Abstracts - Deutsche Zoologische Gesellschaft

112 Behavioral Biology PostersP BB.15 - ENMotor abilities of juvenile laboratory rats from litters of different sizesSusann Meyer, Heiko RödelLehrstuhl Tierphysiologie, Universität BayreuthLitter size of most small mammal species is highly variable. Offspring from larger litters usuallyreceive a lower share of milk leading to lower pre-weaning growth, which may influence the physicalcapabilities of the young shortly after weaning. On the other hand, a higher number of siblingsmay positively affect the motor development of the juveniles by higher rates of behavioural interactionswith their litter mates. We tested the motor skills and strengths of juvenile laboratory rats fromlitters of different sizes (3 to 17 pups/litter) around and shortly after weaning by behavioural tests.The latency time of jumping down from an elevated platform or out of their opened home cage waspositively correlated with litter size. Furthermore, we found a non-linear effect of litter size on thejuveniles’ strength in relation to their body mass, tested by the time they managed to stay attached toan elevated vertical wooden bar. Generally, young rats from large litters fell down earlier from thebar than the ones with less siblings, whereas juveniles from very small litters of 3 or 4 pups also felldown very fast, most likely due to their very high body masses. In conclusion, our study shows thatjuveniles from smaller litters had better motor skills and strength, most probably due to their betterphysical development. However, a very high body mass, as it occurs in juveniles from extremelysmall litters, might negatively affect their physical capabilities shortly after weaning.P BB.16 - ENLearning in freshwater stingrays (Potomotrygon falcneri)Kerstin Elisabeth Thonhauser 1 , Karl Kral 1 , Michael Kuba 21Institut für Zoologie, Karl-Franzens-Universität Graz, Austria; 2 Department of Neurobiology,Hebrew University, Jerusalem, IsraelTesting the behavioral abilities of cartilaginous fish is an important step towards understanding theevolutionary origins of cognitive functions in higher vertebrates. In our study we used 7 SouthAmerican fresh water stingrays (Potomotrygon falcneri) in a social learning and problem-solvingtask. We used a tube apparatus developed for testing the cognitive abilities of aquatic animals. 3 animalswhere chosen as demonstrators that initially learnt to handle the tube and extract a food reward.After the demonstrators had reached criterion the 4 observer animals were positioned to watch themperform trials. The observers were then tested on their ability to learn to handle the tube and extractfood. Comparison showed significant differences between demonstrator and observer groups. Observersrequired less trials to reach criterion (p = 0.0023) and shorter trial duration (p = 0.0005). Thetwo groups also showed a significant difference in acquiring the best strategy for food extraction.This study is the first conclusive evidence of imitation learning in fish.