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Abstract:
Dusky-footed woodrats (Neotoma fuscipes) build large, complex stick houses in which they shelter and store food. The relatively unique addition of the house as a valuable commodity renders N. fuscipes an intriguing species for the study of dispersal and philopatry, parent-offspring conflict, and parental investment theory. In this study I examine patterns of dispersal and house inheritance in the field and identify correlates to the observed outcomes. I successfully elicit dispersal in captivity and observe behavioral development and interactions that precede dispersal from the natal house. Finally, I examine house building and determine whether related individuals benefit from close association through the provision of shelter. Females dispersed from the natal house after successfully weaning litters, and offspring inherited natal houses more often in high population density. This suggests that bequeathal of the natal house is a form of parental care. However, no clear benefit to the offspring could be demonstrated. In captive studies, females remained in the natal house more often than expected based on field data, while juveniles dispersed to new houses. Though levels of aggression rose immediately prior to dispersal and declined sharply after dispersal occurred, rank based on aggressive interactions between siblings did not predict which juvenile in a litter dispersed. In addition, exploratory behavior increased prior to the spike in aggression, suggesting that dispersal may be driven both by inherent exploratory behavior and decreased maternal tolerance at the natal nest. Territorial divisions between family members after dispersal were flexible and characterized by only mild aggression. When houses were dismantled, both mothers and offspring successfully rebuilt their shelters, suggesting that the rarity of building in the wild may be due to external limitations. In addition, mothers who lost their houses sheltered successfully with their offspring, while offspring left homeless were not able to shelter with their mothers. This suggests that some of the cost to mothers in bequeathing the natal house to their offspring or allowing them to settle nearby may be offset by the potential for future direct fitness benefits. Though many aspects of this complicated behavioral strategy remain unexplained, these data suggest that further study of dispersal and house inheritance in the dusky-footed woodrat will benefit our understanding of the dynamics of parental care, philopatry, and nepotism.
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