Introduction Big cities are inhabited by not just humans. Different wild animals have become a part of the urban environment and were forced to adapt to it. Some of them have done this particularly well. This study takes a broad look at the behavioral ecology of black squirrels that are very common animals in big North American cities. Most animals are influenced by environmental patterns and have to respond to them. These patterns impact the risk of predation as well as foraging efficiency. Everybody had noticed that sometimes squirrels eat their food right away, and sometimes carry it to safety before eating. This experiment hypothesizes that black squirrels are trading off their rate of energy intake for the risk of predation. A study that focused on examining foraging efficiency – predation risk trade-off in grey squirrel claimed that the maximal energy efficiency is reached when the animal consumes the food immediately, whereas carrying of the food to the safety of a tree provides a minimal risk of predation for the grey squirrel (Lima et al., 1985). Optimal foraging theory has been causing a lot of commotion in the scientific world of behavioral ecology, and many of its hypotheses have been proven in laboratory conditions. Two paradigms have been dominating in this theory. The first one is the prey choice, and the second is the patch use (Krebs, 1978; Krebs, Stephens, & Sutherland, 1983; Pyke, Pulliam, & Charnov, 1977). In the patch use paradigm, the forager is being faced with food containing well-defined patches (Parker & Stuart, 1976). It is us to the forager to decide whether to leave the current patch and to spend additional time to travel to another, possibly better patch. The animal needs to be fit. Alimentary energy intake is by far not the only source of fitness for black squirrels. Other not less essential factors that determine fitness are avoidance of predators and animal’s reproductive needs. The model of optimal foraging ideally points to the fact that the food item is consumed immediately upon encountering, as transportation of the food to another place is wasteful in terms of time and energy. However, if the animal senses that it is a potential subject of predation, it will carry the food to cover and consume it there. Of course, such actions would waste time and energy, but eating the food in a safer place decreases the risk of being predated. According to Milinski & Heller (1978), the animal would attempt to find a compromise between carrying or staying when it considers the potential risk of predation and compares it to the energy intake. This study performs an analysis of how foraging considerations and predation risk influence the behavior of black squirrels. These animals use trees as a hideout, as well as for feeding. However to obtain food, black squirrels must cover significant distances in their search for food, and when they are looking for something to eat, there might not be any trees around. In this study, I suspect that whether the black squirrel stays and eats the food, or runs to the nearest tree to consume it depends also on the size of the food, which impacts the “handling time” of the item. The following information uses a mathematical framework for measuring the tendency of staying or carrying the food item. Method