Ecology & Behaviour 2015 - Toulouse (France) 17-21 mai 2015

2. Ecological determinants of foraging efficiency:
insights from the group foraging bat
Molossus molossus
Yann GAGER

3. Adapted from [Cvikel et al. 2015]
Information transfer about food

4. Information transfer about food
Adapted from [Cvikel et al. 2015]

5. Information transfer about food
[Dechmann et al. 2010]
Social foraging
confirmed by telemetry,
37 mins foraging time

6. Optimal group size for foraging efficiency?
Group size
Foraging
efficiency
Improved prey detection
Inspired from [Cvikel et al. 2015]

7. Group size
Foraging
efficiency
Improved prey detection conspecific interference
Optimal group size for foraging efficiency?
Inspired from [Cvikel et al. 2015]

8. Small harems of stable size
[81 captures – 14 social groups]
Adultgroupsize
Roost identity
Recruitment
of juveniles
dispersing
Death of
group members
+
-

9. Automated data collection:
transponder reader + scale

10. Reader data from one adult of each sex
SunriseSunset
Typical female:
foraging (x̄ = 38 mins)

11. Reader data from one adult of each sex
Typical female:
foraging (x̄ = 38 mins)
Typical male:
foraging (x̄ = 32 mins)
+ roost guarding
SunriseSunset

12. Mass data for one femaleMass(g)
Month of the year

13. Mass data for one femaleMass(g)
Month of the year
Emergence
Return

14. Mass data for one female
Birth
Pregnancy
Mass(g)
Month of the year

15. Modelling mass data
for after-sunset period
- 5 social groups with group size manipulation
- Evening foraging period [sunset: 3 h after sunset]
- 37 days, 73 individuals, 8681 mass points
The automated dataset of mass

16. Modelling mass data
for after-sunset period
- 5 social groups with group size manipulation
- Evening foraging period [sunset: 3 h after sunset]
- 37 days, 73 individuals, 8681 mass points
The automated dataset of mass
Day 1 Day 6 Day 11 Day 15
Natural size
(100%)
Artificial size
(50-75%)
Natural size
(100%)

17. Modelling mass data
for after-sunset period
Linear mixed-effect models
- Response variable: Mass
- Fixed predictor variables (sex, group size, day, time, weather [rain, wind speed, temp., moon])
- Random effect variables (transponder, roost)
- 5 social groups with group size manipulation
- Evening foraging period [sunset: 3 h after sunset]
- 37 days, 73 individuals, 8681 mass points
The automated dataset of mass

18. Important predictor variables for mass
>
Sex
[Female-defense polygyny]

19. Important predictor variables for mass
>
Sex
[Female-defense polygyny]
Time
[Sunset: 3 h after sunset]

20. Important predictor variables for mass
>
Sex
[Female-defense polygyny]
Rain & wind speed
[Effect on foraging]
Time
[Sunset: 3 h after sunset]

21. Important predictor variables for mass
>
Sex
[Female-defense polygyny]
Rain & wind speed
[Effect on foraging]
Time
[Sunset: 3 h after sunset]
Group size
[Optimal for
mass gain]

22. Mass gain over 3 h ~ group size
Massgain(g)over3h
Group size

23. Mass gain over 3 h ~ group size
95%
Credibility
Interval
Group size
Massgain(g)over3h

24. A cooperative piece of work

25. yanngager.weebly.com

26. Fitness ~ group size
Higashi~1993
Compromise
Stable
Optimal

28. Mass variation: the Linear Mixed-Effect model

29. What are the multiple benefits of bat sociality?
Predator avoidance
Food sharing
Social thermoregulation
Information transfer about food