1. Study of Individual and Group responses of Mexican Free Tailed Bats Presented by Aruna Raghavan

2. Brief Introduction to the Ecological Aspects Bats live as colonies in caves They emerge only during the night and communicate using the Echo-location principle Most of the bat colonies are located in Texas. Some of the bat caves are the Frio caves, Carlsbad caves, Ney caves etc. Study of Bat flight and counting the number of bats present in these caves is the challenge here…!!

3. Frio Cave, Texas

4. Pre Emergence Vortex

5. Column Formation

6. Column formation

7. Disturbance due to a hawk

8. Bat Emergence : Thermal Video

9. Bat Modeling A simple Visual C++ based approach depicting the different rules followed by the bats to remain inside the column is being studied.

10. Boids History Craig Reynolds – 1976 –Looked at bird flocking –Used individual based approach with rules describing movement Nice real-time graphics developed – Platt (2000) 3D-boids

11. Basic Rules Flock forming Collision Avoidance Velocity Matching Community Predator Avoidance Individual Predator Avoidance Foraging Sub Flocking

12. Flock Forming The current bat is indicated using a green triangle. As the simulation proceeds, the program checks for bats that are in the neighborhood of the current bat being iterated on. If any bat is detected, then it is moved to the center of mass of the group (showed as a green dot). This will result in the formation of a LOCAL BAT FLOCK.

13. Flock forming Pseudocode PROCEDURE flock forming rule1(boid b J ) Position Vector pc J FOR EACH BOID b IF b != b J THEN pc J = pc J + b.position END IF END pc J = pc J / N-1 RETURN (pc J - b J.position) / 100 END PROCEDURE

14. Collision Avoidance The bat that is being currently iterated is shown as a green triangle. The program checks for other bats that are in the close neighborhood of the current bat. If the distance exceeds a certain value, the bats move apart. This is done as a precautionary measure to avoid any bat collisions.

15. Collision avoidance Pseudocode PROCEDURE Collision avoidance rule(boid b J )‏ Vector c = 0; FOR EACH BOID b IF b != b J THEN IF |b J.position - b.position| < 100 THEN c = c - (b J.position - b.position) END IF END RETURN c END PROCEDURE

16. Velocity Matching In this rule, the bats that are in the neighborhood try to match the velocity of the current bat. This will lead to a uniform velocity for all the bats in the entire column.

17. Velocity Matching Pseudocode PROCEDURE Velocity Matching rule(boid bJ) Vector pv J FOR EACH BOID b IF b != b J THEN pv J = pv J + b.velocity END IF END pv J = pv J / N-1 RETURN (pv J - b J.velocity) / 8 END PROCEDURE

18. Other Avoidance rules Community Predator Avoidance This concept will be more clear in the simulation. The bats along the ends of the column, try to come inside the column. Individual Predator Avoidance: In this rule, all the bats inside the column tend to move towards the center of mass of the column. This will lead to a line like formation but they will be spatially separated to avoid collisions.

19. Other Behavioral Aspects Foraging: This shows how the bats forage in open fields with all the rules still operating. Sub Flocking: The bats tend to separate into sub columns after flying in a single column for a long time.

20. BATOIDS SIMULATION

21. Dynamic Frame Bat Counting Thousands of bats come out of the cave as shown in the video. The problems faced while counting are : Presence of one bat behind another bat The flow rate is not constant. By this I mean, the number of bats entering one frame is not the same as the number of bats leaving the frame. The problem of OCCLUSION Errors caused due to overcounting and undercounting

22. The Bat video

23. Proposed Work Counting of the bats during emergence Trying to link the simulation with the real time video by using it as the initial conditions and studying the bat flight Add a few more rules to the simulation

24. Thank You !