Behavior and Ethology Commons^™

Factors Influencing Sex-Based Movement Patterns In The Banded Garden Spider, Argiope Trifasciata (Forskal, 1776), Brandon R. Marrone

School of Biological Sciences: Dissertations, Theses, and Student Research

Movement is a fundamental ecological process shaping how individuals acquire mates, secure resources, and navigate heterogeneous landscapes. In species with extreme sexual size dimorphism (eSSD), such as the orb‑weaving spider Argiope trifasciata, males and females are predicted to experience different movement pressures driven by their reproductive roles. This thesis examines how individual traits and environmental conditions jointly influence movement across both sexes. Across two field seasons, we used intensive mark–recapture methods to quantify natural movement patterns of males and females within mapped prairie plots. The first chapter tested long‑standing predictions gravity hypothesis, which posits that smaller males benefit from …

Prey Selection By Birds Of Prey, Anisha Pokharel

School of Biological Sciences: Dissertations, Theses, and Student Research

Prey selection is key to determine predator prey interaction and understanding the complexity of food web structure. In this thesis, we used two different approaches to understanding prey selection by North American birds of prey. Using a conventional method, in Chapter 1 we compared pellet analysis and trapping data to assess patterns of prey selection of barn owls in western Nebraska. Microtus spp. comprised 55.8% of the prey items in the barn owl’s diet. The proportion of several prey types in the diet were significantly different from the expected proportion based on trapping. This pattern may indicate barn owls actively …

Functions Of Vocal Mimicry In The Complex Song Of The European Starling, Sturnus Vulgaris, Maria Goller

School of Biological Sciences: Dissertations, Theses, and Student Research

Vocal learning is an ability that has only evolved in a handful of taxa. Songbirds learn their songs, and some species have flexible learning in which they not only incorporate species-specific sounds, but heterospecific and/or environmental sounds as well. The functions of vocal mimicry are still unknown for many species and studying mimicry can teach us about the variation within the song learning process. In this thesis, I focused on five hypotheses on how mimicry could function in sexual selection. The repertoire size hypothesis suggests that selection for larger repertoire sizes allows mimicry to occur because imitation can increase repertoire …

Behavioral Plasticity Across Non-Social Contexts In Female Green Swordtails, Xiphophorus Helleri, Lindsey M. Coit

School of Biological Sciences: Dissertations, Theses, and Student Research

Phenotypic plasticity is the ability of an individual to alter its phenotype in response to environmental change. Individuals that express plasticity in behavior can quickly respond to changes that occur in the environment. Therefore, individuals that exhibit behavioral plasticity can alter their behavioral expression to best match current environmental conditions. The degree and direction of behavioral plasticity may be influenced by variation in individual characteristics. Understanding how variation in individual traits affects behavioral plasticity, and, whether patterns of behavioral plasticity are consistent across behavioral contexts are important topics to explore as we try to better understand how plasticity evolves and …

Inter- And Intra-Individual Variation In Predator-Related Behavioral Plasticity Expressed By Female Green Swordtails (Xiphophorus Hellerii), Rachael A. Disciullo

School of Biological Sciences: Dissertations, Theses, and Student Research

Phenotypic plasticity is the ability of one genotype to express multiple phenotypes under variable environments. Behavioral plasticity is a type of phenotypic plasticity in which individuals adjust behavior in response to changes in environment. Often, behavioral plasticity is studied at the level of the population, rather than at the level of the individual. Further, few studies have considered the effect of individual traits, such as size and age, on the expression of behavioral plasticity, or, how individual plasticity may be correlated across different contexts. In this study, we used female green swordtails (Xiphophorus hellerii) to test the effects …

Proximate And Evolutionary Causes Of Sexual Size Dimorphism In The Crab Spider Mecaphesa Celer, Marie Claire Chelini

School of Biological Sciences: Dissertations, Theses, and Student Research

Animal species’ body sizes result from the balance between selection for survival and selection for reproduction. In species with sexual size dimorphism (SSD), this balance differs between females and males, resulting in distinct sizes despite similar constraints. I used an integrative approach to understand how sexual section, and differences in developmental trajectories and metabolic physiology, resulted in the female biased SSD of the crab spider Mecaphesa celer (Thomisidae). SSD in spiders is often assumed to be a consequence of selection for early male maturation, which should provide males with additional mating opportunities. My results allow us to discard mate …

Population And Morphological Changes In American Kestrels Through Space And Time, Teresa E. Ely

School of Biological Sciences: Dissertations, Theses, and Student Research

A once common raptor, the American kestrel (Falco sparverius) has experienced population declines in the last two decades throughout North America. Many hypotheses exist about the decline, including mortality from West Nile virus, rodenticide poisoning, climate change, an increase in predators, and core habitat loss or degradation, which could influence food availability. Food availability is key to raptor survival and reproduction, and changes in food availability throughout the year can have lifelong effects on size and body condition. Here we examine how morphology, specifically mass and wing chord, has changed at seven migration sites throughout North America as …

Observational Learning In The Jumping Spider Phidippus Audax, Robert M. Adams

School of Biological Sciences: Dissertations, Theses, and Student Research

Observational learning is a complex form of learning most frequently studied in social vertebrates. However, evidence for social learning exists in several invertebrate species Evidence of invertebrate observational learning also exists, though to a lesser extent. This study addresses observational learning in a jumping spider (Phidippus audax) through video playback. My results suggest that while observational learning is occurring, the exact mechanism in use remains unclear. Spiders that saw a conspecific satiate itself on a prey item readily attacked a similar prey item when exposed to a live prey item. However, spiders exposed to a conspecific rejecting or …

Plasticity In Female Mate Choosiness: A Result Of Variation In Perceived Predation Risk And The Interaction Of Female Age And Male Density, Ashley N. Atwell

School of Biological Sciences: Dissertations, Theses, and Student Research

In many species, female mate choices can be a strong source of sexual selection. Females often prefer a certain male phenotype, and this can be due to benefits females gain from mating with preferred males. However, such benefits can sometimes be outweighed by the cost of searching for a preferred male. These costs and benefits often change concomitantly with changes in environmental (e.g., predator abundance and conspecific density) and internal factors (e.g., female age). Thus, female mate choosiness (the degree to which preferences for certain males are expressed) should often be plastic. Plasticity in female mate choosiness may be complicated …

Costs Of Female Mating Behavior In The Variable Field Cricket, Gryllus Lineaticeps, Cassandra M. Martin

School of Biological Sciences: Dissertations, Theses, and Student Research

Female animals may risk predation by associating with males that have conspicuous mate attraction traits. The mate attraction song of male field crickets also attracts lethal parasitoid flies. Female crickets, which do not sing, may risk parasitism when associating with singing males. If parasitism risk is sufficiently high, it may affect the evolution of female mating behaviors. In this dissertation, I explore the interaction between the female variable field cricket, Gryllus lineaticeps, and the parasitoid fly, Ormia ochracea. To begin, I investigated whether female parasitism risk resulted from being near singing males. I found that females can become …

Trade-Offs In Male Lek Behavior, Sarah A. Cowles

School of Biological Sciences: Dissertations, Theses, and Student Research

In lek mating systems, males aggregate together and perform courtship displays to visiting females. However, display may be energetically expensive and reduce the time available for foraging. These costs in turn could lower energy reserves, which could decrease survival. I examined trade-offs in male lek behavior using two methods: 1) I conducted an empirical study of how sharp-tailed grouse (Tympanuchus phasianellus) males allocate time between courtship display (“dancing”), agonism, foraging, and inactivity in relation to female numbers both within and across days. I also measured head turning rates during these same behaviors as a proxy for visual attentiveness …

Predation And Behavioral Plasticity In Green Swordtails: Mate Choice In Females And Exploratory Behavior In Males, Andrew J. Melie

School of Biological Sciences: Dissertations, Theses, and Student Research

Two studies were carried out with green swordtails, Xiphophorus helleri, to investigate the effect of predation on swordtail behavior, and to determine how behavioral plasticity operates in both a mate choice and an anti-predator context. Male green swordtails vary in colorful conspicuous traits, e.g. the colorful dorsal fin and sword. Female swordtails have a preexisting bias for males with a sword, and prefer long-sworded males to short-sworded males, but this preference is plastic. The first study examined predator-related plasticity in the behavior of males differing in size. Smaller males showed greater behavioral plasticity; they were more active in the …

Spontaneous Male Death And Monogyny In The Dark Fishing Spider Dolomedes Tenebrosus Hentz, 1843 (Araneae, Pisauridae), Steven K. Schwartz

School of Biological Sciences: Dissertations, Theses, and Student Research

Male animals typically attempt to mate with multiple females in order to increase their reproductive success. In some species, however, males instead invest in fertilizing the eggs of a single female. Monogyny (male monogamy) is found in a diverse assemblage of taxa, and recent theoretical work reveals that a male-biased sex ratio can favor the evolution of this relatively rare mating system. We integrate this theoretical framework with field observations and laboratory experiments involving the sexually size dimorphic fishing spider, Dolomedes tenebrosus. Results from mating trials revealed a novel form of self-sacrifice behavior where males spontaneously die when they …

Foraging Challenges: Unsuitable Prey And Limited Information, Travis M. Hinkelman

School of Biological Sciences: Dissertations, Theses, and Student Research

Food acquisition is a complicated task. The profitability of potential food items depends on numerous factors, including the spatial distribution, probability of detection and capture, and suitability of the food. Animals faced with such challenges can use relatively simple mechanisms to maximize foraging efficiency. However, mechanisms that maximize foraging efficiency under some ecological conditions (e.g., prey scarcity) may produce ostensibly suboptimal behavior under different ecological conditions (e.g., prey abundance). In the work presented here, we explore two facets of foraging: (1) consuming unsuitable prey, and (2) searching for resources with limited information about resource location. To explore the consequences of …

Effect Of Diet Quantity And Quality On Female Sampling Behavior And Mating Preferences In A Field Cricket, Heidi L. Bulfer

School of Biological Sciences: Dissertations, Theses, and Student Research

Understanding the adaptive significance of variation in female mating behaviour is important because variation may often be favored by selection instead of a change in mean mating behaviour, particularly in variable environments. Females are known to adjust their mating behaviour to a variety of intrinsic and extrinsic factors including nutrition. There are multiple reasons why female behaviours might vary with nutrition; we tested two of these hypotheses: the search cost hypothesis and the direct benefits hypothesis. These hypotheses are not mutually exclusive, but they make contrasting predictions under some conditions. Low nutrition females may have less available energy to support …

Life History Tradeoffs And Phenotypic Plasticity: The Tale Of A Flight Polyphenic Field Cricket, Chandreyee Mitra

School of Biological Sciences: Dissertations, Theses, and Student Research

Most organisms are resource limited. Such limitations can result in tradeoffs between life history traits -- any traits that affect survival or reproduction. Flight polyphenic field crickets are thought to be a classic example of such a life history tradeoff, in which individuals tradeoff investment in flight capability and investment in reproduction. This polyphenism results from the interaction of two morphological traits: wing morphology (short or long) and flight muscle morphology (functional pink or non-functional white), and is affected by both genes and the environment. I examined life history traits of a flight polyphenic field cricket, Gryllus lineaticeps. First, …

The Effects Of Social Context And Cache Survival On Pinyon Jay Caching Behavior, Christine L. Keefe

School of Biological Sciences: Dissertations, Theses, and Student Research

I examined how pinyon jays (Gymnorhinus cyanocephalus) assess and determine the risk of pilferage to their caches. Jays were allowed to cache in an open room while alone or while being observed by a conspecific. In a counterbalanced design, jays cached in the opposite treatment once they had finished recovering their caches. I compared birds’ behaviors between treatments in order to determine whether jays consider the presence of an observer in measuring the local competitive environment. Once all jays had completed alone- and observed- treatments, I ran the experiment once more to determine if individuals were consistent in …

Exploring Sources Of Selection On The Multimodal Courtship Displays Of Two Sister Species Of Wolf Spiders: Schizocosa Crassipalpata And Schizocosa Bilineata, Mitch D. Bern

School of Biological Sciences: Dissertations, Theses, and Student Research

We examined multiple sources of selection on the multimodal courtship display of two sister species of wolf spiders, Schizocosa crassipalpata and Schizocosa bilineata. We first experimentally altered body condition in these two species by employing divergent diet treatments. We then tested for differences in adult male seismic courtship displays, visual courtship displays, and foreleg morphology; as well as adult female foreleg morphology. We then simultaneously examined both content and efficacy-based sources of selection on the visual and seismic multimodal courtship display of both species by conducting mate choice trials with high and low diet individuals across manipulated signaling environments …

The Complexities Of Wolf Spider Communication: Exploring Courtship Signal Function In Rabidosa Rabida, Dustin J. Wilgers

School of Biological Sciences: Dissertations, Theses, and Student Research

Evidence of signal complexity is seemingly pervasive across animal communication systems. Exploring signal function may provide insight into how these displays evolved and are maintained. This dissertation examines the courtship signal function in a grassland wolf spider. Rabidosa rabida lives in an extremely complex environment, and males use complex displays incorporating both visual and seismic modalities. Using several approaches I provide insight into the content and efficacy of the various signal components, as well as how variation in these displays influence female mating decisions in isolation and combined.

First, I manipulated male and female body condition using diet quantity manipulations …

Ecological Effects Of Virus-Resistant Transgenic Squash, Holly R. Prendeville

School of Biological Sciences: Dissertations, Theses, and Student Research

Two ecological risks associated with the use of transgenic crops include the effects of transgene products on non-target organisms and the effects of a transgene after it moves from crops into a wild plant population. In work presented here, we specifically investigate the ecological risks of virus-resistant transgenic squash. We observed pollinator behavior to determine if pollinators are affected by nontarget effects of the virus-resistant transgene. We found that pollinator behavior did differ between conventional and virus-resistant transgenic squash due to pleiotropic effects of the transgene. This difference in pollinator behavior can affect plant mating patterns, thereby affecting crop-wild hybridization …

Sociality And Reconciliation In Monk Parakeets (Myiopsitta Monachus), Lynnsey Lee Morrison

School of Biological Sciences: Dissertations, Theses, and Student Research

For animals living within socially complex groups, it is beneficial for all individuals to maintain group cohesion. Conflicts often arise in groups, which could potentially have high costs both to the subordinate and dominant members, and could lead to group instability. It has been shown numerous times that highly social group members participate in affiliative relationships with other group members discriminately. They also perform related behavior patterns such as reconciliation at a high rate, which could strengthen group stability. Reconciliation occurs when an affiliative interaction takes place between two individuals following an agonistic encounter. The rate of affiliation is higher …