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Time Activity Budgets for Tadpoles of the American Toad ( Bufo americanus )
| Content Provider | Semantic Scholar |
|---|---|
| Author | Dickman, Taya C. Durtsche, Richard D. |
| Copyright Year | 2003 |
| Abstract | In northern temperature climates, American toads (Bufo americanus) are early spring breeders, laying their eggs in ephemeral ponds. Optimizing behavioral activities, such as foraging, for maximal growth of toad tadpoles would be expected for this species to reach metamorphosis prior to pond desiccation. Prior behavioral studies on toad tadpoles have focused on responses to predators and food resources under laboratory conditions; but little is known of diel activity patterns under natural conditions. We conducted focal samples on B. americanus tadpoles inhabiting ephemeral ponds in northern Minnesota in May and June of 2001. Time activity budgets were created for tadpoles throughout all periods of the day. Nine activities were identified which were evaluated within the context of microhabitat use and solar exposure. Feeding behavior was examined through observations of duration, frequency, and food substrate. Data from these observations were used to estimate mean time spent per activity. Non-moving behaviors made up 65.6% of the tadpole's activities. Feeding comprised 18.4% and moving 7.6% of their daily period. A combination of other activities such as air gulping, predator escape, schooling, social interaction, and squiggle behavior comprised the remaining 8.4 %. The majority of activity bouts, 88%, were less than 65 seconds, and 92% of the distances moved by tadpoles were less than 40 cm. Comparisons were made between activity time and period of the day to determine if temporal activity patterns existed. These analyses suggest daily trends in certain behavioral activities though not in others. Introduction Many Anuran eggs are laid in ephemeral habitats (Britson and Kissel 1996). The tadpoles that do not metamorphosis before the pond dries, will die (Fegraus and Marsh 2000). Thus, the larval stage is under time constraints to optimize foraging (Britson and Kissel 1996). Increased foraging efforts can lead to increased visibility by predators. Therefore, tadpoles must balance foraging benefits and predation risk (Warkentin 1992a). The way that tadpoles balance their time in daily activities may reflect influences such as physical conditions, predation risk, resource availability and social behavior (McDairmid and Altig 1999). Accommodation of behavior in animals occurs in response to changes in their environment in ways that modify both predation risk and resource acquisition (Anholt and Werner 1995). The way that tadpoles distribute their time throughout the day is referred to as a time activity budget. This budget demonstrates how the tadpoles balance behavioral activities. Table 1 lists the types of data gathered when constructing a time activity budget. Physical conditions have been reported to affect activity patterns in tadpoles; these conditions include the distance from shore, oxygen concentration, water depth and flow rate, site duration, temperature (McDairmid and Altig 1999), illumination (Warkentin 1992b; Beiswenger 1977), and pH (Seale 1987). Tadpoles seek warmer water when a temperature gradient exists (Warkentin 1992b; Beiswenger 1977). As well as influencing activity patterns, temperature also influences growth and development, metabolic rate and the timing of metamorphosis (McDairmid and Altig 1999). Responses to temperature are closely linked to light since solar radiation warms the water (Beiswenger 1977). Decreases in dissolved oxygen will cause increases in air gulping behavior (Seale 1987). |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.nku.edu/~norsci/issue1/2003-9dickman.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
