Fowler’s toad, in Canada has been assessed as endangered by both COSEWIC and COSSARO. It is declining at Long Point due to loss of breeding habitat resulting from the invasion of Phragmites australis reeds.
Fieldwork supported by Wildlife Preservation Canada in 2014 was designed to use a monitoring protocol to keep track of the animals’ population abundance, breeding success, survivorship and growth, building upon the results of previous years. The area of study is a stretch of shoreline at the western base of Long Point, Ontario, consisting of beach, dunes, marshlands and areas of settlement.
The aim of the protocol used to survey the Fowler’s toad population has been to find, hand-capture, and identify every toad present by inspecting all known breeding and foraging sites, as well as experimental ponds, every evening throughout a 41-day period, that encompasses the toads’ entire breeding season. The locations of all toads were mapped and recorded electronically. Air temperatures at time of capture were measured with quick-reading digital thermometers.
For every toad upon every capture, snout-vent length (SVL) was measured with dial callipers and the dorsal surface was digitally photographed for individual identification.
How do we identify individual Fowler’s toads?
Fowler’s toads possess distinct and unique spot patterns on their dorsal, or top, side that remain unchanged throughout their lives. Individuals were identified based on these spot patterns using “Foto-spottr” image recognition software developed by Alan Schoen. We were interested to see if we could identify toadlets from 2013 among the juveniles present in 2014 and estimate the abundances of juveniles in both years in the study area.
Although adult males were easily discernible by their black throats and release calls when handled, adult females were distinguished from juveniles using Bhattacharya’s (1967) method to discern the two snout-vent length distributions corresponding to juveniles and adult females.
The photo-ID system we have developed for identifying individual Fowler’s Toads proved to be highly effective and reliable. The patterns of spots on the backs of the toads are proving to be stable throughout life (Fig. 8), enabling us to positively identify animals year after year. For the first time, we were able to employ the software to successfully identify animals released as Green Fowler’s Toads – toadlets in 2013 and recaptured as juvenile in 2014. Use of this system will allow us to track individuals from metamorphosis to adulthood and, in succeeding years, be able to calculate individual growth and survival rates with an accuracy that has not been achieved before for any amphibian population.