Browsing by Subject "Behavior"

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Humans universally demonstrate intrinsically motivated prosocial behavior towards kin, non-kin ingroup members, and strangers. However, humans struggle to extend the same prosocial behavior to more abstract concepts like future-others and non-human species. The Adaptive Motivation Hypothesis posits that humans evolved intrinsic motivations to act prosocially towards more tangible social partners like those within an individual’s ingroup, but prosocial behavior towards more distant and abstract partners is constrained by ecological certainty. Prosocial behavior towards these more abstract concepts is more variable and more likely motivated by extrinsic reward. This dissertation aims to examine the development of motivations for prosocial behavior towards these more abstract concepts. My studies rely on common goods games as a proxy for examining behavior towards abstract recipients of prosocial behavior. Common goods are any resource like forests or fisheries that are non-excludable to a population, but rivalrous. In-demand common goods require cooperation of humans to ensure sustainable use in order to avoid depletion. Chapter One examined how children in three populations that differed in ecological certainty behaved in a common goods game where they were asked to contribute portions of their personal endowment to the maintenance of a forest. Participants were either provided a high extrinsic motivation, a low extrinsic motivation, or no extrinsic motivation for contributing to the maintenance of the common good. Results show that overall, children of all ages were more motivated to contribute to abstract recipients when extrinsic motivation is high. However, noticeable variation in behavior between populations was driven by ecological and cultural differences. Chapter Two examined whether aggregated extrinsic rewards increased contributions to common goods in a sample of children aged six to fourteen. Results suggest that both information about personal loss and delay in an acquiring resource together dramatically increase children’s contributions to common goods within both experimental and real-world contexts. Chapter Three explores whether making a typically abstract social partner more tangible increases an individual’s prosocial behavior towards said partner. Results for Chapter Three, conducted with a population in the Democratic Republic of the Congo, find that increasingly the tangibility of an abstract population marginally increases prosocial behavior in children but not in adults. Together, the results of these studies have implications improved understanding of the development of prosocial motivations in school age children, as well as applications to understanding motivations for socially conscious behavior in the face of environmental and conservation dilemmas.

Social structure is a key determinant of population biology and is central to the way animals exploit their environment. The risk of predation is often invoked as an important factor influencing the evolution of social structure in cetaceans and other mammals, but little direct information is available about how cetaceans actually respond to predators or other perceived threats. The playback of sounds to an animal is a powerful tool for assessing behavioral responses to predators, but quantifying behavioral responses to playback experiments requires baseline knowledge of normal behavioral patterns and variation. The central goal of my dissertation is to describe baseline foraging behavior for the western Atlantic short-finnned pilot whales (Globicephala macrohynchus) and examine the role of social organization in their response to predators. To accomplish this I used multi-sensor digital acoustic tags (DTAGs), satellite-linked time-depth recorders (SLTDR), and playback experiments to study foraging behavior and behavioral response to predators in pilot whales. Fine scale foraging strategies and population level patterns were identified by estimating the body size and examining the location and movement around feeding events using data collected with DTAGs deployed on 40 pilot whales in summers of 2008-2014 off the coast of Cape Hatteras, North Carolina. Pilot whales were found to forage throughout the water column and performed feeding buzzes at depths ranging from 29-1176 meters. The results indicated potential habitat segregation in foraging depth in short-finned pilot whales with larger individuals foraging on average at deeper depths. Calculated aerobic dive limit for large adult males was approximately 6 minutes longer than that of females and likely facilitated the difference in foraging depth. Furthermore, the buzz frequency and speed around feeding attempts indicate this population pilot whales are likely targeting multiple small prey items. Using these results, I built decision trees to inform foraging dive classification in coarse, long-term dive data collected with SLTDRs deployed on 6 pilot whales in the summers of 2014 and 2015 in the same area off the coast of North Carolina. I used these long term foraging records to compare diurnal foraging rates and depths, as well as classify bouts with a maximum likelihood method, and evaluate behavioral aerobic dive limits (ADLB) through examination of dive durations and inter-dive intervals. Dive duration was the best predictor of foraging, with dives >400.6 seconds classified as foraging, and a 96% classification accuracy. There were no diurnal patterns in foraging depth or rates and average duration of bouts was 2.94 hours with maximum bout durations lasting up to 14 hours. The results indicated that pilot whales forage in relatively long bouts and the ADLB indicate that pilot whales rarely, if ever exceed their aerobic limits. To evaluate the response to predators I used controlled playback experiments to examine the behavioral responses of 10 of the tagged short-finned pilot whales off Cape Hatteras, North Carolina and 4 Risso’s dolphins (Grampus griseus) off Southern California to the calls of mammal-eating killer whales (MEK). Both species responded to a subset of MEK calls with increased movement, swim speed and increased cohesion of the focal groups, but the two species exhibited different directional movement and vocal responses. Pilot whales increased their call rate and approached the sound source, but Risso’s dolphins exhibited no change in their vocal behavior and moved in a rapid, directed manner away from the source. Thus, at least to a sub-set of mammal-eating killer whale calls, these two study species reacted in a manner that is consistent with their patterns of social organization. Pilot whales, which live in relatively permanent groups bound by strong social bonds, responded in a manner that built on their high levels of social cohesion. In contrast, Risso’s dolphins exhibited an exaggerated flight response and moved rapidly away from the sound source. The fact that both species responded strongly to a select number of MEK calls, suggests that structural features of signals play critical contextual roles in the probability of response to potential threats in odontocete cetaceans.

How does violence affect political participation and voting behavior? Why does a violent context push some to be politically active, while others decide to stay at home? Our current understanding of political behavior is mostly derived from analyses conducted in a peaceful and democratic context, or in post-conflict periods. However, citizens in many developing countries make their political decisions in the midst of violence.

The dissertation's central argument is that political participation and voting behavior largely depend on the context surrounding the individual. In particular, the level of criminal violence greatly impacts 1) citizens' decision to participate politically, 2) their forms of participation, and 3) the logic of their vote choice. Faced with violence, voters are generally pushed away from electoral politics. I argue that those that do decide to take part of the electoral process will consider their evaluations of security when deciding to punish or reward the incumbent government. While some may be inclined to take further action and demand peace through non-electoral participation, such a decision carries certain risks that are not easily overcome. I contend that social networks can encourage participation by shaping the understanding of crime, as well as the perception of costs and benefits associated with participation amid violence.

To evaluate this argument, I draw on a rich array of sources. I designed an original post-electoral survey that took place in Mexico a few days after the 2012 presidential election. I also created a novel newspaper databank of protests against crime in Mexico during the 2006-2012 period. In addition, together with Guillermo Trejo, I developed a unique dataset on criminal violence in Mexico. My statistical evidence is complemented with participant observation in marches for peace and qualitative in-depth interviews with victims and non-victims of crime in four Mexican cities.

Statistical evidence shows that violent criminal activity depresses electoral turnout. Voters living in violent contexts are less likely to participate in elections. Victims of crime are significantly less likely to participate in elections. However, faced with rising violence, active voters are able to consider both economic and insecurity evaluations in their assessments of government performance and voting decisions. Overall, as a voter's evaluation of national security worsens, her likelihood of supporting the incumbent national party and government diminishes. At the same time, while institutional channels are not attractive to victims of crime, societal accountability mechanisms are also available to citizens affected by insecurity. Victims of crime and those connected to mobilizing networks are more likely to participate in protests against insecurity than non-victims and "socially disconnected" individuals.

Disease risk in wild animal populations is driven by multiple factors, including host, parasite, and environmental traits, that facilitate the transmission of parasites and infection of hosts. Parasites inflict costs on their hosts that affect host fitness with downstream consequences on population structures and disease emergence patterns. Most disease risk-related studies are conducted in captive animals, while few have focused on free-ranging populations because of the logistical challenges associated with long-term monitoring of the hosts and sample collection. Hence, data regarding disease dynamics in natural populations are scarce, which limits our understanding of the ecological and evolutionary context of disease dynamics. In this thesis, we investigate the forces driving disease risk in wild primates and the possible consequences of infection on these hosts.

We used longitudinal and cross-sectional data sets from wild primate populations in Kenya, Eastern Africa, to examine the following aims: 1) the effect of host behavior on hormones associated with disease risk, 2) environmental and host factors that predispose individuals to helminth infections, and 3) the immune responses and fitness costs associated with helminth infections. First, we investigated how two maturational milestones in wild male baboons—natal dispersal and rank attainment—were associated with variation in fecal hormone metabolites (glucocorticoids and testosterone). These two hormones are generally considered to be immunosuppressive and are often associated with high parasite loads. Within this analysis, we also investigated whether changes in the frequencies of behaviors (mating and agonistic encounters) were associated with adult dominance rank attainment. Second, we investigated multiple sources of variance in helminth burdens in a well-studied population of wild female baboons, including factors that contribute to both exposure and susceptibility (group size, social status, rainfall, temperature, age, and reproductive status). Third, we investigated how hematological indices and body mass index were associated with helminth burden.

In the first study, our results revealed that rank attainment is associated with an increase in fecal glucocorticoids (fGC) levels but not fecal testosterone (fT) levels: males that have achieved an adult rank have higher fGC than males that have not yet attained an adult rank. We also found that males win more agonistic encounters and acquire more reproductive opportunities after they have attained adult rank than before they have done so. The second study revealed that female baboons in Amboseli were infected with diverse helminth taxa, including both directly transmitted and indirectly transmitted helminths. In general, high parasite risk was linked to large group sizes, low rainfall conditions, old age, and pregnancy, although these predictors varied somewhat across helminth species. Fecal GC levels were not associated with any measures of helminth burden. The third study found that helminth burdens were positively associated with circulating lymphocyte counts and negatively associated with neutrophil-lymphocyte ratios (NLR). We did not find any associations between helminth burdens and total WBC or eosinophil counts. Red blood cell indices were not predicted by our measures of helminth burden but instead varied with age class and sex. Helminth burdens were also negatively correlated with body mass index (BMI).

Overall, the findings of this thesis are consistent with the hypothesis that host and environmental traits are important predictors of disease risk and infection in wild primate populations. In addition, our results suggest that wild primates mount immune responses to helminth burden and that helminth infections may have detrimental consequences on host body condition. Our work enhances the limited data on sources of disease variation and associated costs in wild populations. It also emphasizes the continued need for disease surveillance and health monitoring in wild populations.

I present a framework that describes how perceived discrepancies from an ideal, or hoped-for, self influence how people view and behave with products associated with identity attainment (i.e., "symbolic props"). In the first half of this framework, I demonstrate that individuals who perceive that they are more discrepant from their aspired identity (i.e., more aspirationally discrepant individuals) view symbolic props as more "instrumental," or useful, in helping them achieve identity goals. I demonstrate that this effect is egocentric, mediated by motivation, and only occurs when the perceived rate of progress toward one's aspirational goals is high enough to merit engagement toward the goal. In the second half of the framework, I show that for more aspirationally discrepant individuals, the use of symbolic props may actually limit effort on goal-relevant tasks. These studies suggest an ironic effect whereby aspirational discrepancy may lead to acquisition of goal-relevant props to the detriment of performance-relevant effort.

The song system of the zebra finch (Taeniopygia guttata) is highly sexually dimorphic, where only males develop the neural structures necessary to learn and produce learned vocalizations in adulthood. During early development, both males and females begin to develop their song system in a monomorphic manner, which diverges shortly after the onset of a critical sensory learning phase and results in reduced cell survival and proliferation in females, and accelerated cell proliferation in males. Estrogen has long been known to be involved in coordinating sexual development of the perinatal brain and nestling female zebra finches treated with estrogen do not exhibit this female-specific atrophy of the song system. How estrogen influences the development of the song system, and what it is doing at the molecular level has not been examined utilizing current generation sequencing technology.

In this dissertation, I tested whether estrogen manipulation impacts the transcriptomic profiles of telencephalic song learning nuclei in males and females. I treated animals with either vehicle, exemestane (an estrogen synthesis inhibitor), or 17-β-estradiol from the moment of hatching until time of sacrifice. I collected the song learning nuclei and their surrounding brain regions during the onset of sensory motor learning for transcriptomic analysis or during adulthood after collecting behavior. I found that of the 4 telencephalic song nuclei examined during the onset of the sensorimotor learning period at post hatch day 30, Area X was the most sexually dimorphic and the most impacted by estrogen administration. HVC was less sexually dimorphic and less impacted by estrogen manipulation. RA and LMAN had limited sexually dimorphic features, with little impact on their transcriptomes with estrogen manipulation. Additionally, I found that chronic estrogen depletion in males delayed male specific plumage development and resulted in impaired song learning. This supports the notion that while estrogen is sufficient in preventing atrophy of the song system in female zebra finches, it is not necessary for the gross development in males and may instead refine normal song development.

Humpback whales (Megaptera novaeangliae) are one of the biggest animals on the planet and thus require large quantities of dense prey to meet their energetic requirements. They feed using discrete lunges and filtration to capture their euphausiid (krill) and schooling fish prey. They forage independently, in small groups, or in larger coordinated groups of up to 15 or more individuals. This dissertation aims to improve our understanding of the fine-scale foraging behavior of humpback whales in Southeast Alaska. High-resolution biologging tags (DTAGs) were deployed and focal follows were conducted on foraging humpback whales in Sitka Sound, Alaska in September 2012 and Tenakee Inlet, Alaska in April 2013. Concurrently, prey around tagged foraging whales was sampled using a Simrad EK 60 scientific echosounder, and acoustic data were ground-truthed with net tows for krill and hook and line samples for fish. Whale and prey data were then spatially and temporally integrated to determine characteristics of prey patches upon which whales fed. Results indicate that humpbacks targeted the densest layer of krill in Sitka Sound, maximizing their energetic gain by capturing the most prey with each lunge. When foraging together in groups, bubble-net feeding humpback whales repeated specific behaviors within a foraging bout, suggesting that whales were feeding cooperatively using role specialization and a division of labor to improve foraging efficiency. Finally, the group size of humpbacks increased throughout a week-long study as whales exploited a pre-spawning Pacific herring (Clupea pallasii) aggregation in Tenakee Inlet, which responded to the increased predation pressure with changes in school behavior. As the population of North Pacific humpback whales increases and global warming continues to affect marine ecosystems, a better understanding of predator-prey interactions is crucial to best conserve and manage humpback whales and their ecosystem as a whole.

High-resolution bio-logging tools were used to examine the fine-scale foraging behaviors of humpback whales (Megaptera novaeangliae) in the coastal waters of the Western Antarctic Peninsula during the austral autumn of 2009 and 2010. Discrete feeding events (i.e., lunges) were inferred from the biologging records of thirteen whales, including a mother and her calf. In general, humpback whales exhibited efficient foraging behaviors that allowed them to maximize energetic gains and minimize energetic costs as predicted by optimal foraging theory. They fed at a continuous and high rate in the upper portion of the water column (< 100 m) from approximately dusk to dawn when their prey (Antarctic krill, Euphausia superba) were most vulnerable and less costly to acquire (i.e., near the surface). When forced to dive to greater depths, they adjusted their behaviors (e.g., descent and ascent rates) so that they could maximize their foraging durations and increase their lunging rates. In addition, humpbacks appeared to accept short term (i.e., dive by dive) costs associated with depleted oxygen stores in favor of maximizing long term (i.e., daily) energetic gains. Such efficient behaviors are particularly beneficial for mother-calf pairs who have additional energetic costs associated with foraging, such as lactation (mother), growth (calf), and maintaining proximity. In addition, because the physiology of humpback whales is poorly understood yet critically important for predicting their behaviors in response to fluctuations in their environmental conditions, foraging behaviors inferred from the bio-logging records were used to estimate their metabolic rates, oxygen storage capacities, and oxygen replenishment rates under the framework of optimal foraging theory. This research suggests that the current techniques used to estimate humpback whale oxygen stores is appropriate but that the estimation of metabolic rates of humpbacks while foraging and while traveling need to be addressed further. This work aims to increase the current understanding of humpback whale foraging behaviors along the Western Antarctic Peninsula so that appropriate measures can be taken to aid in their recovery and in the sustainability of the Antarctic marine ecosystem.