Daily Pattern Of Locomotor Activity Research Articles

Activity Tracker-Based Metrics as Digital Markers of Cardiometabolic Health in Working Adults: Cross-Sectional Study.

BackgroundGreater adoption of wearable devices with multiple sensors may enhance personalized health monitoring, facilitate early detection of some diseases, and further scale up population health screening. However, few studies have explored the utility of data from wearable fitness trackers in cardiovascular and metabolic disease risk prediction.ObjectiveThis study aimed to investigate the associations between a range of activity metrics derived from a wearable consumer-grade fitness tracker and major modifiable biomarkers of cardiometabolic disease in a working-age population.MethodsThis was a cross-sectional study of 83 working adults. Participants wore Fitbit Charge 2 for 21 consecutive days and went through a health assessment, including fasting blood tests. The following clinical biomarkers were collected: BMI, waist circumference, waist-to-hip ratio, blood pressure, triglycerides (TGs), high-density lipoprotein (HDL) and low-density lipoprotein cholesterol, and blood glucose. We used a range of wearable-derived metrics based on steps, heart rate (HR), and energy expenditure, including measures of stability of circadian activity rhythms, sedentary time, and time spent at various intensities of physical activity. Spearman rank correlation was used for preliminary analysis. Multiple linear regression adjusted for potential confounders was used to determine the extent to which each metric of activity was associated with continuous clinical biomarkers. In addition, pairwise multiple regression was used to investigate the significance and mutual dependence of activity metrics when two or more of them had significant association with the same outcome from the previous step of the analysis.ResultsThe participants were predominantly middle aged (mean age 44.3 years, SD 12), Chinese (62/83, 75%), and male (64/83, 77%). Blood biomarkers of cardiometabolic disease (HDL cholesterol and TGs) were significantly associated with steps-based activity metrics independent of age, gender, ethnicity, education, and shift work, whereas body composition biomarkers (BMI, waist circumference, and waist-to-hip ratio) were significantly associated with energy expenditure–based and HR-based metrics when adjusted for the same confounders. Steps-based interdaily stability of circadian activity rhythm was strongly associated with HDL (beta=5.4 per 10% change; 95% CI 1.8 to 9.0; P=.005) and TG (beta=−27.7 per 10% change; 95% CI −48.4 to −7.0; P=.01). Average daily steps were negatively associated with TG (beta=−6.8 per 1000 steps; 95% CI −13.0 to −0.6; P=.04). The difference between average HR and resting HR was significantly associated with BMI (beta=−.5; 95% CI −1.0 to −0.1; P=.01) and waist circumference (beta=−1.3; 95% CI −2.4 to −0.2; P=.03).ConclusionsWearable consumer-grade fitness trackers can provide acceptably accurate and meaningful information, which might be used in the risk prediction of cardiometabolic disease. Our results showed the beneficial effects of stable daily patterns of locomotor activity for cardiometabolic health. Study findings should be further replicated with larger population studies.

Control of Daily Locomotor Activity Patterns in Drosophila suzukii by the Circadian Clock, Light, Temperature and Social Interactions.

Understanding behavioral rhythms in a pest species can contribute to improving the efficacy of control methods targeting that pest. However, in some species, the behavioral patterns recorded in artificial conditions contrast greatly with observed wild-type behavioral rhythms. In this study, we identify the determinants of daily activity rhythms of the soft and stone fruit pest Drosophila suzukii. The impact of gender, space, social housing, temperature, light, fly morph, and the circadian clock on D. suzukii locomotor rhythms was investigated. Assays were performed under artificial laboratory conditions or more natural semifield conditions to identify how these factors affected daily locomotor behavior. Daily locomotor activity patterns collected under semifield conditions varied very little between the various sex and social condition combinations. However, in lab-based assays, individual and group-housed males often exhibited divergent activity patterns, with more prominent hyperactivity at light/dark transitions. In contrast, hyperactivity responses were suppressed under lab protocols mimicking summer conditions for groups of females and mixed-sex groups. Moreover, when environmental cues were removed, flies held in groups displayed stronger rhythmicity than individual flies. Thus, social interactions can reinforce circadian behavior and resist hyperactivity responses in D. suzukii. Fly morph appeared to have little impact on behavioral pattern, with winter and summer morph flies displaying similar activity profiles under April semifield and laboratory mimic environmental conditions. In conclusion, separate and combined effects of light, temperature, circadian clock function, and social interactions were apparent in the daily activity profiles of D. suzukii. When groups of female or mixed-sex flies were used, implementation of matching photoperiods and realistic daily temperature gradients in the lab was sufficient to re-create behavioral patterns observed in summer semifield settings. The ability to leverage lab assays to predict D. suzukii field behavior promises to be a valuable asset in improving control measures for this pest.

Prefrontal cortex and dorsomedial hypothalamus mediate food reward-induced effects via npas2 and egr1 expression in rat.

The effects of food reward on circadian system function were investigated in the hypothalamic nuclei, prefrontal cortex and liver. Food rewards of small hedonic and caloric value were provided for 16 days 3 h after light phase onset to male Wistar rats. The daily pattern of locomotor activity was monitored. Gene expression profiling performed in the dorsomedial hypothalamus (DMH) and liver at the time of reward delivery indicated transcriptional factors egr1 and npas2 as possible mediators of food reward effects. Candidate genes were measured in the suprachiasmatic nuclei (SCN), DMH, arcuate nucleus (ARC), prefrontal cortex (PFC) and liver along with per2 expression. A daily pattern in glycemia and per2 expression in the SCN was emphasized by food reward. The expression of egr1 was rhythmic in the SCN, DMH, PFC and liver and food reward weakened or diminished this rhythm. The expression of npas2 was rhythmic in all tissues except for the PFC where food reward induced rhythm in npas2 expression. Food reward induced npas2 and egr1 expression in the DMH at the time of reward delivery. We suppose that the DMH and PFC participate in the adjustment of the circadian system to utilize food reward-induced input via egr1 and npas2 expression.

Rhodnius prolixus and R. robustus (Hemiptera: Reduviidae) nymphs show different locomotor patterns on an automated recording system.

BackgroundCircadian rhythms of triatomines, vectors of the etiological agent Trypanosoma cruzi responsible for Chagas disease, have been extensively studied in adults of the two most epidemiologically relevant vector species, Rhodnius prolixus and Triatoma infestans. However, little attention has been dedicated to the activity patterns in earlier developmental stages, even though triatomine nymphs are equally capable of transmitting T. cruzi to humans. Because circadian rhythms may differ even between closely related species, studies that focus on this behavioral trait can also be used to shed light on the taxonomy of controversial taxa, which becomes especially relevant regarding vector species.MethodsWe compared the daily locomotor activity patterns of second- and third-instar nymphs of Rhodnius prolixus and Rhodnius robustus in order to unveil possible behavioral differences between these cryptic species. Mitochondrial and nuclear markers were sequenced to confirm species identification.ResultsNymphs of both species had a bimodal pattern of locomotion and similar daily activity patterns, but R. prolixus is more active under light/dark cycles and depicts a more pronounced activity rhythm under constant darkness conditions.ConclusionsWe describe the implementation of an often-used automated method for the recording of individual locomotor activity to differentiate sibling species of Rhodnius with distinct epidemiological relevance. The higher levels of activity observed in the nymphs of R. prolixus could potentially contribute to increased vector capacity.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1482-9) contains supplementary material, which is available to authorized users.

Disruption of Daily Rhythms by High-Fat Diet Is Reversible.

In mammals a network of circadian clocks coordinates behavior and physiology with 24-h environmental cycles. Consumption of high-fat diet disrupts this temporal coordination by advancing the phase of the liver molecular clock and altering daily rhythms of eating behavior and locomotor activity. In this study we sought to determine whether these effects of high-fat diet on circadian rhythms were reversible. We chronically fed mice high-fat diet and then returned them to low-fat chow diet. We found that the phase of the liver PERIOD2::LUCIFERASE rhythm was advanced (by 4h) and the daily rhythms of eating behavior and locomotor activity were altered for the duration of chronic high-fat diet feeding. Upon diet reversal, the eating behavior rhythm was rapidly reversed (within 2 days) and the phase of the liver clock was restored by 7 days of diet reversal. In contrast, the daily pattern of locomotor activity was not restored even after 2 weeks of diet reversal. Thus, while the circadian system is sensitive to changes in the macronutrient composition of food, the eating behavior rhythm and liver circadian clock are specifically tuned to respond to changes in diet.

Inbreeding affects locomotor activity in Drosophila melanogaster at different ages.

The ability to move is essential for many behavioural traits closely related to fitness. Here we studied the effect of inbreeding on locomotor activity (LA) of Drosophila melanogaster at different ages under both dark and light regimes. We expected to find a decreased LA in inbred lines compared to control lines. We also predicted an increased differentiation between lines due to inbreeding. LA was higher in the dark compared to the light regime for both inbred and outbred control lines. As expected, inbreeding increased phenotypic variance in LA, with some inbred lines showing higher and some lower LA than control lines. Moreover, age per se did not affect LA neither in control nor in inbred lines, while we found a strong line by age interaction between inbred lines. Interestingly, inbreeding changed the daily activity pattern of the flies: these patterns were consistent across all control lines but were lost in some inbred lines. The departure in the daily pattern of LA in inbred lines may contribute to the inbreeding depression observed in inbred natural populations.

Chronic exposure to dim light at night suppresses immune responses in Siberian hamsters.

Species have been adapted to specific niches optimizing survival and reproduction; however, urbanization by humans has dramatically altered natural habitats. Artificial light at night (LAN), termed 'light pollution', is an often overlooked, yet increasing disruptor of habitats, which perturbs physiological processes that rely on precise light information. For example, LAN alters the timing of reproduction and activity in some species, which decreases the odds of successful breeding and increases the threat of predation for these individuals, leading to reduced fitness. LAN also suppresses immune function, an important proxy for survival. To investigate the impact of LAN in a species naive to light pollution in its native habitat, immune function was examined in Siberian hamsters derived from wild-caught stock. After four weeks exposure to dim LAN, immune responses to three different challenges were assessed: (i) delayed-type hypersensitivity (DTH), (ii) lipopolysaccharide-induced fever, and (iii) bactericide activity of blood. LAN suppressed DTH response and reduced bactericide activity of blood after lipopolysaccharide treatment, in addition to altering daily patterns of locomotor activity, suggesting that human encroachment on habitats via night-time lighting may inadvertently compromise immune function and ultimately fitness.

Effects of photoperiod on daily locomotor activity, energy expenditure, and feeding behavior in a seasonal mammal

The objective of this study was to determine whether the previously observed effects of photoperiod on body weight in Siberian hamsters were due to changes in the daily patterns of locomotor activity, energy expenditure, and/or feeding behavior. Adult males were monitored through a seasonal cycle using an automated comprehensive laboratory animal monitoring system (CLAMS). Exposure to a short-day photoperiod (SD; 8:16-h light-dark cycle) induced a significant decline in body weight, and oxygen consumption (Vo(2)), carbon dioxide production (Vco(2)), and heat production all decreased reaching a nadir by 16 wk of SD. Clear daily rhythms in locomotor activity, Vo(2), and Vco(2) were observed at the start of the study, but these all progressively diminished after prolonged exposure to SD. Rhythms in feeding behavior were also detected initially, reflecting an increase in meal frequency but not duration during the dark phase. This rhythm was lost by 8 wk of SD exposure such that food intake was relatively constant across dark and light phases. After 18 wk in SD, hamsters were transferred to a long-day photoperiod (LD; 16:8-h light-dark cycle), which induced significant weight gain. This was associated with an increase in energy intake within 2 wk, while Vo(2), Vco(2), and heat production all increased back to basal levels. Rhythmicity was reestablished within 4 wk of reexposure to long days. These results demonstrate that photoperiod impacts on body weight via complex changes in locomotor activity, energy expenditure, and feeding behavior, with a striking loss of daily rhythms during SD exposure.

Comparative Analysis of Pdf-Mediated Circadian Behaviors BetweenDrosophila melanogasterandD. virilis

A group of small ventrolateral neurons (s-LN(v)'s) are the principal pacemaker for circadian locomotor rhythmicity of Drosophila melanogaster, and the pigment-dispersing factor (Pdf) neuropeptide plays an essential role as a clock messenger within these neurons. In our comparative studies on Pdf-associated circadian rhythms, we found that daily locomotor activity patterns of D. virilis were significantly different from those of D. melanogaster. Activities of D. virilis adults were mainly restricted to the photophase under light:dark cycles and subsequently became arrhythmic or weakly rhythmic in constant conditions. Such activity patterns resemble those of Pdf(01) mutant of D. melanogaster. Intriguingly, endogenous D. virilis Pdf (DvPdf) expression was not detected in the s-LN(v)-like neurons in the adult brains, implying that the Pdf(01)-like behavioral phenotypes of D. virilis are attributed in part to the lack of DvPdf in the s-LN(v)-like neurons. Heterologous transgenic analysis showed that cis-regulatory elements of the DvPdf transgene are capable of directing their expression in all endogenous Pdf neurons including s-LN(v)'s, as well as in non-Pdf clock neurons (LN(d)'s and fifth s-LN(v)) in a D. melanogaster host. Together these findings suggest a significant difference in the regulatory mechanisms of Pdf transcription between the two species and such a difference is causally associated with species-specific establishment of daily locomotor activity patterns.

Circannual variations of lizard circadian activity rhythms in constant darkness

The daily pattern of locomotor activity of Podarcis sicula in the field changes from unimodal in spring to bimodal in summer, becoming unimodal again in autumn. Short-term experiments in which P. sicula collected in different months were tested under constant conditions immediately after capture showed that the activity pattern typical of each season is retained in the lizard circadian locomotor rhythm. In constant conditions, the bimodal pattern is associated with a short free-running period (τ) of the circadian locomotor rhythm and a long circadian activity (α), while the unimodal pattern is associated with a long τ and short α. To test whether seasonal changes in circadian locomotor rhythms are driven by a circannual clock, we recorded locomotor activity of lizards over 12–15 months in constant temperature and darkness. The present results demonstrate, for the first time in a vertebrate, the existence of circannual changes in constant darkness of both τ and α. In most lizards, the longest τ along its circannual cycle is associated with a short α, and the shortest τ in the same cycle with a long α, so that the pattern of mutual association between τ and α is the same as in short-term experiments. Most lizards, however, stayed unimodal all the time. This shows that changes in activity pattern from unimodal to bimodal (and vice versa) are induced by seasonal changes in environmental factors, instead of being incorporated into a circannual rhythm. Circannual changes in τ and α of locomotor rhythms may adaptively predispose the circadian system of P. sicula to a change in activity pattern as soon as seasonal changes in the environment demand it.

Circadian patterns of locomotor activity and body temperature in blind mole-rats, Spalax ehrenbergi.

A wide variety of organisms exhibit circadian rhythms, regulated by internal clocks that are entrained primarily by the alternating cycle of light and darkness. There have been few studies of circadian rhythms in fossorial species that inhabit a microenvironment where day-night variations in most environmental parameters are minimized and where exposure to light occurs only infrequently. In this study, daily patterns of locomotor activity and body temperature (Tb) were examined in adult blind mole-rats (Spalax ehrenbergi). These fossorial rodents lack external eyes but possess rudimentary ocular structures that are embedded in the Harderian glands and covered by skin and fur. Most individual mole-rats exhibited circadian rhythms of locomotor activity, but some animals were arrhythmic. Individuals that did exhibit robust rhythms of locomotor activity also showed rhythms of Tb. In most cases, Tb was highest during the phase of intense locomotor activity. Locomotor activity rhythms could be entrained to light:dark cycles, and several mole-rats exhibited entrainment to non-24-h light cycles (T-cycles) with period lengths ranging from T = 23 h to T = 25 h. Some individuals also showed entrainment to daily cycles of ambient temperature. There was considerable interindividual variation in the daily patterns of locomotor activity among mole-rats in virtually all the conditions of environmental lighting and temperature employed in this study. Thus, whereas it appears likely that photic cues have a significant role in the entrainment of circadian rhythms in mole-rats, the amount of variability in rhythm patterns among individuals appears to be much greater than for most species that have been studied.

Seasonal changes of locomotor activity patterns in ruin lizards Podarcis sicula

The daily pattern of locomotor activity of the ruin lizard Podarcis sicula in its natural environment changes from unimodal in spring (with only one activity peak per day) to bimodal in summer (with two well-separated activity peaks per day) and it becomes unimodal again in autumn. In order to establish whether such seasonal changes in pattern might be at least in part controlled by endogenous temporal programs, lizards were collected at different times of the year and immediately after capture their locomotor behavior was tested in the laboratory under constant temperature (29°C) and in darkness. For some individuals tested in the laboratory the locomotor pattern previously expressed in the field was known. Seasonal differences in pattern have been unequivocally found to have an endogenous component, as most lizards in constant conditions retained the locomotor pattern shown in the field during the same season. Besides, in the bimodal lizards the freerunning period of locomotor rhythms (τ) was significantly shorter and circadian activity time (a) longer than in the unimodal ones. Altogether the data are compatible with the idea that both the interdependent changes of τ and a and the changes in locomotor pattern occurring seasonally in the circadian activity rhythms of P. sicula would depend on changes in the phase relationship between mutually coupled oscillators which drive these rhythms.

Daily patterns of locomotor activity in a Lycosid spider

Abstract The locomotor activity of adult female Lycosa tarentula has been registered in cages provided with photoelectrical cells. This activity has been studied a) under natural LD cycle and b) under constant conditions (DD, LL). A circadian rhythm was found under natural LD; an infradian rhythm under LL; and an ultradian rhythm under DD. Our results show that the natural LD cycle is an important Zeitgeber for locomotor activity rhythm.

Sex differences in the daily pattern of locomotor activity in laboratory rats

Recent studies have shown that steroid hormones modulate circadian timekeeping processes in mammals [1]. Furthermore, the neuronal structure of the suprachiasmatic nuclei of the hypothalamus, which are essential for the generation and entrainment of circadian rhythms, appears to be sexually differentiated [2]. Although this morphological dimorphism is suspected to cause sex differences in the circadian control of various functions, only few studies have addressed this question [3-6]. The present study supplies information supporting an obvious sex difference in the daily pattern of locomotor activity in laboratory rats. Ultradian rhythms, which have been found to be genetically fixed in two inbred strains of rats [7], are also sex-specific. They w~re observed in male animals of these strains. The females failed to show any ultradian rhythmicity. Adult male and female rats of the inbred strains BH/Ztm (~/'¥, n = 6) and LEW/Ztm (~, n=12; ~. n=11) were bred in our laboratory on a light-dark cycle of LD 12: 12 under controlled environmental conditions (room temperature 22± 1 °C, relative humidity 55±5%). Locomotor activity was measured continuously for 10 days with an electronic movement analyzer [8]. The animals were individually kept in polycarbonate cages (55 x 33 x 20 em) with free access to food and water. The periodicity of the activity patterns was examined using the generalized harmonic spectral analysis [9], which is based on the calculation of an autocorrelation function, and the chi-square periodogram [1 0], which is a modified version of Enright's periodogram. The locomotor activity patterns of a typical male and a typical female rat of the inbred strains LEW/Ztm and BH/Ztm are compared in Fig. 1. AI-

Daily patterns of locomotor activity in a wandering spider

ABSTRACT. Cupiennius salei Keys., a lycosid spider, is night‐active in its natural habitat in the highlands of Guatemala. Locomotor activity begins at dusk after several transitional states, each of which is correlated with a particular light level. Actograph measurements in controlled conditions (LD 12:12 or reversed cycles) show that the spiders begin walking immediately after dark. The activity maximum is reached within the first 3 h of the scotophase (though some spiders displayed additional lights‐on activity in the first hour of the photophase). In DD, Cupiennius shows an endogenous activity rhythm with a mean period of 24.9 h (± 0.31, SE); typically during the first four to six cycles in DD the rhythm ‘splits’ into two components running at different frequencies. In LL (26 1x) the walking activity became arrhythmic. The results are discussed with reference to field and laboratory observations of Cupiennius behaviour and to the consequences for future physiological research with this species.

Circadian Activity Patterns in the Desert Iguana, Dipsosaurus dorsalis

Daily locomotor activity patterns of the desert iguana, Dipsosaurus dorsalis, were recorded under light (L):dark (D) conditions of 12L:12D. These animals produced daily patterns which (a) were monophasic, (b) showed a response of the lizard to onset of light. Both of these characteristics accord with those reported for other day-active animals. The laboratory-recorded daily activity rhythms correlate remarkably well with the field behavior of movement in burrows before emergence, basking early in the activity period, foraging, and retreating to shade or burrow in the later part of the activity period. It is likely that the laboratory-recorded daily activity patterns would change according to the temperature in the activity chamber. These changes would correlate with the seasonal variations in daily activity patterns reported in field studies. Wide individual differences in phase-angle relationships between activity onset and light onset among lizards was observed. It is possible that these differences are due to one or more of the following factors; (a) the low intensity difference between the light and dark phases of the cycle, (b) individual differences in preferred body temperature, and/or (c) individual differences in daily light requirements.

Effects of season and external testosterone on the freerunning circadian activity rhythm of european starlings (Sturnus vulgaris)

1. Results obtained from activity recordings of birds living under natural photoperiodic conditions have suggested the hypothesis that the daily activity-time (α) and the period (τ) of the circadian locomotor activity rhythm are affected not only by external variables but also by internal changes in the hormonal balance related to the annual cycle of reproduction. 2. To test this hypothesis, in experiment 1, groups of male European starlings were transferred at 4 times of the year from outdoor aviaries to constant condition chambers where their circadian locomotor activity rhythms were recorded for a period of about 3 months in both continuous dim light of about 0.7 lux (LL) and continuous darkness (DD). Testicular size was established in all birds prior to the transfer to experimental conditions and subsequently at about monthly intervals. 3. The results show a close relationship betweenα and testes size: in birds which were transferred to LL or DD during the reproductive season (when testes were large),α during the first 30 days of the experiment was significantly longer than in birds which were transferred to these conditions at other times of the year (when the testes were regressing or small; Fig. 2,3,4). Moreover, birds in which testes size increased in the course of the experiment showed a corresponding lengthening inα (Fig. 2,5). — On the other hand, seasonal effects onτ are suggested only by the results obtained in continuous light: birds transferred to LL during the reproductive season showed slightly shorterτ values than birds transferred to these conditions at other times of the year (Fig. 3). 4. The results of experiments 2 and 3, in which the effects of castration and external testosterone on the circadian locomotor activity rhythm of male starlings were studied, confirmed the conjecture that at least a is under hormonal control. Whereasα increased steadily in intact birds whose testes grew in continuous dim light (about 0.2 lux),α remained essentially constant in castrated birds kept under the same conditions. This inhibiting effect of castration onα could be restored by injections of testosterone (Figs. 6, 7). — No clear effects of either castration or testosterone treatment onτ could be detected. 5. On the basis of these findings some of the peculiarities of the circadian locomotor activity rhythms of birds living under natural lighting conditions can partly be explained. The results confirm the hypothesis that the increased activity time during the reproductive season in spring is due to changes in the circadian system induced by hormonal variations. It is proposed that similar endocrine effects may be responsible for the drastic alterations in the daily pattern of locomotor activity which occur in nocturnally migrating, but otherwise day-active, birds at the beginning of the spring migratory season.

L’écologie du Talapoin du Gabon

A 20 months’ field-study of the Talapoin Miopithecus talapoin was carried out between 1966 and 1970 in North-East Gabon. Twenty five troops were observed, all of them in inundated rain forest along rivers. Seventeen of these troops were located near human settlements. The communal night roost of each troop was invariably found near water. The sleeping sites were very stable throughout the year, though some seasonal changes may occur. The troop size ranged from 59 to 80 individuals, and averaged 63 members. Troops living near human settlements were consistently larger. Talapoins live in multimale groups where adult males act as leaders during troop movement and as «watch-dogs» at night. Within the group, females with their infants and year-old juveniles form definite subgroups, at least during the night. Among adults, females outnumber males. Talapoins breed seasonaly in N.E. Gabon. The birth season of a given troop lasts for about 2 months during the period November-April. Most adult females give birth to one infant every year. The natality rate is therefore high, troops living near human settlements increasing by 11.7 to 25.7 % a year. Talapoins are mainly frugivorous but also eat a number of insects. Their daily pattern of locomotor activity shows two definite peaks ; the one between early morning and 10.30 hours, the other between 13.30 and 18.30 hours. The average distance travelled by a group during a day is 2,323 m (with a range from 1,500 to 2,950 m). During their daily wanderings, talapoins do not venture far from a river (never more than 450 m). The home ranges of troops, established by mapping the daily movements of social groups at different times of the year, range from 1.0 to 1.4 km2. Home ranges include both the inundated forest where the night roosts are located, secondary growth forests and even plantations. The percentage utilization of the inundated forest is higher than expected from its size. About 70 % of the food consumed is found in this particular habitat. Variations in size and location of the Ntsi-Belong troop between 1966 and 1968 can be related to food abundance and availability. No territorial behaviour has been observed.