May 28, 2017
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SNEEZING, EDIBLE DOG
At https://www.backyardnature.net/mexnat/xolo.htm we look at one of the two dogs who reside with me at the hut in the rancho woods. His name is Chichan 'Cho', and he's of the breed formally known as Xoloitzcuintle, but in regular English often called the Mexican Hairless. At the above link, besides showing Chichan 'Cho''s unusual appearance and going into the breed's genetics, we mention that in the old days Mesoamerican people raised Xoloitzcuintles not only to be eaten, but also as bed-warming sleeping companions. We guess that their hairlessness keeps the flea population down, and note that naturally they have high body temperatures, both features enhancing their qualifications as bedding partners.
Since setting up that page I've learned a lot more about Chichan 'Cho' and the Xoloitzcuintle breed. For instance, something they're famous for is having large, wrinkled feet, as seen at https://www.backyardnature.net/n/17/170528xq.jpg
Also, they seem to adapt very well to human households. Few things please Chichan 'Cho' more than lying next to me as I work, and sleeping as close as he can to me at night. He has a basket to sleep in and that's his favorite place. You can see his snoozing posture at https://www.backyardnature.net/n/17/170528xp.jpg
Chichan 'Cho' snores and farts like a fat man, and what's even funnier -- and I don't know if it's typical of the breed or just to him -- when he gets excited, as when a visitor arrives, he grins broadly, which causes him to sneeze repeatedly. You can see him in the midst of a frenzy of sneezing at https://www.backyardnature.net/n/17/170528xo.jpg
That picture shows another feature typical of the breed: They have bad teeth. You can see that not only are his teeth very irregularly formed and spaced, but also his long, sharp biting teeth, his canines, have fallen out. Chichan 'Cho' can't eat tough flesh like a regular dog, and for that reason villagers often say that the breed is vegetarian. Chichan 'Cho' seems happy to eat banana peels and cut-off papaya husks, and gets very excited when offered a tortilla. Why would Xoloitzcuintles habitually have bad teeth? One guess is that ancient dog breeders, thinking in terms of sleeping with them, might have preferred sleeping companions lacking fangs, and thus bred them for that feature.
The lack of canine teeth and dense fur puts Xoloitzcuintles at a severe disadvantage during dogfights. Chichan 'Cho' loses every tussle he gets into. Even the rancho's cats send him running and yelping with a few swipes of their paws. Keeping this in mind, here's a story to make the point that the breed, or at least Chichan 'Cho', is exceptionally loyal to the master.
A few months ago when I passed by the rancho's dogs as they were being fed I noticed that the aggressive, schizophrenic watchdog known as Sombra left his own food, walked over and pushed Chichan 'Cho' from his dish and began eating there. I'd never had problems with Sombra so with my leg I tried to nudge the bowl back to Chichan 'Cho'. Sombra sank his fangs into my leg (I was wearing shorts), let go and bit again, let go, and took another bite. I'll have six conspicuous puncture wound scars on the back of my right leg for the rest of my life. Anyway, despite Chichan 'Cho''s inability to fight, while Sombra was hanging onto my leg for the third time, Chichan 'Cho' attacked Sombra, knocking him off. Immediately Sombra's fangs were in Chichan 'Cho''s back, but this gave me time to get a pole and knock the heck out of Sombra. So -- loyal dog.
Living with a Xoloitzcuintle is almost like having a little clown in the household, and it's always nice to have a loyal friend nearby. Still, I'd not advise anyone to encourage the breed's dispersal. That's because these dogs suffer in ways other dogs don't. Being unable to defend themselves in dogfights, they always have low status in any pack that forms. Without coats of hair, once the temperature drops below about 60°F (15°C), they shiver pitifully. Also, with those bad teeth, frequently they have toothaches. A while back the whole side of Chichan 'Cho''s face swelled up, until a tooth came out. And those big feet seem particularly vulnerable to infections. Poor Chichan 'Cho' spends as much time gnawing and chewing at his paws as regular flea-bitten dogs spend scratching themselves.
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DOG FEET
One day as Chichan 'Cho' slept beside me I began noticing the bottoms of his feet. They were normal dog feet, but the longer I looked at them, the more curious they seemed. You can see the bottom of Chichan 'Cho''s left, front paw at https://www.backyardnature.net/n/17/170528df.jpg
Among vertebrate animals, the feet/hands/paws of the vast majority of species bear five digits, but in the above picture, Chichan 'Cho''s paw seems to have only four. And does the pad at the picture's left side represent a single, deeply divided digit with each section equipped with one part of a split claw, or are we seeing two digits united at their bases? To be sure what I was seeing I had to search on the Internet for pages dealing with dog foot evolution.
It turns out that dog feet feature the normal five digits, but the fifth digit is much reduced and set apart from the pads at the foot's bottom. In the above picture, the fifth one arises from the leg's side near the picture's top, right corner. A side shot of Chichan 'Cho''s leg better shows this appendage's position at https://www.backyardnature.net/n/17/170528dg.jpg
The claw arising from a dog's leg just above the bottom four toes is called the dewclaw. In evolutionary terms it's analogous to the human hand's thumb. In the past, people thought that dog dewclaws were purely vestigial -- useless evolutionary hangovers. However, nowadays it's recognized that dewclaws actually are important because they help prevent torque, or twisting, on the leg when the dog is galloping and making tight turns. Remember how motorcycles lean going around sharp curves, with the tires threatening to slip out from below. When dogs are making such turns, their dewclaws grab the dirt, holding the leg in place.
Once you start thinking in evolutionary terms, other features of the normal dog paw become more understandable. For one thing, the spongy pads at the very bottom serve as shock absorbers.
Slower-running animals such as us humans tend to place our whole foot on the ground, with a rolling heel-to-toe action. Animals displaying that kind of foot action when running are called "plantigrades." Dogs are "digitigrades," meaning that they only walk and run on their digits, which translates to faster running. Humans evolved to jog along for long distance; dogs evolved so they could move very fast for short distances, by "running on their toes."
By the way, horses developed this toe-running feature to an even greater extreme. The horse's bottom-most foot part is a single modified toe, analogous to the human hand's middle, longest finger. The hoof is that toe's fingernail. This arrangement and their longer legs enable horses to run even faster than dogs, at least for short distances
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BIRD PUZZLE
Early one morning this week a certain bird flew onto a branch over the pit next to the hut and was good enough to remain still until my camera got focused and snapped the picture shown at https://www.backyardnature.net/n/17/170528gq.jpg
I'd never seen a bird colored like that, though with its body shape and short, thick-based bill it's easy to recognize as a member of the huge Finch/Sparrow/Grosbeak/Tanager Family, the Emberizidae. His somewhat irregular, yellowish blotches indicate that he's a young bird in the midst of changing plumage. However, not even my big Howell & Webb guide to Mexican birds, which does a fair job showing immature plumages, showed anything even close to this.
However, by eliminating species that don't occur in this area, and paying special attention to the fairly distinct yellow line above the eye -- the yellow "supercilium" -- and the very unusually shaped beak, in the end it was clear that this was a Yellow-faced Grassquit, a common bird here often found feeding on grass seeds in weedy fields. Our page on the species, showing an adult male with his unmistakable facial pattern, and another immature bird in a plumage more advanced than our present one, is at https://www.backyardnature.net/yucatan/grasquit.htm
The really distinctive feature of this species, no matter what plumage it's displaying, is its straight upper mandible -- its "culmen." Normally a finch-like bird's culmen is at least a little curved, usually very noticeably so.
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THE DRY SEASON ENDS
The dry season ended on May 13th when an afternoon storm delivered 27mm of rain (±1inch), then the next afternoon we got another 40mm (±1.5inch). Months had passed without such relief.
During recent decades people here have said that the rainy season should begin around mid May, so this was just on schedule, though in recent years it'd been arriving later, sometimes in early June. However, this year's mid-May rains were brought on by the remnant of the season's first hurricane, which formed over the Pacific, brought flooding and downed trees to southernmost Mexico, then drifted over our area as a mere "zone of disturbance." The hurricane had formed some 44 days before hurricane season formally begins, so our return to a "normal" rainy season was based on an abnormal beginning of the hurricane season.
Still, the landscape here reacted as if everything was normal. Buds on leafless trees burst to release the new season's leaves. This week, each morning as I stepped from the hut I was in awe at how much greener the forest had become overnight. We've been watching the forest beside the hut gradually green. You can see how gray it was in late April at https://www.backyardnature.net/n/17/170423dr.jpg
Two weeks later, after a little 3mm shower (±1/8th inch) certain trees and bushes tentatively began issuing small, undeveloped leaves, as we documented at https://www.backyardnature.net/n/17/170507d2.jpg
Now, below, you can see how this week, a month after our first shot, the forest is truly green, though most leaves still need to expand a little, and some woody species are only beginning to issue small leaves, at https://www.backyardnature.net/n/17/170528d3.jpg
Besides all the fresh greenness, this week the butterfly population has about doubled, the air feels softer, mosquitoes are coming out, and birds are singing more. Though the extreme heat hasn't changed much, the landscape at least looks "springy" to a Northerner.
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RAINY SEASON LAUGH
On a hot afternoon with a nice breeze soughing through trees around the hut, I wondered about Nature's teaching in the fact that this rainy season has begun at the right time, but only because the remnants of an abnormally early hurricane passed over the area. Does this say something about "normality."
For some reason the first thought that came to mind dealt with an asteroid I'd heard about this week, discovered inexplicably moving in the opposite direction to nearly all other bodies in the Asteroid Belt between Mars and Jupiter. At first when I tried to figure out any connection between the two facts I drew a blank, but then I laughed loud enough to waken the dogs.
For, maybe what Nature is saying is this: "Normality" -- as in "normal beginning to the rainy season" -- is just a mental state we humans conjure up for our own psychic comfort.
The mere fact that there's something -- the Universe -- instead of nothing, and that it's evolving and spewing out life forms that themselves can evolve to the point that they have complex thoughts that themselves can evolve, so that at some point you might get a sweating old fellow sitting mostly naked in a forest hut beside an incongruously deep, dangerous pit, trying to figure things out... is so improbable in itself that all cogitations about normality in any context is a little suspect, a little funny, at least worthy of a dog-waking laugh on a hot tropical afternoon.
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Best wishes to all Newsletter readers,
Jim
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