Students investigate this question by sampling the energy stores of moose with and without wolves present. Each cup has about 50-100mL of water in it depending on size of cup. The per capita kill rate or sometimes just called kill rate is a special statistic indicating how much food the average wolf in a population gets. This means when a population is perturbed from the equilibrium it will have a very strong tendency to return rather quickly to the equilibrium. These insights and discoveries are all presented here for you. It also shows wolves have a slightly higher preference for calves than senescent-aged moose.
I warm the bottles up just by putting them in buckets of hot water a period before class. That is, the population will tend to increase when abundance is very low and decrease when abundance is very high. In this graph, the symbols represent the average monthly kill rate for each winter between 1971 and 2011. In fact, the population dynamics of Isle Royale wolves have been affected by genetic processes in ways that have been as important as they are subtle. Even though it is damaging that calves die, it is not unusual because babies in most species have high mortality. Other analyses indicate that 63% of the variation in predation rate can be explained by the number of moose per wolf in the population Vucetich et al.
So how is it on Isle Royale? In fact, annual variation in predation rate is one of the most important influences on moose population growth rate i. The moose population controlled the wolf population through their fluctuating population size. The functional response reveals the extent to which per capita kill rate varies over time as the density of prey varies Section 3. During the winter of 1997, a wolf from Canada immigrated to Isle Royale. No one had ever observed wolves and their prey long enough to know. That is, wolves have an important destabilizing impact on moose population dynamics.
This lab is based on a game invented by G. But those influences do not seem to provide an adequate explanation for why recruitment has experienced such a long-term decline. It is also better for the moose for there to be more moose, because of the magnitude by which the moose population increases. Calves are vulnerable because they are small, and senescent aged moose are vulnerable cause they are often weakened by arthritis, jaw necrosis, or malnutrition. There is one more possibility to assess. The open circles represent years prior to 1980, and the black circles are years after 1980. Nevertheless, there is no worry that wolves would drive Isle Royale moose to extinction.
Climate warming and increased ticks might have something to do with the most recent low levels of recruitment. Then students are presented with reference information about the prenatal effects of alcohol, tobacco, and illegal drugs and asked to summarize the effects and make conclusions. Our challenge is to better understand what accounts for the other half of the fluctuations. The butterflies are played by colored dots that the students can make with a hole punch and a few sheets of colored cardstock. Behavioral ecology can sometimes seem a world apart from population ecology.
Finally, it seems that fluctuation in wolves from year to year, not winter severity, is the primary ultimate cause of fluctuations in predation rate Section 8. Moose first came to Isle Royale in the early 20th century, and for fifty years, their numbers fluctuated with weather conditions and food abundance. The most important events in the history of Isle Royale wolves and moose have been essentially unpredictable events — disease, tick outbreaks, severe winters, and immigrant wolves. Durward found greater merit in continuing to lead these observations. One wolf pack failed after another. From 1980 onward, Isle Royale shifted from being bottom-up to something else.
Consequently, annual variation in predation rate has a big impact on whether the moose abundance will increase or decline. Building on the graph above and to develop a deeper understanding, here is more on the history of wolves and moose on Isle Royale. So far, we know that annual fluctuations in predation rate impact on moose population growth rate Section 6 , predation is a potentially destabilizing force section 5 , and that the moose population is, in fact, quite unstable section 7. Forest succession might also explain some of the decline. But we get a different sense is if we also consider the highest density of moose ever observed on Isle Royale 4. The kill rate is calculated by observing how frequently wolves kill moose.
Students start out by characterizing the growth of a colonizing population of moose in the absence of predators. By 2011, the population was reduced to 9 wolves living in one pack and another half dozen wolves, the socially disorganized remnants of Middle Pack. Those calculations were made for each year between 1971 and 2003. The greatest benefit to the population is the prime-age moose are rarely hunted, meaning that they are able to survive and reproduce The wolf population would rapidly decline because the wolves were living in such a high density, that an infectious disease could travel quickly and easily. For the broadest context, consider panel C.
Inbreeding depression and genetic rescue in the wolf population. Wolves took advantage of weakened moose, fueling high rates of predation. The graph to the left suggests that predation rate has only a slight tendency to be greater during severe winters. Prime-aged moose have the highest rates of survival and reproduction, senescent moose have lower rates of survival and reproduction, and calves have the lowest rate of survival and do not reproduce. If your complaint is justified, we will remove the cardset as soon as possible.