The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note any observations you have made of the world around you. Sun, rain, trees, fish, insects, mollusks, meteorites, climate, birds and/or flowers... all are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located.Bisbee, Arizona.
2 Aug 2013
Late in the afternoon, shortly after a significant storm had passed, a raucous noise welled up from across the street. Could that din be the Couch's spadefoot toad mating call? The sound certainly fit the description of bleating sheep or goats. After some time passed, I couldn't resist the temptation to record it. The sun had set, leaving only the distant flashes of lightning over toward Mexico visible to accompany the chorus. With a flashlight and a little "point and shoot" camera (with video capability) in hand, I cautiously ventured closer to the chorus. Here is the recording of their calls.
My curiosity about the Couch's spadefoot toad began with Petey Mesquitey, our very own local radio personality. "Growing Native" is only a side gig. Petey's main occupation is growing native plants. I met Petey at the Bisbee farmer's market where he sells plants through his venture The Spadefoot Nursery. By listening to his stories, it was easy to appreciate the remarkable Couch's spadefoot toad that can survive in the arid land of the Sonoran and Chihauhuan desert. Below the orange puddle, I'll share my observations of the Couch's spadefoot hustle, a frenzied dance for survival, in the pond created by this year's unusually wet July.
7 Aug 2013
Reading 6412093's diary Bullfrog Banter I was reminded that I wanted to investigate the area where the chorus on the 2nd took place. This picture shows the pond, only recently created, where I discovered thousands of tadpoles.
During that single mating party, the female spadefoot produces about 3,000 eggs and the male fertilizes them. Deposited on the pool's vegetation, the eggs usually hatch within a day. In that case these tadpoles should be 4 days old. The pond is in continuous motion from the non-stop feeding frenzy. They were mainly feeding on the vegetation and the pebbles along the perimeter of the pond. Notice the gut spiral is visible at this stage.
9 Aug 2013
The pond's size is decreasing about 2 feet each day. Amazingly, the tadpoles size had nearly doubled and the hind legs were already visible. Their mouths continued to be in constant motion.
10 Aug 2013
The alarming rate that the pond was dissipating caused me to worry about the spadefoot tadpoles' fate. Even though it rained nearly every day in July, the area was dry since the mating calls 8 days ago. The remaining pool of water was rapidly closing in on the tadpoles causing a crowded environment. It is reported that an environmentally stressed population can lead to cannibalism behavior.
I thought this one was giving up the ghost but it finally flipped over and resumed to feed. It provided a good look at it's underside and I noticed the gut spiral was no longer visible.
Against my guiding principle to let nature take it's course in the wild, my mother instinct took over. I made the decision to run interference by scooping up 6 tadpoles from the pond. I placed them in a bucket, adding some of the mud from the perimeter of the shrinking pond and water from another puddle. I carried them home wondering how I was going to care for them. It may seem strange, but I never had the childhood experience of caring for tadpoles. Fortunately, both of my neighbors grew up here and shared with me their memories of capturing the tadpoles in their youth. I surmised from their experiences that the Couch's spadefoot tadpoles were fairly resilient and my odds were pretty good in keeping them alive.
11 Aug 2013
Nature continued to withhold precipitation turning the pond into a mud hole. I felt sick about it but by this time, I understood that the primary cause of mortality for Couch's Spadefoot tadpoles was desiccation. Even with their adaptation to develop quickly, there is a study showing that about 50% of the natal pools dry up before metamorphosis is completed. I braced myself before moving closer.
What I found was that the majority of the tadpoles were still alive and they had developed part of their forearms. About a third of the population struggled in the dampest areas in the mud hole. Another large group was climbing over each other toward the closest damp shelter provided by dried reedy grasses, while the rest were fanning out, moving in a rather awkward motion, trekking to a more distant unknown location. Only a small number of tadpoles were seen desiccated. The ants were wasting no time removing them from the premises.
Meanwhile, back at home, the tadpoles in the bucket appeared to be healthy in their new digs. I convinced myself that the disgruntle look was only a developing phase and not to take it personally.
14 Aug 2013
The rescued spadefoot toad's metamorphosis was nearly over. I still held out hope for their brothers and sisters across the street. I contemplated about how they could have survived the continuous dry days. There is a chance that some of them found a moist crack in the earth under cover. I couldn't find the information about when they develop the sickle-shaped tubercle, or spade on the inner surface of their hind feet. The spade is used to burrow under the surface when it is dry. The juveniles usually use the remaining monsoon to feast on a great number of garden pests in the lush vegetation. They need to store up energy to prepare for the long fasting period. The Couch's spadefoot will spend the next 8-10 months burrowed deep under the surface until the next rain season begins.
I transferred the young spadefoots from the bucket into a larger basin that had a sandy dirt beach, live vegetation and a shallow pool. The toads promptly left the water and found a spot to burrow in, usually at the base of a stone or wood. They dug backwards scooting into the dirt using their hind legs indicating that their feet may have developed the tubercle. The toads were active at night and they still enjoyed a dip in the pool. I suspected that they were lacking access to food. I started putting sliced fruit in their habitat to attract small flying insects.
18 Aug 2013
While I was fine tuning this account, at 5:15 p.m., the weather switch back to normal. A light storm moved in and gave us enough rain to form small puddles. With great expectations, I softly returned to the dried pond across the street. I'm excited to report that juvenile toads hopped across my path and inhabit the area. In fact, they looked like they had gained more weight than my so-called rescued team. The time was overdue to let my team loose in the garden. The six spadefoot toads tentatively left their woman-made shelter one at a time. They are situated close to the compost where food is in abundance. Do the Hustle!
Additional Listening & Reading
I'm passing the bucket over to you. What has caught your attention lately?