Legal Space Requirement Stipulations for Animals in the Laboratory: Are They Adequate?

Animals in the laboratory need the legally required “empty space” to meet their basic spatial requirements for postural adjustment, but they also deserve functional-structured-space for species-typical locomotor behavior and dynamic interaction with their physical environment. Primary enclosures of these animals traditionally are unfurnished, and there is no reason to believe that the biomedical research industry will change the status quo on its own accord. Rather than counting on the professional judgment of attending veterinarians, investigators, and facility administrators, the U.S. Department of Agriculture should explicitly require primary enclosures of laboratory animals to provide not only a specific volume of space, but also species-appropriate space structured for optimal use by the confined subject.     

Exposure to humans and activity pattern of European souslik (Spermophilus citellus) in zoo conditions

European souslik (Spermophilus citellus) is an endangered species being the subject of reintroduction plan in some European countries, including Poland. It is important to obtain data about behavior of reintroduced species, especially a reaction to captivity of specimens prepared to release. The aim of this study was to evaluate influence of human exposure on sousliks behavior. Observed animals were kept in Poznań zoo in three enclosures. Two of them (called "high noise") were in part of the zoo available to the visitors, whereas one ("low noise") was in part closed for them. In "high noise" enclosures sousliks spent more time outside burrows and more specimens were present above ground. They also ate and ran more frequently in "high noise" enclosure, whereas emitted loud voices more often in the "low noise" one. In all enclosures more animals were present above grounds in absence of humans. Time spent by one souslik above ground was positively significantly correlated with the number of sousliks outside burrows. European sousliks observed in this study were used to humans and were less vigilant if they were exposed to permanent humans presence, but they did not become tamed and behave in a way similar to free living animals.     

Contribution to the welfare of captive wolves (Canis lupus lupus): A behavioral comparison of six wolf packs

An interesting way to understand and eventually improve the well‐being of captive animals is to compare different living and social conditions, in order to analyze the behavioral differences between animals living in very restrictive conditions and animals enjoying more permissive ones. In the present study we performed 10 observations of six wolf enclosures with quite different living and social conditions. The rest/activity balance, behavioral diversity, and use of available space were used as welfare criteria. Results show that the proportion of time resting was higher in large, comfortable enclosures. In each park, animals used only a part of the available space, the proportion being lower in large enclosures. The behavioral diversity was little affected by the size of the enclosure, but highly related to the composition of the pack. The results underline the importance of spatial choice and social group management. Zoo Biol 22:33–44, 2003 © 2003 Wiley‐Liss, Inc.     

Do naturalistic enclosures provide suitable environments for zoo animals?

Zoo visitors perceive naturalistic enclosures (i.e. those attempting to replicate identifiable parts of the landscape of the species' habitat) as those that best satisfy the biological needs of the animals, and ensure therefore their welfare. However, the provision of a suitable environment with the resources that will allow the animals to satisfy their main biological needs in naturalistic enclosures has never been systematically explored; instead, it has been assumed. In this study we provide evidence that supports the general idea that naturalistic designs provide suitable environments for the animals. For that purpose, we analyzed 1,381 naturalistic and non-naturalistic enclosures in 63 Spanish zoological parks. In order to assess the suitability of the environment provided within each enclosure, a number of aspects related to the animals' main biological requirements were analyzed. We found a relationship between naturalistic designs and the suitability of the environment for the species housed. Most naturalistic enclosures (77.8%) provided suitable environments for their inhabitants. Non-naturalistic ones also had suitable environments, but in a lower percentage (39.7%). These results should be taken into account during zoo inspection and accreditation appointments, where enclosure suitability must be assessed in an accurate and fast manner. In this regard, a naturalistic design can be used as an adjunct indicator of enclosure suitability, but not exclusively, as not every naturalistic enclosure was suitable for the animals, neither as an indispensable one, given that near 40% of non-naturalistic ones were appropriate for the species housed.     

Relationship between sunlight exposure, housing condition, and serum vitamin D and related physiologic biomarker levels in captive chimpanzees (Pan troglodytes)

In primates, the primary source of vitamin D is synthesis in the skin through sun exposure. Decreased sun exposure may lead to vitamin D deficiency and consequently other health issues. In laboratory, sanctuary, and zoo settings, chimpanzees (Pan troglodytes) may be housed indoors for prolonged periods of time without regular exposure to unfiltered sunlight. However, little research has examined the relationship between housing conditions and vitamin D serum levels in captive chimpanzees. In this study, we retrospectively compared serum levels of total vitamin D, calcium, ionic calcium, phosphorous, albumin, and alkaline phosphatase in 18 female and 12 male chimpanzees as they cycled between indoor-only and indoor-outdoor enclosures. Total vitamin D was significantly lower and alkaline phosphatase significantly higher when subjects were in the indoor-only enclosures compared with when they had regular access to outdoor enclosures. A vitamin D effect occurred only in young and prime-adult animals. Changes were significant in female but not in male chimpanzees. Calcium, ionic calcium, phosphorus, and albumin did not differ between indoor-only and indoor-outdoor enclosures. However, female chimpanzees exhibited significantly lower calcium and phosphorous levels while in the indoor-only enclosures. These results suggest that adult captive chimpanzees experience vitamin D deficiency when housed without regular access to unfiltered sunlight and that these effects may be more acute for adult female animals.     

Embryonic duration and post-embryonic growth rates of the tropical freshwater shrimp Caridina nilotica (Decapoda:Atyidae) under laboratory and experimental field conditions

SUMMARY. Embryonic durations and post embryonic growth rates of Caridina nilotica were determined under laboratory conditions at constant temperatures near 18, 24 and 30°C. Embryonic durations and intermoult intervals were negative curvilinear functions of temperature. At a given temperature moulting frequency varied inversely with shrimp size and slight sexual differences were apparent. Moulting frequency of berried females was governed by the temperature-specific embryonic durations. Growth rates were determined from changes in carapace length (CL) of individual shrimps (laboratory) or batches of shrimps (field enclosures) over 1 month and these data were used to calculate temperature-specific life-long growth curves for males and females. Growth in body mass was estimated indirectly from the carapace length-mass relationship of C. nilotica. On average, males grew marginally faster than females during the first 2 months of life, but growth of males larger than CL= 4 mm was considerably depressed relative to that of females. Inflexions in growth rate, apparently related to the onset of sexual maturity, were apparent in both sexes. Under laboratory conditions, the growth rate of males increased with temperature, but temperature-related differences were not as marked in females. Notwithstanding the more rapid moulting rate at 30°C the growth rate of females was slightly slower at 30 than at 24°C as a result of marginally but significantly smaller per moult growth increments observed at 30°C in animals up to CL= 5.5 mm. Possible reasons for this depressed growth are discussed. Growth rates of animals in field enclosures in Lake Sibaya over 1 month in winter (20 ± 3°C) were generally comparable to those estimated for the 18°C laboratory experiments. Growth rates in enclosures containing tripled standing stocks were almost identical to those containing the naturally occurring biomass of animals, suggesting a non-limited environment at least during the time of the experiment.     

Differential Impacts of Copepods and Cladocerans on Lake Seston,and Resulting Effects on Zooplankton Growth

In an enclosure study in Schöhsee, a small mesotrophic lake in Northern Germany, the impact of copepods and daphniids on the seston community was studied. In general, these two guilds differ in their feeding behaviour. Copepods actively select their food, with a preference for larger particles, whereas most cladocerans are unselective filter-feeders. In this study we investigate how the impact of the two different grazers affects zooplankton growth. We combine results obtained in the laboratory with results measured in situ in the enclosures. Copepods and cladocerans were cultured on seston from enclosures that were inhabited by density gradients of copepods or daphniids. We observed that Daphnia grew faster on seston that was pre-handled by copepods than on seston that was pre-handled by daphniids, and that somatic growth decreased with increasing densities of daphniids in the enclosures. In contrast, we observed no differences in development rates for copepods grown on the different media. The population growth rates of Daphnia in the Daphnia treatments were determined in the enclosures. Growth differences in both somatic- and population growth of Daphnia were correlated to food quality aspects of the seston. In the laboratory we found that Daphnia growth was correlated with several fatty acids. The strongest regression was with the concentration of 20:43 (r ²= 0.37). This particular fatty acid also showed the highest correlation with growth after normalisation of the fatty acids to the carbon content of the enclosures (r ²= 0.33). On the other hand, in the enclosure the population growth correlated most to the particulate nitrogen content (r ²= 0.78) and only to the N:C ratio, when normalised to carbon (r ²= 0.51).     

Validating standardised personality tests under semi‐natural conditions in wild house mice (Mus musculus domesticus)

Personality traits in animals are often measured using standardised behavioural tests for activity, boldness/shyness, sociability, aggression and exploration. These tests are quick and convenient, as well as easy to repeat. As the interest in studying the impact of animal personality on ecological and evolutionary consequences has been growing rapidly, there is increasing focus on cross‐validating measurements taken during these tests with behaviours shown under natural situations. In our experiment, we aimed to study the relationship between standardised measurements for activity, exploration and anxiety‐like behaviour measured in Open Field, Novel Object and Elevated Plus Maze tests with exploration and colonisation in semi‐natural conditions. We carried out a semi‐natural enclosure experiment in parallel with standardised behavioural tests, creating a scenario similar to an invasion or dispersal event. We compared behaviours in standardised tests and in enclosures for animals of two populations of wild house mice (Mus musculus domesticus). Several behavioural variables taken during the standardised tests, such as distance moved and time spent with novel object, were negatively correlated with space‐use in the enclosure while being highly positively correlated among each other. Based on their relationship with space use, we refer to behavioural measurements from standardised tests as activity/exploration. The time spent near the walls in an open field, probably reflecting anxiety, was not correlated to any other variable or the behaviour in the enclosure. In addition, we found differences in activity/exploration behaviour between the two populations in the standardised tests, but not during the colonisation of the novel environment. These results emphasise that researchers have to be careful when trying to extrapolate behaviour shown in standardised laboratory test setups to more natural, ecologically relevant situations. This has to be taken into account in distantly related species but even when studying the wild relative of laboratory rodents, for which these standardised tests have originally been developed.     

Spatial memory and foraging competition in captive western lowland gorillas (Gorilla gorilla gorilla)

Spatial memory and foraging competition were investigated in three mother/offspring pairs of western lowland gorillas,Gorilla gorilla gorilla, using a naturalistic foraging task at the Toronto Zoo. Sixteen permanent food sites were placed throughout the animals’ enclosures. All of the sites were baited and a pair of animals was free to visit the sites and collect the food. Five of the subjects collected the food with accuracy better than chance. Most of the subjects visited the sites using a pattern, and for half the subjects this was one of adjacency. The high accuracy of five of the subjects and the lack of a consistent adjacency pattern suggest that the animals did in fact use spatial memory. Furthermore, the gorillas tended to avoid visiting food sites that had been previously depleted by their partner. They also appeared to split their search of the enclosures, each visiting only a proportion of the food sites. This indicated that the animals were competing and altering their foraging behaviour based on the behaviour of their partner. Therefore, accuracy was recalculated to take this into account. When the sites depleted by either animal in a pair during a given trial were worked into the accuracy calculations for individual animals, three of the animals still maintained accuracy above chance. This suggests that the animals were not only able to remember which sites they had depleted, but those sites depleted by their foraging partner as well.     

Eurasian lynx hunting red deer: is there an influence of a winter enclosure system?

As in several Central European areas, in the Bohemian Forest Ecosystem (Germany and the Czech Republic), fenced feeding enclosures are used for the winter management of red deer (Cervus elaphus), which is an important component of the Eurasian lynx’s (Lynx lynx) winter diet. Using GPS telemetry data, we tested whether (1) lynx hunted red deer mainly selecting for high prey densities and environmental characteristics like a good level of habitat heterogeneity, independently of the enclosures’ presence; (2) enclosures attracted lynx and (3) positively influenced their predation on red deer, being predictable and abundant prey sources throughout the winter; or (4) extremely high deer densities inside the enclosures rather negatively influenced lynx predation on this species. We first compared lynx space usage and predation on red deer inside and outside the enclosures. Then, we investigated the effects of the environment, prey densities and the enclosure distance for the area outside of enclosures. Prey densities positively influenced lynx space usage, whilst the probability of predation on red deer was highest at medium to low red deer densities. Habitat heterogeneity and terrain ruggedness influenced both lynx space usage and probability of predation on red deer. Regarding the effect of enclosures, the ratio “area used during night vs. daytime” was larger by a factor of 2 inside compared to outside enclosures, and the probability of predation on red deer was three times higher inside rather than outside of enclosures; however, these differences were not statistically significant, suggesting that the influence of the enclosures is not very pronounced.     

Compensating for a bad start: catch-up growth in juvenile lizards (Amphibolurus muricatus, Agamidae)

In most natural environments, food availability varies unpredictably through space and time, and growth rates of individual organisms respond accordingly. However, growth rates are not necessarily a simple function of current nutritional conditions: growth rates can be affected by earlier nutritional experience as well as current circumstances. Thus, even a brief period of dietary restriction early in life might influence growth rates later on: either reducing them (if early experience sets subsequent rates, as in the "silver spoon" effect) or increasing them (if underfed individuals can compensate by growing more rapidly to cancel out the early decrement). Alternatively, later growth may be unaffected by earlier rates of growth. We experimentally manipulated food supply (and thus, growth rates) of hatchling lizards (Amphibolurus muricatus) for 1 month post-hatching, then maintained both high-food and low-food animals under identical nutritional conditions in outdoor enclosures for another 6 months. Low food abundance early in life significantly reduced juvenile growth, but these previously underfed animals exploited the subsequent (common garden) conditions to grow much faster than their larger (initially better-fed) siblings. Thus, the two groups were indistinguishable in body size at 6 months of age. Intriguingly, the compensatory growth occurred in winter, a period that is generally unsuitable for rapid growth in ectotherms.     

Swarming and mating activity of Anopheles gambiae mosquitoes in semi‐field enclosures

Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) is the major Afro‐tropical vector of malaria. Novel strategies proposed for the elimination and eradication of this mosquito vector are based on the use of genetic approaches, such as the sterile insect technique (SIT). These approaches rely on the ability of released males to mate with wild females, and depend on the application of effective protocols to assess the swarming and mating behaviours of laboratory‐reared insects prior to their release. The present study evaluated whether large semi‐field enclosures can be utilized to study the ability of males from a laboratory colony to respond to natural environmental stimuli and initiate normal mating behaviour. Laboratory‐reared males exhibited spatiotemporally consistent swarming behaviour within the study enclosures. Swarm initiation, peak and termination time closely tracked sunset. Comparable insemination rates were observed in females captured in copula in the semi‐field cages relative to females in small laboratory cages. Oviposition rates after blood feeding were also similar to those observed in laboratory settings. The data suggest that outdoor enclosures are suitable for studying swarming and mating in laboratory‐bred males in field‐like settings, providing an important reference for future studies aimed at assessing the comparative mating ability of strains for SIT and other vector control strategies.     

Space utilization of Peromyscus: social and spatial factors

Space utilization of Peromyscus maniculatus bairdi and P. leucopus noveboracensis was studied in laboratory enclosures. After 1 week, individuals were given access to twice as much space for an additional week. The new rea was either vacant or was occupied by a similarly experienced conspecific of the same or opposite sex. Patterns of space utilization and reaction to the doubling of space were species specific. Each species displayed specific patterns of social behaviour and only P. maniculatus reproduced. Both species exhibited similar patterns of space utilization in the presence of another individual. Social regulation of space utilization did not result from territorial defence of mutually exclusive areas, but from the initial mutual avoidance of two individuals.     

Genetic diversity in European red deer (Cervus elaphus L.): anthropogenic influences on natural populations

Allozyme, microsatellite and mtDNA (RFLP and sequence) data of European red deer populations were examined as to their capability of indicating anthropogenic influences such as the keeping of animals in enclosures, selective hunting for trophies translocation of specimens to improve trophy quality and habitat fragmentation. Deer in enclosures revealed considerable deviations of allele frequencies from isolation-by-distance expectations but no remarkable loss of genetic diversity. Particular allozyme genotypes were associated with antler morphology, and selective hunting was shown to alter allele frequencies in the expected direction. Habitat fragmentation is reflected by various kinds of genetic markers but due to the lack of information on population histories no unequivocal evidence on particular human activities could be obtained.     

Effects of fragmented breeding habitat and resource distribution on behavior and survival of the bank vole (Myodes glareolus)

Habitat fragmentation causes negative population trends or even local extinction in many species. Understanding the role of fragmentation on behavior and space use of animals is an essential part of revealing the mechanism behind observed population declines. We studied experimentally the effects of small-scale habitat fragmentation on the distribution and movement of bank voles (Myodes glareolus) in seminatural enclosures. We predicted that besides habitat structure, availability of two resources, food for both sexes, and receptive females for males, determine individual distribution. We manipulated female density (either 0, 4, or 12 per enclosure) and followed movements of radio-collared males. We also studied the effect of unequal food distribution between the fragments on vole distribution. The habitat of 0.25-ha enclosures was manipulated by forming either one large, two medium-sized, or four small habitat patches surrounded by an inhospitable matrix. Female density and distribution clearly affected male spacing behavior. Males had larger home ranges in the medium female density enclosures. Furthermore, the use of the inhospitable and risky matrix area increased with habitat fragmentation. Food supplementation improved individual condition measured as body mass but did not affect breeding success. Our experiments demonstrated that both small-scale habitat fragmentation and resource distribution affect the behavior and condition of individuals. Increased fragmentation led to increased risk taking in both mating and foraging behavior. This should have direct survival and fitness consequences, and therefore our results may be extrapolated to population-level consequences of habitat fragmentation.     

Space use selectivity by chimpanzees and gorillas in an indoor-outdoor enclosure

Understanding the relationship between physical environments and nonhuman primate behavior is a key element for effective care and management in a range of settings. The physical features of the captive environment, including not only gross useable space but also environmental complexity, can have a significant influence on primate behavior and ultimately, animal welfare. But despite this connection, there remains relatively little conclusive data on how captive primates, especially great apes, use the spaces provided to them, especially in modern, indoor-outdoor enclosures that have become more prevalent in recent years. In this study, we used four years of detailed data on where 23 great apes (chimpanzees and gorillas) positioned themselves within a modern, indoor-outdoor zoo enclosure to determine not only how the apes utilized their space but also how access to outdoor areas affected their spatial selectivity. We found that both species used relatively little of their available space: chimpanzees and gorillas spent half their time in only 3.2 and 1.5% of their useable three-dimensional space, respectively. Chimpanzees utilized the outdoor space more than gorillas, but access to the outdoors did not affect space selectivity in the indoor area for either species. Although both species of ape were highly selective in their space use, consideration should be given to the importance of providing the choice to locate in a variety of spaces, including outdoor areas. These data represent an extremely detailed account of space selectivity by great apes in an indoor-outdoor environment and have substantial implications for future facility design and captive primate management.     

Multiple intraguild predators reduce mortality risk of a mutual agricultural pest prey in simple,but not in complex,experimental settings

Multiple predator species that coexist with each other and their mutual prey can have combined effects on prey mortality that are similar to the sum of each predator's individual impact (linear effects), greater than the sum of each predator's individual impact (risk enhancement), or less than the sum of each predator's individual impact (risk reduction). Understanding multiple predator effects is important to determine the impact of predators on pest prey in agroecosystems. If two predators share the same broad spatial domain and hunting mode and engage in intraguild predation, then their combination is expected to result in risk reduction for a mutual prey. We tested this hypothesis using both additive and replacement experimental designs on two species of generalist wolf spider predators (Tasmanicosa leuckartii and Hogna crispipes) that hunt in the same domain, and a mutual insect prey (cotton bollworm Helicoverpa armigera). We used two types of enclosures: a small simple laboratory enclosure, and a larger more complex cotton plant enclosure. We found that in the small simple laboratory enclosures, the presence of two spiders led to risk reduction of Helicoverpa larva mortality as expected, but in larger more complex cotton plant enclosures the presence of both species resulted in linear effects rather than risk reduction on Helicoverpa mortality. Furthermore, intraguild predation did not change multiple predator effects in laboratory or plant enclosures. This study has implications for managing arthropod predators in agroecosystems; contrary to predictions of ecological frameworks, coexistence of predators that share the same hunting mode and hunting domain may not lead to risk reduction on a mutual prey in more complex environments, where encounters among predators can be lower. Conservation of multiple predators of a single guild can play an essential role on biological control of insect pests.     

Limitations on the Use of Impermeable Mesocosms for Ecological Experiments Involving Aurelia sp. (Scyphozoa: Semaeostomeae)

Microcosms permit controlled ecological experiments but theeffects of small enclosures on predators, prey, and their interactions,compromise their relevance to field populations. I examinedthe effects of Aurelia size on the utility of impermeable mesocosmsdeployed in highly stable water columns. Aurelia of all sizes(5-29 cm bell diameter) were observed adhered to walls. Individualslarger than 10 cm adhered to walls in disproportionately highnumbers, experienced a significant decline in mean size, andincurred physical damage at greater rates, than those less than10 cm. These results demonstrate that, at least for impermeablewalled mesocosms deployed in low turbulence environments, largerenclosures will not necessarily (i) ameliorate wall effectsfor animals of the size typically manipulated in microcosmsand (ii) make enclosures suitable for manipulating Aurelia largerthan those normally enclosed in microcosms. The mechanism proposedto explain adhesion suggests that enclosure walls alter thehydrodynamics of fluid flow around Aurelia, which may have implicationsfor estimating the predation impact of these animals since thehydrodynamics of feeding and swimming have co-evolved.     

Survival, growth and feeding of vendace, Coregonus albula (L.), larvae in net enclosures

Vendace, Coregonus albula (L.), larvae reared in net enclosures anchored in the littoral zone of Lake Ylä-Enonvesi, eastern Finland, were observed for a period of 44 days in order to determine the effects of density on mortality, growth and feeding of the larvae. The ratio of newly-hatched fish to their food was regulated by controlling the number of fish stocked into the enclosures. Prey animals were expected to move freely in and out of the enclosures. The effect of nylon mesh (500 μm) on the penetration of zooplankters into the enclosures was negligible. The influence of possible starvation was determined by analysing the growth of the larvae, their Fulton condition factor, the instantaneous amount of food ingested, and the food composition in their guts. All these indicators were inversely correlated with larval density. Vendace larvae were found to be resistant to mortality from direct starvation. At all densities the survival rate was over 60%. At the time of complete yolk absorption, there was no increase in mortality.     

The risk of zoological parks as potential pathways for the introduction of non-indigenous species

Zoological parks have been associated with an increasingly frequent origin for accidentally released animal species. Such species have become invasive in some cases. The goals of this study are to evaluate the risk of potential animal escape at zoological parks by assessing the security of animal enclosures, and to identify which factors could be affecting such security. We visited a random sample of 1,568 animal enclosures belonging to 63 Spanish zoological parks, and assessed their security with a defined criteria based on the suitability of the physical barrier of the enclosure and the impossibility for the public to release the animals. To our criteria, we found 221 enclosures which were non-secure against animal escape. Such enclosures were unevenly distributed among 47 zoological parks (74.60% of the sample), and housed non-indigenous species in 79.64% of the cases (21 species listed by the European Inventory of Invasive Species). Seven factors were analyzed to assess their effect on enclosure security. Six of them were found to have an effect, and three were selected by a logistic regression model as the main predictors for secure enclosures. Such factors are discussed, and measures are suggested to reduce the risk of zoological parks as a potential pathway for the introduction of non-indigenous species.