Movement Patterns and Association of Activity With Climatic Variables in Terrestrial Toads, Rhinella Arenarum
Several aspects of orientation, spatial navigation abilities, and use of space in amphibians have received some attention in research analyses in natural environments. However, given the lack of information on spatial cognition of terrestrial toads (Rhinella arenarum) in the wild, we collected data on space use dynamics in their natural habitat. Sampling was conducted around the Chascomús Lagoon, Argentina, for two spring-summer seasons (from October to March). Toads were marked, their locations GPS-recorded, and the type of shelters used was identified. Results indicated that most toads exclusively used drain-type shelters, while a smaller proportion used field-type shelters. Those toads that shared a shelter had a greater overlap of home ranges than those that did not. There was no association between size of home ranges and sex, or type of shelter used. No differences were found in distance from shelter to home range centroid between different groups of toads. Data revealed that toads were inconsistent in directions moved and distance traveled. In addition, as expected, toads were more active on days of higher maximum temperatures and rainfall, and when fewer days had elapsed since rainy days. This basic information on space use of this species in their natural environment promotes future spatial orientation studies to allow comparisons with previous results on use of reference cues obtained under controlled laboratory conditions.ABSTRACT
Two examples of types of markings made on toads (tattoos on the hind limbs, dorsal region of the thigh). (A) Toad with “dot-dot” mark on the left leg. (B) Toad with “stripe-dot” mark on the right leg.
Number of sampled toads (females/males) with their respective number of sightings for (A) Year 1 and (B) Year 2.
Home ranges for two of the monitored toads at the Instituto Tecnológico de Chascomús (INTECH) campus. (A) Home ranges for a female in two consecutive years (Year 1: pink polygon; Year 2: orange polygon). (B) Home ranges for the female toad with the highest number of recorded locations for Year 2.
Home range overlap between toads that shared or did not share shelters. Boxes show median and interquartile range; whiskers show minimum and maximum values.
(A) Polar plot showing the direction and distance traveled by toads from their shelter to their initial feeding location. Each vector corresponds to a different individual. Length of the vector represents the distance traveled. Data from one individual that moved 155 meters and went out of the plot scale was removed for clarity. (B) Polar plot showing the direction and distance traveled by each toad when leaving from their shelter on different nights. Length of the vector represents distance traveled. Except for toad 42, the animals were not consistent in the direction they moved, or distance traveled from home.
Best-fit regression lines showing number of active toads observed as a function of days elapsed since last rainfall and season period (categorized as period 1 for October-November, period 2 for December-January, and period 3 for February-March).
Best-fit regression lines showing number of active toads observed as a function of maximum temperature and season period (categorized as period 1 for October-November, period 2 for December-January, and period 3 for February-March).
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