Comparative Skull Analysis Suggests Species-Specific Captivity-Related Malformation in Lions (Panthera leo)

Lion (Panthera leo) populations have dramatically decreased worldwide with a surviving population estimated at 32,000 across the African savannah. Lions have been kept in captivity for centuries and, although they reproduce well, high rates of stillbirths as well as morbidity and mortality of neonate and young lions are reported. Many of these cases are associated with bone malformations, including foramen magnum (FM) stenosis and thickened tentorium cerebelli. The precise causes of these malformations and whether they are unique to captive lions remain unclear. To test whether captivity is associated with FM stenosis, we evaluated 575 lion skulls of wild (N = 512) and captive (N = 63) origin. Tiger skulls (N = 276; 56 captive, 220 wild) were measured for comparison. While no differences were found between males and females or between subadults and adults in FM height (FMH), FMH of captive lions (17.36±3.20 mm) was significantly smaller and with greater variability when compared to that in wild lions (19.77±2.11 mm). There was no difference between wild (18.47±1.26 mm) and captive (18.56±1.64 mm) tigers in FMH. Birth origin (wild vs. captive) as a factor for FMH remained significant in lions even after controlling for age and sex. Whereas only 20/473 wild lions (4.2%) had FMH equal to or smaller than the 5^th percentile of the wild population (16.60 mm), this was evident in 40.4% (23/57) of captive lion skulls. Similar comparison for tigers found no differences between the captive and wild populations. Lions with FMH equal to or smaller than the 5^th percentile had wider skulls with smaller cranial volume. Cranial volume remained smaller in both male and female captive lions when controlled for skull size. These findings suggest species- and captivity-related predisposition for the pathology in lions.     

Preliminary investigation of social interactions and feeding behavior in captive group-housed Tasmanian devils (Sarcophilus Harrisii)

As the number of Tasmanian devils (Sarcophilus harrisii) in captivity increases, an understanding of captive social dynamics and behavior is becoming increasingly important. In the wild, devils are solitary, although sometimes, they congregate to feed on a large carcass. However, it is common to house devils in groups as a form of social enrichment. This study investigated how behavior at feeding time of captive Tasmanian devils varied in groups of different sizes. Observations were made of individually housed devils and devils in groups of two, three, five, and six, when presented with a carcass on which to feed. Total feeding duration ranged from 6.5 to 47.4 minutes per observation period (70 minutes). There was no significant interaction between feeding duration and group size during the experiment. Feeding duration varied daily and depended on carcass size. Social housing of Tasmanian devils enabled them to display dyadic and agonistic behaviors during feeding. Observing behaviors and learning from the outcomes of these interactions can improve husbandry techniques. Creating a captive environment that encourages natural behaviors may enhance survival in the wild following translocation.     

Chew,shake, and tear: Prey processing in Australian sea lions (Neophoca cinerea)

Pinnipeds generally target relatively small prey that can be swallowed whole, yet often include larger prey in their diet. To eat large prey, they must first process it into pieces small enough to swallow. In this study we explored the range of prey‐processing behaviors used by Australian sea lions (Neophoca cinerea) when presented with large prey during captive feeding trials. The most common methods were chewing using the teeth, shaking prey at the surface, and tearing prey held between the teeth and forelimbs. Although pinnipeds do not masticate their food, we found that sea lions used chewing to create weak points in large prey to aid further processing and to prepare secured pieces of prey for swallowing. Shake feeding matches the processing behaviors observed in fur seals, but use of forelimbs for “hold and tear” feeding has not been previously reported for other otariids. When performing this processing method, prey was torn by being stretched between the teeth and forelimbs, where it was secured by being squeezed between the palms of their flippers. These results show that Australian sea lions use a broad repertoire of behaviors for prey processing, which matches the wide range of prey species in their diet.     

Olfactory Enrichment in California Sea Lions (Zalophus californianus): An Effective Tool for Captive Welfare?

In the wild, California sea lions (Zalophus californianus) are exposed to a wide variety of sensory information, which cannot be replicated in captive environments. Therefore, unique procedures are necessary for maintaining physiological and psychological health in nonhuman animals in captivity. The effects of introducing natural scents to captive enclosures have been investigated in a variety of species, yet they have not been examined in marine mammals. This project explored the behavioral effect of scent added to the environment, with the goal of improving the welfare of sea lions in captivity. Two scent types were introduced: (a) natural scents, found in their native environment, and (b) non-natural scents, not found in their native environment. This study examined not only scent enrichment but also the possible evolutionary underpinnings of pinniped olfaction. Scent enrichment was found to significantly impact sea lion behavior as demonstrated by a reduction in pattern swimming, an increase in habitat utilization, and a reduction in stereotypical behavior. However, there were no differences in behavior between natural and non-natural scent conditions.     

Effects of Environmental Complexity and Temporary Captivity on Foraging Behavior of Wild-Caught Meadow Voles

Increased housing of wild nonhuman animals in captivity for conservation, research, and rehabilitation has revealed the importance of systematically analyzing effects of the captive environment on behavior. This study focused on the effects of complexity and time held in captivity on foraging behaviors of wild-caught, adult meadow voles (Microtus pennsylvanicus). Forty-six individuals captured from a meadow outside Oshkosh, WI, were assigned to 1 of 4 captive treatment groups: simple/<50 days (SS), simple/>50 days, complex/<50 days, and complex/>50 days. Number of dish visits, proportion foraging, and frequency of nonforaging behaviors recorded during a 15-min foraging trial were measured for all subjects. Kruskal-Wallis and Mann-Whitney U Tests were conducted to analyze 4 different comparisons within this behavioral data. Overall, neither time in captivity or environmental complexity affected nonforaging behaviors. In contrast, foraging behaviors did change with treatment: Voles were less active at food dishes and visited control dishes more in treatment group SS than in the other treatment groups. In addition, sex-related differences in foraging behaviors were maintained when voles were exposed to environmental complexity. This article includes options for wildlife managers to adapt captive environments to meet the welfare and behavioral needs of translocated wild nonhuman mammals.     

Seroepidemiology of parapoxvirus infections in captive and free-ranging California sea lions Zalophus californianus

Cutaneous nodular lesions caused by parapoxvirus infections are commonly observed in stranded pinnipeds following their arrival at rehabilitation facilities. An indirect enzyme-linked immunosorbent assay (ELISA) was developed and validated to determine exposure to parapoxviruses in California sea lions Zalophus californianus in captivity and in the wild. The diagnostic performance of this assay was evaluated using receiver-operating characteristic analysis. At a selected cut-off value, the calculated sensitivity was 100% (95% CI = 86 to 100%) and the specificity was 100% (95% CI = 87 to 100%). Analysis of sera collected from 26 affected sea lions during various stages of the disease revealed anti-parapoxvirus antibodies in all affected sea lions prior to the development of cutaneous pox lesions. This indicated that previous exposure to a parapoxvirus does not confer protection against clinical disease. In at least 7 cases, exposure to the virus occurred during hospitalization. Analysis of paired sera from 74 unaffected sea lions indicated subclinical infections in at least 3 animals. Finally, the prevalence of anti-parapoxviral antibodies in 761 free-ranging California sea lions captured and tested was 91% (95% CI = 89 to 93%). This indicated that infection with a parapoxvirus is a common occurrence in the wild and that the release of captive sea lions infected with parapoxvirus into the wild should not increase the risk of a parapoxvirus outbreak in free-ranging sea lions.     

Maintaining the genetic health of putative Barbary lions in captivity: an analysis of Moroccan Royal Lions

The last representatives of the Barbary lion (Panthera leo leo), once numerous in North Africa but exterminated from the wild by the 1940s, are believed to be the captive lions descended from the Moroccan Royal Collection, numbering less than 90 animals in zoos worldwide. The genetic fitness of these captive “Royal Lions” may now be under threat since, although most zoos have avoided hybridisation with animals of other origin, no formal breeding programme currently exists and several institutions have halted breeding activities. This situation has arisen since the distinctiveness of Barbary lions and the representative status of Royal Lions remain inconclusive and definitive molecular studies have yet to be completed. Previously, in the 1970s, morphological and phenotypic traits were used to match Royal Lions and the historic Barbary lion and an ex situ breeding programme was initiated involving a number of selected “founder” animals. This paper outlines the status of the descendent population within zoos in Morocco and Europe, including all known pure-bred descendents from the Royal Palace collection. Founder representation is shown to be greater across European collections than the Moroccan collection. Breeding exchanges are recommended between institutions in order to improve genetic diversity and maintain the genetic health of the population and a studbook for European zoo animals has been developed to support this action. This analysis serves as a benchmark for guiding effective maintenance of the captive population, thereby allowing time to clarify the conservation value of Royal Lions and their relevance to North African ecology.     

Establishing Meal Patterns by Lickometry in the Marmoset Monkey (Callithrix jacchus): Translational Applications From the Bench to the Field and the Clinic

The ability to measure and interpret variables associated with feeding behavior and food intake is essential to a variety of nonhuman primate study modalities. The development of a technique to accurately and efficiently measure food intake and meal patterning in captivity will enhance both the interpretation of foraging behavior in the wild as well as our ability to model clinically relevant human feeding pathologies. In this study, we successfully developed the use of a rodent lickometer system to monitor meal patterning in captive common marmosets. We describe the modifications necessary for this type of instrumentation to be used successfully with marmosets. We define variables of interest that relate to both previous rodent literature and human clinical measures. Finally, we relate our findings to potential translational value for both primate field research and biomedical applications. Am. J. Primatol. 74:901‐914, 2012. © 2012 Wiley Periodicals, Inc.     

Hunting success of lions affected by the moon's phase in a wooded habitat

Variation in moonlight affects foraging, hunting and vigilance behaviours in many nocturnal species. Here, we explore the effect of moonlight on the movement and hunting behaviour of African lions. Previous studies found bright moonlight is associated with reduced hunting success; however, those studies were largely undertaken in open habitats where predators are easily seen by prey species on moonlit nights. In this study, we explored whether moonlight affected hunting behaviour and success in a largely wooded environment. Measures of short‐term lion movements (distance moved, displacement and path tortuosity) derived from GPS telemetry data were used as indicators of movement behaviour. Field observations of belly distension were used to assess recent food intake. Lions had greater belly distension (indicating feeding success) on dark nights. However, this change in feeding success was not reflected by lion movement patterns—there was no evidence that these changed across moon phases. There was no evidence that lions used more covered habitats on brighter nights to facilitate concealment.     

Assessing the effects of cognitive experiments on the welfare of captive chimpanzees (Pan troglodytes) by direct comparison of activity budget between wild and captive chimpanzees

We investigated the effects of cognitive experiments by direct comparison of activity budgets between wild and captive chimpanzees. One goal of captive management is to ensure that the activity budgets of captive animals are as similar as possible to those of their wild counterparts. However, such similarity has rarely been achieved. We compared the activity budget among three groups of chimpanzees: wild chimpanzees in Bossou (Guinea, n = 10), and captive chimpanzees who participated in cognitive experiments (experimental chimpanzees, n = 6) or did not participate in the experiments (nonexperimental chimpanzees, n = 6) at the Primate Research Institute (Japan). The experimental chimpanzees voluntarily participated in computer‐controlled cognitive tasks and small pieces of fruits were provided as rewards. The data from captivity were obtained on the experimental days (weekdays) and nonexperimental days (weekends). In both study sites, we followed each chimpanzee from about 7 a.m. until the time when chimpanzees started to rest in the evening. The behaviors were recorded every 1 min. The results showed that on weekdays, feeding time and resting time of the experimental chimpanzees were almost the same as those of wild chimpanzees. However, for the nonexperimental chimpanzees, feeding time was significantly shorter and resting time was longer than those of the wild chimpanzees. In contrast, no difference was found in feeding time or resting time of the two groups of captive chimpanzees on weekends. The results suggested that the cognitive experiments worked as an efficient method for food‐based enrichment. Am. J. Primatol. 73:1231–1238, 2011. © 2011 Wiley Periodicals, Inc.     

Tooth wear in captive wild ruminant species differs from that of free-ranging conspecifics

The mesowear method evaluates the wear patterns of herbivore cheek teeth by visually evaluating the facet development of the occlusal surfaces. It thus allows classification of most herbivorous ungulates into browsers, grazers or intermediate feeders, due to the fact that in grazers, tooth wear is characterized by a comparatively high degree of abrasion, most probably due to the presence of silicacious phytoliths in grasses, a higher amount of dust and grit adhering to their forage, or both. It has been suggested that excessive tooth wear could be a particularly limiting factor in the husbandry of captive large browsing species, and major tooth wear was demonstrated in captive as compared to free-ranging giraffe. If this increased tooth wear in captivity was an effect of feeding type and diets fed, then it would be expected that other browsing species are affected in a similar manner. In order to test this hypothesis, we investigated the dental mesowear pattern in captive individuals of 19 ruminant species and compared the results to data on free-ranging animals. Compared to free-ranging populations, captive browsers show a significantly more abrasion-dominated tooth wear signal. The reverse applies to captive grazers, which tend to show a less abrasion-dominated wear in captivity. Captive ruminants were generally more homogenous in their wear signature than free-ranging ruminants. If grit contamination in the natural habitat is a major cause of dental wear in grazers, then diets in captivity, although similar in botanical composition, most likely contain less abrasives due to feeding hygiene. If dental wear is one of the major factors limiting longevity, then captive grazers should achieve longer lifespans than both captive browsers and free-ranging grazers. In particular with respect to browsers, the results suggest that captive feeding regimes could be improved.     

The influence of experimental manipulations on chewing speed during in vivo laboratory research in tufted capuchins (Cebus apella)

Even though in vivo studies of mastication in living primates are often used to test functional and adaptive hypotheses explaining primate masticatory behavior, we currently have little data addressing how experimental procedures performed in the laboratory influence mastication. The obvious logistical issue in assessing how animal manipulation impacts feeding physiology reflects the difficulty in quantifying mechanical parameters without handling the animal. In this study, we measured chewing cycle duration as a mechanical variable that can be collected remotely to: 1) assess how experimental manipulations affect chewing speed in Cebus apella, 2) compare captive chewing cycle durations to that of wild conspecifics, and 3) document sources of variation (beyond experimental manipulation) impacting captive chewing cycle durations. We find that experimental manipulations do increase chewing cycle durations in C. apella by as much as 152 milliseconds (ms) on average. These slower chewing speeds are mainly an effect of anesthesia (and/or restraint), rather than electrode implantation or more invasive surgical procedures. Comparison of captive and wild C. apella suggest there is no novel effect of captivity on chewing speed, although this cannot unequivocally demonstrate that masticatory mechanics are similar in captive and wild individuals. Furthermore, we document significant differences in cycle durations due to inter-individual variation and food type, although duration did not always significantly correlate with mechanical properties of foods. We advocate that the significant reduction in chewing speed be considered as an appropriate qualification when applying the results of laboratory-based feeding studies to adaptive explanations of primate feeding behaviors.     

Nutrient Balancing by Captive Golden Snub-Nosed Monkeys <Emphasis Type="Italic">(Rhinopithecus roxellana</Emphasis>)

An organism’s fitness is tied closely to its ability to obtain food. However, many foods are nutritionally suboptimal on their own, forcing an individual to develop a feeding strategy that actively manages both type and amount of food consumed. Animals in captivity are additionally limited to human provisioned diets, which may be nutritionally inadequate and negatively affect behavior and health. We studied the nutritional intake of captive golden snub-nosed monkeys (Rhinopithecus roxellana) at two locations in China (132 days of continuous, sunrise to sunset focal samples of 7 individuals at each site) and used the Geometric Framework for nutrition to identify their feeding strategy and evaluate diet variation across sites, seasons, and age–sex classes. Captive golden snub-nosed monkeys had a mean nutrient intake of 75% carbohydrates (15% neutral detergent fiber, 60% total nonstructural carbohydrates), 12% fat, and 13% protein (by energy) that differed by location and season owing to differences in the type and amount of food items offered and consumed. Intake at one location differed from that of wild golden snub-nosed monkeys, suggesting that the captive diet was inadequate. These results highlight the importance of developing nutritionally adequate diets for captive animals based on an understanding of their nutritional requirements.     

ACCLIMATION TO CAPTIVITY: A QUANTITATIVE ESTIMATE BASED ON SURVIVAL OF BOTTLENOSE DOLPHINS AND CALIFORNIA SEA LIONS

An estimate of how long marine mammals need to acclimate to captivity would permit more precise comparisons of husbandry practices, yet no quantitative analysis of acclimation has been performed. Therefore, we estimated the duration of acclimation to captivity for bottlenose dolphins (BD) and California sea lions (CSL) by comparing 5-d survival rates during the first 90 d of captivity with a survival rate based on days 91-365 in captivity. Wild-born BD (n = 1,270) and CSL (n = 1,650) acclimate to captivity in approximately 35 and 40 d, respectively, whereas captive born BD (n = 332) and CSL (n = 992) acclimate in approximately 50 and 40 d, respectively. When transferred between two institutions, BD (n = 911) acclimated in the same amount of time (45 d) as when first transferred from the wild, whereas transferred CSL (n = 336) acclimated more rapidly (15 VJ. 40 d) than when first transferred from the wild. Based on results from these two species, a 60-d acclimation period is recognized as a distinct interval of relatively high mortality that should be treated separately from long-term survival estimates when evaluating husbandry practices of ocean-aria and zoos.     

Examining the potential for nutritional stress in young Steller sea lions: physiological effects of prey composition

The effects of high- and low-lipid prey on the body mass, body condition, and metabolic rates of young captive Steller sea lions (Eumetopias jubatus) were examined to better understand how changes in prey composition might impact the physiology and health of wild sea lions and contribute to their population decline. Results of three feeding experiments suggest that prey lipid content did not significantly affect body mass or relative body condition (lipid mass as a percent of total mass) when sea lions could consume sufficient prey to meet their energy needs. However, when energy intake was insufficient to meet daily requirements, sea lions lost more lipid mass (9.16±1.80 kg±SE) consuming low-lipid prey compared with eating high-lipid prey (6.52±1.65 kg). Similarly, the sea lions lost 2.7±0.9 kg of lipid mass while consuming oil-supplemented pollock at maintenance energy levels but gained 5.2±2.7 kg lipid mass while consuming identical energetic levels of herring. Contrary to expectations, there was a 9.7±1.8% increase in metabolism during mass loss on submaintenance diets. Relative body condition decreased only 3.7±3.8% during periods of imposed nutritional stress, despite a 10.4±4.8% decrease in body mass. These findings raise questions regarding the efficacy of measures of relative body condition to detect such changes in nutritional status among wild animals. The results of these three experiments suggest that prey composition can have additional effects on sea lion energy stores beyond the direct effects of insufficient energy intake.     

Scheduled feeding results in adipogenesis and increased acylated ghrelin

Ghrelin, known to stimulate adipogenesis, displays an endogenous secretory rhythmicity closely related to meal patterns. Therefore, a chronic imposed feeding schedule might induce modified ghrelin levels and consequently adiposity. Growing Wistar rats were schedule-fed by imposing a particular fixed feeding schedule of 3 meals/day without caloric restriction compared with total daily control intake. After 14 days, their body composition was measured by DEXA and compared with ad libitum-fed controls and to rats daily intraperitoneal injection with ghrelin. Feeding patterns, circadian activity, and pulsatile acylated ghrelin variations were monitored. After 14 days, rats on the imposed feeding schedule displayed, despite an equal daily calorie intake, a slower growth rate compared with ad libitum-fed controls. Moreover, schedule-fed rats exhibiting a feeding pattern with intermittent fasting periods had a higher fat/lean ratio compared with ad libitum-fed controls. Interestingly, ghrelin-treated rats also showed an increase in fat mass, but the fat/lean ratio was not significantly increased compared with controls. In the schedule-fed rats, spontaneous activity and acylated ghrelin levels were increased and associated with the scheduled meals, indicating anticipatory effects. Our results suggest that scheduled feeding, associated with intermittent fasting periods, even without nutrient/calorie restriction on a daily basis, results in adipogenesis. This repartitioning effect is associated with increased endogenous acylated ghrelin levels. This schedule-fed model points out the delicate role of meal frequency in adipogenesis and provides an investigative tool to clarify any effects of endogenous ghrelin without the need for ghrelin administration.     

Assessing the Welfare of Dairy Cattle

This article attempts to determine the effects of environment (captive or wild) and a simple form of environmental enrichment on the behavior and physiology of a nonhuman animal. Specifically, analyses first compared behavioral budgets and stereotypic behavior of captive coyotes (Canis latrans) in kennels and pens to their counterparts in the wild. Second, experiments examined the effect of a simple form of environmental enrichment for captive coyotes (food-filled bones) on behavioral budgets, stereotypies, and corticosteroid levels. Overall, behavioral budgets of captive coyotes in both kennels and pens were similar to those observed in the wild, but coyotes in captivity exhibited significantly more stereotypic behavior. Intermittently providing a bone generally lowered resting and increased foraging behaviors but did not significantly reduce stereotypic behavior or alter corticosteroid levels. Thus, coyote behavior in captivity can be similar to that exhibited in the wild; in addition, although enrichment can affect proportions of elicited behaviors, abnormal behaviors and corticosteroid levels may require more than a simple form of environmental enrichment for their reduction.     

Effects of summer microclimates on behavior of lions and tigers in zoos

The surrounding thermal environment has a direct influence on the well-being of an animal. However, few studies have investigated the microclimatic conditions that result from outdoor zoo enclosure designs and whether this affects where animals choose to spend time. Two African lions (Panthera leo) and two Siberian/Amur tigers (Panthera tigris altaica) were observed for a total of 18 full days during the summer and fall of 2009. Their activities and locations were recorded to the nearest minute of each test day. Simultaneous on-site microclimate measurements were taken of air temperature, relative humidity, solar radiation, and wind. Observations indicated that the locations where the animals chose to spend time were influenced by the microclimatic conditions. All subjects spent more time in the shade on their sunny warm days than on other days and differed from one another in their choice of shade source on all days. Temperature-comparable sunny and cloudy days showed a greater use of sun on the cloudy days. Species-specific differences between the lions (whose native habitat is hot) and the tigers (whose native habitat is temperate with cold winters) were observed with the tigers displaying more cooling behaviors than the lions in terms of solar radiation input and evaporative heat loss. The tigers were also more active than the lions. The results of this study provide new insight into how lions and tigers respond to microclimatic conditions in a captive environment.     

Haptoglobin concentrations in free-range and temporarily captive juvenile steller sea lions

Haptoglobin (Hp) is an acute-phase protein synthesized in the liver that circulates at elevated concentrations in response to tissue damage caused by inflammation, infection, and trauma. As part of a larger study, sera Hp concentrations were measured in temporarily captive (n = 21) and free-range (n = 38) western stock juvenile Steller sea lions (Eumetopias jubatus) sampled from 2003 to 2006. Baseline Hp concentration at time of capture was 133.3 +/- 17.4 mg/dl. Temporarily captive animals exhibited a 3.2-fold increase in Hp concentrations during the first 4 wk of captivity, followed by a return to entry levels by week 5. Haptoglobin levels were not influenced by age, season, or parasite load. There was a significant positive correlation between Hp concentrations and white blood cell count (P < 0.001) and globulin levels (P < 0.001) and a negative correlation to red blood cell count and hematocrit (P < 0.001 for both). There was no correlation between Hp levels and platelet count (P = 0.095) or hemoglobin (P = 0.457). Routine blubber biopsies collected under gas anesthesia did not produce a measurable Hp response. One animal with a large abscess had an Hp spike of 1,006.0 mg/dl that returned to entry levels after treatment. In conclusion, serum Hp levels correlate to the stable clinical health status observed during captivity, with moderate Hp response during capture and initial acclimation to captivity and acute response to inflammation and infection.     

Changes in nectar concentration: how quickly do whitebellied sunbirds (Cinnyris talatala) adjust feeding patterns and food intake?

Nectarivorous birds encounter varying nectar concentrations while foraging on different food plants and must adjust their consumption to maintain constant energy intake. We determined how rapidly captive whitebellied sunbirds (Cinnyris talatala) adjust their volumetric intake and feeding patterns after changes in diet concentration. On four consecutive days, birds were fed sucrose diets alternating between a standard diet of 16% w/w and test diets of 2.5, 8.5, 16 or 30% w/w, respectively, for 1.5 h periods. Feeding events were recorded with an infrared photo-detection system and food intake and body mass were monitored continuously by electronic balances interfaced to a computer. Generally, birds demonstrated a measurable increase in feeding frequency and food intake within 10 min after a decrease in sucrose concentration. However, individuals responded differently to the most dilute diet (2.5%): while most increased their food intake, others stopped feeding for a short while, appearing to dislike this diet. Furthermore, the number and duration of feeding events increased in the first 5 min after the switch from 2.5% back to 16%, as the birds attempted to compensate for previous reduced sugar intake. Daily sugar intake was lower when birds alternated between 2.5 and 16% diets than on other test days, but birds were able to maintain body mass, presumably through behavioural adjustments.