Neuroethology Research Articles

Effect of two different feeding strategies on energy intake from pasture, feed efficiency and growth performance of growing-finishing pigs in a mobile pasture system

Free-range rearing allows pigs to perform species-specific and normal behavior, and is an important welfare attraction among consumers, but high inputs of concentrate challenge the sustainability of this practice. Exposing pigs to limited access to concentrate followed by ad libitum feeding could reduce feed input while improving average daily gain and feed conversion ratio. The objective of the study was to investigate the effects of restricted feeding in the grower phase followed by ad libitum feeding in the finisher phase on growth performance, feed efficiency and intakes from concentrate and the range area in a rotational pasture system. A total of 64 pigs with a mean live weight (LW) of 30 kg (SD 3.9) and an average age of 69 days were randomly assigned to one of two feeding strategies; AL (ad libitum from 30 kg LW to slaughter) or RES-AL (restricted feeding supplying 95–67% of recommended supply from 30 kg to 70 kg followed by ad libitum feeding until slaughter). Slaughter of RES-AL pigs was performed after 84 days, while AL pigs were slaughtered after 76 days. Access to new pasture area was provided twice a week throughout the experiment using mobile paddocks. Results showed that RES-AL pigs partially achieved compensatory growth as their growth rate was numerically greater (71 g/d) than for AL pigs during realimentation from 70 kg to slaughter (1419 vs. 1348 g/d). Daily growth rates from 30 kg to slaughter were high across feeding strategies, 1051 g vs. 1139 g for RES-AL and AL, respectively (P < .001). Concentrate feed conversion efficiencies were also high, 34.2 MJ ME/kg LW gain for RES-AL pigs and 34.5 MJ ME/kg LW gain for AL pigs (P > 0.05). It was estimated that RES-AL pigs covered 25% of daily energy requirements from direct foraging during restricted period and 10% during realimentation. For comparison on the corresponding periods, AL pigs covered 14% and 6%, respectively. Findings indicate a great potential for high growth rates and high feed efficiencies under free-range conditions as well as substantial energy inputs from direct foraging, most pronounced during concentrate restriction. Due to the lack of improved feed efficiency for RES-AL pigs compared with AL pigs, the sustainability was not improved in free-range reared pigs when focusing on concentrate input exclusively.

Learning to cricket hunt by the laboratory mouse (Mus musculus): Skilled movements of the hands and mouth in cricket capture and consumption

Although the mouse (Mus musculus) is preyed upon by many other species of animals, it is also a predator and will hunt and consume crickets. There has been no previous description of how mice learn to hunt and no report on the extent to which they use their hands and mouth to assist prey capture and these were the objectives of the present study. Mice given one cricket each day displayed decreasing hunt times over 25-days for three phases of a hunt: investigate, in which a mouse explored and periodically encounter a cricket and often bit at it; pursue, in which a mouse’s approach remained focused on the cricket until it was captured; and consume, in which the cricket was handled, decapitated, its core eaten, with its shell discarded. Although visual and auditory cues may contribute to locating a cricket, the vibrissae appeared to provide guidance in pursuit and capture when the cricket and mouse were proximate. Cricket capture involved extensive collaborative use of the mouth and the hands and mice could initiate capture with either the mouth or hands. Handling to eat involved manipulating the cricket into a head-up, ventrum-in position for decapitation and selective eating of the core of the cricket. The results are discussed in relation to mouse learning of a complex natural behavior, the use of tactile cues in the species-specific behavior of predation, and the contributions of the hands and mouth to predation.

Behavioral dynamics provide insight into resource exploitation and habitat coexistence of two octopus species in a shallow Florida lagoon

Multiple octopus species inhabit overlapping ecohabitats worldwide yet little is known about the behavioral mechanisms that facilitate such coexistence. To distinguish coexistence mechanisms of Octopus vulgaris and Macrotritopus defilippi in high densities, rigorous fieldwork was conducted to examine their respective foraging strategies. Direct observations via SCUBA diving combined with active and remote video demonstrated that O. vulgaris was primarily nocturnal, foraged on hard bottom substrate, and consumed mostly bivalves while M. defilippi was strictly diurnal, foraged on soft bottom substrate, and consumed exclusively crustaceans. Both species showed a saltatory (stop and go) foraging tactic dominated by speculative bottom searching, which is guided by visual scanning and decision making, followed by tactile endeavors of the arms and chemotactile suckers. Species-specific behaviors were parachute attack (O. vulgaris), mimicry of flounder swimming (M. defilippi), and tripod stance (M. defilippi). Coexistence between these two species results primarily from differences in resource use (habitat and diet) and temporal and spatial heterogeneity. Incorporating species-specific behavioral habits is a key tool for understanding octopus ecology and coexistence.

Swimming behavior of cryptophyte prey affects prey preference of the ambush-feeding ciliate Mesodinium rubrum

The mixotrophic ciliate Mesodinium rubrum is an ambush feeder relying on cryptophyte prey motility for prey encounter and perception; therefore, cryptophyte species-specific swimming behaviors affect M. rubrum’s prey preference. Here, a high-speed microscale imaging system was used to quantify the swimming behaviors of 3 cryptophyte species (Teleaulax amphioxeia, Storeatula major, and Guillardia theta) and to conduct quantitative microvideography of M. rubrum-T. amphioxeia predator-prey interaction. T. amphioxeia, a preferred prey of M. rubrum, swam at path-averaged speeds of 155 ± 73 µm s-1 along rather straight paths. In contrast, S. major regularly tumbled slowly downward or upward at 64 ± 16 µm s-1, while G. theta moved slowly in looped/curved trajectories at 57 ± 15 µm s-1; neither supports M. rubrum growth. Only while motionlessly sinking passively did M. rubrum detect and initiate an attack on swimming T. amphioxeia at reaction distances of 8.2 ± 8.2 µm. It seemed that M. rubrum needed to use oral tentacles to initially poke T. amphioxeia’s ventral posterior part and subsequently poke the prey multiple times in a short duration to compromise the prey’s escape ability, presumably by discharging extrusomes into the prey. T. amphioxeia also responded to nearby predators by switching to tumbling similar to S. major in normal swimming, suggesting an effective anti-predator defense behavior that prevents M. rubrum from accurately poking the prey’s ventral posterior part. T. amphioxeia swimming at significantly higher speeds leads to sufficiently high prey encounters and hydrodynamic signals for M. rubrum, thereby partially explaining M. rubrum’s ability to select T. amphioxeia prey.

Double tailed scorpiand-type calix[10]phyrin: Synthesis and proton-driven anion recognition features

Reported here is a large oligopyrrole macrocycle, a calix[10]phyrin bearing two diformyl substituents. The combination of conjugation provided by two pentapyrrolic subunits and flexibility resulting from the presence of sp 3 hybridized meso bridges allows the system to adopt a double tailed, scorpiand-like structure with two near-symmetric binding pockets. In methanol solution, this macrocycle was found to interact with a number of test acids, including sulfuric acid, trifluoroacetic acid, phosphoric acid, hydrochloric acid, and fluoroboric acid, via a combination of protonation and counter anion binding. Species specific behavior was seen, allowing for the colorimetric-based discrimination between the acids. Efforts to model the underlying binding equilibria led to the conclusion that upon treatment with excess H 2 SO 4 , up to four protons and two counteranions are bound, whereas in the case of HCl the dominant species is a monoanionic complex. The responses of several other acids were rationalized in terms of these limiting scenarios.

Conspecific scarring on wild belugas (Delphinapterus leucas) in Cunningham Inlet

Abstract Intra-specific aggression is not frequently observed in wild cetaceans, including belugas. One proxy, identified in past research, that indicates past aggressive behaviour is the presence of rake marks (scars left on skin by the teeth of conspecifics). Behavioural observations of belugas, compared to bottlenose dolphins, suggest that belugas engage in less physically aggressive behaviour; yet, a detailed study of beluga aggressive behaviour remains to be conducted. Beluga intra-specific aggression was assessed by scoring photographs taken from July to August in 2015 at Cunningham Inlet, Canada for the presence/absence and body location of rake marks. Of the 252 belugas analysed, 44% had rake marks. The results suggest that physical aggression occurs comparatively less with only half of the observed beluga population having rake marks compared to almost all bottlenose dolphins previously surveyed. We suggest social structure, skin pigmentation, and/or species-specific behaviours as explanations for the differences in rake marks among species.

Species-Specific Settling Behaviors of Benthic Foraminifera: Size, Density and Structure

ABSTRACT Settling velocity is a key hydrodynamic parameter to understand the transport behavior of benthic foraminiferal tests. Both size and density are fundamental in predicting settling velocity, but their relative importance is unclear. We used specimens of four benthic foraminiferal species from a carbonate-sand sample collected from Xisha Qundao, South China Sea, to investigate this question. Measurements on foraminiferal test size, shape, and density were combined with settling velocity observations using a laboratory settling tube. In addition, a micro-Computed Tomography (CT) Scanner was used to extract the internal-structure patterns of the tests of four representative specimens. Our study revealed that both size and density are important in affecting settling velocity, but the relative importance is species-specific. Size is more important than density for Amphistegina lobifera and Heterostegina depressa; these two factors are equally important for Peneroplis pertusus, but the settling velocity of Sorites orbiculus is also considerably controlled by their unique structure, besides size and density. This species-specific pattern was further compared with test development to reveal the associated biological mechanisms. As a result, a novel parameter, DT (density*TND2), is proposed as a better variable for predicting the species-specific settling behaviors.

Evaluation of a Configurable, Mobile and Modular Floor-Pen System for Group-Housing of Laboratory Rabbits.

Simple SummaryThe group housing of animals supports species-specific behavior and avoids stress induction. Therefore, novel housing systems need to be established that provide sufficient space and meet the hygiene criteria for laboratory animals. Here, we describe the successful implementation of an improved housing system for single and group housing of laboratory rabbits under high hygiene environmental conditions. This system includes modular and mobile floor pens of different size and shape. Rabbits housed in this system showed species-specific behavior that depended on the circadian rhythm—a prerequisite for interpretable animal experiments. We propose that this housing system will be of great benefit for the well-being of laboratory rabbits used in biomedical science.The major responsibility of researchers and laboratory animal facilities is to ensure animal well-being during the time of acclimatization, experiments, and recovery. In this context, animal housing conditions are of utmost importance. Here, we implemented a mobile and modular floor-pen housing system for laboratory rabbits that combines rabbits’ natural behavioral requirements and the high hygiene standards needed in biomedical science. Twelve female New Zealand White (NZW) rabbits were single- or group-housed for 12 months in mobile and modular floor-pens. Their general health status was evaluated at the end of the experimental setup. Further, we performed behavioral analysis of six additional NZW females group-housed for eight weeks in pens of two different sizes. We show that our improved housing concept supported species-specific behavioral patterns. Taken together, our housing system provides an optimal setup for rabbits in animal facilities that combines strict requirements for animal experiments with animal welfare.

Effects of Rearing on the Behaviour of Zoo-Housed Chimpanzees (Pan troglodytes)

Early-life experiences may considerably affect the behavioural patterns of adult primates. Particularly, atypical rearing practices might lead to abnormal behaviours and social-sexual deficiencies in captive, adult non-human primates. We conducted behavioural observations of mother-reared (n = 5) and hand-reared (n = 6) adult chimpanzees in a social group at Parco Natura Viva, Italy. We used continuous focal animal sampling to collect behavioural data focusing on individual and social behaviours. We found that all study subjects performed individual and social species-specific behaviours. However, mother-reared chimpanzees performed locomotion and affiliative behaviours significantly more than hand-reared subjects. In addition to these species-typical behaviours, hand-reared chimpanzees showed significantly more abnormal behaviours than mother-reared subjects. Therefore, these findings suggest that hand-rearing could have wide-reaching effects on the behavioural repertoire in adult zoo-housed chimpanzees. Hence, even if sometimes human intervention in rearing may be necessary to ensure the survival of captive infant chimpanzees, our results suggest that zoo-housed chimpanzees might benefit from minimised human-animal interactions and exposure to conspecifics throughout their development. These suggestions should be implemented in regular husbandry practices.

Density-Dependent and Species-Specific Effects on Self-Organization Modulate the Resistance of Mussel Bed Ecosystems to Hydrodynamic Stress.

AbstractSelf-organized, regular spatial patterns emerging from local interactions among individuals enhance the ability of ecosystems to respond to environmental disturbances. Mussels self-organize to form large, regularly patterned biogenic structures that modify the biotic and abiotic environment and provide numerous ecosystem functions and services. We used two mussel species that form monospecific and mixed beds to investigate how species-specific behavior affects self-organization and resistance to wave stress. Perna perna has strong attachment but low motility, while Mytilus galloprovincialis shows the reverse. At low density, the less motile P. perna has limited spatial self-organization compared with M. galloprovincialis, while when coexisting, the two species formed random spatial patterns. At high density, the two species self-organized in similar ways, while when coexisting, patterns were less strong. Spatial pattern formations significantly shaped resistance to hydrodynamic stress. At low density, P. perna beds with strong attachment and M. galloprovincialis beds with strong spatial organization showed higher retention rates than mixed beds. At high density, the presence of strongly attached P. perna significantly increased retention in mixed and P. perna beds compared with M. galloprovincialis beds. Our study emphasizes the importance of the interplay of species-specific behaviors to spatial self-organization and stress tolerance in natural communities.

Effects of scent enrichment on behavioral and physiological indicators of stress in zoo primates.

Captive breeding is vital for primate conservation, with modern zoos serving a crucial role in breeding populations of threatened species and educating the general public. However, captive populations can experience welfare issues that may also undermine their reproductive success. To enhance the wellbeing of endangered zoo primates, we conducted a study to assess the effects of a new scent enrichment program on captive red-ruffed lemurs (Varecia rubra), black howler monkeys (Alouatta caraya), siamangs (Symphalangus syndactylus), lar gibbons (Hylobates lar) and orangutans (Pongo pygmaeus pygmaeus). We combined behavioral observations and fecal endocrinology analyses to evaluate the effects of a series of essential oils (benzoin, lavender, lemongrass) on five captive troops (N = 19) housed at Dudley Zoo & Castle and Twycross Zoo (UK). We recorded observations of natural species-specific and abnormal stress-related behaviors for 480 h using instantaneous scan sampling. We collected 189 fecal samples and measured the fecal cortisol concentrations using radioimmunoassay. We found a significant effect of the scent enrichment on behaviors, with red-ruffed lemurs and black howler monkeys reducing their social interactions, as well as red-ruffed lemurs and lar gibbons decreasing their stress-related behaviors after they were exposed to the series of essential oils. We also found that red-ruffed lemurs displayed a significant increase in fecal glucocorticoids following exposure to essential oils. Our contradictory findings suggest that the effects of this series of essential oils may change depending on the species-specific social lives and olfactory repertoires of primates. In conclusion, we cannot recommend using these essential oils widely with zoo primates without additional evaluation.

Effect of plant-based enrichment materials on exploration in rearing and fattening pigs (Sus scrofa domesticus)

When pigs cannot perform innate species-specific behaviours (e.g. rooting or chewing), behavioural disorders, like tail biting, can occur. However, it seems that various enrichment materials enhance the pigs to perform exploration behaviour and therefore can help to reduce and prevent tail biting. The aim of this study was to identify such highly explored plant-based enrichment material for undocked pigs during rearing and fattening. Furthermore, we evaluated the impact of the offered enrichment materials on tail length and injuries. Therefore, we continuously recorded the individuals’ exploration durations in 20 groups by using an ultra-high-frequency radio-frequency identification system, installed at material dispensers. Lucerne pellets (LP), straw pellets (SP), chopped hay (CH) and chopped straw (CS) were offered in a systematically alternating order for two-week sections, respectively. At weaning and at days of material change (i.e. eight times in total), animals were weighed and scored for tail length losses and tail injuries. For analysis, the changes in tail length compared to the previous section were calculated as Δ-tail-length losses. Our study revealed that the different offered plant-based enrichment materials affected the duration of exploration behaviour (e.g. rooting, nosing or chewing) during rearing (4 groups, LME, p < 0.0001) and fattening (16 groups, LME, p < 0.0001). In piglets, exploration duration was higher for pelletized materials (LP, SP) than for chopped materials. Fattening pigs explored materials of hay (CH) more often compared to straw-based materials (CS, SP). Daily weight gains of rearing pigs were affected by the type of enrichment material offered in the respective section (LME, p < 0.0001). The highest daily weight gains were achieved when CH was offered. Exploration duration during rearing and fattening was affected by section (LME, both p < 0.0001 for rearing and fattening). Exploration duration during rearing was highest in section 4 and continuously increased from the first section to the last section during fattening. During rearing, the plant-based enrichment materials affected tail injuries (GLMM, p < 0.0001) and Δ-tail-length losses tended to be affected (GLMM, p = 0.057). Fewest tail injuries and Δ-tail-length losses occurred when SP was offered. During fattening, section affected tail injuries (GLMM, p = 0.01). Most injuries occurred during sections 1 and 2. Our results show that pigs of different ages seem to prefer different plant-based enrichment materials. High exploration durations do not necessarily maintain intact tails if material is changed biweekly. However, exploration durations can be maintained at high levels from rearing through fattening period by regularly alternating the provided plant-based enrichment materials.

Effects of Electrical Pulse Stimulation on Behaviour and Survival of Marine Benthic Invertebrates

Electrical pulse trawling is an alternative to conventional beam trawling for common sole (Solea solea), with the potential for higher revenues and less impact on the marine ecosystem. Concerns exist, however, that benthic invertebrates might be seriously affected by pulse fishing. Even if direct injuries and mortality were limited, changes in behaviour might compromise their survival, with potentially large impacts on food webs. Here, we investigate effects of electrical pulses on locomotion behaviour and 14-days survival of six invertebrate species from four phyla that may encounter pulse fishing gears. Electrical stimulation consisted of a Pulsed Bipolar Current at 200 V m–1, 30 Hz, 0.33 ms pulse width, and 3 s duration. We quantified species-specific behaviours before, during, and after electrical stimulation and compared these to a non-exposed control group. Responses during stimulation varied from no visible effect (echinoderms) to squirming (sea mouse) and retractions (whelk and crustaceans). Within 30 s after stimulation, all animals resumed normal behavioural patterns, without signs of lasting immobilisation. Starfish, serpent star, whelk and sea mouse showed no change in movement patterns after stimulation, whereas flying crab and hermit crab showed significant changes in activity that were indicative of increased shelter behaviour. For none of the species, survival at 14-days after stimulation was negatively affected. These findings suggest that changes in locomotion behaviour due to electrical stimulation as used in pulse trawling are unlikely to substantially compromise survival of the investigated species.

Species-Specific and Distance-Dependent Dispersive Behaviour of Forisomes in Different Legume Species.

Forisomes are giant fusiform protein complexes composed of sieve element occlusion (SEO) protein monomers, exclusively found in sieve elements (SEs) of legumes. Forisomes block the phloem mass flow by a Ca2+-induced conformational change (swelling and rounding). We studied the forisome reactivity in four different legume species—Medicago sativa, Pisum sativum, Trifolium pratense and Vicia faba. Depending on the species, we found direct relationships between SE diameter, forisome surface area and distance from the leaf tip, all indicative of a developmentally tuned regulation of SE diameter and forisome size. Heat-induced forisome dispersion occurred later with increasing distance from the stimulus site. T. pratense and V. faba dispersion occurred faster for forisomes with a smaller surface area. Near the stimulus site, electro potential waves (EPWs)—overlapping action (APs), and variation potentials (VPs)—were linked with high full-dispersion rates of forisomes. Distance-associated reduction of forisome reactivity was assigned to the disintegration of EPWs into APs, VPs and system potentials (SPs). Overall, APs and SPs alone were unable to induce forisome dispersion and only VPs above a critical threshold were capable of inducing forisome reactions.

Short- and long-term growth response to climate in mixed and monospecific forests of Pinus pinea and Pinus pinaster

Over recent decades, climate change has been particularly severe in the Mediterranean basin, where the intensity and frequency of drought events have had a significant effect on tree growth and mortality. In this context, differences in structural and physiological strategies between tree species could help to mitigate the damage inflicted by climate variability and drought events. Here, we used dendroecological approaches to observe common associations (synchrony) between indexed ring width in Pinus pinea and P. pinaster, as a measure of degree of dependence on climate variation or growth sensitivity to climate, as well as to analyze species growth responses to drought events through the Lloret’s indices of resistance, recovery and resilience. Based on data from 75 mixed and pure plots installed in the Northern Plateau of Spain, we used modeling tools to detect the effect of the mixture, along with climate and stand-related variables, on the short-term responses and long-term growth sensitivity to climate. Our results showed a trade-off between resistance and recovery after the drought episodes. In addition, different attributes of tree species, such as age and size as well as stand density seemed to act synergistically and compensate drought stress in different ways. The presence of age and quadratic mean diameter as covariates in the final synchrony model for P. pinaster reflected the influence of other variables as modulators of growth response to climate. Furthermore, differences in growth synchrony in mixed and monospecific composition suggested the existence of interactions between the two species and some degree of temporal niche complementarity. In mixed stands, P. pinaster exhibited a lower sensitivity to climate than in monospecific composition, whereas P. pinea enhanced its resistance to extreme droughts. These results allowed us to identify the species-specific behavior of P. pinea and P. pinaster to mitigate vulnerability to climate-related extremes.

Behavioral Deficits in Mice with Postnatal Disruption of Ndel1 in Forebrain Excitatory Neurons: Implications for Epilepsy and Neuropsychiatric Disorders.

Dysfunction of nuclear distribution element-like 1 (Ndel1) is associated with schizophrenia, a neuropsychiatric disorder characterized by cognitive impairment and with seizures as comorbidity. The levels of Ndel1 are also altered in human and models with epilepsy, a chronic condition whose hallmark feature is the occurrence of spontaneous recurrent seizures and is typically associated with comorbid conditions including learning and memory deficits, anxiety, and depression. In this study, we analyzed the behaviors of mice postnatally deficient for Ndel1 in forebrain excitatory neurons (Ndel1 CKO) that exhibit spatial learning and memory deficits, seizures, and shortened lifespan. Ndel1 CKO mice underperformed in species-specific tasks, that is, the nest building, open field, Y maze, forced swim, and dry cylinder tasks. We surveyed the expression and/or activity of a dozen molecules related to Ndel1 functions and found changes that may contribute to the abnormal behaviors. Finally, we tested the impact of Reelin glycoprotein that shows protective effects in the hippocampus of Ndel1 CKO, on the performance of the mutant animals in the nest building task. Our study highlights the importance of Ndel1 in the manifestation of species-specific animal behaviors that may be relevant to our understanding of the clinical conditions shared between neuropsychiatric disorders and epilepsy.

Divergent effects of oxytocin on eye contact in bonobos and chimpanzees

Oxytocin has drawn significant research attention for its role in modulating mammalian social behavior. Despite generally conserved roles, oxytocin can function differently even in closely related species. Previous studies have shown that bonobos and chimpanzees, humans’ two closest relatives, demonstrate considerable behavioral differences, including that bonobos look more at others’ eyes than chimpanzees. Oxytocin is known to increase attention to another’s eyes in many mammalian species (e.g. dogs, monkeys, and humans), yet this effect has not been tested in any nonhuman great ape species. This study examined how intranasally-administered oxytocin affects eye contact in bonobos and chimpanzees using eye tracking. Following administration of either oxytocin or saline control with a nebulizer, chimpanzees (n = 6) and bonobos (n = 5) were shown images of conspecific faces while their eye movement was recorded. Oxytocin changed the eye-looking behavior of bonobos and chimpanzees differently. We found that oxytocin increased eye contact in bonobos but not chimpanzees; while one chimpanzee showed an increase, interestingly, 5 out of 6 chimpanzees showed decreased looking to the eyes compared to the mouth, suggesting moderate eye avoidance. Given the importance of eye contact in their social interactions, our results suggest that oxytocin may play modulatory roles in bonobos’ and chimpanzees’ species-specific social behavior and underscore the importance of oxytocin in hominid social evolution.

On the edge: assessing fish habitat use across the boundary between Pacific oyster aquaculture and eelgrass in Willapa Bay, Washington, USA

Estuaries are subject to diverse anthropogenic stressors, such as shellfish aquaculture, which involve extensive use of estuarine tidelands. Pacific oyster Crassostrea gigas aquaculture is a century-old practice in US West Coast estuaries that contributes significantly to the regional culture and economy. Native eelgrass Zostera marina also commonly occurs in intertidal areas where oyster aquaculture is practiced. Eelgrass is federally protected in the USA as ‘essential fish habitat’, restricting aquaculture activities within or near eelgrass. To contribute scientific information useful for management decisions, we sought to compare fish habitat use of oyster aquaculture and eelgrass, as well as the edges between these 2 habitats, in Willapa Bay, Washington, USA. Furthermore, given a recent shift towards off-bottom culture methods, in part to protect seagrasses, long-line and on-bottom oyster aquaculture habitats were compared. A combination of direct (underwater video, minnow traps) and indirect (predation tethering units, eelgrass surveys) methods were employed to characterize differences in fish habitat use. Eelgrass density declined within both aquaculture habitats but less so within long-line aquaculture. Most fish species in our study used long-line oyster aquaculture and eelgrass habitats similarly with minimal edge effects, and on-bottom aquaculture was used less than either of the other 2 habitat types. These results are consistent with previously observed positive relationships between fish abundance and vertical habitat structure, but also reveal species-specific behavior; larger mesopredators like Pacific staghorn sculpins were sighted more often in aquaculture than in interior eelgrass habitats.

Goats work for food in a contrafreeloading task

Contrafreeloading (CFL) is the phenomenon when animals work for a resource although an identical resource is available for free. Possible explanations for CFL are that animals seek context for species-specific behaviours or to control their environments. We investigated whether goats show CFL and whether breeding for productivity traits has altered its occurrence. In a manipulation task, we compared two selection lines: 27 Nigerian dwarf goats, not bred for productivity traits, and 30 dairy goats, bred for high milk yield. Over 10 trials, each goat could perform one of three behaviours: not participating in the trial, feeding for free from an open door, or opening a sliding door for a feed of similar value. The results were analysed using an Item Response Tree (IRTree) generalized linear mixed model (GLMM). The fitted probabilities to participate were > 0.87 over all trials in both selection lines. For dwarf goats, the probability of choosing the closed door, and thereby demonstrating CFL, increased from 0.30 in Trial 1 to 0.53 in Trial 10. For dairy goats, this probability was constant at approximately 0.43. Unlike dwarf goats, dairy goats were faster to approach the closed compared to the open door. Overall, our results suggest that both selection lines were similarly interested in CFL.

Cage-lid hanging behavior as a translationally relevant measure of pain in mice.

The development of new analgesic drugs has been hampered by the inability to translate preclinical findings to humans. This failure is due in part to the weak connection between commonly used pain outcome measures in rodents and the clinical symptoms of chronic pain. Most rodent studies rely on the use of experimenter-evoked measures of pain and assess behavior under ethologically unnatural conditions, which limits the translational potential of preclinical research. Here, we addressed this problem by conducting an unbiased, prospective study of behavioral changes in mice within a natural homecage environment using conventional preclinical pain assays. Unexpectedly, we observed that cage-lid hanging, a species-specific elective behavior, was the only homecage behavior reliably impacted by pain assays. Noxious stimuli reduced hanging behavior in an intensity-dependent manner, and the reduction in hanging could be restored by analgesics. Finally, we developed an automated approach to assess hanging behavior. Collectively, our results indicate that the depression of hanging behavior is a novel, ethologically valid, and translationally relevant pain outcome measure in mice that could facilitate the study of pain and analgesic development.