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Bird Migration
Trade-offs
Paper Logistics
Metabolism
100
Why do birds participate in non-stop long-term migration and what benefits does this serve?
To avoid environmental stress such as relative food abundance, pathogen levels, and heat stress, and to reach breeding grounds for reproduction.
100
What trade-offs are there in the skeletal structures of migrants birds that allow them to make their seasonal migration?
The hollow bones in migrant birds allow them to fly more efficiently though they are more prone to injury because the bones are weaker.
100
What physiological factors contributed to the death of Captain Scott and his crew?
On average, a man in Captain Scott's crew used over 25 MJ (7000 kcal) in daily energy expenditures while only replenishing 60-70% of this. Because of this, these men on average lost a kilogram in body mass every 4 days and ultimately died of starvation.
100
Why is pacing beneficial for animals?
An organism has only so much energy available to it. By pacing the use of this energy can be spread over longer periods of time instead of being used all at once. Along with this, maintaining higher metabolic levels can be dangerous to an organism. E.g. Overheating
200
What changes do migratory birds go through from the beginning of their journeys to the end and why?
In the course of non-stop flights, shorebirds not only deplete much of their fat stores but also lose protein due to atrophy of organs in the body cavity and even in the working flight muscles.
200
What trade-offs are represented in Figure 5?
Figure 5 shows the trade-offs between energy consumption in raising chicks and survival rate of parent. As the parent puts more energy into raising chicks, their fitness decreases.
200
What study was done on mice to show effects of heat dissipation and what do you think was the cause of these results?
Mice were shaved during lactation and found to have increased milk production that correlated with increased mass of pups at weaning. This could possibly be because of over-compensation in the diet of these mice to maintain energy levels while maintaining heat levels.
200
How are VO2 max and metabolic ceilings related?
VO2 max is maximum oxygen consumption rate while metabolic ceiling is how much heat and work are produced. VO2 max is an indirect measurement of the metabolic ceiling.
300
If some shorebirds were unable to perform their seasonal migration, what effect would this have on their fitness?
These birds would be unable to make it to the breeding ground and would not be able to reproduce.
300
During migration birds maintain metabolism high above their BMR for extended periods of time. Why can't they maintain these levels constantly?
After extended periods, these birds need time to rest and replenish their energy stores.
300
Using Table 1, compare Captain Scott's polar party to cross-country skiing. Discuss the different factors that contribute to the difference in energy balance of the two.
Difference in duration and energy expenditure is high for both but the energy intake was much lower in the polar party which resulted in a much higher deficit.
300
What nutrient stores the most energy per gram and why?
Lipids. Lipids are typically structured as long change of hydrogen and carbon atoms, thus when broken down much more chemical bond energy is released.
400
What are the benefits of being a resident species vs a non resident species? (Non-migratory vs. Migratory)
Resident species don't have to go through the long expenditure of energy but have to stay and fight through the cold, predation and pathogen risks.
400
What are the different mechanisms of heat production between mammals and birds? What are some possible reasons for these differences?
Mammals can use brown fat stores while birds have a higher shivering capacity. This could potentially be because brown fat would weigh down birds during flight, ultimately requiring higher energy costs, so shivering is more beneficial for this.
400
Using Figure 4, why would a parent choose to expend more energy in itself as compared to its offspring?
If the parents expends to much energy on its offspring it can lower its own fitness and decrease its chances at passing on its genes to future generations.
400
How do humans prepare for an extensive period of metabolic work as compared to migrant bird species?
Migrant bird store up excess energy by eating extra and resting while humans train and condition their bodies to handle extreme metabolic conditions
500
How do these seasonal bird migrations differ from the expedition of Captain Scott and crew in terms of energy use?
In terms of energy, the birds can store up excess energy before their long trip, while Captain Scott's crew needed to stop and eat. Because of this, Captain Scott could not maintain energy levels while the birds could.
500
Create a potential graph comparing the number of surviving offspring vs. clutch size in mice. Explain why you would see this trend.
See slide.
500
Other than death, what other adverse effects could maintaining excessive metabolic rates have on an organism and why?
Muscle tissue damage, gastric ulcers, increased intestinal permeability, and organ damage. As energy is used, the body of the organism begins to break down proteins that build up muscles and organs and produces excessive amounts of lactic acid due to anaerobic ATP production.
500
How does heat constraint change the behavior in metabolic performance of animals?
-Long-distance migrant birds tend to fly in cool air at night. -Fueling rates of migrant shorebirds are so low in the tropics. -Human ability to sweat allows us to outrun pretty much any running game in midday heat.