Tanuki: Diet

Summary: What are Tanuki eating? Join Kiersten as she discusses just what raccoon dogs are eating in the wild.

 

For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean

 

Show Notes: 

Biology and Conservation of Wild Canids, edited by David W. Macdonald and Claudio Sillero-Zubiri. Raccoon dogs: Finnish and Japanese raccoon dogs - on the road to speciation?” By Kaarina Kauhala and Midair Saeki, pgs 217-226. https://static1.squarespace.com

 

Music written and performed by Katherine Camp

 

Transcript 

(Piano music plays)

Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

(Piano music stops)

Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating. 

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

This is episode three and the third thing I like about raccoon dogs is their diet. I actually do enjoy some of the same foods that raccoons dogs eat, but what I really like about their diet is how varied it is depending on their location.

As mentioned before, Tanuki are classified as omnivores. Omnivores are animals that eat both meat and veggies. This is exactly what the Tanuki does. Let’s look at what often determines the kind of food animals eat, their teeth.

Tanukis are canids, which is the family of animals that include wolves, foxes, and domestic dogs. These animals usually share the same kind of dentition, or structure and layout of teeth. Most canids are classified as carnivores, even though many do eat fruits and vegetables at some time during the year.

Takunis have six incisors in the top jaw and six incisors in the bottom jaw. They have two canines, top and bottom. They have four premolars, top and bottom. And two to three molars, top and bottom. This gives them a total of 42 to 44 teeth. This is a typical amount for a canine. In canids, the premolars are carnassial teeth. These are essentially modified molars that are sharp to help shred and tear meat. The carnassial teeth in the Tanuki are reduced compared to other canids and their molars are larger. This pattern speaks to their omnivorous diet.

In the previous episodes we discussed a few differences between the indigenous Japanese populations and the introduced Finnish populations. We will continue this comparison with their teeth, because there are noticeable difference between the different populations, so much so that scientists can determine the origin of a raccoon dog by inspecting their teeth. Whoa! That’s exactly what I thought, too!

The case study I’m referencing measured 65 skulls from Finland raccoon dogs and 104 skulls from raccoon dogs in Honshu, Japan. They took 22 different measurements of adult teeth and skulls. The skulls of Finnish raccoon dogs were larger both overall and in relative body size than those of the Japanese population. Mandible width and jaw height were the most useful measurements in determining location of each raccoon dog with a 100% correct classification. 

The mandibles of the Finnish raccoon dogs are more robust with a more powerful jaw than those of Japanese origin. Japanese individuals have a longer snout with longer tooth rows than the Finnish specimens. Molars of the Japanese raccoon dogs are larger in relation to skull size versus the Finnish Tanuki. What do these differences in skull and tooth morphology tell us about these creatures? Excellent question, listeners! It tells us what they are eating. 

So what are Tanuki eating in the wild. As we just discovered, it appears to depend on where they are located. I find that fascinating! They are the same animal but their diet varies depending on what habitat they live in. It shows how adaptable they are and this is certainly an attribute they share with the North American Raccoon, after whom they are named. 

Tanuki, in general, are ominous, which means they eat both meat and vegetation. The percentage and type of food varied depending on Japan versus Finland. As we just determined, Finland raccoon dogs have slightly larger jaws meaning their massater muscles are larger which in turn mean they probably eat more meat and possibly larger prey than Japanese Tanuki. 

How do researchers determine what animals in the wild are eating? Poop! A lot of poop. Scientists, often undergraduates eager to get into the sciences, collect lots and lots of feces. You have to note the area where it is found, the date, time of day, and any other factors that might be important, such as the weather. These samples are then returned to the lab were they will be processed and someone gets to dissect an awful lot of poo! 

In this case study the researchers determined that thought the year the diet of raccoon dogs, whether in Finland or Japan, varies. This is most likely due to natural resource fluctuations. In Finland frogs, lizards, and invertebrates are commonly eaten in summer and autumn. Fish are eaten in late winter. Berries and fruits are eaten in late summer and autumn. If we look at food resources in percentages we see 56% of mammals, voles and shrews being very popular, 34% were bird remains, 8% were frogs or lizards, 20% fish, 51% invertebrates, 89% plants, and 49% carrion, which is dead, decaying animal matter.

A note on the most common bird remains found in Finland raccoon dog feces, the Common Eider, a type of duck found in coastal waters, and eggs were most often found in Finland’s raccoon dogs feces. It is not believed that at the time of the recording of this podcast that the predation of the Tanuki on the Common Eider in Finland detrimentally impacts their populations.

Let’s take a look at the diet of the Japanese populations. In Japan, Tanuki diet has been studied in different habitats. For the most part, it follows the same pattern as the Finland population with invertebrates fruits, rodents, birds, frogs and fish. In the subalpine zone diet consisted of 90% insects mainly Coleoptera, which is the family that includes a lot of beetles, and these were seen year round. 58% included earthworms except in the cooler months of January to April. Berries and seeds made up 49% of the diet. These were also seen year round with a lower amount in January to April when fewer plants are producing berries and seeds. 46% of the diet consisted of small mammals, January to June. 

In mountainous regions diet consisted of 78 to 100% of Coleoptera insects in spring and summer, Orthoptera in autumn, that’s grasshoppers and crickets, and Hemiptera, which includes the True Bugs, in winter. Fruits are eaten year round with a percentage of 77 to 100%, except in May. This is may be because the fruits are just ripening at this time. From April to December, crustaceans, such as Japanese freshwater crabs, make up 28 to 71% of the diet with fish at 9 to 27%, birds 8 to 21%, small mammals 7 to 25%, carrion consisting mainly of sika deer and serow, aka goat-antelopes, at 10 to 37%. 

In the countryside, insects seem to be the most important food resource year round with available fruits such as persimmon supplementing the diet in autumn and early winter. 

In urban and suburban areas, raccoon dogs will feed mainly around human dwellings and have included garbage into their diet. No surprise there! Any animal that has adapted to living in human dominated areas has taken advantage of our propensity to create a lot of trash. Garbage was found year round at a percentage of 72%, with insects, mainly beetles, at 46%, persimmon fruit at 30% in spring and summer, earthworms at 24%, birds at 21% in winter and spring, and Myriapoda, millipedes and centipedes at 11% year round.  

This may have been a bit more specific than you expected in our talk about diet. But I found the differences and similarities across the populations interesting enough to highlight the percentages. Plus, someone did a lot of poop scooping and dissection to get this information, so I thought I’d spread the information around as far as possible. No pun intended. 

Once again I think this episode shows the adaptability of the Tanuki and makes them an even more fascinating canine. Thanks for hanging in there to the end, listeners, because my third favorite thing about this unknown canine is their diet.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change. 

 

Join me next week for another fascinating episode about Tanuki.    

 

(Piano Music plays) 

This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.