For species to reproduce and survive, they depend on the acquisition of energy. The optimal foraging theory is focused on explaining the feeding strategies among carnivores and herbivores. Foraging involves actions that are related to the acquisition of food by the species, and these behaviors are critical in the evolutionary and ecological feedbacks between the species and their environments (Sovie et al., 2019). For instance, the theory is concerned about how an individual could maximize the intake of energy through foraging while minimizing expenditure to determine where, when, and how long to forage. There are other species of animals cache food, including several birds and other small mammals. People exhibit several caching behaviors, securing food quantities to use in the future and hoarding unnecessary objects. The caching presence in the animal kingdom indicates many species have adapted the behavior as a strategy (Newbury & Hodges, 2018). Squirrels require essential resources for many urban animals as their populations change with the same predators and environmental conditions. Fox Squirrel, as many animals in the wild, changes their behavior patterns with the seasons. Similarly, the eastern grey squirrel (Sciurus carolinensis) shows the scatter-hoarding behavior, keeping food in small hoards underground. This study reviews various researches conducted over the years on the foraging and storing behavior of the Fox Squirrel compared to the Eastern Gray Squirrel (Sciurus carolinensis).
Fox squirrels are a group of North American tree squirrels that are the largest and most ground-dwelling, which have raised conservation concerns due to their declining population. These squirrels act as crucial agents of dispersal for hypogeous fungi. Eastern gray squirrels, on the other hand, use forested habitats by relying on similar resources such as fox squirrels (Newbury & Hodges, 2018). The interaction of these two categories of squirrels was limited because of the partitioning of habitat. As the interaction between the two species changes, it causes an opportunity to examine the predation effects of sublethal since it relates to the risk of a perception of species and habitat structure (Amspacher et al., 2019). Unlike eastern gray squirrels, fox squirrels are found in areas where the predator densities are higher. This shows that the vigilance is increased for fox squirrels as an adaptation behavior. Thus, the foraging and food storing decisions are made by the squirrels in line with minimizing the risk of predation in their habitat. This is because, with caching, squirrels are able to survive when there is scarcity and helps reduce the foraging time in the future while searching for food that may expose them to risks.
Significant research of scatter-hoarding among tree squirrels has focused on the gray and fox squirrels because of the similar morphology and behavior, especially in handling and bury food. Both the squirrels do little to no hibernation and have to intensely cache during fall masting to have what is considered enough food to continue surviving even in winter, which goes for almost nine months (Haverland & Veech, 2017). Thus, these two types of tree squirrels make economic investments in a short period and amidst social competition, which affects their survival and reproduction fitness over an extended term. They tailor their cache investment that includes the amount of energy and time spent caching to the context of the social competition, availability of food, and nut quality. The cache decisions by these squirrels are affected by the size of the seed, concentration of tannin, and fat content. Seeds that are larger and those having higher fat or lower concentration of tannin or both tend to be removed quicker compared to the smaller ones (Amspacher et al., 2019). The larger seeds are also scatter-hoarded as compared to being eaten and often more reached and eaten more quickly once cached. Both scatter-hoarding animals and trees are adaptive to these effects since apart from providing more energy, larger nuts survive longer as caches. Since gray and fox squirrels take food afar from the place when pilferage is more likely, caching is also affected by social factors. This makes these squirrels turn backs to potential competitors.
Therefore, extensive evidence shows that the information on the nuts quality is used by gray and fox squirrels as they make cache decisions. Though, it remains unknown the type of features they attend to and the way the information perceptually is processed (Flower et al., 2019). Various possible indicators of the quality of nuts used by the tree squirrels exist, such as the sensory indices of color and texture, density, weight, size, and shell presence (Sovie et al., 2019). People have conducted many experiments that show the effects of seed size as being highly confounded with weight. Paw maneuvers or head flick are two behaviors of nut-handling that have the potential function to assess the nut size or weight.
Conspicuously, fox squirrel spends time handling food items before eating and caching. First, squirrels “paw manipulate” food items and loosely hold them in their jaws, and rotate in their mouth (Sovie et al., 2019). This is followed by head-flicking to rapidly move the head in rotation as they hold the items in their mouth. Fox squirrel head-click food items that are heavier, less perishable, and subsequent caching instead of eating these items. Thus, they show some unique behaviors which are likely to assess the spoilage probability, the weight, or other food quality aspects (Kotler et al., 1999). Fox, as other tree squirrels, either eat or cache food items after assessing it, which then move to a place away from the source of food and conspecifics for the process. Fox squirrel differs from other squirrels when it comes to caching. There are some squirrels whose cache is incomplete since the digging by the squirrel does not bury the nut; instead, they move to other locations to continue the cache sequence. Fox squirrels begin their caching with digging, choose the final cache location before using the front teeth to tamp the nut, and more firmly set into the ground.
Fox squirrels have seasonal fluctuations in food availability because the trees form the largest source of their food. These trees only produce their seeds during the late summer and early fall and at the annual intervals that are irregular. The caching by fox squirrels is typical winter and fall and retrieves the caches through the summer and spring. With time, the value of the cached food increases as the abundance of natural food becomes reduced while energetic costs rise during winter (Kotler et al., 1999). These squirrels tend to increase their behaviors of investment and assessment in summer, the period when food is scarce from trees which then results in low body weights of squirrels.
Sometimes, fox squirrels may not only be sensitive to the abundance of food during seasons; instead, they might respond to the session of the environmental test as an ephemeral abundance of the environment. The squirrels attempt to match effort strictly to value based on an item by item; then, trials should not change the investment and assessment unless there are other external variables (Sovie et al., 2019). The value of the item leads to the response by fox squirrels when modifying foraging decisions. This means that the food items have various values, including heavier, less perishable, and thicker-shelled. In an attempt to cache heavier or larger nuts, squirrels travel farther to reduce the pilferage through the dispersion of caches at a lower density. Sometimes, these squirrels tend to move to more open areas, and the risks of predation may deter pilferers (Kotler et al., 1999). Hence, there is a need for squirrels to invest more effort in caches with less perishable food items. The perception of scarcity of fox squirrels could be affected by social pressures, which also influence its caching decisions.
The situation is, however, different with eastern gray squirrels, which adjust caching behavior in their situations where they face competition. The competition includes digs that are more frequent and spending time on caches when other squirrels are present (Sovie et al., 2019). The eastern gray squirrels show scatter-hoarding behaviors where they store food underground in their small hoards. By exhibiting scatter-hoarding, which is a caching strategy, the animals are able to bury several small food caches in different locations. The hoards are usually had low cache density that minimizes the loss that might potentially occur in any case; a cache was to be found by another animal than eastern gray squirrels (Newbury & Hodges, 2018). These eventualities are likely to happen, considering that the hoards cannot be guarded. The eastern grey squirrel’s diet varies season after season depending on the availability during the summer and spring months. They spend much time during the autumn months to scatter hoard their foods and disperse single items in various locations within the range of their home.
For the eastern gray squirrels, their primary food source is tree seeds though, their availability and distribution vary in various seasons, climates, and habitats. As the name suggests, eastern gray squirrels inhabit most of the eastern U.S., where they live in various habitats from forests to urban (Flower et al., 2019). Therefore, grey squirrels hoard the food they use in the future when the food is highly available. However, for eastern gray squirrels, foraging is a constant trade-off that happens between those that are actively searching for food and consuming it and those who remain vigilant to ensure that the stored food is protected from predators. At the same time, other eastern animals, including weasels, owls, and foxes, subject grey squirrels to face predation. This is the case because squirrels spend some time burying some of the food they have, making them face the risk of increased predation since much of the time is spent on burying instead of vigilance.
Therefore, in conclusion, as the human species who exhibit cache and scatter-hoarding behaviors to secure food for future use, tree squirrels, including fox and eastern gray, forage and store foods. The two squirrels have similar morphology and behavior in handling and burying food and intensely cache during fall masting to have enough food for continuous survival, even in winter. They tailor their cache investment of the amount of energy and time spent caching to the context of the social competition, availability of food, and nut quality. However, as fox squirrels spend time handling food items before eating and caching, eastern gray squirrels store food underground in their small hoards in different locations and keep vigilance to protect it.
References
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