On Friday April 12 I had a really uncommon and fascinating experience: the emergence of Eastern Spadefoot Toads!
A few months ago we moved back to New Jersey (more on that in a future post) and I resumed working at my old nature center as a naturalist. I was preparing for an amphibian presentation and a coworker was telling me about her experience with Eastern spadefoot toads, an elusive and rare frog in the northeastern United States. She said that in 2018 she witnessed a spadefoot eruption – where a large group of toads emerged in the center’s vernal pool to breed.
So you can imagine my excitement when she texted me Friday to say that the spadefoots were erupting at that moment. I rushed over to the center and was not disappointed.
Eastern spadefoot toads can be found throughout the eastern United States from Massachusetts to the Florida Keys and in parts of the interior southeast. They are rare and considered endangered in some states. 78% of frogs and toads have horizontal pupils, but spadefoot toads have distinctive bright yellow eyes with vertical pupils. Many species with vertical pupils, like the spadefoots, are active at night.
Why was I in such a rush to observe the toads at the nature center? Spadefoot toads spend a majority of their lives in underground burrows, which they use their spade-like projections on their feet to excavate. They can stay in torpor (a state of decreased metabolic rate, low body temperature, and motor inactivity) for months at a time. They wait to emerge until warm, heavy rains of typically 2 or more inches in the spring and summer. Spadefoots feed at night, making them harder to observe. Although they can breed up to 3 times a year, if conditions are not right they can skip breeding completely for the year.
Spadefoot toads are considered explosive breeders. Explosive breeders use temporary bodies of water such as vernal pools. As a result they need to reproduce and develop quickly. Explosive breeder males will call females to the breeding site. The spadefoot male’s call is a low pitched ‘waaaah, waaaah’ that sounds similar to a crow’s ‘caw’. Once the females arrive and breeding commences they can lay between 800 to 4,500 eggs per event. Many times eggs can hatch within 24 hours and within 14 days juveniles will metamorphize and leave the area.
The experience of seeing the spadefoots at the nature center’s vernal pool was amazing. I’d estimate that there were at least 50-70 toads in the vernal pool. They were calling when I quietly approached the pool then stopped. Once they adjusted to my presence they started to call again. I could see little pairs of eyes emerge and float around the pool, with small groups rippling around together. I did get to see some mating using the amplexus position, where the male wraps his arms around the female’s torso. I could also clearly see the vocal sacs of many males expand and contract while calling and swimming.
The next day I was presenting a program at the center and went to check the vernal pool. There was no indication that less than 24 hours earlier there was a large number of mating toads loudly calling and swimming throughout the vernal pool. They disappeared as quickly as they emerged. I feel so lucky (and thankful to my coworker for informing me!) to be able to witness such an amazing and rare event.
References
- Connecticut Department of Energy & Environmental Protection. (n.d.). Eastern Spadefoot. CT.gov. https://portal.ct.gov/-/media/deep/wildlife/pdf_files/outreach/fact_sheets/spadefootpdf.pdf
- Norman, C. (2020, November 16). Eastern Spadefoot Toad. PennState Extension. https://extension.psu.edu/eastern-spadefoot-toad
- Overduijn, K. (n.d.). Eastern Spadefoot Toad (Scaphiopus holbrookii). Savannah River Ecology Lab University of Georgia. https://srelherp.uga.edu/anurans/scahol.htm
- Wilke, C. (2021, August 24). Frog and toad pupils mainly come in seven different shapes. ScienceNews. https://www.sciencenews.org/article/frog-toad-pupil-eye-seven-different-shapes
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