Environmental and demographic variation impact the nightly movement and activity of Fowler’s toads (Anaxyrus fowleri)

Population Ecology
vendredi 20 déc. 03:25 PM (15 minutes)
Salle AB

Animal movements impact the structure and dynamics of a population. Several factors are proposed to potentially drive an animal to disperse (i.e. move away from its natal site). Toads are nocturnal, and so they typically find daytime refugia (such as burrows) to hide in during the day. The fact that they do not always emerge from their daytime slumbers leads us to hypothesize that they might wait for certain external conditions to be met. According to the literature, environmental and demographic varying components and conditions drive amphibian movement, with less literature found on nighttime emergence from refugia. However, some of the theoretical causes proposed in some studies lack empirical evidence. Using 8 years of data collected on an endangered toad population, the Fowler’s toad (Anaxyrus fowleri) found in Long Point, Ontario, I have explored some of these theories. Nightly surveys of this population have been carried out every year (2012-2019) from the beginning of May until mid-August. Pictures taken of the toads’ backs were used to identify individuals through their wart patterns. A presence-absence matrix was used to estimate the percentage of our toad population which was active on a particular night. The UTM coordinates collected for each toad allowed us to obtain individual toad movement distances, calculated as Euclidean distances between 2 consecutive data points. The overall objectives of this study are to (1) test whether external factors (i.e. weather conditions) impact night-to-night movement distances, (2) test whether there is a sex-bias, age-bias, or seasonal-bias for night-to-night movement distances, and (3) test whether nighttime activity (i.e. emergence from daytime burrows) varies with varying external conditions.

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