While substrate-borne vibrations are utilized by different reptile species, true conspecific communication via biotremors has not yet been demonstrated in reptiles. This study follows a preliminary report that the veiled chameleon (Chamaeleo calyptratus) could produce biotremors in communicative contexts. I tested chameleon behavioral sensitivity to vibrations by placing them on a dowel attached to a shaker emitting vibrations of 25, 50, 150, 300, and 600 Hz and then measured their changes in velocity before and after the stimulus. I then paired chameleons in various social contexts [anthropogenic disturbance (human disruption of animal); dominance (malemale; female-female C. calyptratus); courtship (male-female C. calyptratus); heterospecific (C. calyptratus + C. gracilis); and predator-prey (adult + juvenile C. calyptratus)] and used a video camera and accelerometers to record their behavior. This study demonstrates that chameleons produce biotremors and that receivers exhibit a freeze response when exposed to a simulated biotremor stimulus. Furthermore, veiled chameleons produce biotremors in anthropogenic disturbance, conspecific dominance and courtship contexts, and these biotremors are elicited by visual contact with another adult conspecific and heterospecifics. Overall, two classes of biotremor were identified, "hoots” and “rumbles,” which differ significantly in dominant frequency and waveform. No correlation was identified between animal size and dominant frequency of the biotremors they produced as biotremors originate from rapid muscle contractions. Juvenile chameleons of two months of age are able to produce biotremors, suggesting this behavior may have multiple functions. Overall, the data suggest that the veiled chameleon has the potential to utilize substrate-borne vibrational communication during conspecific and possibly heterospecific interactions.

While much work has been done on regional vocal variation in birds, relatively few studies have found evidence of similar variation in mammalian vocalizations. This study quantifies individual, colonial, and regional level variation in T. brasiliensis songs in the southeastern United States. Brazilian free-tailed bats (Tadarida brasiliensis) are among a handful of mammals that produce complex, hierarchically structured vocalizations. Their songs are composed of multiple syllables that are combined into three phrases that vary in number and order across renditions. Tadarida brasiliensis songs showed considerable amount of variation, and differed significantly between locations in terms of syllable structure and song syntax. Some of the variation observed was not correlated to geographical distance, and is unlikely to be explained by genetic divergence or differences in habitat use. These results indicate the existence of vocal dialects and a possible role of vocal production learning in dialect formation in this species.

Predators exert strong direct and indirect effects on ecological communities by intimidating their prey. Non-consumptive effects (NCEs) of predators are important features of many ecosystems and have changed the way we understand predator-prey interactions, but are not well understood in some systems. For my dissertation research I combined a variety of approaches to examine the effect of predation risk on herbivore foraging and reproductive behaviors in a coral reef ecosystem. In the first part of my dissertation, I investigated how diet and territoriality of herbivorous fish varied across multiple reefs with different levels of predator biomass in the Florida Keys National Marine Sanctuary. I show that both predator and damselfish abundance impacted diet diversity within populations for two herbivores in different ways. Additionally, reef protection and the associated recovery of large predators appeared to shape the trade-off reef herbivores made between territory size and quality. In the second part of my dissertation, I investigated context-dependent causal linkages between predation risk, herbivore foraging behavior and resource consumption in multiple field experiments. I found that reef complexity, predator hunting mode, light availability and prey hunger influenced prey perception of threat and their willingness to feed. This research argues for more emphasis on the role of predation risk in affecting individual herbivore foraging behavior in order to understand the implications of human-mediated predator removal and recovery in coral reef ecosystems.

The different ways that animals extract and analyze visual information from their environment is of interest to sensory ecologists. Jumping spiders, well-known for visually guided mating and hunting behavior, are an interesting model for the study of visual attention because they quickly and efficiently integrate information from eight eyes with a small brain. Stimuli in front of the spider are examined by two functionally and morphologically distinct pairs of forward-facing eyes. The principal eyes discern fine details and have small retinas and thus a small visual field. However, their position at the back of moveable tubes within the cephalothorax expands this visual field. The anterolateral eyes, one of the three pairs of secondary eyes, have lower spatial acuity and a larger visual field that overlaps with that of the principal eyes. They act as motion detectors, directing the principal eyes to objects appearing in their visual field. In Chapter 1, using a salticid-specific eyetracker, I explore how characteristics of a stimulus influence whether the secondary eyes redirect the gaze of the principal eyes from a principal stimulus to a new stimulus appearing in the visual field. I found that spiders suppressed redirection of the principal eyes when engaged by a salient stimulus, and redirected to moving peripheral stimuli more frequently than to stationary peripheral stimuli. The principal eyes are also known to engage in a complex behavior called “scanning,” involving both dorsoventral and rotational movement. One hypothesis regarding scanning’s function is that it helps spiders identify important lines and angles in stimuli. However, scanning routines are not well understood. In Chapter 2, I measured scanning behaviors when spiders were watching quickly moving versus still or slowly moving images. I found that spiders spent more time overall looking at still or slowly moving images, and that stimulus speed does not appear to affect rotational movement of the retinas. Overall, I conclude that motion in an appearing stimulus elicits the attention of the principal eyes, but it remains unclear how and whether scanning functions in the extraction of detail from moving stimuli.

This study investigated selective pressures associated with encephalization in mammals and discussed broader implications. Relative brain size as measured by EQ (Encephalization Quotient) was compared between ecological categories. Omnivores had higher average EQ than ecological specialists. Since specialists are disproportionately affected by extinction events, selection for ecological generalism is proposed as encephalization mechanism. This mechanism may reinforce the more widely known Cognitive Buffer Hypothesis (CBH)—the idea that possessing relatively large brains has buffered lineages against environmental change. CBH is tested here by comparing EQs in Procyon lotor (raccoon) in urban and rural environments. CBH predicts that raccoons in the most radically altered environment, the city, experience the strongest selection for encephalization. Urban raccoons studied here exhibit a higher EQ. Although results are preliminary, data suggest that encephalization is accelerated during abrupt periods of environmental change. Finally, implications for the evolution of biological complexity more generally are discussed.

Conserving and restoring anadromous fish populations is an important research and management priority. For conservation to be effective, researchers must understand the behavior of the fish they seek to restore. Telemetry has allowed researchers to understand the upstream migrations of these fish in freshwater, how migration patterns vary, and if there is a relationship between behavior and environmental variables. In the northeastern United States, alewife (Alosa pseudoharengus), one of two species collectively referred to as river herring, has historically been an important component of coastal rivers. However, populations of these fish have experienced recent declines, and a commonly used method to restore river herring is stocking. In this thesis, I summarize research that seeks to understand anadromous alewife behavior with the goal of providing insights that will help manage and conserve this species and the coastal systems in which they live. My thesis has a primary research chapter (Chapter 1), a second ancillary research chapter (Chapter 2), and four appendices that summarize related information as part of the funding proposal. First, to examine if fish origin (native or stocked) and fish release location (upstream or downstream) affected the pre-spawning movements of fecund alewives, I undertook a reciprocal experiment. In Chapter 1, for fish of both origins and release locations, I examined how long fish were in the river, where they spent their time, and how much and how fast they moved. For this, I gastrically tagged alewives with Lotek Nanotags NTC-6-1 radio tags and monitored movements in the lower 30 km of the Ipswich River (northeastern Massachusetts) using an array of 9 Lotek SRX_400 receivers. Based on these movement trajectories I concluded that in 2007, origin affected the total time fish spend in the river and release location affected where they spend their time. Downstream movements of upstream migrating fish have typically been viewed as a behavioral assay of adverse tag effects. For this reason, alosine telemetry studies rarely release tagged fish upstream of the capture site. However, fisheries managers often release fish upstream near spawning grounds during stocking. In Chapter 2, I re-evaluated whether downstream movements of upstream stocked fish were consistent with an adverse tag effect. By combining physiological experiments with select movement trajectories, I showed that pre-spawning migrations of alewife included an array of up and downstream directed movements with various interpretations. In my research, these downstream movements were unlikely to be related to tagging stress (Chapter 2), as the cortisol, glucose, and chlorides of tagged fish were not different from untagged fish (Appendix A, Physiology). Furthermore, I suggested metrics that should be recorded in telemetry studies to standardize how downstream fish movements are measured. In 2006, native fish were released at a downstream site (river km 6) and stocked fish were released upstream (rkm 25). I compared the behaviors of these same treatments across years. I showed that the behaviors of fish released in different years may differ based on temperature and discharge (Appendix B, Across Year Comparison). To determine the amount and location of potential spawning habitat, I undertook a habitat study that utilized a geographic information system (GIS) to maps the size and distribution of habitat types. I located multiple mainstem pools in the Ipswich River that may serve as suitable spawning grounds for alewife. Tagged fish were primarily located in these habitats (Appendix C, Habitat). To determine if juveniles were produced, I sampled various sites in the river for the presence of juveniles, using active and passive sampling techniques. Juveniles were not captured during these surveys (Appendix D, Juvenile Sampling). Before this research, little was known about the pre-spawning migrations of river herring. While river herring are assumed to be a generalist species, I found their behaviors to be complex. I have identified a number of gaps in the current knowledge of how these fish behave in the field. Restoration efforts must take into account the behavior of the fish, as well as the capacity of a system to accommodate those needs. Within the context of understanding fish behavior, protecting habitat, and providing regulatory restrictions on the fishery, stocking may contribute to broader management and restoration goals.

Pieris oleracea, formerly Pieries napi, was once a widespread pierid butterfly in New England until the introduction of a biological control agent, Cotesia glomerata. It has been suggested that C. glomerata is responsible for the range reduction of P. oleracea. There are been several introductions of a second more specialized biological control agent, Cotesia rubecula, to the United States since the 1960’s. My first goal was to determine the current distribution and status of P. rapae parasitoids and the effectiveness of C. rubecula as a biological control agent since its release. The findings of a survey I conducted of the parasitoid community of P. rapae indicate that C. rubecula now occurs as far west as North Dakota and has become the dominant parasitoid of P. rapae in the northeastern and north central United States and adjacent parts of southeastern Canada, where it has displaced C. glomerata, the previously dominant parasitoid. Survival of artificially established cohorts of P. rapae larvae was assessed in a collard patch on an organic vegetable farm in western Massachusetts. There was a significant drop in larval survival between the 4th and 5th instar due to parasitism by C. rubecula. This was change from survival curves of P. rapae from a 1985-1986 study, in which there was a significant drop in survival between the 5th instar and pupal stage due to C. glomerata. The final goal of my thesis work is to try to understand why P. oleracea was able to survive at the focal study site in Lenox, MA despite parasitoid pressure and range reduction elsewhere in New England. In olfactometer tests, there was no difference in attractiveness of naïve C. glomerata females to volatiles of either Cardamine pratensis (cuckooflower) foliage, the host plant of P. oleracea or Brassica olercea (collard) foliage (P = 0.51). In order to determine if overtopping by other vegetation may provide an enemy free space for P. oleracea by affecting detection by C. glomerata, cage experiments were conducted. Overtopping vegetation had a significant effect on parasitism by C. glomerata (F = 12.8, df = 3, PP. oleracea has been able to thrive at the Lenox, MA site.

Roads are long linear features on the landscape that impact wildlife and their habitats. Among all forms of wildlife turtles are one of the most negatively affected by roads. Wildlife biologists and civil engineers have developed and implemented road design measures to mitigate the negative effects associated with roads. One common approach used to reduce road mortality and to facilitate movement of turtles is to construct a road mitigation system. There are currently 28 road mitigation systems for wildlife in Massachusetts, of which 14 were specifically built for turtles. We identified all known systems in Massachusetts and collected site and structural design information for each. In addition, we also examined the relative effectiveness of experimental passages for freshwater turtles. Structures were evaluated with respect to how their height, width, and position (at or below-grade), influenced the movements of painted turtles. A total of 190 turtles were exposed to the experiential trials and their behavior was characterized by 3 response variables (Total time to complete the trial, Total hesitations observed, and Success based on no hesitations and completion of the trial in less than 120 minutes). We concluded that painted turtles exposed to below-grade tunnels were less hesitant and traveled faster through them as the tunnel size increased from 0.6 m x 0.6 m to 1.2 m x 1.2 m. The 1.2 m x 1.2 m tunnel size overall proved to be the size with the fewest hesitations observed, fastest total times, and highest success rate.

Quantifying individual differences in behavior and the extent that behavior is influenced by circadian control is of paramount importance in behavioral ecology. In addition, the proximate mechanisms underlying behavior are also critical in order to obtain a more complete picture of how behavior evolves. Biogenic amines (BAs) are simple nitrogenous compounds derived from amino acids and have been consistently and extensively linked to behavior. For this study, we analyzed temporal patterns of BAs in relation to the antipredator (boldness) and aggressive behavior in female Agelenopsis pennsylvanica, a funnel-web spider. Using HPLC-ED, we compared behavioral responses to temporal patterns of octopamine and serotonin, two BAs known to influence behavior in invertebrates. Our results suggest that, while there was a clear diel cycling pattern of both aggression and boldness, BAs do not follow this same pattern, suggesting that oscillations in absolute levels of BAs are not the underpinnings of behavioral oscillations.

The unifying concept of endosymbiosis and the ‘holobiont’ is that the interaction of the microbial community and the host’s biology can affect myriad processes from speciation to physiology to behavior. This study explored the role of the microbiome as a potential facilitator of rapid evolution of social behavior in a socially polymorphic species of spider, Anelosimus studiosus. Adult females were collected from solitary and social colonies at two geographically distinct locations, and behaviorally assayed to assign individuals to ‘docile’ or ‘aggressive’ phenotypes. Microbiomes of each individual were analyzed by 16s rRNA sequencing. Correlations were found with external influences on the microbiome (colony type, local environmental microbiota, and among colony), and also between the microbiome and individual’s behavioral phenotype. While causation has not yet been established, these data suggest that demographics and ecology affect the microbiome, and that behavior may be affected by the microbiome.