Dissertation Defense: Madison Miketa
Candidate Name: Madison Layne Miketa
Advisor: Janet Mann, Ph.D.
Title: Social and Behavioral Responses to Environmental Stressors in Bottlenose Dolphins in Shark Bay
Animals experience a variety of natural and anthropogenic environmental stressors. Although individuals exhibit behavioral plasticity, responses can impact survival and fitness. Bottlenose dolphins are long-lived, socially complex, and behaviorally flexible. I examine how individuals adjust their behavior in response to environmental stressors and the importance of long-term female-female bonds as a potential mitigating factor.
Chapter 1 investigates mother-calf diving behavior. Because calves initially have limited swimming and diving capabilities, mothers must adjust their behavior accordingly. I found that calves increased their dive durations with age. However, mothers were more likely to adjust their diving behavior when near female calves, but not male calves. This is consistent with sex-specific socio-ecological strategies, where vertical learning is more important for female than male calves.
Chapter 2 examines the behavioral impacts of an entanglement event. In a rare observation throughout entanglement, I found that there was a decrease in foraging and socializing, but an increase in traveling and erratic behaviors. Further, the entangled individual was alone nearly all of entanglement. Post-entanglement, her activity budget and behavior returned to normal.
Chapter 3 quantifies the impacts of a major seagrass die-off on dolphin behavior. I found that, paradoxically, dolphins increased their use of seagrass habitat following the die-off. Seagrass specialists shifted habitat use and foraging from their preferred seagrass species to the less preferred, but less damaged species. Calving rate and calf survival were not different in the 5 years post die-off, but there may longer-term impacts.
Chapter 4 explores the temporal dynamics of female social bonds. I found that 65% of females maintained long-term bonds with top associates for 4 to 18 years. Females that maintained at least one long-term bond were more likely to have a surviving calf than females who did not. Also that partner similarity, degree of alter, and bond strength were important for the maintenance of ties, while friends-of-friends and age difference were important for the creation of ties.
This work improves our knowledge of how animals mitigate various environmental stressors. Long-term datasets on long-lived, socially complex mammals are rare, but invaluable for understanding how individuals respond to a changing environment.
Friday, August 10 at 10:00am to 12:00pm
Healy Hall, 104
37th and O St., N.W., Washington