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Gray foxes coordinate attack on turkeys

This is a remarkable bit of trail camera footage from Putnam County, Florida.

Here we have two gray foxes coordinating an attack on a flock of Osceola turkeys. They are engaging in behavior I’d expect more from wolves or coyotes.  One fox harries the birds, while the other sneaks around from behind.

Although the foxes don’t catch a turkey that day, they might sometimes succeed if they keep doing this behavior.

I’ve read old accounts of gray foxes working together to hunt rabbits, but I put them away as hearsay.

After seeing this footage, I am convinced they do sometimes engage in cooperative hunting.

Gray foxes, especially in Florida, aren’t that big, and a turkey is a fighting dinosaur of a chicken. My guess is they aren’t regularly preying on mature turkeys, but they do engage in this sort of behavior to test them in much the same way wolves test elk or caribou.

Maybe I’m reading too much into this footage, but it is pretty remarkable.

I’ve always admired the gray fox. It’s a truly unique American canid, for it has no Old World congeners.

They and turkeys have been interacting for millions of years in the Southeast and Southwest, a dance far more ancient than wolf and bison in Yellowstone. And certainly far more ancient than man versus beast on this continent.

And this drama happened in the third most populous state in the union, not in some far wilderness of the West. Indeed, just a stone’s throw from the first permanent European settlement in North America.

 

 

Just the Good Ol’ Boy

Sagan turned 11 months old on Tuesday. He is just a good boy all around.

He’s turned into fetching fool.  That Herm Sprenger ball gets a lot of use!

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Chicken study complicates brain size and domestication assumptions

One of the issues I’m most careful with in looking at domestication literature is claims about brain size reduction. Brain size reduction from wolf to dog is a way more complex topic than some popularizers of science would have you believe.

We should also not assume that smaller brains in domestic animals means that the domestic animal are automatically less intelligent than the wild form. In dogs, there is an argument to be made that domestication has enhanced some parts of their intelligence.  I believe part of this problem comes from the romantic delusions that existed in the early study of animal behavior, some of which were openly fascistic in their understanding of wild versus domestic.

A more nuanced way of looking at domestic animals is that their evolution changes to fit an environment that is fully dominated by human society.  In this world, humans are not a major predator, though humans certain do eat many of the animals.  However, the animals live out their lives with humans as benefactors and protectors, and the evolutionary pressures that work on domestic animals change how their brains operate.

A recent study on red junglefowl found that selection for a lack of fear does change their and brain anatomy. The researchers bred a high fear line and a low fear line of red junglefowl. The low fear line birds had smaller overall brains.  However, they much reduced brainstems and tended to have larger cerebra than the high fear line ones. They had a harder time with remembering fearful situations that the high fear line birds easily remembered, but both strains were of equal ability in terms of general associative learning.

This means that the domestication process does not just dull the intelligence of a species and make its brain smaller. Instead, the process makes it easier for the species to live in concert with our societies.

Our popular understanding is that dog domestication made them significantly less intelligent than wolves, and the best proof we have is the proportionality of brain size, as well as some low n experiments that looked at problem-solving ability between captive wolves and very well-trained domestic dogs.

We need to be very careful about what these studies say, for domestication is a process of evolution as much as anything that goes on in the wild. To live with humans in the way that domestic dogs do, their brains have experienced rather dramatic changes from the wild form, and we must be careful about making simplistic explanations that posit “domesticated” as a synonym for “dumber.”

It’s a much more complex conversation, and this study on red junglefowl clearly demonstrates how difficult the reality of brain changes and domestication clearly is.

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Bulldog History III: The Bulldogs of Northwestern Europe

The bulldog family as we understand now is a bit complicated.

One of the harder distinctions in the literature is to come across distinctions between mastiff and bulldog, but it is very clear that by the late Middle Ages, there were specialized dogs that were used as catch dogs on wild boar and to control cattle through gripping.

A certain lineage of these dogs became known as bulldogs in the British Isles, but there are three other lines that are not as well explore.

The first of these lines is the Bullenbeisser and the Bärenbeisser lineage. These dogs appeared in Germanic Europe, including areas of the Netherlands and Belgium.

These dogs were evident in that region by the seventeenth century, where nobles used them to hunt wild boar and bears, and in some eastern region, the relict populations of aurochs. They also likely grappled with wolves, but I could find very few accounts of them being used for that purpose. These were the dogs of the nobles, and they were famous in their courage as catch dogs.

When the Napoleonic Wars transformed this part of Europe, things changed dramatically.  Although Napoleon was an autocratic ruler, his revolutionary ideas changed the remnants of feudal society in that region, which meant that nobles had to give up a lot of their traditional hunting estates.

These Germanic bulldogs wound up in the hands of cattle dealers, who used them in much the same way the British had used them. They were cattle controlling dogs that were sometimes used for baiting contests.

By the nineteenth century, two distinct strains were evident.  In the region around Danzig, a large bulldog called the Danziger bullenbeisser was pretty common.  In Belgium and the Netherlands, a smaller strain was developed called the Brabanter bullenbeisser,

We know now that the Brabanter bullenbeisser was quite common as a pet in Munich, and in the very last few years of the nineteenth century, this breed was bred with the variants of the English bulldog (and supposedly one black schnauzer) to found the modern boxer breed.

In France, a very similar story went with their bulldogs.  What we call the Dogue de Bordeaux is actually a bulldog, not a mastiff. It is the last survivor of a long line of French catch dogs. The larger ones were called dogues and the smaller ones were called doguin. Noble families used them as catch dogs, but as France lurched into a Republic, the dogs became commonly used as working bulldogs in much the same way that the English used theirs.

Today, when we think of French bulldogs, we think of the small ones that became popular in Paris at the end of the nineteenth century. These dogs were largely created by the pet market in England, then transported to France, where they were widely accepted. I will have more on these bulldogs in a later post, but they are not the traditional bulldog of France. The dogue and the doguin are.

Some may quibble with my inclusion of the dogue as a bulldog. But we know from genome-wide assays that the bulldog of England, the boxer, and the Dogue de Bordeaux form a clade.

That means that these dogs share a deep common ancestry in Northwestern Europe. Indeed, these three breeds share a close common ancestry that puts them closer to each other than to the other bulldog breeds.

This discovery raises an interesting idea. There have been attempts to re-create the Brabanter bullenbeisser through crossbreeding boxers with other bull breeds.  The result is the Banter bulldogge.

However, I’ve been more interested in the Danziger bullenbeisser, which was larger, and my guess is to recreate that breed, you would breed the boxer to the Dogue de Bordeaux and then select for black skin pigment, brindle and fawn color, and a more athletic build.

So it has captured my imagination a bit. Big, fell bulldogs really didn’t have much of a place in Europe as the larger game species disappeared, but in the American South, the larger bulldog would hold on.

That will be the next installment of the this series.

***

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So does the maned wolf break the “costs of carnivory” paradigm?

In recent post I wrote about the new research regarding the thylacine’s size, I mentioned that maned wolves might violated the “costs of carnivory” rule, which states that predatory mammals that weigh more than 21 kilograms (46 pounds) must haunt larger prey sources to survive.

Maned wolves do exceed this size, but their diet does not consist of large prey. They are not a threat to ungulate livestock. They take only small prey, such as rabbits, rodents, and small birds. They could be a threat to chickens and other poultry, but they aren’t cattle killers.

On a superficial reading of their ecology and diet, one would assume they would break this 21 kilogram rule. The largest ones do get to around 23 kilograms, and if they are that large, then they surely break this “costs of carnivory” rule.

But they don’t.

The reason is they have a most unusual diet for a canid.  Between 40 and 90 percent of their diet can consist of a single fruit called a lobeira or “wolf apple.” The average diet of a maned wolf is around 50 percent vegetable matter, which means they aren’t as bound by the rules of carnivorous diets as other mammalian predators are.

The maned wolf first appeared in the fossil record in what is today the Desert Southwest what is called the Blancan faunal age (late Pilocene to early Pleistocene).

It entered South America, along with a whole host of other canids, and it evolved to a specialist niche as a grassland predator. Many species of similar-sized dog were also diversifying in South America, it is likely that it evolved its unusual diet as a way of avoiding competition with more carnivorous canids.

So vegetarian are maned wolves that when fed a typical wild carnivoran diet in zoos, they often develop bladder stones. Their kidneys cannot absorb a particular amino acid called cystine, and the excess cystine turns into stones.

Most mid-sized canids are true generalists in their diets. The exceptions are the maned and Ethiopian wolves. The Ethiopian wolf runs between 14-19 kilograms, so its rodent specialized diet does not violate the rule.

But the maned wolf’s heavily frugivorous almost takes them out of the predator guild entirely.  They are as almost omnivorous as most bears are, and all extant bear species exceed 21 kilograms at maturity.

So maned wolves don’t violate the costs of carnivory rule. They do so, because they are far less predatory than virtually any other dog species. They are certainly less predatory that other dogs of their size.

T

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The Thylacine was more a marsupial coyote than a marsupial wolf

One of the most common memes in our popular understanding of zoology is that the thylacine of Tasmania was the marsupial equivalent of the gray wolf.  This idea comes from a rather superficial understanding of its morphology, and lots of speculation about its behavior have stemmed from this popular understanding. One idea is that they were pack-hunters like wolves and dingoes, and they would have been murder on Tasmania’s sheep industry. Therefore, the final extinction of the thylacine was largely predicated upon a rational fear that the creatures would have been detrimental to sheep husbandry.

A lot of these speculations come from a belief that the thylacine was quite large. As I have discussed before on this space, larger carnivores are largely forced to hunt larger prey to survive. Otherwise, the larger size is of no benefit to the animal. Ecologists have found that the mass of 21 kg (about 46 pounds) is the size at which a carnivorous mammal can no longer subsist on smaller prey alone.

Thylacines were estimated to have weighed 29. 5 kg (about 65 pounds), which meant that their diet would have been larger prey. However, really big prey species are almost absent from Tasmania. The largest kangaroo in Tasmania is the Tasmanian Eastern gray kangaroo, which weighs is roughly the size of the smaller forms of white-tailed deer in the US.  Further, analysis of Thylacine skulls revealed that they could not withstand very much force. So the thylacine would not have been a very effective predator of prey the size of an Eastern gray kangroo, and it would have had a lot of trouble grappling with a fully grown sheep.

The fact that thylacines would have had problems killing large prey creates a contradiction in their supposed larger size.  If thylacines really did weigh 65 pounds on average, then they would be a major exception to the rule that larger predators must hunt larger prey to survive.

Well, a new analysis by researchers at Monash University has revealed that traditional estimates of thylacine size were greatly exaggerated.  Using complex morphometric analyses on various preserved specimens, the researchers revealed that the mean weight of a male thylacine was 19.7 kilograms (43 pounds). The mean weight of a female was 13. 7 kilograms (30 pounds).

These animals would have been roughly the same size of an Eastern coyote. Now, Eastern coyotes can live on large prey or small prey, and they can scavenge quite well. But they have skulls that can withstand blunt force from a sheep or a deer that a pack of them has run down. The Eastern coyote can live as a fox or a wolf, depending upon the conditions of the ecosystem in which it lives.

A thylacine would have been a smaller prey specialist, and because its weight did not exceed 21 kilograms, its subsistence on smaller prey did not violate the “costs of carnivory” rule.

Indeed, the only predatory mammal I can think of that does come close to violating this rule is the maned wolf, which sometimes weighs 22 or 23 kg. It lives almost entirely on small prey and fruit. This species has been persecuted for its attacks on livestock, but like the thylacine, it is not much of a threat to them.

Of course, there will be debate about this finding. Many historical accounts of thylacines suggest or imply or even outright claim that they were killing sheep and dogs left and right.

But the truth is that Europeans had their own concept of what a creature like this could do or was likely to do, and they merely transposed these ideas onto a creature that had the superficial appearance of a wolf or hyena.

We should by now stop trying to pigeonhole the thylacine into a marsupial wolf and should try to appreciate it for what it was.

Or might still be.*

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*I don’t believe they still exist, but I certainly wish they did!

 

 

 

 

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