quality offspring, while males compete among each other to mate with a female. Group living provides the presence of social information within the group, allowing both male and female members to find and select potential mating partners. Alongside this, living in a group allows for higher reproductive success as individuals have access to a greater number of potential mates, and the possibility to choose between them. Therefore, individuals living in groups have a higher chance of finding a mate and successfully reproducing, on the basis that larger groups present a greater number of accessible mates nearby. Costs of group living Despite the many benefits of living in groups, individuals of the group may also incur costs when forming groups. Ectoparasitism and disease When individuals of the same species aggregate to form groups, there is an increased risk of diseases and parasites spreading throughout the group. Because individuals of a group live together in close proximity, when one individual is infected with a disease or parasite, they bring this disease or parasite into a habitat full of susceptible individuals. Also, larger groups of animals will produce larger amounts of waste material, allowing for a favorable environment for pathogens, that may spread to individuals. Thus, transmissions of diseases and parasites are more likely to occur and more rapidly than if an individual lived alone. A great example was shown in colonies of cliff swallows by Brown and Brown (1986). Cliff swallows are commonly parasitized by swallow bugs and this study showed that the number of swallow bugs per nest increased significantly with an increase of the number of cliff swallows per colony, which thus reduced the survivability of the nests’ offspring by up to 50%. Another study shows that bank swallows have an increased likelihood of flea infestations per burrow with the increase of colony size, which also increased mortality rates of offspring in infected burrows. Intraspecific competition A consequence that may arise from forming large groups is the increased intraspecific competition between group members. If resources in a group’s environment becomes limited, group members will then have to compete with one another for the available resources. The increased competition then results in reduced nutritional intake in some individuals compared to others. An example of this can be seen in a study conducted on leaf monkeys. This study showed that females in a larger group of leaf monkeys had a reduced energetic