1. Hunting Behavior of a Marine Mammal Beneath the Antarctic Fast Ice R.W. Davis, L.A. Fuiman, T.M. Williams, S.O. Collier, W.P. Hagely, S.B. Kanatous, S. Kohin, M. Horning. (1999). Science, 283: 993-996. Biology 457 Presented by Kimberly Forbes

2. Background Little known about marine mammal foraging behavior Little known about marine mammal foraging behavior Difficulty with observation Difficulty with observation Previous methods insufficient Previous methods insufficient (a) based on indirect information (b) don’t allow direct observation

3. Purpose & Method Purpose Purpose To gain insight of the foraging behavior of marine mammals. In particular: (a) how do they find their prey? (b) where do they find their prey? (c) how do they stalk and capture their prey? Method Method Observe Weddel Seal foraging behavior through the use of animal-borne video system and data recorder in order to compute their 3-D dive path.

4. Weddel Seal Leptonychotes weddellii Leptonychotes weddellii Large marine predator Large marine predator Feeds on small, nototheniid fish and Atlantic cod Feeds on small, nototheniid fish and Atlantic cod

5. Experiment 1. Attach video system to 4 seals 2. Occurred between Oct.-Dec., 1997 3. Fast ice environment of McMurdo Sound, Antarctica 4. Recorded time, depth, water speed, bearing, stroke frequency, and ambient sound

6. Figure 1a & 1b Travel path = 760m Travel path = 760m Did not veer horizontally prior to viewing cod Did not veer horizontally prior to viewing cod Accelerated and changed horizontal direction upon viewing cod Accelerated and changed horizontal direction upon viewing cod Non-aggressive contact Non-aggressive contact Point of contact Breathing hole

7. Figure 1C Seal with back- mounted camera Seal with back- mounted camera Seal remained out of the cod’s sight Seal remained out of the cod’s sight The cod was visible due to backlighting The cod was visible due to backlighting

8. Figure 2 Seal followed path of fish to sub-ice area Seal followed path of fish to sub-ice area Seal blew air into crevice to expel fish Seal blew air into crevice to expel fish Fish expelled, but both escaped Fish expelled, but both escaped Erect vibrissae Erect vibrissae Expelled fish

9. Discussion Weddell seals don’t use sonar to locate prey. Weddell seals don’t use sonar to locate prey. Not all predator-prey interactions are aggressive. Not all predator-prey interactions are aggressive. Seals can come within a close distance (few cm) of the prey without being detected. Seals can come within a close distance (few cm) of the prey without being detected.

10. Tactics for Foraging A. Bite off exposed tail of prey B. Flushing out the fish with air C. Pursue fish through the platelet ice

11. Conclusion Vision is important for foraging and interaction with prey. In particular, backlighting is critical for the seal to visualize the prey underneath the fast ice surface.