your neighborhood. Make sure they stay wild, but also make sure they stay nervous.

6)  Are coyotes frequently reported as rabid wildlife species? Nope.

Rabies is a common fear among those of us that live in the city. The Center for Disease Control reports that raccoons account for most of the rabies outbreaks in the U.S., followed by bats, skunks, and foxes. Unlike raccoons, the coyote-strain rabies (except for a tiny population in South Texas) has not been an issue in the U.S (Clark and Wilson 1995). However, raccoon-strain rabies or raccoon rabies virus (RRV) can spillover into coyote populations. This has happened only occasionally (Wang 2010).

7) Can you ever get rid of all the coyotes? It doesn’t look like it.

If a pest-control company tells you they can take care of the “problem” and eliminate coyotes, they can’t (at least not permanently). Most predators are either solitary (mountain lions) or social (gray wolves), but not both. Coyotes, however, can be both. They can also catch a variety of prey, from small mice to deer. These are just some of the characteristics that allow them to live just about anywhere. Also, coyotes seem to be somewhat immune to exploitation. Knowlton et al. (1999) showed that unexploited coyote populations tend to have older age structure, high adult survival rates, and low reproductive rates. However, in highly exploited populations, coyotes are characterized by younger age structures, lower adult survival rates, and increased percentages of yearlings reproducing, and increased liter sizes. What can you do? Removal programs that target problem coyotes on an individually basis may be more cost-effective. It is important to remember how you define “problem”. Not all individual coyotes are problems just because of their presence.

 

References

Bollin-Booth, H. A. 2007. Diet analysis of the coyote (Canis Latrans) in metropolitanpark systems of northeast Ohio. Master’s thesis. Cleveland State University, Ohio.

Crooks, K. R., and M. E. Soule. 1999. Mesopredator release and avifaunal extinctions in a fragmented system. Nature, 400: 563-566.

Flores, D. 2016. Coyote America: A Natural and Supernatural History. Basic Books: New York, NY.

Gehrt, S. D. 2007. Biology of coyotes in urban landscapes. Pages 303-311 in D. L. Nolte, W.M. Arjo, and D. H. Stalman, eds. Proceedings of the 12th Wildlife Damage Management Conference. Corpus Christi, TX.

Howell, R. G. 1982. The urban coyote problem in Los Angelos County. Pages 21-23 in R. E. Marsh, ed Proceedings of the tenth Vertebrate Pest Conference. University of California, Davis.

Kays, R. et al. 2015. Cats are rare where coyotes roam. Journal of Mammalogy, 96: 981-987.

Knowlton, F. F., E. M. Gese, and M. M. Jaeger. 1999. Coyote depradation control: An interface between biology and management. Journal of Range Management, 52: 398-412.

MacCracken, J. G. 1982. Coyote foods in a Southern California suberb. Wildlife Society Bulletin, 10: 280-281.

McClure, M. F. et al. 1995. Diets of coyotes near the boundary of Saguaro national monument and Tucson, Arizona. Southwestern Naturalist, 40: 101-104.

VonHoldt, B. M. et al. 2011. A Genome-Wide Perspective on the Evolutionary History of Enigmatic Wolf-Like Canids. Genome Research, 8: 1294-1305.

Wang, X. et al. 2010. Aggression and Rabid Coyotes, Massachusetts, USA. Emerging Infectious Diseases, 16: 357-369.

White, L. A., & Gehrt, S. D. 2009. Coyote Attacks on Humans in the United States and Canada. Human Dimensions of Wildlife, 14(6), 419–432. http://doi.org/10.1080/10871200903055326

 

Suggested Readings

Bekoff, M. 1977. Canis latrans. Mammal Species, 79:1-9.

Gehrt, S. D., Wilson, E. C., Brown, J. L., & Anchor, C. 2013. Population Ecology of Free-Roaming Cats and Interference Competition by Coyotes in Urban Parks. PLoS ONE, 8(9), e75718–11. http://doi.org/10.1371/journal.pone.0075718

Gehrt, S. D., C. Anchor, and L. A. White. 2009. Home range and landscape use of coyotes in a major metropolitan landscape: Coexistence or conflict? Journal of Mammalogy, 90: 1045-1057.

Gehrt, S. D., & Prange, S. 2006. Interference competition between coyotes and raccoons: a test of the mesopredator release hypothesis. Behavioral Ecology, 18(1), 204–214. http://doi.org/10.1093/beheco/arl075

Heinrich, R.E., Strait, S.G., and Houde, P. 2008. Earliest Eocene Miacidae (Mammalia: Carnivora) from northwestern Wyoming. Journal of Paleontology, 82: 154–162.

Kays, R., Curtis, A., and Kirchman, J. 2010. Rapid adaptive evolution of northeastern coyotes via hybridization with wolves. Biology Letters, 6:89-93.

Kilgo, J., Ray, S., Vukovich, M., Goode, M., and Ruth, C. 2012. Wildlife Management, 76:1420-1430.

Meachen, J., Janowicz, A., Avery, J., and Sandleir, R. 2014. Ecological Changes in Coyotes (Canis latrans) in Response to the Ice Age Megafaunal Extinctions. PLoS ONE 9(12): e116041. doi:10. 1371/journal.pone.0116041

Meachen, J. and Samuels, J. 2012. Evolution in coyotes (Canis latrans) megafaunal extinctions. PNAS, 109: 4194-4196.

Mech, L. D. 1974. Canis lupus. Mammal Species, 37:1-6.

Newsome, S. D., Garbe, H. M., Wilson, E. C., & Gehrt, S. D. 2015. Individual variation in anthropogenic resource use in an urban carnivore. Oecologia, 178(1), 115–128. http://doi.org/10.1007/s00442-014-3205-2

Tallian, A., Smith, D. W., Stahler, D. R., Metz, M. C., Wallen, R. L., Geremia, C., et al. 2017. Predator foraging response to a resurgent dangerous prey. Functional Ecology, 96, 1151–12. http://doi.org/10.1111/1365-2435.12866

 

A Relationship Older Than Dirt

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Lichen and moss living together on an oak

No one made chasing down ancient artifacts cooler than Indiana Jones. He would leave the safety of his classroom, which required battling bad guys, to track down artifacts. Fortunately for us, all we have to do is step outside to be in the midst of something much more primitive than anything Dr. Jones collected.

Take a walk, and you will easily find yourself in the presence of a species from another age. It surrounds us, but we rarely notice it. Some researchers even think it may have even laid the foundation for terrestrial life. It’s not just one species. It’s two different species intertwined as one, which creates various types of colors and structures.

Lichen is actually a symbiotic relationship between two partner species. The mycobiont partner is a fungus that gives structure to the lichen. Fungi are made up of eukaryotic cells, meaning the internal structure is made up of organized compartments and also a membrane-bound nucleus that stores and protects the delicate genetic code. As such, fungi are heterotrophic organisms,  obtaining their nutrients externally. In the case of fungi, food comes in the form of fixed carbon, which is often acquired through the process of decomposition. If not through decomposition, the fungus must get the required carbon through a symbiotic relationship with a partner.

A photobiont is the second partner into this lichen relationship.  Either green algae or cyanobacteria can fulfill the needs of the fungus because they can both photosynthesize. Green algae belongs to the plant kingdom and cyanobacteria is a prokaryotic organism so they are not even grouped together. However, they both have the ability to harness light energy from the sun and use it to make food in the form of glucose, or sugar (carbon source). This works out well for the fungus. The photobiont provides an endless supply of glucose for the fungus, and in return, the fungus provides structure and protection. This partnership seems to have set the stage in primitive times for two important events.

In 2001, results from a massive genetic study revealed that early plants and fungi played a major role in instigating the environment in such a way that global glaciation and the evolution of land animals eventually both took place. The process of photosynthesis, presumably from the photobiont partner, was a major player because it takes up carbon dioxide, thus lowering atmospheric levels, and at the same time, increases oxygen levels. Here’s what the overall process looks like:

                                                                       sunlight
                 Carbon dioxide + Water  —————>  Oxygen + Glucose (carbon-based sugar)

This particular study looked at when, specifically, plants and fungi colonized land. Earlier studies had concluded that both came on land about 480 million years ago (mya). Before that, supposedly only rocks and bacteria covered the land. Campbell Biology, a popular academic text, states, “But it was only within the last 500 million years that small plants, fungi, and animals joined them (bacteria) ashore.” Heckman et al. (2001) concluded that for plants actually colonized land 700 mya and fungi around 1300 mya. This is significant because this would mean that these two groups colonized land during the Precambrian, the oldest geological eon. If land fungi and plants did appear during the Precambrian, how exactly could they have played a role in both ice age events and the explosion of various animal forms that we see in the fossil record?

screenshot-2017-01-21-13-57-41

Figure 1. Geological time By United States Geological Survey [Public domain], via Wikimedia Commons

To understand this, it is important that one understands just how hard it is to live on land. Compared with living in the water, or at least near water, plants need to have certain vascular tissue like roots, stems, and leaves to transport water and sugars. Some plants benefit from having a thick waxy layer on leaves to keep too much water from escaping. Living on land is tough, and it would have been especially hard 700 mya. This is where lichen come into the picture.

The terrestrial plants and fungi were not living separately during this early time. They were living in this lichen relationship. It was this relationship that allowed them to live in these harsh conditions. Lichen can live without rain for months, which explains why it is found in harsh places like the arctic and the hottest deserts. Early in the earth’s history, the green algae needed protection, which is exactly what the fungi provided. Now, photosynthesis could work on a large scale. Carbon dioxide levels in the atmosphere decreased and oxygen levels increased.

When carbon dioxide levels decrease, global temperatures decrease. Photosynthesis probably was the main reason why the Earth experienced global glaciation events from 750 mya to 580 mya. This time period lines right up with the appearance of lichen and early land plants like moss (seen mixed in with lichen in above picture). There may have been some other explanations for the decreased carbon dioxide levels. One may have been the mosses and early land plants that are made up of lignin. Lignin is a tough organic compound that does not easily decompose. Carbon gets “locked” up in the lignin and cannot get out. This ends up eventually producing fossil fuels if the plant material gets buried over years and years. Another event that may have helped the decrease of carbon dioxide levels could have been the fact that the first lichen may have produced acids that dissolved the rocks they were living on. This acid released calcium from the rock. When calcium is washed away, calcium carbonate limestone forms, which prevents carbon atoms from forming carbon dioxide in the atmosphere.

There was an increase in atmospheric oxygen during the Neoproterozoic era, right before what scientists refer to as the Cambrian explosion. Campbell Biology explains the Cambrian period this way, “Early in the Cambrian period, some 530 million years ago, and immense variety of invertebrate animals inhabited the Earth’s oceans.”  In fact, from 535 mya to 525 mya, the oldest fossils of nearly half of all extant animal phyla have been found, including the first arthropods, chordates, echinoderms, and the precursor organisms to vertebrates. The lichen (and the moss) may have been responsible for this oxygen increase that led to this evolution boom of animals.

According to a recent study, soil has only been around for the last 450 mya. If this is true, this lichen relationship is truly older than dirt. The next time you are walking in the woods or even in your own backyard, pay close attention to the lichen growing on the trees and rocks. Then, to show respect to your elder, give a slight nod of the head.


Heckman, D. S. et al. 2001. Molecular Evidence for the Early Colonization of Land by Fungi and Plants. Science, 293: 1129-1133.

Reece, J. B. et al. 2014. Campbell Biology. Boston: Benjamin Cummings/Pearson.

 

NewsBits 07- Laser-activated hunters and the Origins of CRISPR

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If you’ve ever wondered about weird animal organs, here’s your chance to satisfy your curiosity. Learn about 7 animal organs that humans don’t have here.

A woman in Nevada died of a bacterial infection that was shown to be resistant to all available antibiotics in the U.S.  Will the international community realize that something needs to be done or is it too late?

When it comes to intertidal prey, the impacts of coastal bears and raccoons seems to be redundant. Does this mean that in coastal areas where bears have been eliminated, raccoons could fully replace them,?

The story linking Yellowstone National Park and DNA testing is fascinating. You can find a good write-up here.

Why would the fear and hunting behavior of mice be located in the same part of the brain? Scientists have found a way to flip a switch in mice and turn them into hunters.

Another case of parthenogenesis happened with a zebra shark recently. This s not the first time that a female has gotten pregnant without male contact. This process has been observed in species before, including komodo dragons and copperheads. However, it is believed this is the first time a shark has switched from sexual reproduction to asexual reproduction. This particular shark had previously had babies with a male.

Want to learn more about CRISPR? Here’s your chance to understand it in the context of its origins and some of the scientists involved.

Holding Tight

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American Beech trees, still holding leaves in January, are scattered throughout the understory of a local forest.

And to this very day, when all the other trees lose their leaves, the great oaks (and for the sake of this post, the American Beech) keep theirs in memory of their ancestor’s promise. Only in Spring’s time, when the other trees grow new leaves, do the oaks drop theirs. Winter cannot steal spring away and control the weather forever.”

As the days get shorter and colder, trees have an important “decision” to make. They must shed their leaves or hold tight through the winter. Evergreens hold tight to their needles or leaves, but in evolutionary terms, evergreens are old. Over time, trees diversified and accumulated many beneficial adaptations. One of those was the ability to lose leaves. It is these deciduous trees that dominate areas like Statesville, where there are patches of mixed evergreen and deciduous forests. Between evergreens and deciduous trees, there seem to be some that do not obey all the rules. Tree such as oaks and beeches belong somewhere in the middle.  To understand why these trees hold their leaves longer than others, we must first understand why deciduous trees shed in the first place.

Shorter periods of daylight coupled with colder temperatures trigger a hormone in deciduous trees that sends a chemical message to every leaf. This message is to, essentially, “get off.” Cells then appear at the exact point where the leaf and stem meet. These cells start to rapidly divide, creating what is called an abscission layer. The division of these “abscission” cells prevents nutrients from reaching the leaves and also prevents chlorophyll from being replaced. Therefore, the leaves start to die just as other pigments (yellow, red, and orange) start to be seen and enjoyed by many people. Abscission comes from the Latin word abscissio, meaning “breaking off” (think scissors).

Leaves are the main food producers for trees through the process of photosynthesis. The leaves trap energy from the sun and use it to convert water and carbon dioxide into glucose (food) and oxygen. On short, cold days, food production decreases significantly. Deciduous trees choose to push these food producers away rather than keep them around with decreased productivity. Not that there’s anything wrong with retaining what gives you food. Evergreens do it. For example, one of the luxuries that a southern magnolia, a broad-leaved evergreen, has is it is able to produce food through photosynthesis all year long. Another advantage of retaining leaves would be that the tree would not have to allocate energy and resources into growing new ones every year. For deciduous trees, though, the bad outweighs the good.

If there happened to be several warm days in the winter, the leaves would resume photosynthesis (which requires water). If this warm spell was following by a frost, the leaves would be in trouble. The water would be trapped and would freeze. Because water expands when it freezes, the ice crystals would damage internal structures beyond repair, killing cells and tissue. In areas where snow and ice accumulates, entire branches could even be pulled off of trees, putting the tree in serious danger. So, for many trees, abscission keeps trees from becoming damaged and also helps conserve water and energy.

Even with the risks, the American Beech tree, Fagus grandifolia, decides to hold most of its leaves throughout the winter. The process of retaining dead plant organs that are normally shed is called marcescence. How do beech trees get away with this strategy and is there any advantage? There are three main theories, but these theories trigger more questions than answers.

Marcescence could be a trait found in both juvenile trees and/or lower branches of older trees. Holding on to leaves throughout the winter could benefit younger trees simply because after the taller trees shed leaves, more sunlight would reach the bottom. This would allow these understory trees to take advantage of the increased sunlight and photosynthesize longer. The American Beech tree does really well in the shadows of larger maples, oaks, and birches. Could it be that retaining leaves is what allows the beech to be so shade-tolerant? It’s hard to imagine that the beech trees are able to take advantage the increased food production process since their leaves look to be out of chlorophyll in the winter (see the yellowish, brown leaves above).

Another idea is that having these leaves “stick” around plays an important role in nutrient cycling for the tree. If the leaves shed in autumn, they would join all the other leaves on the forest floor and start the decomposition process. There’s a chance that the nutrients produced from this decomposition could leach away and the trees would have none for the spring when they are growing. Instead, the beech trees wait to drop their leaves in the spring to ensure that are some nutrients in the soil. This could be important for small understory trees that have small root systems. However, the problem with this theory is that big leaves often take months to decompose. Maybe there’s another answer.

Retaining leaves may help to deter large herbivores, such as deer, from browsing. At least one researcher thinks that the leaves protect buds and twigs from being chewed off because the leaves are less nutritious and palatable. Svendsen (2001) showed that the European beech tree, Fagus sylvatica, was browsed significantly more by weight and number of branches when the leaves were removed. Chemical analyses revealed that the protein and fiber content of beech twigs was higher of higher quality when compare to marcescent leaves. Maybe these leaves do act as an herbivore deterrent.

No one seems to know for sure why these trees chose to not give in to peer pressure and drop their leaves. It could be one of the previous theories. It could, in fact, be a combination of these theories. It could be something yet to be discovered.

Ah, the beauty of nature.


Svendsen, C. R. 2001. Effects of marcescent leaves on winter browsing by large herbivores in northern temperate deciduous forests. Alces, 37: 475-482.

NewsBits 06- Declining cheetahs, bird migrations, and a beneficial centrifuge

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Mucus is gross, right? Have you ever wondered if this “troublesome” substance has any advantages? This article investigates the advantages of snot.

One recent paper shows that cheetahs are declining in dramatic fashion. With a global population estimated at 7100 individuals, cheetahs are thought to occupy only 9% of their historical range. Not only are they threatened by range contraction, but also range fragmentation.

If you’re interested, you can find out here why a wild monkey tried to have sex with a deer. He even acted in an aggressive manner when other monkeys got close.

Bird migrations look to be well-timed with high levels of vegetation along the way. If this is true, what will be the impact of climate change on these stops? Will there still be food where the birds expect there to be food?

Why hasn’t nectar evolved to be really sweet? The answer will drive you batty. Read here.

The rusty patched bumblebee, Bombus affinis, became the first bee of any kind in the contiguous 48 states to be declared endangered. Its population had declined 87% in the last 20 years. You can read the U.S. Fish and Wildlife announcement here.

The Pioneer Cabin tree, a giant sequoia in California, fell as a result of heavy rains. It was carved out in 1880’s and instantly became a tourist attraction. See here.

And, finally, you can find out here how a researcher constructed a DIY centrifuge that will help developing countries.