There is a variety of goose species, each having a slight difference in physical characteristics, as well as their adaptations to their environments.
This graph shows how through many different factors, the goose population follows a pattern of logistic growth. Over time, the population starts out with slow growth, rapidly increases, and eventually evens out again. You can see how the population numbers start out small, but as more resources become available, the population increases. Later when the resources run low again, the population stops increasing and plateaus.
Immigration: When more geese immigrate, or come into a population, it causes an increase in the overall goose population. Geese migrate South into warmer climates during the winter, so the geese populations that already reside in southern areas will experience an increase in their population.
Emigration: Geese that are unable to keep warm in the colder months are required to leave their habitat, or emigrate, to warmer regions. The original population will then experience a decline, or even be completely gone, after they emigrate elsewhere.
Births: If a population undergoes a rise in crude birth rate (CBR), the population will do so as well. This also depends on the total fertility rate (TFR). When the number of offspring increases per mother, the CBR also increases. If more offspring are produced, this also means that a larger amount of resources are required to sustain the population, growing closer and closer to the set carrying capacity of their environment.
Deaths: Deaths can not only be detrimental to the geese population, but also to their predators who rely on them for food and energy. On the other hand, the prey of the geese will experience an incline in population since there will be less predators eating them.
Limited Resources: Limited resources play an extensive role in influencing the goose population. When resources run low, so does the population, and when they increase, the population does so as well. Many factors can affect the supply of resources, including what other animals are relying on them and (if it is a plant) if they are able to grow at the existing climate and temperature. By following this pattern, a "S" shape emerges on a graph showing the population by time. Once the population evens out at the more current date, you are able to assume it has either reached its carrying capacity or is sufficient in its needs. Carrying capacity is defined as the maximum number of individuals of a particular species (geese) that the environment can normally and consistently support.
Density-Dependent Limiting Factors: Two density-dependent factors include disease and competition. Disease can greatly limit population size by making sick and eventually killing groups of geese. If the disease spreads and is contagious, it can definitely drop the size on a graph- no longer following logistic growth. Competition can increase one species population while decreasing another. The least fit will experience a decrease, while the fittest will increase (survival of the fittest).
Density-Independent Limiting Factors: Examples of density-independent factors are temperature and storms. In the case of geese, temperature causes geese to migrate south to warmer weather. If they are unable to move, they may also be unable to survive from the cold. As for storms, it can also act as a barrier to migration, making them unable to migrate. Storms can also make other daily activities, such as searching for food, much harder to accomplish.
This image is showing how geese are required to migrate south to warmer weather in order to survive. They often fly in a "V" shape, with the alpha geese as leaders.