Hoarding Strategies Research Articles

Boldness suppresses hoarding behavior in food hoarding season and reduces over-wintering survival in a social rodent.

The "pace-of-life" syndrome (POLS) framework can encompass multiple personality axes that drive important functional behaviors (e.g., foraging behavior) and that co-vary with multiple life history traits. Food hoarding is an adaptive behavior important for an animal's ability to adapt to seasonal fluctuations in food availability. However, the empirical evidence for the relationships between animal personality and hoarding behavior remains unclear, including its fitness consequences in the POLS framework. In this study, the Mongolian gerbil (Meriones unguiculatus), a social rodent, was used as a model system to investigate how boldness or shyness is associated with food hoarding strategies during the food hoarding season and their impact on over-winter survival and reproduction at both individual and group levels. The results of this study showed that, compared with shy gerbils, bold gerbils had a lower effort foraging strategy during the food hoarding season and exhibited lower over-winter survival rates. However, bold-shy personality differences had no effect on over-winter reproduction. These findings suggest that the personality is a crucial factor influencing the foraging strategy during the food hoarding season in Mongolian gerbils. Personality may be related to energy states or the reaction to environmental changes (e.g., predation risk and food availability) in bold or shy social animals. These results reflect animal life history trade-offs between current versus future reproduction and reproduction versus self-maintenance, thereby helping Mongolian gerbils in adapting to seasonal fluctuations in their habitat.

Choose, Not Hoard: Information-to-Model Matching for Artificial Intelligence in O-RAN

Open Radio Access Network (O-RAN) is an emerging paradigm, whereby virtualized network infrastructure elements from different vendors communicate via open, standardized interfaces. A key element therein is the RAN Intelligent Controller (RIC), an Artificial Intelligence (AI)-based controller. Traditionally, all data available in the network has been used to train a single AI model to be used at the RIC. This article introduces, discusses, and evaluates the creation of multiple AI model instances at different RICs, leveraging information from some (or all) locations for their training. This brings about a flexible relationship between gNBs, the AI models used to control them, and the data such models are trained with. Experiments with real-world traces show how using multiple AI model instances that choose training data from specific locations improve the performance of traditional approaches following the hoarding strategy.

Effects of habitat differences on the scatter-hoarding behaviour of rodents (Mammalia, Rodentia) in temperate forests.

To discover the differences in hoarding strategies of rodents for different seeds in different habitats, we labelled and released three different types of seeds, including Pinuskoraiensis, Corylusmandshurica, and Quercusmongolica, in temperate forests of northeastern China and investigated the fate of seeds in four different habitats that included a broad-leaved forest, mixed-forest edge, mixed forest, and artificial larch forest. Our research showed that the hoarding strategy of rodents was found to vary substantially in different habitats. The survival curves of seeds from different habitats showed the same trend, but the rates of consumption in different habitats varied. More than 50% of the seeds in the four habitats were consumed by the tenth day. It took 20 days to consume more than 70% of the seeds. The rate of consumption of P.koraiensis seeds reached 96.70%; 99.09% of the C.mandshurica seeds were consumed, and 93.07% of the Q.mongolica seeds were consumed. The seeds were consumed most quickly in the artificial larch forest. In general, most of the early seeds were quickly devoured. After day 20, the consumption gradually decreased. Rodents found the seeds in the artificial larch forest in a shorter average time than those in the other types of forests. The average earliest discovery time was 1.4 ± 0.9 d (1-3 d). The average earliest discovery time in all the other three habitats exceeded 7 d. The median removal times (MRT) was distributed around the seeds at 14.24 ± 10.53 d (1-60 d). There were significant differences in the MRT among different habitats. It was shortest in the artificial larch forest at 7.67 ± 6.80 d (1-28 d). In contrast, the MRT in the broad-leaved forest was the longest at 17.52 ± 12.91 d (4-60 d). There were significant differences in the MRT between the artificial larch forest and the other habitats. There was less predation of the three types of seeds at the mixed-forest edge, and the most seeds were dispersed. The rates of predation of the P.koraiensis, C.mandshurica, and Q.mongolica seeds were 28.33%, 15.83%, and 44.0%, and 59.17%, 84.17%, and 48.0% of the seeds were dispersed, respectively. The average dispersal distances of all the seeds were less than 6 m, and the longest distance recorded was 18.66 m. The dispersal distances and burial depths differed significantly among the four types of habitats. The distance of seed dispersal was primarily distributed in 1-6 m.

Bank Liquidity Hoarding Strategies in Uncertain Times: New Evidence from an Emerging Market with Bank-level Data


 
 
 The paper explores the impact of uncertainty on bank liquidity hoarding, particularly providing new insights on the nature of the impact by bank-level heterogeneity. We consider the cross-sectional dispersion of shocks to key bank variables to estimate uncertainty in the banking sector and include all banking items to construct a comprehensive measure of bank liquidity hoarding. Using a sample of Vietnamese banks during 2007–2019, we document that banks tend to increase total liquidity hoarding in response to higher uncertainty; this pattern is still valid for on- and off-balance sheet liquidity hoarding. Further analysis with bank-level heterogeneity indicates that the impact of banking uncertainty on liquidity hoarding is significantly stronger for weaker banks, i. e., banks that are smaller, more poorly capitalized, and riskier. In testing the “search for yield” hypothesis to explain the linkage between uncertainty and bank liquidity hoarding, we do not find it to be the case. Our findings remain extremely robust after multiple robustness tests.
 
 

Effects of season and food on the scatter-hoarding behavior of rodents in temperate forests of Northeast China

To explore the differences in hoarding strategies of rodents for different seeds in various seasons, we labeled and released the seeds of Pinus koraiensis, Corylus mandshurica, Quercus mongolica and Prunus sibirica in temperate forests of Northeast China and investigated the fate of the seeds in spring and autumn. The analysis showed that the hoarding strategies of the rodents varied substantially between seasons. The seeds were consumed faster in the spring than in the autumn. More than 50% of the seeds in the two seasons were consumed by the 16th day. It took 36 days to consume 75% of the seeds in the spring and 44 days in the autumn. The rate of consumption of the seeds in the spring was greater than in the autumn, and the rate of spread of the seeds was greater in the autumn. The distances of removal for the consumption and dispersal of seeds in the spring (3.26 ± 3.21 m and 4.15 ± 3.52 m, respectively) were both shorter than those in the autumn (3.74 ± 3.41 m and 4.87 ± 3.94 m, respectively). In addition, the fate of different seeds varied significantly owing to differences in hoarding strategies. The seeds of the three preferred species, P. koraiensis, C. mandshurica, and Q. mongolica, were quickly consumed. More than 90% of the seeds of these species were consumed. Only 21% of Pr. sibirica seeds were slowly consumed, and the two seasons had the same seed consumption rate patterns: the consumption rate of P. koraiensis seeds was the highest, followed by C. mandshurica, then Q. mongolica, and finally Pr. sibirica. The median removal times of the two seasons were different, but the rules were the same: P. koraiensis was the shortest, followed by C. mandshurica, and the third was Q. mongolica. In both seasons, the most predated in situ seeds were those of P. koraiensis; the most hoarded seeds were those of C. mandshurica, and the most unconsumed seeds were those of Pr. sibirica.

Exploring the potentials of behavioral system dynamics: insights from the field

Purpose This study aims to contribute to the ongoing debate on behavioral operational research (BOR), specifically discussing the potential of system dynamics (SD) models to analyze decision-making heuristics. In more detail, the study suggests using an SD model as an ex-post research tool adopted not only to mimic a role-playing game (RPG) – reproducing the whole physical structure, and the complete set of decision rules specified for a supply chain (SC) management game – but also, and specifically, to replicate and analyze the players’ in-game behavior and decision-making. Design/methodology/approach After presenting a brief literature review devoted to highlighting the key concepts of the emerging streams of research named BOR and behavioral system dynamics (BehSD), the study presents the characteristics and results of an SC management-based RPG and describes the SD model that was developed to mimic the game and provide the base-run. A triangulation of data sources (which included feedback questionnaires and reports drawn up by 86 participants, as well as notes collected through direct observation of one of the authors) was used to infer information about and in-game decisions. Subsequently, four alternative versions of the SD model were calibrated to reproduce, investigate and explain ex-post the players’ in-game behavior and decision-making heuristics; this study specifically refers to one of them. Findings The SD model can be considered as the first output of this research. The model was calibrated to mimic the game and subsequently used to develop a few alternative models, helpful to replicate players’ behavior and analyze decision-making heuristics. The findings reveal not fully rational decisions taken by the players and share common findings with previous literature on the emergence of sub-optimal strategies (e.g. phantom ordering and hoarding strategies). The data collected from questionnaires, reports and direct observation additionally revealed that stress and behavioral factors played a role in affecting in-game decision-making. Practical implications Considering a specific RPG setting, the SD model developed in this study replicated and captured the range of factors affecting decision-making heuristics, allowing an ex-post analysis of in-game decisions. Notably, the research design presented and used in this study can be considered a generic one, which could be applied subsequently in a variety of contexts, also in combination with simulation/gaming tools and techniques different from role-playing, and both for educational and training purposes, and for research validation. Originality/value This study builds on and makes a contribution to the debate related to the emerging stream of research of BOR and more specifically, provides insights and evidence for the yet growing field of BehSD, at the same time advocating and suggesting further research in this area. Overall, the research revealed that behavioral factors may play a relevant role in driving and affecting human decision-making in simulation/gaming contexts.

A Systematic Access Through Machine Learning Methods For Expectation In Malady Related Qualities

There are Many learning strategies that are been identified with distinguish infection based related qualities. At the early, they as a rule moved toward this issue as a parallel arrangement, where preparing set is involved examples. Examples developed sickness qualities, whereas negative examples are there mining which are not known to be connected with contaminations. This is the essential of the twofold deals based diagrams, since the negative arranging set ought to be true non-infection qualities; regardless, advancement of this set is on a very basic level unfeasible in biomedical inspects. Therefore, to reduce this delicacy, insightfully sensible social gathering based techniques have been proposed. For example, unary outline strategy subject to one-class SVM framework was proposed by grabbing from fundamentally positive models. Also, there mining set may contain cloud torment qualities; as such, semi-formed methodologies, for example, twofold semi-controlled & positive & unlabeled (PU) learning blueprints have been proposed. Specifically, PU learning frameworks, which increase from both known suffering qualities & there mining attributes, were appeared to beat others. In these examinations, information sources are commonly tended to by vectorial plan for cemented classifiers, while they are in bit frameworks for unary & PU learning ones. The bit based information blend is reasonable for information with various sorts & it has the majority of the stores of being uncalled for or the relationship subject to various information diagrams. In like manner, in this examination, we looked accumulating structures for the ailment quality figure dependent on vectorial delineation of tests. The spread outcome demonstrated that the unary strategy structure, which joins both thickness & class likelihood estimation approachs, accomplished the best execution, where as it is most recognizably stunning for the one-class SVM-based technique. fascinatingly, execution of a best twofold outline framework is in each rational sense misty with that of uneven SVM-based PU learning & twofold semidirected hoarding strategy they are altogether improved.

Cache placement near nests by a multiple-prey loader, the Siberian chipmunk

The rapid sequestering hypothesis predicts that scatter-hoarding animals quickly sequester food items by storing seeds in caches near seed sources to reduce competition. However, tests of this hypothesis usually use food-hoarding animals with a single load or a small load size. How multiple-load animals place their caches between food sources and nests remains largely unknown. Here, we hypothesized that multiple-load animals, compared to single-load animals, may not necessarily sequester food items but adopt alternative hoarding strategies due to their multiple-load ability. In this study, we presented seeds at different distances from the nests of the multiple-loading Siberian chipmunk, Tamias sibiricus, and mapped the spatial distribution of their caches in multiple-compartment enclosures to test our hypothesis that a multiple-prey loader will consistently establish caches near nests rather than rapidly sequester near the seed source. By using multiple-compartment enclosures with different distances between the seed source and nests, and given potential intra- and interspecific competition, we found chipmunks consistently placed their caches near nests but away from the seed source. Cache placement near nests may serve as an alternative strategy that not only guarantees a maximum harvest rate at the seed source but also ensures effective cache defence near nests. Moreover, scatter-hoarding seeds near nests may alternatively guarantee a food supply if larder-hoarded seeds are depleted or lost. Unlike seeds sequestered near food sources, caches near nests imply long dispersal distances for seeds in our study. Therefore, scatter hoarding by multiple-prey loaders is expected to be ecologically important for the structure and function of tree communities, especially in ecosystems in which seeds depend on food-hoarding animals for dispersal and germination.

Scatter-Hoarding the Seeds of Sympatric Forest Trees by Apodemus peninsulae in a Temperate Forest in Northeast China

As the main predator and disperser of seeds, rodents play an important role in the process of vegetation regeneration by adopting different foraging and hoarding strategies in forest ecosystems. Infrared automated detection cameras and seed-tagging methods were used to understand the effects of rodents on seeds in natural environments. We chose the dominant species Apodemus peninsulae (Korean field mouse) as the focus of this study, and seeds of the three species Pinus koraiensis, Corylus mandshurica and Quercus mongolica were released and tracked in a temperate forest in northeast China. The results showed that approximately 80% of the seeds were manipulated by A. peninsulae, 15.1% of the seeds were used as food, 20.4% of the seeds were handled after feeding, 41.3% of the seeds were handled during storage, and 23.3% of the seeds remained intact. In addition, A. peninsulae preferred Q. mongolica (85.3%) and P. koraiensis (85.6%) over C. mandshurica (59.2%). The rodents frequently hoarded seeds from every species in many small, close-range, widely dispersed, single scatter-hoarded caches around the seed station. Most caches were dispersed approximately 2–4 m from the seed station. The results indicated that A. peninsulae adopted significant discriminatory processing strategies for predation, consumption, dispersal and hoarding of the different seeds of sympatric species. Seed size, proportion of kernel mass, nutrient content, and hull thickness characteristics affected the scatter-hoarding decision processes.

Interbank Runs: A Network Model of Systemic Liquidity Crunches

I study how interbank lending network structures affect financial fragility. Interbank lending is beneficial but subject to coordination failure. With interbank wholesale funding, banks' balance sheets become inflated, and give the senior retail depositors a sense of safety to allow more illiquid assets. In interbank runs, banks run on banks as they mutually reinforce each other to withdraw interbank lending. Banks' individually precautionary liquidity hoarding strategies are connected by the pairwise lending relationships. Mean-field analysis extracts the systemic behavior from the network of strategic interactions. I show such dispersed and indirectly linked interactions also lead to discontinuous and system-wide liquidity crunches, as if the interactions are centralized. Local insolvency shocks trigger the interbank run if the network is unraveled beyond a critical point. The model is applied to identify the optimal capital injection targets of government bailouts, and study the systemic effects of the proposed regulations on restraining the highly connected banks.

Discriminatory pre-hoarding handling and hoarding behaviour towards germinated acorns by Niviventer confucianus

Germination is an important stage in the seed life cycle, but it decreases seed nutrients and increases secondary compounds, which is disadvantageous to seed hoarders or consumers. Therefore, seed hoarders often use pre-hoarding handling behaviour (PHB) to prevent the further deterioration of germinated seeds. Although PHB is an important component of seed dispersal ecology, few studies have described or estimated the effectiveness of PHB. In this study, we investigated the PHB and hoarding strategies of Niviventer confucianus Milne-Edwards towards germinated and ungerminated acorns (Quercus variabilis Bl.). We observed that N. confucianus (1) displayed radicle-excision behaviour towards germinated acorns; (2) often removed the pericarps of the germinated acorns more than those of ungerminated acorns before hoarding; and (3) tended to larder-hoard ungerminated acorns but scatter-hoard germinated acorns. Our results indicate that (1) PHB towards germinated seeds exists in this species as well as in members of the family Sciuridae; (2) N. confucianus consumed and hoarded acorns in different condition discriminately, and adopted a flexible strategy when hoarding perishable seeds. These pre-hoarding handling and hoarding behaviours are possibly evolutionary adaptations in rodents to manage and hoard easily germinated acorns and inevitably impacts on seed dispersal, seed fate, seed germination, and sapling recruitment.

Food availability and animal space use both determine cache density of Eurasian red squirrels.

Scatter hoarders are not able to defend their caches. A longer hoarding distance combined with lower cache density can reduce cache losses but increase the costs of hoarding and retrieving. Scatter hoarders arrange their cache density to achieve an optimal balance between hoarding costs and main cache losses. We conducted systematic cache sampling investigations to estimate the effects of food availability on cache patterns of Eurasian red squirrels (Sciurus vulgaris). This study was conducted over a five-year period at two sample plots in a Korean pine (Pinus koraiensis)-dominated forest with contrasting seed production patterns. During these investigations, the locations of nest trees were treated as indicators of squirrel space use to explore how space use affected cache pattern. The squirrels selectively hoarded heavier pine seeds farther away from seed-bearing trees. The heaviest seeds were placed in caches around nest trees regardless of the nest tree location, and this placement was not in response to decreased food availability. The cache density declined with the hoarding distance. Cache density was lower at sites with lower seed production and during poor seed years. During seed mast years, the cache density around nest trees was higher and invariant. The pine seeds were dispersed over a larger distance when seed availability was lower. Our results suggest that 1) animal space use is an important factor that affects food hoarding distance and associated cache densities, 2) animals employ different hoarding strategies based on food availability, and 3) seed dispersal outside the original stand is stimulated in poor seed years.

Seed caching and cache pilferage by three rodent species in a temperate forest in the Xiaoxinganling Mountains

Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence, differentiation in cache pilfering abilities among sympatric rodents with different hoarding strategies is seldom addressed. We carried out semi-natural enclosure experiments to investigate seed hoarding tactics among three sympatric rodent species (Tamias sibiricus, Apodemus peninsulae and Clethrionomys rufocanus) and the relationship of their pilfering abilities at the inter- and intraspecific levels. Our results showed that T. sibiricus exhibited a relatively stronger pilfering ability than A. peninsulae and C. rufocanus, as indicated by its higher recovery rate of artificial caches. Meanwhile A. peninsulae showed a medium pilfering ability and C. rufocanus displayed the lowest ability. We also noted that both cache size and cache depth significantly affected cache recovery in all three species. T. sibiricus scatter-hoarded more seeds than it larder-hoarded, A. peninsulae larder-hoarded more than scatter-hoarded, and C. rufocanus acted as a pure larder-hoarder. In T. sibiricus, individuals with lower pilfering abilities tended to scatter hoard seeds, indicating an intraspecific variation in hoarding propensity. Collectively, these results indicated that sympatric rodent species seem to deploy different food hoarding tactics that allow their coexistence in the temperate forests, suggesting a strong connection between hoarding strategy and pilfering ability.

Comparison of food hoarding of two sympatric rodent species under interspecific competition

Competition can greatly affect the food hoarding strategies of rodents and the fate of seeds hoarded. In order to understand the influence of interspecific competition on food caching behavior of sympatric rodents, we investigated food hoarding patterns of two sympatric rodent species, buff-breasted rat (Rattus flavipectus) and Chinese white-bellied rat (Niviventor confucianus), and compared their responses and adjustment in hoarding behavior under interspecific competition. The results showed that: (1) the buff-breasted rat larder hoarded seeds only, while Chinese white-bellied rat hoarded seeds in both larder and scatter forms; (2) two species of rodents both larder hoarded more seeds when competitors were present; and (3) the Chinese white-bellied rats adjusted their seed hoarding from scatter to larder when competitors were introduced, which reduced the seed availability. Therefore, we concluded that rodents would adjust their food hoarding strategy when interspecific competitors were present, and this may produce a different effect on the fate of seeds and the recruitment of plants.This article is part of a Special Issue entitled: insert SI title.

Differences in hoarding behaviors among six sympatric rodent species on seeds of oil tea ( Camellia oleifera) in Southwest China

Seed hoarding is an important behavioral adaptation to food shortages for many rodent species. Sympatric rodents may affect the natural regeneration of large-seeded trees differently as seed dispersers or seed predators. Using seeds of oil tea ( Camellia oleifera), we investigated differences in hoarding behaviors among six sympatric rodent species in semi-natural enclosures in a subtropical forest in southwest of China. We found that all these six species ate seeds of C. oleifera, but only Edward’s long-tailed rats ( Leopoldamys edwardsi) were predominantly scatter hoarders; chestnut rats ( Niviventer fulvescens) and white-bellied rats ( Niviventer confucianus) scatter hoarded and larder hoarded few seeds, but were seed predators; South China field mice ( Apodemus draco) exhibited little larder-hoarding behavior; and Chevrier’s field mice ( A. chevrieri) as well as Himalayan rats ( Rattus nitidusa) did not hoard seeds at all. The rodents that engaged in scatter hoarding often formed single-seed caches and tended to cache seeds under grass or shrubs. Our findings indicate that sympatric rodents consuming seeds of the same species of plant can have different hoarding strategies, affecting seed dispersal and plant regeneration differently. We conclude by discussing the role of these species in hoarding seeds of C. oleifera and highlight the essential role of Edward’s long-tailed rats as predominantly potential dispersers of this plant species.

Behavioural responses of sympatric rodents to complete pilferage

Food-hoarding animals employ a variety of tactics to minimize the loss of caches to pilferers. It remains unclear, however, how these responses are affected by complete pilferage events and if differences occur between species and between the sexes within a species that adopt different hoarding strategies. We studied the behavioural responses to complete pilferage in five species that scatter-hoard or larder-hoard. Under natural conditions and within outdoor enclosures we simulated complete pilferage events by removing wild apricot, Prunus armeniaca , seeds hoarded by Pere David’s rock squirrels, Sciurotamias davidianus , Korean field mice, Apodemus peninsulae , striped field mice, Apodemus agrarius , Chinese white-bellied rats, Niviventer confucianus , and rat-like hamsters, Tscherskia triton . Following pilferage, all five species increased seed removal from the source and total hoarding intensity under both natural and captive conditions, but no effect of sex was found. Pere David’s rock squirrels, Korean field mice and striped field mice, which show both scatter and larder hoarding, increased scatter hoarding, but not larder hoarding. Our pilferage manipulations in the field also increased the distance that seeds were buried from the source. These findings suggest that complete pilferage may increase seed-hoarding behaviour in rodents and that scatter hoarding might be better than larder hoarding in avoiding complete pilferage in rodents that already perform both of these.

Effects of burrow condition and seed handling time on hoarding strategies of Edward's long-tailed rat (Leopoldamys edwardsi)

Many hoarding rodents use burrows not only for dwelling and protection from natural enemies, but also for food storage. However, little is known how burrows used by scatter-hoarding animals influence their foraging behaviors. In addition, handling time for a given food item has a fundamental impact on hoarding strategies of these hoarding animals: food items with longer handling time are more likely to be hoarded due to increasing predation risk because the animals spend more time outside their burrows if they consumed such food. By providing with two types of artificial burrows (aboveground vs. underground) and two types of food items (i.e. seeds) with contrasting handling times, we investigated how burrow condition and handling time co-influence hoarding strategies of a key scatter-hoarding rodent, Edward's long-tailed rat (Leopoldamys edwardsi) in large enclosures in southwest China. We found that only a few animals larder-hoarded fewer seeds when only aboveground burrows were available, while over 80% of the animals preferred to use the underground burrows and hoard significantly more seeds in the burrows when both aboveground and underground burrows were provided simultaneously. We also found that seed handling time significantly affected hoarding strategies of the animals: they consumed and/or scatter-hoarded more Camellia oleifera seeds with shorter handling time outside the burrow, but consumed and larder-hoarded more Lithocarpus harlandii seeds with longer handling time in underground burrows. Our study indicates that both burrow types and seed handling time have important impacts on hoarding strategies of scatter-hoarding animals.

The history of scatter hoarding studies

In this review, I will present an overview of the development of the field of scatter hoarding studies. Scatter hoarding is a conspicuous behaviour and it has been observed by humans for a long time. Apart from an exceptional experimental study already published in 1720, it started with observational field studies of scatter hoarding birds in the 1940s. Driven by a general interest in birds, several ornithologists made large-scale studies of hoarding behaviour in species such as nutcrackers and boreal titmice. Scatter hoarding birds seem to remember caching locations accurately, and it was shown in the 1960s that successful retrieval is dependent on a specific part of the brain, the hippocampus. The study of scatter hoarding, spatial memory and the hippocampus has since then developed into a study system for evolutionary studies of spatial memory. In 1978, a game theoretical paper started the era of modern studies by establishing that a recovery advantage is necessary for individual hoarders for the evolution of a hoarding strategy. The same year, a combined theoretical and empirical study on scatter hoarding squirrels investigated how caches should be spaced out in order to minimize cache loss, a phenomenon sometimes called optimal cache density theory. Since then, the scatter hoarding paradigm has branched into a number of different fields: (i) theoretical and empirical studies of the evolution of hoarding, (ii) field studies with modern sampling methods, (iii) studies of the precise nature of the caching memory, (iv) a variety of studies of caching memory and its relationship to the hippocampus. Scatter hoarding has also been the subject of studies of (v) coevolution between scatter hoarding animals and the plants that are dispersed by these.

Mechanisms of Cache Retrieval in the Group Nesting Southern Flying Squirrel (Glaucomys volans)

AbstractWe examined the proximate mechanisms of cache retrieval in the group‐living, southern flying squirrel,Glaucomys volans, through a series of behavioral experiments conducted in a large indoor arena. The effectiveness of several retrieval mechanisms was determined including spatial memory, olfaction, random searching and a heuristic under different environmental conditions. Our goal was to elucidate the hoarding strategy of individuals in a nest group and to address whether food storing individuals possess a retrieval advantage over pilfering nestmates. A storer's retrieval advantage is necessary for scatter hoarding to be an evolutionarily stable strategy (ESS) within aggregations of unrelated individuals. Our previous work has shown that,G. volanslives in such groups, and consequently it was important to address the storer's retrieval advantage under a range of environmental conditions. Initially in our baseline experiment, we developed methods to eliminate olfactory‐based retrieval and to control for random searching. Subsequently, we experimentally determined the effectiveness of cache retrieval via spatial memory, a heuristic and olfaction. We examined the mechanisms of cache retrieval in three additional experiments using two independent subject populations and found that under dry, odorless conditions spatial memory was the most effective retrieval mechanism in support of a storer's retrieval advantage. In a fifth experiment we examined cache retrieval under wet environmental conditions and showed that olfactory‐based retrieval was effective and the storer's advantage was reduced. We interpret these laboratory results based on considerations of natural environmental conditions and game theory. We propose a conditional ESS strategy where animals store and retrieve their own caches as the primary food hoarding tactic and opportunistically pilfer caches as a secondary tactic.

FOOD PILFERING IN LARDER-HOARDING RED SQUIRRELS (TAMIASCIURUS HUDSONICUS)

Loss of cached foods is a constant threat to animals that hoard food, and pilfering plays an important role in the evolution of hoarding strategies. Although pilfering is known to affect the behavior of scatter hoarders, pilfering has been assumed to be less important for larder-hoarding animals. In this study, I used a mark-recapture study of cached Norway spruce (Picea abies) cones to quantify pilfering rates in larder-hoarding red squirrels (Tamiasciurus hudsonicus). Red squirrels stole 26% of the cones that they ate and lost 25% of the cones cached in their middens. Most squirrels stole cones (97%) and lost cones to stealing (92%). However, individual squirrels stole 1–100% of the cones that they ate and lost 1–84% of the cones cached in their middens. Numbers of cones gained by and lost to stealing were not related to the age or sex of individual squirrels or the distances between or numbers of cones cached in individual territories. Squirrels with small middens, however, ultimately gained cones, and those with large middens lost cones. Because food is frequently a limiting resource for red squirrels, these changes in food abundance may directly affect the fitness of individual squirrels. Thus, pilfering likely plays an important role in shaping the hoarding and defensive behaviors of larder-hoarding animals.