1. Parental Investment “any characteristics or actions of parents that increase the fitness of offspring at a cost…to the parent’s fitness” Clutton-Brock 1991

2. Territory Bequeathal Mother gives part or all of her territory to her offspring stops defending territory becomes vagrant shows up on vacant middens offspring take over midden

3. Why Bequeath? Parental Investment? Alternatives: Improve territory quality Parent-Offspring conflict

4. Longterm Evidence 9 years (89-97) 2835 tagged individuals 1013 litters 590 litters with young to weaning Post-breeding behaviour for 485 litters (302 females) Analyses by Dominique Berteaux

5. Post-breeding Options Keep Share Bequeath Increasing investment

6. Keep % Proportion using each behavioural strategy ShareBequeath n = 214 n = 71 n = 200

7. % survivorship Owned another territory Did not own any territory Owned their mother’s territory Effect of territory ownership on juvenile overwinter survival n = 186 n = 288 n = 206

8. Costs/Benefits to Females Survive70.46957.7 Reproduce8079.680.5 Litter size2.73 1.1 2.87 1.3 2.70 1.2 # Weaned.98 1.0 1.54 1.2 1.09 1.1 KeepShareBequeath Subsample of keep,share n=30-70

9. Who Bequeaths? Can this be predicted by parental investment theory?

10. Factors affecting whether females bequeathed or not Age NoYes Cone production NoYes # of juveniles NoYes Cone reserves NoYes

11. Parental Investment Theory PredictionsRed Squirrels Increase: With ageyes With # weanedyes With foodyes In sex with >returnno

12. Which Juveniles obtained middens from their mother? P<0.009 n=411

13. Experimental Evidence Permanent and temporary removal of neighbours in late summer Monitor takeovers –attempts –successes Design:

14. Who took over removal territories? P=0.021 Mothers with offspring

15. Parental investment Pre- lactation? Do females acquire middens as a form of parental investment? Do females acquire middens as a form of parental investment?

16. Experiment Experimental removal of neighbouring males in October 8 Experienced (had produced young) 8 Inexperienced (no young) Monitored fates of vacant middens

17. Results No females switched territories but some acquired a second midden October X X April X X 6 of 7 Experienced 1 of 6 Inexperienced

18. Results Acquired second midden61 Weaned young54 Gave midden to offspring51 Variable Exp Inexp

19. Why Experienced Females? BreedersFirst-time Breeders Probability of breeding 100% 7-100% next year

20. Conclusion Female red squirrels acquire middens well in advance of mating or offspring dependency and relinquish these to their offspring Anticipatory Parental Investment

21. Bequeathal Unanswered Questions: Proximate cues –Availability of vacant middens –Resources on and off territory Anticipation – is it real The male-female thing Heritability of bequeathal behaviour