Large Enclosure Research Articles

Parentage assignment reveals multiple paternity in the critically-endangered Guatemalan beaded lizard (Heloderma charlesbogerti)

Within captive management programs for species of conservation concern, understanding the genetic mating system is of fundamental importance, given its role in generating and maintaining genetic diversity and promoting opportunities for sperm competition. If a goal of a conservation program is reintroduction, knowledge of the mating system may also inform prediction models aimed at understanding how genetic diversity may be spatially organized, thus informing decisions regarding where and which individuals should be released to maximize genetic diversity in the wild population. Within captive populations, such information may also influence how animals are maintained in order to promote natural behaviors. Here we investigate the genetic mating system of the Guatemalan beaded lizard, Heloderma charlesbogerti, a member of an entire clade lacking such information. A group of adult male and female H. charlesbogerti co-habited a large outdoor enclosure for five years during the species’ perceived breeding season. Through genomic parentage analysis, 50% of clutches comprising multiple offspring were found to result from multiple paternity, with up to three males siring offspring within single clutches. Both males and females were observed to produce offspring with multiple partners within a given year. As such, within this captive environment, where opportunities existed for mating with multiple partners, the genetic mating system was found to be highly polygamous, with multiple paternity common within clutches. These findings are novel for the family Helodermatidae, and the results have broader implications about how reproductive opportunities should be managed within captive conservation programs.

전자파 흡수체를 이용한 대형 함체의 차폐효과 개선

This study analyzed that the penetration of electromagnetic waves through an unknown opening in a large enclosure generated standing waves within the enclosure, thereby reducing its shielding characteristics. A 3D numerical analysis confirmed that the shielding performance can be improved by using electromagnetic absorbers to reduce the standing wave. This was verified experimentally.

Adaptive management in a conservation breeding program: Mimicking habitat complexities facilitates reproductive success in narrow-headed gartersnakes (Thamnophis rufipunctatus).

Mimicking natural parameters and complexities in zoo conservation breeding programs can facilitate natural physiological and behavioral traits, which in turn can inform more effective species reintroduction efforts. To curtail population declines of threatened narrow-headed gartersnakes (Thamnophis rufipunctatus), the Arizona Center for Nature Conservation/Phoenix Zoo partnered with a multiagency conservation working group to develop an ex situ propagation-for-release program. Initially, Zoo staff followed common snake husbandry protocols of manually inducing brumation (i.e., winter dormancy). Copulation was observed during the first few years, but no births resulted. Also, some older individuals developed post-brumation health abnormalities, prompting a strategic reassessment. To facilitate propagation and improve health, Zoo staff applied ecological knowledge of T. rufipunctatus and an adaptive management strategy to implement key parameters for success: sociality, refugia, breeding and foraging behaviors, and natural brumation. Zoo staff developed a large multisnake enclosure that mimicked natural ecological and habitat complexities including a hibernaculum to stimulate natural brumation. Gartersnakes were left mostly unimpeded to conduct natural behaviors across seasons in the enriched environment. We referenced change in body mass after ten brumation periods as a proxy for health. Under natural brumation, gartersnakes did not lose body mass, and this shift resulted in fully ex situ parturition events-the first for this imperiled species. We highlight the efficacy of adaptive management and incorporation of natural parameters and environmental complexities into conservation breeding programs. These actions can improve the health and success of animals under managed care-processes applicable to a range of taxa targeted for conservation translocations.

Deriving observation distances for camera trap distance sampling

AbstractCamera trap distance sampling (CTDS)o is a recently developed survey method to estimate animal abundance from camera trap data for unmarked populations. It requires the estimation of camera‐animal observation distances, which previously was done by comparing animal positions to reference labels at predefined intervals. Here, we test a photogrammetry approach to derive camera‐animal observation distances. We applied both, the reference label and photogrammetry approaches to five ungulate species varying widely in body size (Giraffa camelopardalis,Equus grevyi,Oryx dammah,Kobus megacerosandEudorcas thomsonii) and one ground‐dwelling bird species (Numida meleagris) inhabiting a large enclosure and estimated their density with CTDS. Both procedures provided highly correlated observation distances (ρ = 0.99,p < 0.001). A paired t test revealed a minor but significantly higher mean of the photogrammetry approach (MD = 0.28 m,p < 0.001). This, however, seems negligible as for analyses, distances were grouped in intervals of 2 to 5 metres. In general, estimated animal abundance was close to the true number of individuals in the enclosure for both approaches, with the exception of zebra, whose density was underestimated. The photogrammetry approach offers an alternative approach for deriving camera‐animal observation distances and is particularly useful for application in open habitats, with little occlusion of animals.

Universal Statistical Tradeoffs for Shielding Effectiveness Evaluation of Electrically Large Enclosures in Reverberation Chambers

Shielding effectiveness (SE) evaluation of electrically large enclosures within reverberation chambers (RCs) is standardized procedure for electromagnetic compatibility (EMC) applications. In this work the potential relationship between SE and electromagnetic resonances have been investigated with respect to the ambiguity in definition of SE for the international standards, e.g., IEC 61000-4-21 or IEEE Std 299.1. From a statistical point of view, we derive the expansions of SE defined by the ratio of the maxima and the averages respectively. To evaluate SE more prudently as well as to obtain a much smaller uncertainty, we can make the tradeoffs for SE, which should be defined as the ratio of the averages for the overmoded frequency, and the ratio of the maxima for the undermoded using a common criterion aimed to discriminate the electromagnetic field behavior between the undermoded and the overmoded, and also verify the corresponding results by numerical simulations and measurement performed in RC.

Investigation on Ceiling Damages at 6 Large Enclosures Damaged during off the Coast of Fukushima Earthquake on Mar. 16, 2022

Investigation on Ceiling Damages at 6 Large Enclosures Damaged during off the Coast of Fukushima Earthquake on Mar. 16, 2022

Experimental evidence for opposing effects of high deer density on tick-borne pathogen prevalence and hazard

BackgroundIdentifying the mechanisms driving disease risk is challenging for multi-host pathogens, such as Borrelia burgdorferi sensu lato (s.l.), the tick-borne bacteria causing Lyme disease. Deer are tick reproduction hosts but do not transmit B. burgdorferi s.l., whereas rodents and birds are competent transmission hosts. Here, we use a long-term deer exclosure experiment to test three mechanisms for how high deer density might shape B. burgdorferi s.l. prevalence in ticks: increased prevalence due to higher larval tick densities facilitating high transmission on rodents (M1); alternatively, reduced B. burgdorferi s.l. prevalence because more larval ticks feed on deer rather than transmission-competent rodents (dilution effect) (M2), potentially due to ecological cascades, whereby higher deer grazing pressure shortens vegetation which decreases rodent abundance thus reducing transmission (M3).MethodsIn a large enclosure where red deer stags were kept at high density (35.5 deer km−2), we used an experimental design consisting of eight plots of 0.23 ha, four of which were fenced to simulate the absence of deer and four that were accessible to deer. In each plot we measured the density of questing nymphs and nymphal infection prevalence in spring, summer and autumn, and quantified vegetation height and density, and small mammal abundance.ResultsPrevalence tended to be lower, though not conclusively so, in high deer density plots compared to exclosures (predicted prevalence of 1.0% vs 2.2%), suggesting that the dilution and cascade mechanisms might outweigh the increased opportunities for transmission mechanism. Presence of deer at high density led to shorter vegetation and fewer rodents, consistent with an ecological cascade. However, Lyme disease hazard (density of infected I. ricinus nymphs) was five times higher in high deer density plots due to tick density being 18 times higher.ConclusionsHigh densities of tick reproduction hosts such as deer can drive up vector-borne disease hazard, despite the potential to simultaneously reduce pathogen prevalence. This has implications for environmental pathogen management and for deer management, although the impact of intermediate deer densities now needs testing.Graphical abstract

Does enclosure size influence the behaviour & welfare of captive snakes (Pantherophis guttatus)?

There is much evidence in mammals and birds demonstrating the importance of providing sufficient space to allow captive animals to exhibit natural behaviours, however, little such evidence exists for reptiles. The aim of this study was to ascertain whether enclosure size impacted on the behaviour and welfare of captive corn snakes (Pantherophis guttatus). Snakes (N = 12) were housed in enclosures that were either 2/3 their length (small) or longer than the length of the snake (large) for c.32 days. Their welfare was assessed through observations of the animals in their enclosure and behavioural tests; after completing these tests, each animal was switched to the other housing condition (order counterbalanced across individuals) and received the same welfare assessment. Following the second set of behavioural tests, all animals received a preference test. When housed in large enclosures, snakes were found to be more active and spent time stretched out - a behaviour that was not possible in the small enclosure. The behavioural tests revealed few effects of space provision; however, when given a choice, snakes showed a clear preference for the large enclosure whilst active, although this preference was not observed while resting. These findings suggest that providing a larger enclosure is beneficial to the behaviour and welfare of captive snakes. Not providing sufficient space to allow snakes to fully elongate appears to thwart a behavioural need and thus impacts negatively on their welfare. We therefore recommend that captive snakes be kept in an enclosure longer than their body length.

Separation of geometric and featural information in children’s spatial representation: Evidence from a model selection task

Previous studies in spatial reorientation have found that young children rely mainly on geometric shapes for reorientation and sometimes ignore features in the environment. Theoretical interpretations of children’s reorientation performance are usually attributed to children’s spatial representation of their surrounding environments. The geometric module theory states that featural information is represented separately from geometric shape in young children’s reorientation, whereas the adaptive combination model depicts an integral representation. Reorientation tasks, however, require the recognition of a specific location, and thus how the whole environment is represented remains unknown. The current study, using a model selection task, explored young children’s representation of the whole surrounding environment. A total of 75 children aged 3–5 years participated in the study. In each trial, children observed a large enclosure and were then asked to choose the corresponding model from two small models. The geometric shapes of the enclosure (rectangle vs. rhombus) and the types of distractors (shape distraction vs. feature position distraction) varied. Results showed that all three age groups performed above the chance level in the shape distraction conditions. Children had more difficulty with the feature position distraction conditions than with the shape distraction conditions. When the distractor shared the feature but at an inappropriate position, children’s performance was significantly poorer, especially in the rhombic enclosure. The results provide evidence that young children may represent featural cues separately from geometric shapes.

Improved nutritional status may promote an “asset protection” reproductive strategy in male rock lizards

AbstractInvesting in the current reproduction requires diverting energy resources from other metabolic functions, which may compromise future reproduction and lifespan. To solve this trade-off, an individual may consider its labile state to decide how much to invest in current reproduction. We tested experimentally whether the “state quality” of male rock lizards influences their reproductive strategies. To improve the nutritional status of males before the mating season, we captured and supplemented experimental males (N = 20) with dietary vitamin D3 (an essential nutrient for lizards) and had a control group of males (N = 20). Then, we released all these males and females (N = 31) in a large semi-natural outdoor enclosure where lizards could interact and mate freely during the mating period. Activity levels of males did not vary between treatments, but supplemented males started fewer intrasexual agonistic interactions and made fewer mating advances to females. When the mating season ended, we incubated eggs laid by females to obtain the offspring and estimated the paternity of males using DNA microsatellites. Supplemented males sired fewer offspring than control males. These results suggest that vitamin D3 supplemented males used a low risk/less costly mating strategy to protect their assets (i.e., vitamin D reserves), but that still resulted in “some” current reproductive success, while likely increasing longevity and the expected future total reproductive success.

Post-release Movement Behaviour and Survival of Kulan Reintroduced to the Steppes and Deserts of Central Kazakhstan

Asiatic wild ass, or kulan (Equus hemionus kulan) were once a key species of the Eurasian steppes and deserts. In Kazakhstan they went extinct by the 1930s. Early reintroductions have reestablished the species in two protected areas, but the species has reclaimed <1% of their former range and remained absent from central Kazakhstan. To initiate restoration in this vast region, we captured and transported a first group of nine wild kulan to a large pre-release enclosure in the Torgai region in 2017, and two more in 2019. We used direct observations and post-release movement data of four kulan equipped with GPS-Iridium collars to document their adaptation process in a vast novel habitat without conspecifics. For comparison with movements in the source populations, we additionally equipped two kulan in Altyn Emel National Park and six in Barsa Kelmes State Nature Reserve. The nine transported kulan formed a cohesive group with very high movement correlation in the enclosure. After release, the group initially stayed tightly together but started to break up by mid-May and all kulan travelled independently by mid-August. With 48,680–136,953 km2, the 95% Autocorrelated Kernel Density Estimation ranges of the reintroduced kulan were huge and about 10–100 times larger than those in the source populations. The reintroduced mares never reconnected, there was no evidence of successful reproduction, and two of the four collared mares were killed by poachers and one died of natural causes. At least one stallion survived in the wild, but the fate of the other uncollared animals remains unclear. We speculate that the fission-fusion dynamics and low movement correlation of kulan societies and the need for migratory movements harbours the risk that animals released into a novel environment loose contact with each other. This risk is likely enhanced in steppe habitats where movement constraining factors are absent. Further kulan reintroductions to the steppes and deserts of central Kazakhstan should aim to release larger groups and build up the free-ranging population quickly to reach a critical mass, increasing the chance of kulan encountering conspecifics to successfully breed and increase their chances of survival.

Spatial Representations in Rat Orbitofrontal Cortex.

The orbitofrontal cortex (OFC) and hippocampus share striking cognitive and functional similarities. As a result, both structures have been proposed to encode "cognitive maps" that provide useful scaffolds for planning complex behaviors. However, while this function has been exemplified by spatial coding in neurons of hippocampal regions-particularly place and grid cells-spatial representations in the OFC have been investigated far less. Here we sought to address this by recording OFC neurons from male rats engaged in an open-field foraging task like that originally developed to characterize place fields in rodent hippocampal neurons. Single-unit activity was recorded as rats searched for food pellets scattered randomly throughout a large enclosure. In some sessions, particular flavors of food occurred more frequently in particular parts of the enclosure; in others, only a single flavor was used. OFC neurons showed spatially localized firing fields in both conditions, and representations changed between flavored and unflavored foraging periods in a manner reminiscent of remapping in the hippocampus. Compared with hippocampal recordings taken under similar behavioral conditions, OFC spatial representations were less temporally reliable, and there was no significant evidence of grid tuning in OFC neurons. These data confirm that OFC neurons show spatial firing fields in a large, two-dimensional environment in a manner similar to hippocampus. Consistent with the focus of the OFC on biological meaning and goals, spatial coding was weaker than in hippocampus and influenced by outcome identity.SIGNIFICANCE STATEMENT The orbitofrontal cortex (OFC) and hippocampus have both been proposed to encode "cognitive maps" that provide useful scaffolds for planning complex behaviors. This function is exemplified by place and grid cells identified in hippocampus, the activity of which maps spatial environments. The current study directly demonstrates very similar, though not identical, spatial representatives in OFC neurons, confirming that OFC-like hippocampus-can represent a spatial map under the appropriate experimental conditions.

A multiproxy approach to studying a large prehistoric enclosure in Ojców, Kraków Upland, Poland

AbstractDue to the presence of multiple caves and rock shelters as well as flint outcrops, Ojców Upland is a region with an exceptionally high concentration of prehistoric human settlement traces. It has attracted archaeologists for over 150 years, leading to what was considered to have been a proper prospection of the area. Nonetheless, the analysis of airborne laser scanning has recently brought surprising results. In the very centre of the upland, on the densely forested hill ‘Złota Góra’ (Golden Hill), the remains of an exceptionally large defensive structure in the form of several rows of embankments were found. The use of magnetic methods made it possible to confirm their anthropogenic origin and the likely type of embankment construction. In turn, the layout of embankments combined with the results of a surface survey and the analyses of the acquired artefacts and the settlement context speak in favour of linking this defensive structure with a high degree of probability with the Neolithic or Eneolithic, most likely the Lengyel‐Polgár cycle or Baden culture. The presence of such a large fortification in the immediate vicinity of flint mines could shed new light on the image of the Late Neolithic‐Early/Middle Eneolithic period in this part of Europe.

A Novel Multicamera System for High-Speed Touchless Palm Recognition

Palm-related biometrics have been widely studied for a long time, as the palm contains many distinctive patterns. However, most of the existing systems are designed to work within an ideal environment, such as in front of a unicolor background or in a large enclosure. Those preconditions can avoid influences of ambient light and hand distance change, but at the same time, they also limit the applications of palm recognition. In the work reported in this paper, we designed a novel red-green-blue and depth-based four-camera system that can capture the palm-related images separately in real time. The techniques of region-of-interest (ROI) location, ROI alignment, and light-source intensity optimization were studied. The ROI location method is modified to increase the robustness of hand gesture variation. Based on the depth information, we proposed the coordinate mapping and inclination rectification methods to obtain aligned ROI pairs. Using this device, we collected a video-based multimodal palm image database. After the parameter optimization and information fusion, the equal-error-rate of our approach on this database is lower than 0.47%. The recognition rate obtained from the support-vector-machine-based fusion is higher than 99.8%. The experimental results prove that the proposed system achieves advantages of anti-spoofing, high speed, high accuracy, and small size.

Potentialities and Limitations of Research on VHRS Data: Alexander the Great’s Military Camp at Gaugamela on the Navkur Plain in Kurdish Iraq as a Test Case

This paper presents a selected aspect of research conducted within the Gaugamela Project, which seeks to finally identify the location of one of the most important ancient battles: the Battle of Gaugamela (331 BCE). The aim of this study was to discover material remains of the Macedonian military camp on the Navkur Plain in Kurdish Iraq. For this purpose, three very high resolution satellite (VHRS) datasets from Pleiades and WorldView-2 were acquired and subjected to multi-variant image processing (development of different color composites, integration of multispectral and panchromatic images, use of principle component analysis transformation, use of vegetation indices). Documentation of photointerpretation was carried out through the vectorization of features/areas. Due to the character of the sought-after artifacts (remnants of a large enclosure), features were categorized into two types: linear features and areal features. As a result, 19 linear features and 2 areal features were found in the study area of the Mahad hills. However, only a few features fulfilled the expected geometric criteria (layout and size) and were subjected to field groundtruthing, which ended in negative results. It is concluded that no traces have been found that could be interpreted as remnants of an earthen enclosure capable of accommodating around 47,000 soldiers. Further research perspectives are also suggested.

Investigation on Large Enclosures Damaged during off the Coast of Fukushima Earthquake on Feb. 13, 2021

Investigation on Large Enclosures Damaged during off the Coast of Fukushima Earthquake on Feb. 13, 2021

Historia y arqueología de dos ciudades en los siglos VI-VIII d.C. Valentia y Valencia la Vella

En Valentia y su entorno se registró una intensa actividad constructiva en determinados lugares y momentos entre los siglos VI y VIII. La construcción del monumental centro episcopal en la primera mitad del s. VI, iniciativa del obispo Justiniano, cambió el paisaje urbano. En sus edificios (catedral, baptisterio, mausoleo y otros) se aprecia el uso continuado, pero selectivo y diferenciado, según cada uno de los conjuntos, de gran cantidad de elementos romanos. A partir de mediados del s. VI la actividad edilicia en Valentia decayó. Lo único a destacar es que se urbanizó la arena del Circo, un amplio espacio de 70 por 350 metros. Estos hallazgos se conocen peor, por ser excavaciones de poca extensión que no permiten identificar ningún edificio entre los muros aparecidos, pero sí que atestiguan un proyecto constructivo unitario, aunque de menor entidad que en la zona episcopal. Los materiales arqueológicos presentan una importante proporción de importaciones orientales y africanas.A finales del s. VI, a 16 km. de Valentia surgió un nuevo asentamiento fortificado de cierta extensión, 5 hectáreas, València la Vella. Su construcción, ex novo, supuso un gran esfuerzo edilicio. Además del gran recinto amurallado se han localizado dos edificios públicos en la parte baja y otro en la ciudadela. Debió ser el centro del poder de la provincia Carthaginensis.El yacimiento se abandonó a finales del s. VII o inicios del VIII. Al mismo tiempo, se creó otro centro monumental, el importante centro de poder de Pla de Nadal, a unos 2 km. de València la Vella. Su elemento más notorio fue el gran palacio de patio central, pero los diversos edificios que van apareciendo a su alrededor, indican que sería un complejo aún por delimitar. An intense constructive activity was developed in certain places and times in Valentia and around between the 6th and 8th centuries. The construction of the monumental episcopal center in the first half of the 6th century changed the urban landscape. The new buildings (cathedral, baptistery, mausoleum and others) continuously and selectively used a large number of Roman elements. The Circus arena was urbanized from the second half of the 6th century until the middle of the 7th. These findings are small excavations. There are a lot of walls but they do not allow to identify any building. Anyway, they attest the continuity in the reuse of Roman materials. This area had less entity than the Episcopal area. In both cases, the supply of the reused material would be from the remains of the old Roman town. Archaeological materials have a significant proportion of Eastern and African imports.Valencia la Vella, a new and very important fortified settlement of 5 hectares, emerged at the end of the 6th century. The site is 16 km away from Valentia on the Turia river. This new city was made ex novo, so it was necessary a great building effort. In addition to the large walled enclosure two public buildings have been located in the lower part and another in the citadel. This site must have been the center of power in Carthaginensis province.Valencia la Vella was abandoned in the late 7th or early 8th centuries. Contemporarily another important power center was created in Pla de Nadal, about 2 km. from Valencia la Vella. Probably the recently disappeared site would be used as a quarry.

Dynamics of Gastro-Intestinal Strongyle Parasites in a Group of Translocated, Wild-Captured Asiatic Wild Asses in Kazakhstan.

Asiatic wild ass (Kulan, Equus hemionus) population range and numbers became severely reduced and a reintroduction project is currently aiming to re-establish a population in the Central Steppe of Kazakhstan. Pre-emptive deworming is often recommended for equid translocations but eliminating parasites prior to translocation could cause disruptions in a balanced host-parasite relationship, adding an additional stressor to an already stressful intervention involving capture, transport, and adaptation to a new environment. Following a disease risk assessment, we decided against pre-emptive deworming and focused on monitoring the first group of nine translocated kulan in a large acclimatization enclosure prior to release. Over the 5-month acclimatization period, we regularly collected fecal samples and analyzed the shedding intensity of gastro-intestinal parasite eggs, obtained time budgets through behavioral observations, and visually assessed body condition. We identified strongyles (Strongylinae and Cyathostominae) and pinworms (Oxyuris equi) in fecal samples. All individuals shed strongyle eggs and two of the nine individuals had higher shedding intensities, but rarely reached levels for which deworming is recommended. All kulan appeared healthy throughout the observation period, aggressive interactions were very rare, and time budgets were very similar and dominated by feeding. Our results suggest that in translocation projects where the risk of introducing new parasites is minimal, pre-emptive treatment in wild equids can be replaced with non-invasive monitoring during the acclimatization period. We acknowledge that the small number of kulan, the large size of the enclosure, and the low temperatures during the animals stay in the acclimatization enclosure may all have reduced infestation pressure.

Through the lens of the glass cabinet: entering the material realm of museum objects

This article discusses questions of spatial configuration and display design in museums, and how this affects the way museum objects are perceived. Based on an in-depth analysis of the Glass Cabinet at Rosenborg Castle in Copenhagen, Denmark, the article explores how the glass items on display are seen not as singular objects, with a curated (hi)story to tell, but more as a collected mass of disparate glass objects with a material reality of their own. When looking at these objects, the spectator is placed within a large glass enclosure which protects the objects on display from the curious hands of museum visitors. However, this glass ‘vitrine’ also has the effect of putting the museum visitor on display, thereby challenging conventional subject-object relations within museums. In order to discuss the particular subversive ways in which the Glass Cabinet presents its objects, the article will partly draw on museological research on object collections and museum display, and partly on current thinking within the fields of object-oriented ontology and new materialism, where a de-centering of humans is proposed and the material realm of objects is emphasized. By speculating about the obscure life of objects within the Glass Cabinet, and the effects this might have upon the visual operations at play, this article will reflect on – and challenge – the ways in which we display and look at objects within museums today.

Responses of a scatter-hoarding squirrel to conspecific pilfering: a test of the reciprocal pilferage hypothesis

The reciprocal pilferage hypothesis argues that, despite the occurrence of pilferage, scatter-hoarding behaviour could evolve if cache loss is compensated by gains pilfered from others. However, this model has not been strictly tested because of the difficulty associated with tracking caches, including ownership, over long periods. Using infrared radiation cameras, we tracked caching of Juglans regia seeds by groups of two Pere David's rock squirrels, Sciurotamias davidianus, within a large natural enclosure. Our goal was to quantify how squirrels responded to the presence of a conspecific when seed hoarding and pilfering and test the reciprocal pilferage hypothesis. We found that the numbers of seeds harvested from the seed sources and pilfered from conspecifics was initially low, increasing as seeds were removed and then dropping off once few seeds remained at the seed sources. Additionally, the number of seeds scatter hoarded increased with a decreasing number of seeds remaining at the sources. Seeds harvested from the source and pilfered from competitors were at first cached randomly within the enclosure and then centralized to the low-competition area near the nest as seed sources declined. Overall, pilferage was not high. The proportions of seeds pilfered did not vary between conspecifics and were positively correlated with each other over trials. More seeds were harvested from the seed sources than pilfered by competitors at the early stage of hoarding. These results suggest that, under conspecific competition, squirrels appeared first to compete for food at the sources, then for caches with each other as food sources decreased, and finally cache ownership became relatively stable. Squirrels compensated for cache loss by both harvesting food from the sources and pilfering caches from its competitor. The amount of seeds gained from pilfering was sufficient to replace pilfered caches, supporting the reciprocal pilferage hypothesis.