Thursday, September 15, 2016

Sonoran Desert Toads in our backyard

In Arizona, the Sonoran Desert Toad Incilius alvarius is still rather common. Our two neighbors, CA and NM list them as threatened. I am rather certain that our AZ population is declining as well. Among the reasons of course are habitat loss and our on-going drought.

Red-spotted Toad Anaxyrus punctatus , Woodhouse's Toad Anaxyrus woodhousii, Couch's Spadefoot  Scaphiopus couchii
 We have several smaller toads and spadefoots whose adaptation to desert condition includes an extremely short aquatic tadpole phase. They can lay their eggs in very temporary puddles, and within days little toadlets are ready to move onto the land. Around Picture Rocks, AZ, monsoon storms usually provide sufficient precipitation at least every couple of years, and then juvenile toads abound. Their paratoid glands right behind the ear are round, not kidney shaped, so most of the young toads are red-spotted toads, not Sonoran Desert Toads.

Sonoran Desert Toads Incilius alvarius, mating in Sabino Creek Photo Ned Harris
 To breed successfully, Sonoran Desert Toads need more permanent bodies of water for their longer aquatic tadpole phase. They are annually breeding in Sabino Canyon for example. But I doubt that our population here in Picture Rocks had any offspring in years.
I think that one adaptation of Incilius alvarius might be in its potential longevity - defined as the long lifespan of the individual. Maybe they are simply able to wait for years until conditions get better. At that time they may be able to produce a new generation of offspring that can outlast the next period of drought. Saguaro procreation follows that pattern, why not, on a smaller scale, SDT procreation?

While I have not tried to mark any of our toads for individual recognition, I have photographed them often and believe that I can recognize several individuals. I'm rather certain that I have seen about 4 individual toads each summer since I started watching them at our porch lights in 2007. They were already fully grown at that time. Longevity in toads is not impossible. In Germany I raised Bufo bufo in my aquaterrarium while I was still in high school. When I left for my postdoc time in Norway, I first had to find a home for a couple of those toads, then 14 years old.
Here in our yard in Arizona, the over-all number of individuals has been declining over time. Since 2007 I found only one less-than-fist-sized juvenile. It's in the picture above. The adult toads are sometimes rescued from swimming pools, but I have never heard of any swimming pool tadpoles. There has not been any lasting natural pond here for years, so I don't know where he's been hatched.

Animals that are short-lived usually breed copiously and fall victim to predators easily.
Long-lived species need to protect themselves against predation to reach their full potential. So the evolution of individual longevity usually includes some potent defense against predation. The primary defense of the Sonoran Desert Toad is a milky fluid produced in skin glands, the most obvious one being the bulging, kidney-shaped paratoid gland.  The exudant of these glands is a potent cocktail of toxins, among them:

5-methoxy-N,N-dimethyltryptamine) is a psychedelic of the tryptamine class.

Bufotenin (5-HO-DMT, N,N-dimethylserotonin, bufotenine) is a tryptamine related to the neurotransmitter serotonin

digoxin-like cardiac glycosides

If ingested by a potential predator, the milky juice causes a series of reactions:
 Excessive salivation or foaming at the mouth, pawing at the mouth, head shaking, red or irritated gums, drunken gait, confusion, vomiting, diarrhea, weakness or complete collapse, heart arrhythmia. Death can occur by respiratory arrest.
 So especially for small dogs, the experience can be lethal. Seizures and death can occur within 30 minutes. Before veterinary help can be reached a vigorous mouth rinse from a water hose may be the best first aid.
 Like most defensive weapons, the toad toxins seem to come with a warning:  the strongly irritating effect on the mucous membranes of the mouth (as well as the mouthwash applied by the terrified owner) probably warns most dogs and should keep them from repeating the experience.

Cody, surveying his realm
 But there are always exceptions: One summer evening in 2004, our all time favorite dog, Cody, who feared nothing except thunder and lightning, danced up to me with brightly shining eyes, his normally flat coat all fluffed up, his tail wagging, and he happily began to hump my leg. That was not his normal behavior at all. Shortly after, his breathing got labored, his heart raced, his front legs bent and seemed paralyzed. You can imagine that by then we were already crossing Contzen Pass on our frantic drive to the vet. When we got there though, Cody, fully recovered, marched into the practice in his usual way - like he owned the place. Even though they were completely gone, the vet recognized the described symptoms as those of a toad-licking-episode,  explained that  foaming from the mouth was optional, and that no further treatment was recommended. 
But Cody should have gone to rehab. For three more years, he indulged his addiction: in early June, just once, he would show up bushy-tailed and shiny-eyed and aroused by any fence post. He never went through breathing and  arrhythmia again - he had learned to dose his drug. We did find a dead toad after one of his orgies. But Cody got over it. He just stopped. When the fourth June arrived Cody completely ignored the toads.

Bilbo, ignoring a toad
 Cody was never our only dog who shared the yard with toads. We always had a whole pack of medium to large canines. I never saw any of them go even close to the toads. When we got a new dog I usually showed him the next toad I could find and gave him sharp 'NO!'

After I rescued the toad from the dogs tub, Mecki had to be coaxed to come this close
But none of our dogs besides Cody ever seemed at all interested in contact with a toad. Instead, there seems to be a very slight avoidance reaction - only about as much as a provocatively tossed  ball would elicit from a convinced non-retriever. Our dogs were all rescues with unknown histories. Maybe they all had tried to grab a toad once and got their mouths burned? Who knows.

Mecki pulls back into a more comfortable distance. Bilbo checks on us but looses interest right away. Laika, visible over my right shoulder, never bothered to get up.
But I do know that the big toads are very old denizens of the desert who should not be persecuted for protecting themselves against predators.  They should not be evicted from their ever shrinking habitat for the sake of our pets. On public forums I see many hateful comments when images of these toads are shown. Most are based on exaggerated fear. Dogs are smart (most of them) and can be trained. They can also be kept indoors during summer nights when the toads are most active. We've learned that since our experiences with Cody.

It  helps to learn about the behavior of the toads. They are hidden underground during winter and spring months but they begin to emerge in June, weeks before the first monsoon storms can be expected. Night active, they feed mostly on insects up to the size of a Palo Verde Beetle. In their large scats, wings of  June Beetles and whole abdomens of Pinacate Beetles dominate. Desert  Toads quickly learn to hunt under porch lights where their prey bugs congregate.

Nightly pool party in our neighbors' bird bath. These are Red-spotted Toads 
Sonoran Desert Toads, June 2008 in our front yard
  Amphibian skin is no great protection against dehydration, so they regularly need water to rehydrate. Skin areas under thighs and belly are specialized to absorb water quickly. That's why they like to sit in shallow water - be it a pond, a bird bath or a tub for the dogs.

For dog owners, that's where supervision and maybe interference are most necessary.  And if someone is convinced that his yard is his property and it's his right to do everything to protect his beloved pets, he should consider this: it's impossible to kill, transplant or exclude every last snake or toad.  It's nearly impossible to seal your yard against determined desert creatures that dig and climb surprisingly well.  So you better have your dog under control for that unexpected one that will eventually try to reclaim your yard as its territory. 

Friday, September 9, 2016

Rancho el Aribabi in northern Sonora, Mexico

Our bobcat hiding under the ironwood tree in Picture Rocks AZ. Taken at  the only sunny moment of Sep. 7, 2016
Tuesday Sep. 6 2016. The remnants of hurricane Newton have reached Tucson. Not a leaf is moving, but steady rain has been falling all day. The washes are not running because it's all soaking in. Great! The Tucson mountains are hidden behind veils of falling rain and fog that's raising up from the warm desert floor. The dogs are wet and smelly and should stay outside, but there's a bobcat hiding up front under the big Ironwood Tree and young coyotes leave tracks in the mud along the fence - so Mecki gives alarm every few minutes. Tough. Time to write up last weekend's adventure:

Photo Tom Mc Donald
A loosely organized group of Arizonans regularly visits Rancho el Aribabi in northern Sonora, Mexico. Naturalists and scientists, they are doing follow-up of projects that were started by the U.S. Forest  and Fish and Wildlife Service in conjunction with Mexican organizations, the Sky Island Alliance and of course the rancher who was our host.

A photo from one of the trail cameras (via Jim Rorabaugh's FB page). Of course there were also many of swishing tails and windblown branches.
 The group regularly monitors  wildlife cameras that are positioned at water-holes and wildlife crossings all over the 10 000 hectare ranch about 30 mi south of Nogales. We stayed at a beautiful  ranch house surrounded by deep patios under arcades reminding of old mission buildings, full kitchen and many comfortable bed rooms.

Our Mexican hosts live in Magdalena, so I never met them. We were looking for biodiversity, but the diversity within the group was also impressive - ranging  from biologists to mathematicians and Egyptologists - it guaranteed interesting conversations throughout. All weekend, Cathy and Marianne spoiled us with their cooking. Everyone was very welcoming and let me join in their activities and also do my own nightly insect surveys.

Photo Tom McDonald
With its riparian woodland, cienegas (wetlands), Saguaro rich lower slopes and high elevation mountain ranges - both dry and bare or covered in oak/juniper and thorn brush, the rancho offered an amazing variety of habitats.

Cattle tank Photo Tom McDonald

mating Tiger Beetles and White-tail Skimmer
I got a great overview over the immense stretches of land during a long bumpy trip along narrow, winding ridge roads to some of the cameras that overlook the upper cattle tanks. Thanks to the folks who brought their heavy duty 4 wheel drives with good truck tires. My Forrester would not have made it up there.

Dung beetles: very common Digonthophagus gazella, imported species from Eurasia, some specimens of the big Dichotomius colonicus, and the day-active green metallic tumble bug Canthon indigaceus. But check out the multitude of tiny ones that eventually made the sheet look black!
 We saw only few cattle (there would be more during other seasons) and once a small heard of horses thundered by me on the narrow river path. Grazing overall seemed not very intensive, and  critical areas along the perennial stream were fenced to keep livestock out. The fences were part of a U.S. Fish and Wildlife Service project but are now maintained by the cowboys of the rancho.

I spent the day time hours  mostly in the riparian  forest and the swampy meadows around the house. I can't call it hiking, because there was so much to see and photograph that my progress was extremely slow.

The perennial stream Photo Tom McDowel
Bird calls with distinctly tropical accent and flashes of bright color were tantalizing, Yellow-billed Cuckoos and Sinaloa Wrens were common here, but I finally understood that I cannot follow all my passions at once, so I concentrated on the arthropods.

Even that proved difficult because I could have spent more than a weekend just trying to shoot just a few of those elusive Hymenopterans and Orthopterans that buzzed around seep-willow flowers and hopped through the lush grass. So I'm pretty certain that I saw a Mexican Blue-wing Grasshopper, but it got away.

Neoconocephalus (Common Conehead), Schistocerca albo-lineata (White-lined Birdgrasshopper), Melanoplus differentialis (Differential Grasshopper), Leprus intermedius (Saussure's Blue-winged Grasshopper),  Taeniopoda eques (Horse Lubber)
My main interest was to photograph beetles. As expected, this close to the border most of the species were still the same as in AZ.  Always searching for specimens to photograph for the planned AZ Beetle Book, I was very excited to find examples of species that have been reported from AZ but are so rare that I had been searching for them for years.

For example, on knee-high vegetation along the ranch road I finally spotted Leptinotarsa colinsi, the last species in the Potato Beetle genus that I still needed to photograph. That alone made the trip worthwhile.

Old acquaintances in the same genus were also around:  Leptinotarsa lineolata on burrowbush (Hymenoclea monogyra). and Leptinotarsa haldemani on blooming buffalo bur Solanum rostratum

Close to Calopteron reticulatum (Banded Net-wing)
A species of Banded Net-winged Beetles, found on leafy plants under the canopy of the riparian forest, seems to belong to the genus Calopteron. This genus has a mainly eastern distribution in the US.  Several characters resemble Calopteron reticulatum, except that the pronotum of the el Aribabi specimen is entirely orange, while in Texan specimens the middle of the pronotum is dark.
The nights were full of wonder, too.  Arial displays of Firefly males, nearly forgotten while living in Arizona, corresponded to the ground-bound blinking of females or larvae.

From under a piece of plywood on the back patio, Jim Rorabaugh pulled a Tailless Whipscorpion and a huge Scolopender.
 On Saturday night, we visited the nearby village. There the entire population including the village dogs was on their way to a great outdoor fiesta with barbecue and life music. Maybe it was a wedding, because  one side of the plaza was taken up by an arbor made of hundreds of blue and white balloons.

The fiesta looked quite inviting, but we headed for the creek that crossed under the main road, looking for frogs and toads. Indeed, a few Low-land Leopard Frogs and Woodhouse Toads paddled in the  fast flowing, clear water that was shallow enough to walk in, at least if you had no plans to dance at the fiesta afterwards.


My black-lighting sheet was up both nights. The response was enormous, not only from all those insects  coming in in better numbers than I had seen all year, but also from people, some of whom were amazed and interested, while others found this multitude of bugs quite overwhelming.

To our human senses, most parameters were similar between the two nights. Location and moonphase were rather identical,  temperature, wind and humidity seemed similar and yet, the two nights produced rather different results.

Interestingly, the first night brought mainly beetles, among them many scarabs. To see beetle images and identifications please click here.

The the second night was richer in moths and water bugs, while the only beetles that showed up in numbers were blister beetles. To see most moth species with identification, go to my flickr album Moths of el Aribabi
Owlfly, Mantisfly, Antlion - all Neuroptera. female Dobsonfly, earwig, toebiter in Belostomatidae (Giant Water Bugs), and Western Floodplains Cicada
Of the countless insects at the sheet I was able to photograph identify 17 Carabid species, 5 Clerids, 7 Cerambycids, 14 Chrysomelids, 15 Scarabaeids,  6 Tenebrionids (those are all beetles),  more than 50 species of  moths,  many True Bugs,  plus neuropterans, Dobsonflies, Caddisflies, earwigs and even one big Western Floodpains Cicada. For the moth ids, I relied on a very helpful group of Facebook friends. Special thanks to Randy Hardy and Paul John! 
The lighted sheet also drew  a swarm of bats hunting in the night sky above. They live right under the patio beams of the casona.

Overwhelmed by all that bug photography, I did not remember to take a group photo before we were all busy packing and two people had already left.

Trichodes peninsularis, a Clerid