Relationships of maternal nesting to thermoregulatory nesting in house mice (Mus musculus) at warm and cold temperatures

Thermoregulatory and maternal nesting in Mus musculus (indexed as weight of cotton pulled into the cage) was measured at 5 C and 22 C on mice representing lines from a bidirectional selection experiment for nest size at room temperature. The effects of both selection and temperature were significant across the entire experiment. Nesting on the day of parturition correlated highly with thermoregulatory nesting, and with the number of offspring that survived to weaning, indicating a common genetic basis for maternal and thermoregulatory nesting and a direct correlation of these traits with Darwinian fitness. Amount of cotton used increased soon after mating and remained high with a large amount of variability until about 10 days after parturition, and then decreased sharply. The pattern of changes in nest size during pregnancy resembled changes in progesterone levels reported previously in the literature for mice, and contrasted with models of a smooth symmetric curve peaking at parturition.     

Heat or insulation: behavioral titration of mouse preference for warmth or access to a nest

In laboratories, mice are housed at 20–24°C, which is below their lower critical temperature (≈30°C). This increased thermal stress has the potential to alter scientific outcomes. Nesting material should allow for improved behavioral thermoregulation and thus alleviate this thermal stress. Nesting behavior should change with temperature and material, and the choice between nesting or thermotaxis (movement in response to temperature) should also depend on the balance of these factors, such that mice titrate nesting material against temperature. Naïve CD-1, BALB/c, and C57BL/6 mice (36 male and 36 female/strain in groups of 3) were housed in a set of 2 connected cages, each maintained at a different temperature using a water bath. One cage in each set was 20°C (Nesting cage; NC) while the other was one of 6 temperatures (Temperature cage; TC: 20, 23, 26, 29, 32, or 35°C). The NC contained one of 6 nesting provisions (0, 2, 4, 6, 8, or 10g), changed daily. Food intake and nest scores were measured in both cages. As the difference in temperature between paired cages increased, feed consumption in NC increased. Nesting provision altered differences in nest scores between the 2 paired temperatures. Nest scores in NC increased with increasing provision. In addition, temperature pairings altered the difference in nest scores with the smallest difference between locations at 26°C and 29°C. Mice transferred material from NC to TC but the likelihood of transfer decreased with increasing provision. Overall, mice of different strains and sexes prefer temperatures between 26–29°C and the shift from thermotaxis to nest building is seen between 6 and 10 g of material. Our results suggest that under normal laboratory temperatures, mice should be provided with no less than 6 grams of nesting material, but up to 10 grams may be needed to alleviate thermal distress under typical temperatures.     

Working with what you’ve got: Changes in thermal preference and behavior in mice with or without nesting material

In laboratories mice are typically housed at ambient temperatures (T_a) of 20-24 °C, which are below their average preferred T_a of ≈30 °C. Adjusting laboratory T_a is not a solution because preferences differ depending on activity, time of the day, and gender. We tested the hypothesis that providing mice with nesting material will allow behavioral thermoregulation and reduce aversion to colder T_a. We housed C57BL/6J mice with and without nesting material in a set of 3 connected cages, each maintained at a different T_a (20, 25, or 30 °C). Mice were confined in and given free access to the T_a options to determine if thermotaxis or nest building was the primary mode of behavioral thermoregulation. As predicted, nesting material reduced aversion to 20 °C but the overall preference, in both treatments, was still 30 °C. Inactive and nesting behaviors were more likely to be seen in contact with nesting material while active behaviors were more likely to be observed when not in contact. Nest quality increased with decreasing T_a when mice could not use thermotaxis but nest quality was uncorrelated with T_a when thermotaxis was possible. Males decreased nest quality with increasing temperatures but females showed no correlation. We conclude that nesting material does not alter thermal preferences for 30 °C when thermotaxis is possible, indicating thermotaxis as the primary mode of behavioral thermoregulation. However, when thermotaxis is not possible, mice adjust nest shape depending on the T_a. Nesting material appears to partially compensate for cooler T_a and is especially important when mice are inactive. Therefore, nesting material may be a solution to the mismatch between laboratory T_a and mouse thermal preferences.     

The importance of odor in nest site selection by a lodger bee, Centris Bicornuta Mocsáry (Hymenoptera: Apidae) in the dry forest of Costa Rica

The more common lodger bee occurring in the dry forest of Costa Rica, Centris bicornuta Muscáry), has been observed nesting in new nest cavities drilled into wooden blocks placed next to cavities used by another female within 2-3 days. In contrast, new nest cavities placed in similar areas with no nesting Centris nearby were not used for weeks. These observations suggest that the presence of nesting bees may play a role in nest site selection. To confirm our observations, new nest cavities were placed in areas with or without nesting. We found nest initiation in newly placed nest cavities only in areas where bees were actively nesting. To examine the possibility that nesting locations are not unique, we placed new nest cavities in new locations either with (a) a number of completed nest cavities or (b) placed alone. Within three days we only found bees nesting in the newly placed nest cavities in situation "a". The results suggested that odor might be involved. We next compared nesting in new cavities placed alone with cavities contaminated with either (a) nest entrance plug material, (b) nest nectar, (c) nest pollen or (d) a combination of pollen and nectar. Nesting was significantly low in cavities placed next to cavities with nest entrance plug material (a), and high in cavities placed next to cavities "b, c, or d". The results suggest that pollen and /or nectar odor play a role in the location of potential nest sites.     

青藏高原常见雀形目鸟类的筑巢特征

于1990—2004年的繁殖季节,在青藏高原北部地区收集了12种常见的雀形目鸟类的巢,并且对这些鸟巢的分布格局和结构特征进行了比较研究。所有鸟巢分布表现出草地、灌木丛和沼泽的水平分割和地上、地面及地下的垂直分割的空间分布模式,其中地面杯状巢最普遍。巢结构特征,存在从简单到复杂的系列谱变化,主要表现:巢形状从浅到深,从开放到封闭;巢材性质从单一的植物性到复合的动植物性;巢材重从少到多。不管这些变化有多大,都反映了所有鸟种选择巢址是在安全和隔热两种基本条件之间权衡。在变化谱上的每种鸟巢都有自己的利弊,选择哪种类型的巢是由鸟本身的遗传和环境特征两方面的因素决定的。另外,巢材的运输反映了亲鸟对筑巢活动的投资,是繁殖投入的重要组成部分。因此,巢材重与亲鸟体重之比可以反映出筑巢活动投资的高低。百灵科鸟的开放式地面巢材重大约是亲鸟体重的1/2;而褐背拟地鸦的地下封闭巢的巢材重约为亲鸟体重的5倍以上。其余种类都在两者之间变化。总之,如此不同的投资差异是在捕食压力和种间竞争作用下以及亲鸟为满足鸟卵胚胎和雏鸟迅速生长发育的必要条件下,各种生物学特征协调的结果。     

城市化对鸟类筑巢的影响研究综述

繁殖期筑巢是鸟类生活史的重要阶段, 是鸟类繁殖成功的关键保障。全球范围的城市化加速推进, 使城市中筑巢繁殖的鸟类面临挑战的同时又为其提供了特殊机遇。本文通过搜索现有文献, 利用Biblioshiny程序提取并整合关键词, 得到城市鸟类生态研究的热点领域, 分析了城市气候、食物资源、巢址资源、捕食压力、污染和人为干扰对鸟类筑巢的影响, 并对今后城市化对鸟类筑巢影响研究中亟需解决的问题进行了展望。城市化对鸟类筑巢期、巢址选择及巢材选择产生显著影响, 与栖息在村镇生境的鸟类相比, 在城市中繁殖的鸟类在筑巢时间、空间和巢材使用上出现变化。在城市中筑巢的鸟类到底是通过调整行为策略作出积极适应, 还是被动接受城市环境中的诸多负面干扰, 需要针对研究对象和特定的城市栖息生境进行及时评估, 而非泛泛之谈。要在研究结论基础上, 深入思考并提出城市化建设过程中有利于鸟类种群和群落保护的具体措施, 高效发挥公民科学作用以解决城市中的鸟类保护实践问题。     

Environmental modification and agonistic behavior in NIH/S male mice: nesting material enhances fighting but shelters prevent it

Outbred NIH/S male mice were housed from weaning in groups of 4 without enrichment (control) or with nesting material (nest), nesting material and a box (nest-and-box), or nesting material and a tube (nest-and-tube) as environmental modification. The aim of the study was to investigate effects of widely recommended nesting material and additional shelters on male mice. The aggressiveness of the mice in their home cages clearly increased in the nest group, as assessed by the number of wounds. In the nest group, fighting was a stressful situation for the mice, leading to changes in weight gain and in the weights of the thymus, adrenals, spleen, and epididymal adipose tissue. Moreover, the agonistic behavior of these mice toward an intruder was increased both in individual tests (an intruder with the individual mouse) and group tests (an intruder with a group of mice). The provision of a box or tube as a shelter, in addition to nesting material, prevented intracage fighting and did not lead to alterations in the weight gain or organ weights of the mice. However, the agonistic behavior of mice with shelters was slightly increased in behavioral tests. Anxiety in the elevated plus-maze was not affected by any of the housing systems. In conclusion, the agonistic behavior of NIH/S mice, an aggressive strain, seemed to be easily enhanced by these environmental modifications. The suitability of any enrichment should be carefully evaluated, especially when highly aggressive mice are used.     

Evolution of nest-weaving behaviour in arboreal nesting ants of the genus Polyrhachis Fr. Smith (Hymenoptera: Formicidae)

Abstract  Polyrhachis ants represent one of the most taxonomically and ecologically diverse ant genera, with over 500 described species organised into 12 subgenera. Nesting habits range from subterranean localities to arboreal nests incorporating silk produced by the ants' own larvae (nest weaving). In this article, we combine scanning electron microscopy and gross observations of the nests of 35 species representing nine subgenera thought to contain individuals that nest above the ground (Cyrtomyrma, Hagiomyrma, Hedomyrma, Hemioptica, Myrma, Myrmatopa, Myrmhopla, Myrmothrinax, Polyrhachis) to revaluate the relationship between nest locale, the type of nest material used and the use of larval silk for nest construction. Nesting habits are highly diverse, ranging from truly arboreal nests on or between leaves and branches, to lignicolous nests inside hollow stems or bamboo internodes and lithocolous nests on the sides of rock walls. Flat sheets of larval silk are used only by arboreal nesting species within the subgenera Cyrtomyrma , Hemioptica , Myrma , Myrmatopa , Myrmothrinax and Polyrhachis . Lignicolous nesting habits were demonstrated predominantly by Hedomyrma spp., but these habits also occur in Myrma and Myrmhopla . Lithicolous nesting habits occur within Hagiomyrma and Hedomyrma , though the actual nesting material used can be either carton or dense masses of spider silk. Based on existing phylogenetic hypotheses, the use of larval silk for nest construction has evolved independently within the genus, and has evolved independently of the construction of silk nests per se . Further examination of the exact type of silk found in the colonies of 'nest-weaving' Polyrhachis is warranted.     

Nest site selection of loggerhead sea turtles: The case of the island of Zakynthos, W Greece

The sandy beaches of Zakynthos Island support the largest single nesting aggregation in the Mediterranean Region of the endangered loggerhead turtle Caretta caretta. The present study attempts to determine possible correlations between a series of habitat variables and nest site selection. Nesting activities, including total and nesting emergences were examined in response to the recorded biotic and abiotic variables. The results of the analysis indicate that beach width is the most critical habitat variable affecting nest site selection. Further analysis of nesting performance implies that sea turtles use multiple environmental cues for nest site selection during the different steps of the nesting processes such as emergence from the surf and nesting. Nevertheless, we caution that a detailed study needs to be conducted over a more extensive period of time to verify these suggestions.     

Nest preference and ecology of cavity-nesting bees (Hymenoptera: Apoidea) in Punjab,Pakistan

Among bees, 85 % are solitary species, most of them are ground-nester and some are cavity-nesting and construct their nests in pre-existing cavities. This work was conducted to evaluate the substrate preference and nest architecture (acceptance, occupation percentage, seasonality and parasitism) of cavity-nesting bees in different substrates. Trap nests offered comprised five different materials (drilled cavities in wood, bamboo, cardboard tubes, plastic soda straws, and mud blocks). These were installed in four districts for two years. The nesting cavities of five different diameters (6, 8, 10, 12 and 14 mm) were provided in each nesting material with an average length of 180 ± 9.92 mm. In all the materials, 5400 nesting cavities were offered, out of which 628 were colonized by bees from two families (Megachilidae and Apidae) and six species (Megachile cephalotes, M. lanata, M. bicolor, Xylocopa basalis, X. fenestrata and Ceratina smaragdula), including one parasitic bee (Euaspis carbonaria). The bee species differed significantly in occupying five nesting materials. The most preferred diameters were 8 mm and 10 mm, with 52.20% and 29.45% of colonization, respectively. Nesting was done throughout the year except in winter. This study will serve as a baseline for future studies and conservation programs of cavity-nesting bees in Pakistan.     

Olfactory cues and nest recognition in the solitary bee Osmia lignaria

Abstract.  The use of olfactory cues for nest recognition by the solitary bee Osmia lignaria is studied in a greenhouse environment. Glass tubes are provided as nesting cavities to allow the in-nest behaviour of bees to be observed. In addition, each glass tube is cut into three sections for experimental manipulation and for subsequent chemical analysis. Nesting females drag their abdomen along the tube before exiting, spiral inside the tube, and sometimes deposit fluid droplets from the tip of the abdomen. For the manipulation, the outer section, the middle section, or both sections are removed and replaced with similar clean glass tube sections, and the behaviour exhibited by test females is recorded upon arrival in front of the nesting site and inside the nesting tubes. The resulting hesitation behaviour displayed by females after treatments appears to indicate the loss of some olfactory cues used for nest recognition inside the entire nest. Chemical analysis of the depositions inside the nesting tube, as well as analysis of the cuticular lipids of the nesting bees, reveals the presence of free fatty acids, hydrocarbons and wax esters.     

Role of nesting resources in organising diverse bee communities in a Mediterranean landscape

Abstract.  1. The habitat components determining the structure of bee communities are well known when considering foraging resources; however, there is little data with respect to the role of nesting resources.
2. As a model system this study uses 21 diverse bee communities in a Mediterranean landscape comprising a variety of habitats regenerating after fire. The findings clearly demonstrate that a variety of nesting substrates and nest building materials have key roles in organising the composition of bee communities.
3. The availability of bare ground and potential nesting cavities were the two primary factors influencing the structure of the entire bee community, the composition of guilds, and also the relative abundance of the dominant species. Other nesting resources shown to be important include availability of steep and sloping ground, abundance of plant species providing pithy stems, and the occurrence of pre-existing burrows.
4. Nesting resource availability and guild structure varied markedly across habitats in different stages of post-fire regeneration; however, in all cases, nest sites and nesting resources were important determinants of bee community structure.     

Circadian wheel-running activity rhythms are unaltered by acute cage enrichment with nests and shelters

C57BL/6J inbred male mice were assessed for the effects of cotton nesting material on circadian running-wheel assays at 60, 157 and 222 days of age. The oldest mice were also tested for effects of access to plastic igloo shelters and the combination of cotton plus igloos. All mice were assayed for mean activity level, acrophase and entrained circadian period in 12:12 LD, and mean activity level and free-running period in DD for circadian wheel-running activity. There were no significant effects, at any age, of either nesting material or shelters, or the combination of both, on any measures of circadian running-wheel activity. We conclude that circadian rhythm assessment is unlikely to be significantly altered by the inclusion of enrichment materials in running wheel cages.     

Aspen wood-wool is preferred as a resting place, but does not affect intracage fighting of male BALB/c and C57BL/6J mice

Aspen wood-wool, provided as nesting material, was evaluated as a possible improvement of cage environment for 10-14-week-old inbred male mice maintained in groups of six (BALB/c n = 72 and C57BL/6J n = 36). The daily behaviour of mice was video recorded and their body weight, food consumption, weights of some organs and serum corticosterone concentrations were measured. Aggressive interactions between cage mates and against a strange intruder as well as the number of wounds on the back of the animals was monitored in order to evaluate the effect of nesting material on intermale aggression. Nesting material did not affect the daily active/passive behaviour patterns of mice, although animals clearly preferred it as a resting place. BALB/c mice given nesting material showed less weight gain and smaller brown adipose tissue weights than animals without nesting material. The other characteristics measured were not affected by the presence of nesting material in either strain. The presence of nesting material had no effect on fighting in cages. C57BL/6J mice were more aggressive than BALB/c mice according to the number of wounded animals in a cage. Wounded BALB/c mice had enlarged spleens and decreased epididymal adipose tissue weights. In conclusion, the nesting material used in this study did not adversely affect the animals. On the other hand, the material was clearly preferred to conventional bedding as a resting place. These findings suggest that nesting material may improve the cage environment of laboratory mice. Furthermore, there was an indication of strain differences in aggressive behaviour. It could be suggested that C57BL/6J mice are less tolerant towards intruders and housing six mice per cage is not suitable for this strain.     

筑巢材料在实验大、小鼠环境丰荣中的应用

相对于标准鼠盒,实验大、小鼠更喜好有筑巢材料的“环境丰荣”鼠盒.向标准鼠盒中放入筑巢材料,可以为大、小鼠提供筑巢、躲避、攀爬、休息的环境.因此,在实验大、小鼠饲养过程中,提供筑巢材料,是一个简单有效的丰富实验动物环境,提高实验动物福利的方法.本文就筑巢材料应用背景、近年来在啮齿类实验动物环境丰荣中的应用、对实验动物福利的影响三方面做以综述,并对今后筑巢材料在改善实验动物福利的应用前景作以展望.     

Inheritance of nesting behaviour across natural environmental variation in a turtle with temperature-dependent sex determination

Nesting behaviour is critical for reproductive success in oviparous organisms with no parental care. In organisms where sex is determined by incubation temperature, nesting behaviour may be a prime target of selection in response to unbalanced sex ratios. To produce an evolutionary change in response to sex-ratio selection, components of nesting behaviour must be heritable. We estimated the field heritability of two key components of nesting behaviour in a population of painted turtles (Chrysemys picta) with temperature-dependent sex determination by applying the ‘animal model’ to a pedigree reconstructed from genotype data. We obtained estimates of low to non-detectable heritability using repeated records across all environments. We then determined environment-specific heritability by grouping records with similar temperatures for the winter preceding the nesting season, a variable known to be highly associated with our two traits of interest, nest vegetation cover and Julian date of nesting. The heritability estimates of nest vegetation cover and Julian date of nesting were qualitatively highest and significant, or nearly so, after hot winters. Additive genetic variance for these traits was not detectable after cold winters. Our analysis suggests that the potential for evolutionary change of nesting behaviour may be dependent on the thermal conditions of the preceding winter, a season that is predicted to be especially subject to climate change.     

BREEDING OF SACRED IBIS THRESKIORNIS AETHIOPICA AT LAKE SHALA, ETHIOPIA

Data are based on more than 200 h of observation at Ethiopia's Lake Shala from 1966 to 1972. Except for differences in size of bill, there are no useful field characters separating male and female Sacred Ibis. The breeding plumage is described; vivid blood-red colour underneath the wings and the ornamental plumes are especially obvious when nesting commences. Physical and biological features of Lake Shala, Ethiopia, and its nesting islands are described; the species of birds nesting on the Shala islands are given. Ibises nest at Shah from March to August; no nesting has been recorded from September to February during the last months of the ‘big’ rains through the main dry season. Nesting normally begins in the ‘small’ rains (between 14 March-24 April), although instances were recorded as early as 1 March and as late as 20 August. The ibises normally nest once per year, although it is possible that occasionally a second nesting may occur after an unsuccessful first attempt. The ibises at Shala nest in discrete groups; several nesting groups may form on any or all of the islands; the number of groups attempting to nest varied from year to year. Nesting activity begins when males arrive and establish pairing territories, usually in a small tree but sometimes on the ground. When females and other males arrive at the pairing territories, pair formation ensues. At this time males perform forward threat, modified forward threat, pursuit flight, supplanting attack and modified snap displays, while both sexes perform stretch and bow displays. Once established, the pair abandons the pairing territory and moves to the nesting area, usually near but always distinct from the pairing territory, and establishes a nest-site territory. Most members of the nesting group move to the nesting area on the same day. Copulation then takes place, and is followed by collection of nest material, usually by the male. Nests are built close together. The average area of 10 nests measured was 0.09 m². Nests are usually less than 20 cm thick and are made of many small branches and sticks. The average clutch in 34 nests was 2.24 eggs; the average size of 34 eggs was 63.4×43.5 mm. Incubation probably begins when the clutch is complete. Both sexes incubate, and the incubation period probably lasts 28–29 days. The development of the young is described. The young leave the nest-site territory when 14–21 days old. Although they are capable of some flight when 35–40 days old, the young do not leave the colony until they are 44–48 days old. In the colony, both parents care for the young. Usually only one parent at a time is with the young. The parents recognize their own young and are usually recognized by them. The behavioural interactions between young and parents are described. Fledging success in 1968 was 1.06 young per pair. The number of pairs successfully rearing young varied annually from none to 81%, on average over six years (1966–70, 1972) 35%. Predation at the breeding colonies is minimal. The food of one one-month old chick consisted of beetle larvae, lepidopteran larvae and beetles. Feeding areas, although undetermined, must be widespread. Inter-specific competition between Sacred Ibis and other nesting birds at Shala is discussed. Among possible factors stimulating nesting at Shala one, fairly heavy rainfall, seems to be especially important. It is also suggested that especially heavy rain-storms cause ibises to abandon the colonies, and result in poor breeding success.     

Nesting preferences of common buzzard Buteo buteo and goshawk Accipiter gentilis in forest stands of different structure (Niepolomice Forest, Southern Poland)

Studies on nesting preferences of common buzzard and goshawk were carried out in two distinctly different parts of the Niepolomice Forest (S Poland): deciduous (oak-hornbeam wood) and coniferous. Characteristics of nest sites were determined on three spatial scales, separately for: (1) nest tree; (2) nest tree area (0.07 ha circle centred at nest tree) and (3) nest stand (15 ha circle centred at nest tree). Nesting preferences discovered for the nest tree and its surroundings, included height and diameter of trees, age of the forest stand, distance to the nearest open area or forest road and occurrence of open areas in the vicinity of the nest. In the diverse habitat of oak-hornbeam wood, more similar to natural woods, nest site selection operated on several levels, possibly starting at the most extensive end of the scale before narrowing to the selection of a particular nest tree. In the more homogeneous habitat of commercially exploited coniferous forest, the surrounding of the nest were found to be insignificant, and the nesting decisions were likely to be based principally on individual characteristics of a tree i.e. its shape and size, being suitable for nesting.     

Nesting bird species in sun coffee, pasture, and understory forest in southern Costa Rica

We investigated avian nest distribution and success in understoryforest, sun coffee plantations, and pasture in southern Costa Rica. Nestsearching occurred in plantations and forest in 1999 and 2000 and in pastures in2000. Nests were monitored until they failed or fledged young. Antbirds(Thamnophilidae) were the most common understory forest nesters and were notfound nesting in the plantations or pastures. Common nesting species in theplantations included Turdidae, Tyrannidae, Cardinalidae, and Thraupidae, many ofwhich are typical of forest edge/canopy or open, scrubby habitats. Two speciesassociated with forest interior, Henicorhina leucostictaand Buarremon brunneinucha, were found nesting in theplantations. Pastures supported similar types of nesting species as theplantations, with the exception of the forest-interior species. Daily mortalityrates (DMRs) for above-ground cup-nesting species in plantations and pastureswere similar to those for species nesting in forest at our site and a site inPanama. The results indicate that conversion from forest to pastures and suncoffee plantations diminishes nesting habitat for forest-interior species, whilenumerous forest edge/canopy species and open-country species are able to nest inthese agricultural land-cover types. As a group, species nesting in theplantations and pastures do not have unusually high nest mortality rates,although species-specific studies are lacking. Nesting species distributionsacross habitat types and DMRs at our study site may be influenced by the largeamount of forest in the landscape.     

Assessment of the use of two commercially available environmental enrichments by laboratory mice by preference testing

In the field of biomedical research, the demand for standardization of environmental enrichment for laboratory animals is growing. For laboratory mice, a wide variety of environmental enrichment items are commercially available. Most of these comply with the demands for standardization, hygiene and ergonomics. Whether these items also comply with their actual purpose, to enhance the well-being of the mice, is often not assessed scientifically. In this study, we tested the preference of mice for two commercially available nest boxes differing in shape and material: the Shepherd Shack/DesRes (SS/DR) and the Tecniplast Mouse House (TMH), in a simple preference test. To indicate strength of preference, both nest boxes were also tested against a highly preferred nesting material. Preference for the most preferred nest box was investigated further. Our results indicated a strong preference by mice for the SS/DR, but not for the TMH. Furthermore, nesting material was almost always combined with the SS/DR, but not with the TMH. More elaborate testing of the SS/DR in an automated preference test system confirmed that mice spent significantly more time in a cage in which an SS/DR is provided. Differences between both nest boxes are discussed with regard to their attractiveness to mice. It is also argued that enrichment should primarily be developed in concordance with the animals' needs prior to the marketing of enrichment tools.