Seasonal Changes In Behavior Research Articles

Seasonal changes in habitat use and behavior of the threatened Pampas meadowlark Leistes defilippii

The Pampas grasslands’ biodiversity is severely threatened by habitat modification, as is the case for the Pampas meadowlark ( Leistes defilippii). Here we study the areas used by the species throughout the year in the Southern Pampas of Argentina, in association with seasonal changes in behavior, in an attempt to provide information for its effective conservation. We selected four grassland sites with livestock activities in which we studied vegetation characteristics and the abundance and behavior of the Pampas meadowlark, during breeding and non-breeding seasons. The species was absent in sites with higher bare ground cover and lower cover of >30 cm vegetation, and with high proportions of forb, shrub or exotic grass species. In those areas where the Pampas meadowlark was present during the breeding season, its abundance was higher where the grassland was entirely dominated by native grasses, and abandoned another site when the grassland became dominated by introduced plant species, after the breeding period. We are the first to report the behavior of a Pampas meadowlark population throughout an entire year with its seasonal changes. Our results and description of the behavior throughout the year highlight the importance of structural heterogeneity of the grasslands, determined by a low intensity of grazing, for the breeding of the Pampas meadowlark. Also, features associated with breeding habitat can’t predict the presence of flocks during the non-breeding season, as noted in our results for vegetation structure, but vegetation composition, food availability and landscape variables could play an important role in determining which areas serve as appropriate habitat during the non-breeding season, when large flocks search the grasslands for food. A better understanding of the habitat requirements and the use of space at different scales by the Pampas meadowlark will allow the identification of the most urgent and effective measures for its conservation.

Influence of Seasonal Hazards on Water, Sanitation, and Hygiene-Related Behavior and Implications for Cholera Transmission in Bangladesh.

Most cholera outbreaks in Bangladesh are seasonal, peaking in the dry and post-monsoon periods. Therefore, we investigated whether changes in water, sanitation, and hygiene (WASH) behavior in three populations in Bangladesh during the year could help explain why these two periods are particular to cholera transmission. The study used a mixed-method design, including a repeated cross-sectional study, focus group discussions, and key informant interviews. Through a repeated cross-sectional study, WASH-related variables were assessed during the dry, monsoon, and control seasons in 600 households from coastal Satkhira, inland Sirajganj, and the Dhaka slums. Seasonal behavioral changes were observed in all study areas. Dhaka and Satkhira had an increased mean distance to water sources during the dry and monsoon seasons (Dhaka: control season, 12 m [95% CI, 11-13]; dry season, 36 m [95% CI, 18-55]; and monsoon season, 180 m [95% CI, 118-243]; Satkhira: control season, 334 m [95% CI, 258-411]; dry season, 669 m [95% CI, 515-822]; and monsoon season, 2,437 m [95% CI, 1,665-3,209]). The participants attributed this to pollution of the usual water source. Perceived water quantity was lowest during the dry season in Dhaka and Sirajganj, and during the monsoon season in Satkhira. Handwashing with soap declined in all areas during the dry and monsoon seasons. Open defecation was frequent among children younger than 5 years, increasing during seasonal climate hazards. Results show that WASH-related behavior changed seasonally, increasing the risk of cholera transmission through multiple hygiene-related transmission pathways. Future research would benefit by ensuring that the length of studies covers all seasons throughout the year and also by looking in more detail at people's behavior and hygiene practices.

Physical Activity And Screen Time Patterns During The Covid-19 Pandemic: The Role Of School Format.

Schools and communities across the United States shifted between virtual and in-person formats and reduced recreational offerings throughout the 2020-2021 school year due to widespread COVID-19 infection. Early cross-sectional studies indicate children’s physical activity (PA) decreased during the pandemic, but variation may be seen according to school format and seasonal changes in behavior. Purpose: The purpose of this study was to longitudinally assess changes in PA and screen time (ST) behaviors throughout one year of the COVID-19 pandemic and according to changes in school format. Methods: Parents of children ages 6-17y were recruited via email and social media. Most participants (57%) lived in the Midwestern region of the United States. The survey included questions about school format, home characteristics, child PA, child ST, child sleep habits, and parental support of PA. Initial data were collected in November 2020 with follow-up surveys in February, May, and August 2021. Children were first classified according to school format in each season then further grouped based on longitudinal changes in school format (i.e., in-person all year vs. remote to in-person, etc.). PA and ST behaviors were compared by season and school format using repeated measures ANOVA. Results: Overall, children achieved 60 minutes of PA on fewer days in winter (2.4 ± 0.3 days; p < 0.001; n = 176) than compared to fall (3.7 ± 0.3 days; n = 175), spring (3.8 ± 0.3 days; n = 141), and summer (3.8 ± 0.3 days; n = 112). Longitudinal analysis (n = 61) showed that PA was consistently highest among students attending school fully in-person and lowest among students attending remotely, though school format differences did not reach statistical significance. Non-school ST did not differ by season or school format but tended to be highest in winter and amongst students attending school remotely. Conclusion: In general, children demonstrated healthier lifestyle behavior patterns when attending school in-person than when attending school remotely. Seasonal variation in activity followed the expected pattern with the lowest PA in winter. These results provide a unique opportunity to evaluate lifestyle behaviors by school format throughout the year and suggest that students exhibit healthier behavior patterns when school occurs in person.

An autonomous compartmental model for accelerating epidemics.

In Fall 2020, several European countries reported rapid increases in COVID-19 cases along with growing estimates of the effective reproduction rates. Such an acceleration in epidemic spread is usually attributed to time-dependent effects, e.g. human travel, seasonal behavioral changes, mutations of the pathogen etc. In this case however the acceleration occurred when counter measures such as testing and contact tracing exceeded their capacity limit. Considering Austria as an example, here we show that this dynamics can be captured by a time-independent, i.e. autonomous, compartmental model that incorporates these capacity limits. In this model, the epidemic acceleration coincides with the exhaustion of mitigation efforts, resulting in an increasing fraction of undetected cases that drive the effective reproduction rate progressively higher. We demonstrate that standard models which does not include this effect necessarily result in a systematic underestimation of the effective reproduction rate.

Extracting foraging behavior from passive acoustic monitoring data to better understand harbor porpoise (Phocoena phocoena) foraging habitat use

AbstractFor odontocetes, passive acoustic monitoring (PAM) can be used to differentiate between occurrence and foraging through analysis of click characteristics. Feeding buzzes and navigation/searching echolocation clicks of harbor porpoise (Phocoena phocoena) were differentiated within C‐POD data from northwest Ireland between 2009 and 2017. The spatiotemporal distribution of foraging behavior was investigated using generalized additive modelling, at multiple temporal scales. Both the presence/absence of buzzes and foraging intensity (defined by buzz:click ratios) were determined. Feeding buzzes were identified in one third of porpoise positive hours, ranging from 15% in summer, to 40% in autumn, highlighting seasonal variation irrespective of porpoise occurrence. Complex interannual variation in foraging behavior was also shown across the time series. A strong nocturnal peak in foraging intensity was observed. We found increased porpoise foraging with dolphin species detections within the same hour, and a negative impact of construction activities, involving both impulsive and broadband noise. Results highlight the value of long‐term acoustic time series, by quantifying variation, and show that extracting foraging behavior from occurrence data can help to unravel habitat use patterns, responses to disturbance, and seasonal changes in behavior. Understanding when and how a species uses an area can better inform marine spatial planning and help mitigate anthropogenic impacts.

Control and adaptability of seasonal changes in behavior and physiology of latitudinal avian migrants: Insights from laboratory studies in Palearctic-Indian migratory buntings.

Twice-a-year migrations, one in autumn and the other in spring, occur within a discrete time window with striking alterations in the behavior and physiology, as regulated by the interaction of endogenous rhythms with prevailing photoperiod. These seasonal voyages are not isolated events; rather, they are part of an overall annual itinerary and remain closely coupled to the other annual subcycles, called seasonal life history states (LHSs). The success of migration depends on appropriate timing of the initiation and termination of each LHS, for example, reproduction, molt, summer nonmigratory, preautumn migratory (fattening and weight gain), autumn migratory, winter nonmigratory (wnM), prevernal (spring) migratory (fattening and weight gain), and spring migratory LHSs. Migration-linked photoperiod-induced changes include the body fattening and weight gain, nocturnal Zugunruhe (migratory restlessness), elevated triglycerides and free fatty acids, triiodothyronine and corticosterone levels. Hypothalamic expression of the thyroid hormone-responsive dio2 and dio3, light-responsive per2, cry1,and adcyap1 and th (tyrosine hydroxylase, involved in dopamine biosynthesis) genes also show significant changes with transition from wnM to the vernal migratory LHS. Concurrent changes in the expression of genes associated with lipid metabolism and its transport also occur in the liver and flight muscles, respectively. Interestingly, there are clear differences in the behavioral and physiological phenotypes, and associated molecular changes, between the autumn and vernal migrations. In this review, we discuss seasonal changes in the behavior and physiology, and present molecular insights into the development of migratory phenotypes in latitudinal avian migrants, with special reference to Palearctic-Indian migratory buntings.

Genetic sampling and an activity index indicate contrasting outcomes of lethal control for an invasive predator

ABSTRACTInvasive mammalian predators are implicated in the ongoing decline of a suite of fauna and continue to be a major cause of human–wildlife conflict globally. Lethal control of invasive predators is a common management strategy; however, the use of activity indices to measure management effectiveness is problematic. Non‐invasive genetic sampling may be a viable alternative approach to monitoring as individual animals can be identified, allowing for direct estimation of population density through newly developed spatially explicit capture–recapture techniques. Here we compare inferences derived from a basic activity index (number of scats per survey) and genetic sampling of scats within a before–after control–impact design to evaluate the effectiveness of a lethal control programme targeting red foxes (Vulpes vulpes) in south‐eastern Australia. The activity index was highly variable through time and suggested the baiting programme reduced fox activity on the treatment transect relative to changes on the non‐treatment transect. In contrast, genetic sampling and spatially explicit capture–recapture analysis suggested fox density varied little throughout the study, with any changes unable to be attributed to the baiting programme. Additionally, genetic sampling confirmed many individuals persisted through 7 months of baiting. These contrasting results may be partially explained by changes in scat detectability due to seasonal changes in behaviour and the disproportionate contribution of some individuals to scat counts. Our pre‐baiting density estimate of 0.28 foxes km2 (95% CI: 0.22–0.38) was lower than expected given the high productivity, abundant prey species and lack of larger predators in the study region. Our results highlight the need for cautious interpretation of activity indices and demonstrates the value of incorporating recent methodological and statistical advances when evaluating lethal control programmes.

Uncovering the seasonal brain: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a biochemical approach for studying seasonal social behaviors

Many animals show pronounced changes in physiology and behavior across the annual cycle, and these adaptations enable individuals to prioritize investing in the neuroendocrine mechanisms underlying reproduction and/or survival based on the time of year. While prior research has offered valuable insight into how seasonal variation in neuroendocrine processes regulates social behavior, the majority of these studies have investigated how a single hormone influences a single behavioral phenotype. Given that hormones are synthesized and metabolized via complex biochemical pathways and often act in concert to control social behavior, these approaches provide a limited view of how hormones regulate seasonal changes in behavior. In this review, we discuss how seasonal influences on hormones, the brain, and social behavior can be studied using liquid chromatography-tandem mass spectrometry (LC-MS/MS), an analytical chemistry technique that enables researchers to simultaneously quantify the concentrations of multiple hormones and the activities of their synthetic enzymes. First, we examine studies that have investigated seasonal plasticity in brain-behavior interactions, specifically by focusing on how two groups of hormones, sex steroids and nonapeptides, regulate sexual and aggressive behavior. Then, we explain the operations of LC-MS/MS, highlight studies that have used LC-MS/MS to study the neuroendocrine mechanisms underlying social behavior, both within and outside of a seasonal context, and discuss potential applications for LC-MS/MS in the field of behavioral neuroendocrinology. We propose that this cutting-edge technology will provide a more comprehensive understanding of how the multitude of hormones that comprise complex neuroendocrine networks affect seasonal variation in the brain and behavior.

Running on Empty: Of Hypopinealism and Human Seasonality.

The pineal hormone melatonin is the natural transducer of the environmental light–dark signal to the body. Although the responsiveness to photoperiod is well-conserved in humans, only about 25 percent of the human population experiences seasonal changes in behavior. As a consequence, humans seem to have adapted—at least partly—to the seasonal changes in day length. The aim of the study was to demonstrate that the individual melatonin deficit marker DOC (degree of pineal calcification) is related to variation of seasonal phenomena in humans. Out of 3,011 patients in which cranial computer tomography (cCT) was performed for diagnostic reasons, 97 consecutive “healthy” subjects (43 female, 54 male; age 18–68 yrs, mean ± SD: 35.0 ± 13.1) were included. Exclusion criteria were pathological finding in cCT, acute/chronic illness including alcohol/drug abuse, shift work, and medication, which are known to influence melatonin excretion. The degree of pineal calcification (DOC) was semiquantitatively determined using the previously validated method. The Seasonal Pattern Assessment Questionnaire (SPAQ) was performed in a telephone interview. Twenty-six subjects fulfilled the criteria for seasonal affective disorder (SAD) or subsyndromal (S) SAD. Seasonality was more pronounced in women than in men (SPAQ seasonality score: 7.8 ± 4.0 vs. 4.9 ± 4.5; p = 0.001) and negatively and significantly associated with age (r = −0.178; p = 0.04). The subjective sleep length significantly varied between seasons (one-way repeated measures ANOVA: F = 45.75; p < 0.0001), with sleep during winter being 53 min (±70 min) longer than during summer. Controlling for age, the total seasonality score was negatively and significantly associated with DOC (r94 = −0.214; p = 0.036). Data confirm earlier studies with respect to distribution of seasonality with sex and age. The survival of seasonality in the sleep length of people living in an urban environment underlines functionality of the circadian timing system in modern societies. Moreover, data confirm for the first time that diminished experience of seasonality in behavior is associated with a reduced individual capacity to produce melatonin.

Statistical and geographical modelling of Moravian (Czech Republic) Late Upper Palaeolithic occupation

The period of the second half of the Last Glacial Maximum (LGM) and the beginning of the Late Glacial (LGT) belongs to a remarkably interesting period of human history because humans had to adapt to severe conditions. Moravia, in the eastern part of the Czech Republic, is one of the crucial European regions where we can study human behaviour during the mentioned period. This area was not depopulated due to the presence of local refuges. There are 50 sites that are attributed to the Epigravettian or the Epiaurignacian. Some of these have been dated between 23 and 15 ka cal BP. One approach to studying relations between both technocomplexes is related to the analysis of settlement strategies. Earlier analyses have indicated people changed their behaviour during the end of the LGM and the beginning of the LGT. They preferred protected locations and we are able to identify two mains strategies – sites in low elevations near main rivers or higher elevations on the eastern slopes.New analyses based on statistics confirm two different settlement strategies in Moravia during the time under analysis. The first, which is better defined, is related to sites classified as Epiaurignacian. The second group is represented by Epigravettian assemblages. The settlement strategy for this technocomplex is more variable. Two different settlement strategies during the Late Upper Palaeolithic (LUP) in Moravia may indicate two different communities, seasonal changes in behaviour of one community or cultural evolution of one community over time.

Seasonal regulation of behaviour: what role do hormone receptors play?

Many animals differentially express behaviours across the annual cycle as life stages are coordinated with seasonal environmental conditions. Understanding of the mechanistic basis of such seasonal changes in behaviour has traditionally focused on the role of changes in circulating hormone levels. However, it is increasingly apparent that other endocrine regulation mechanisms such as changes in local hormone synthesis and receptor abundance also play a role. Here I review what is known about seasonal changes in steroid hormone receptor abundance in relation to seasonal behaviour in vertebrates. I find that there is widespread, though not ubiquitous, seasonal variation in the expression of steroid hormone receptors in the brain, with such variation being best documented in association with courtship, mating and aggression. The most common pattern of seasonal variation is for there to be upregulation of sex steroid receptors with the expression of courtship and mating behaviours, when circulating hormone levels are also high. Less well-documented are cases in which seasonal increases in receptor expression could compensate for low circulating hormone levels or seasonal downregulation that could serve a protective function. I conclude by identifying important directions for future research.

Variation in chronotype is associated with migratory timing in a songbird.

Like many organisms, birds exhibit daily (circadian) and seasonal biological rhythms, and within populations both daily and seasonal timing often vary among individuals. Because photoperiod interacts with the circadian rhythms of many organisms to induce seasonal changes in behaviour and physiology, it is hypothesized that differences in daily timing, called chronotypes, underpin differences among individuals in the timing of seasonal events. For seasonal events stimulated by increasing daylength, this hypothesis predicts a positive relationship between the timing of daily and seasonal activities of individuals, with advanced chronotypes expressing events earlier in the year. The few previous tests of this hypothesis have focused on seasonal reproductive timing in birds. However, the hypothesis predicts that this relationship should extend to other photoinduced seasonal events. Therefore, we tested whether variation in chronotype was associated with variation in spring migratory timing in a captive songbird model, the pine siskin (Spinus pinus). We found that pine siskins expressing migratory restlessness exhibited repeatable chronotypes in their timing of nocturnal activity. Further, chronotype was significantly associated with the onset date of migratory behaviour, consistent with the hypothesized relationship between chronotype and seasonal timing.

Understanding the molecular basis of seasonal changes in behavior

Understanding the molecular basis of seasonal changes in behavior

Demographic-specific Validity of the Cancer Prevention Study-3 Sedentary Time Survey.

This study examined the 1-yr test-retest reliability and criterion validity of sedentary time survey items in a subset of participants from a large, nationwide prospective cohort. Participants included 423 women and 290 men age 31 to 72 yr in the Cancer Prevention Study-3. Reliability was assessed by computing Spearman correlation coefficients between responses from prestudy and poststudy surveys. Validity was assessed by comparing survey-estimated sedentary time with a latent variable representing true sedentary time estimated from the 7-d diaries, accelerometry, and surveys through the method of triads. Sensitivity analyses were restricted to 566 participants with an average of 14+ h of diary and accelerometer data per day for 7 d per quarter. Reliability estimates for total sitting time were moderate or strong across all demographic strata (Spearman ρ ≥ 0.6), with significant differences by race (P = 0.01). Reliability estimates were strongest for the TV-related sedentary time item (Spearman ρ, 0.74; 95% confidence interval, 0.70-0.77). The overall validity coefficient (VC) for survey-assessed total sedentary time was 0.62 (95% confidence interval, 0.55-0.69), although VC varied by age group and activity level (P < 0.05). However, VC were similar across groups (P < 0.05) when restricting to highly compliant participants in a sensitivity analysis. The Cancer Prevention Study-3 sedentary behavior questionnaire has acceptable reliability and validity for ranking or categorizing participants according to sedentary time. Acceptable reliability and validity estimates persist across various demographic subgroups.

Site fidelity and population structure of blue land crabs (Cardisoma guanhumi Latreille, 1825) in a restricted-access mangrove area, analyzed using PIT tags

Understanding the patterns of displacement and site fidelity in blue land crabs (Cardisoma guanhumi Latreille, 1825) has important implications for their conservation and management. The central objective of this study was to analyze seasonal variations in site fidelity in C. guanhumi, a species that is intensively exploited in Brazil, in spite of being part of the Official National List of Critically Endangered Species. This species currently suffers multiple severe threats, such as overharvesting and habitat destruction. C. guanhumi were sampled monthly at four fixed sectors that were delimited at the upper fringe of a restricted-access mangrove at Itamaracá Island between April 2015 and March 2016. One thousand and seventy-eight individuals were captured, measured, sexed, weighed, and their color patterns registered. Of these, 291 individuals were tagged with PIT (Passive Integrated Transponder) tags. Ninety-seven individuals (size range 27.0–62.6 mm carapace width) were successfully recaptured, totaling 135 recapture events. The largest interval between marking and recapture was 331 days. Through the use of mark-recapture-based models, it was possible to estimate the local population as being 1312 (± 417) individuals (mean density 2.23 ± 0.71 ind. m−2). Considering the mean density of burrow openings and individuals, there were 3.4 burrow openings per individual. C. guanhumi showed a clear philopatric behavior. Seventy-seven percent of recaptured individuals were recaptured in their sector of origin, and the remainder in an adjacent sector. Site fidelity was higher in females. Males showed minimum site fidelity in October, which is most likely related to be the onset of the reproductive season. The present study opens new perspectives for the definition of reproductive seasons, based on seasonal changes in behavior, and thus to improve the conservation of exploited and severely threatened species.

Foraging suggests high behavioral ?exibility in the blue-winged parrotlet (Forpus xanthopterygius, Psittacidae) in response to ?eshy fruit availability

Parrots primarily consume seeds and pulp and sometimes flowers, nectar and leaves. Plants usually offer these items seasonally, forcing flexible consumption behavior in parrots, mostly when food is scarce. However, seasonal changes in behavior in the Forpus genus (the small Neotropical parrots) guided by the food supply have still not been identifed. Here, we investigate the foraging patterns of Forpus xanthopterygius (the blue-winged parrotlet) and identify the plants and items it consumes. This information, together with data on its occurrence, flock size and dietary niche breadth, were used to elucidate whether the behavioral flexibility of this bird is related to shifts in fleshy fruit availability from the wet to the dry season. The data were obtained during two years of systematic sampling (n = 432) along nine roadside transects located in an anthropogenic landscape. Forpus xanthopterygius consumed the seeds, flowers/nectar and fruit pulp (in this order of preference) of 24 plant species (10 exotics) belonging to 18 families. Te dietary niche breadth was narrow, likely because fleshy fruits of Cecropia pachystachya , Maclura tinctoria , and especially Trema micrantha predominated in their diet. Forpus xanthopterygius was shown to be seasonal, being more common in the wet season, when the availability of fleshy fruits was greater. Tis parrot proved to be flexible in some behaviors, perhaps to minimize the negative impacts of the decline in fleshy fruit availability during the driest period. Evidence of this flexibility is the increase in flock size and the number of food plant species, as well as the use of dry fruits, nectar and exotic plants as alternative food sources.

Food as a supplementary cue triggers seasonal changes in aggression, but not reproduction, in Siberian hamsters

Animals living in temperate regions prepare for harsh winter conditions by responding to environmental cues that signal resource availability (e.g., food, day length). Siberian hamsters (Phodopus sungorus) breed in long, summer-like days (LD, >14h light), i.e., photoperiods, and undergo robust gonadal regression and become more aggressive when exposed to short, winter-like photoperiods that signal impending limited resources (SD, <10h light). When hamsters are reared within an intermediate photoperiod (ID, 13.5h light), they are reproductively active, but undergo gonadal regression in response to mild food restriction (FR) over 6–12weeks. We hypothesized that short-term (1–2weeks) FR in an ID photoperiod would provide a signal of impending limited resources and initiate the seasonal increase in aggression typical of SD photoperiods, as well as alter reproductive behaviors in advance of gonadal regression. To test this, we housed male and female hamsters in LD or ID photoperiods, with ad libitum (AL) access to food or a 90%-AL ration. We tested aggressive behavior after one week and reproductive behavior after two weeks, and subsequently monitored females for pregnancy and litter production. Both sexes displayed increased aggression in the ID-FR treatment. Untreated male intruders were less likely to ejaculate when paired with ID females during reproductive encounters. ID-FR males were undergoing gonadal regression after two weeks, but were more likely to have ejaculated. Female pregnancy and litter characteristics were unaltered by treatment: females were equally likely to achieve pregnancy and produce comparable litters across treatment groups. Collectively, we demonstrate that a signal of diminishing resources in an ID photoperiod is sufficient to trigger seasonal aggression, but that hamsters are reproductively resilient to inhibitory environmental cues in the short term. Broadly, our findings provide an important context for exploring seasonal changes in behavior and physiology from an ultimate perspective.

Seasonal variations in auditory processing in the inferior colliculus of Eptesicus fuscus

Eptesicus fuscus is typical of temperate zone bats in that both sexes undergo marked seasonal changes in behavior, endocrine status, and reproductive status. Acoustic communication plays a key role in many seasonal behaviors. For example, males emit specialized vocalizations during mating in the fall, and females use different specialized vocalizations to communicate with infants in late spring. Bats of both sexes use echolocation for foraging during times of activity, but engage in little sound-directed behavior during torpor and hibernation in winter. Auditory processing might be expected to reflect these marked seasonal changes.To explore the possibility that seasonal changes in hormonal status could drive functional plasticity in the central auditory system, we examined responses of single neurons in the inferior colliculus throughout the year.The average first spike latency in females varied seasonally, almost doubling in spring compared to other times of year. First spike latencies in males remained relatively stable throughout the year. Latency jitter for both sexes was higher in winter and spring than in summer or fall.Females had more burst responders than other discharge patterns throughout the year whereas males had more transient responders at all times of year except fall, when burst responses were the predominant type. The percentage of simple discharge patterns (sustained and transient) was higher in males than females in the spring and higher in females than males in the fall.In females, the percentage of shortpass duration-tuned neurons doubled in summer and remained elevated through fall and early winter. In males, the percentage of shortpass duration-tuned cells increased in spring and the percentage of bandpass duration-tuned cells doubled in the fall.These findings suggest that there are clear seasonal changes in basic response characteristics of midbrain auditory neurons in Eptesicus, especially in temporal response properties and duration sensitivity. Moreover, the pattern of changes is different in males and females, suggesting that hormone-driven plasticity adjusts central auditory processing to fit the characteristics of vocalizations specific to seasonal behavioral patterns.

Identification of motivational state in adult male Atlantic walruses inferred from changes in movement and diving behavior

AbstractMotivational changes in animals are likely to be detectable retrospectively through observed changes in behavior. Breeding represents one of the strongest motivational states in mammals, and its timing is often tied to a seasonally optimal suite of environmental and physical conditions. While seasonal changes in behavior may be directly observable in some species, for others that breed cryptically or in difficult to access areas, detecting behavioral changes may only be feasible using data collected remotely. Herein, we explore whether behavioral changes can be used to infer motivational state for a wild, free‐ and wide‐ranging high arctic marine mammal, adult male Atlantic walruses (Odobenus rosmarus rosmarus). Using satellite‐relayed location and dive data from 23 adult male walruses instrumented in the Svalbard Archipelago, we identify seasonal movement to discrete geographic regions deep into winter pack ice. Adult male walrus diving behavior underwent marked seasonal movements between geographical areas that coincided with changes in light regime. At offshore wintering sites adult males (n = 4) shifted from a summer pattern of deep, long benthic dives to much shallower diving. Some males performed similar shallow, winter dive behavior at coastal locations (n = 12) suggesting that breeding might also occur around the coast of Svalbard. However, interpretation of behavioral changes of these coastal individuals was challenging. The presumed breeding sites at the winter off‐shore locations were situated in areas where polynyas are known to occur, making them a predictable resource even if they are located deep inside the winter pack‐ice. We demonstrate that remotely collected behavioral data can be used to identify seasonally explicit changes in the behavior of cryptic species.

The effect of seasonal temperature variation on behaviour and metabolism in the freshwater mussel (Unio tumidus)

Temperature plays a critical role in determining the biology of ectotherms. Many animals have evolved mechanisms that allow them to compensate biological rates, i.e. adjust biological rates to overcome thermodynamic effects. For low energy-organisms, such as bivalves, the costs of thermal compensation may be greater than the benefits, and thus prohibitive. To examine this, two experiments were designed to explore thermal compensation in Unio tumidus. Experiment 1 examined seasonal changes in behaviour in U. tumidus throughout a year. Temperature had a clear effect on burrowing rate with no evidence of compensation. Valve closure duration and frequency were also strongly affected by seasonal temperature change, but there was slight evidence of partial compensation. Experiment 2 examined oxygen consumption during burrowing, immediately following valve opening and at rest in summer (24 °C), autumn (14 °C), winter (4 °C), and spring (14 °C) acclimatized U. tumidus. Again, there was little evidence of burrowing rate compensation, but some evidence of partial compensation of valve closure duration and frequency. None of the oxygen compensation rates showed any evidence of thermal compensation. Thus, in general, there was only very limited evidence of thermal compensation of behaviour and no evidence of thermal compensation of oxygen compensation rates. Based upon this evidence, we argue that there is no evolutionary pressure for these bivalves to compensate these biological rates. Any pressure may be to maintain or even lower oxygen consumption as their only defence against predation is to close their valves and wait. An increase in oxygen consumption will be detrimental in this regard so the cost of thermal compensation may outweigh the benefits.