1Why and how did the Pagett-Flohr and Isakson 2003 research measure the number of unique individuals?
The animals measured were marked to prevent double-counting, and the areas were randomly surveyed to measure the abundance of species in each microhabitat. They used the "minimum number of unique individuals" as opposed to other estimation methods because it is the most conservative and straight-forward measure of abundance.
2Explain how biotic factors limiting factors in distributions?
Competition and predation play a significant role in limiting distributions due to how successful species are in finding and competing for food. FOR EXAMPLE, where fox ranges overlap, the southern limit of arctic foxes is determined by interspecific competition with the red fox, whereas the northern limit is determined by the availability of food.
3What are the assumptions that must be met for a mark recapture technique?
- B and C
- All of the above
- All animals are equally catchable
- There is no immigration or emigration
4How was the Pagett-Flohr and Isakson 2003 study on the salt marsh harvest mouse design done?
- Traps were randomly placed in a selected 500m^2 area
- The mice were observed through 6 randomly placed towers and noted by number seen
- They did none of the above
- They Divided the area into 50x50 m blocks and randomly selected 40 blocks with one trap each to sample.
5According to Smith et. al 2020 is SMHM abundance different in managed vs tidal wetlands? Part one. The experiment. What methods were used?
The methods consisted of small mammal trapping in managed and tidal wetland sites. Mark-recapture techniques were used to derive population abundance estimates, and microhabitat characteristics were measured to incorporate their effects of abundance, population growth, survival, and fecundity.
6In the Pagett-Flohr & Isakson 2003 study, what were the habitat characteristics they researched that affected SMHM presence/absence?
- All of the above
- Only a & b
- Presence of other rodent species
- Pickleweed salinity
- Changing tides
7The density model would you use if you were given a decreasing probability of seeing or hearing an animal the farther you went from a transect or point, where all animals that were detected were on the line?
Some kind of unbounded estimation method that incorporates the sighting distances, such as the Hayne Estimator: D=(1/2L)Σk (1), where L refers to the transect length, R= radial distance (distance between observed animals), and K=total # of animals that were detected.
8How does the population density of SMHM compare between the south bay and the Suisun Marsh, and what about these locations might help explain this?
South Bay has the lowest SMHM densities; the Suisun Marsh has the highest. Where as the Suisun Marsh is primarily managed for waterfowl, it provides habitat for lots of other species. The South Bay, on the other hand, is highly urbanized and fragmented, which might account for the small and isolated populations of SMHM there.
9What is considered a "null pattern" of animal movement?
A random walk model, a pattern of movement present in diffusive spread, is considered a "null" pattern, because it is the pattern you would expect from individuals within a population as they move randomly one step at a time in equally probable directions. Thus, creating a method of movement with no set patterns/ no specific expectations.
10How is dispersal different from dispersion?
Dispersal refers to the movement of animals from their birthplace or population while dispersion refers to the spatial distribution or patterns animals take in an area.
11When are Finite and Exponential rate of increase used to estimate population size?
Finite is for geometric growth, applicable to patterns of deaths and births that follow annual or seasonal cycles. Exponential is more appropriate for animals with overlapping generations and smaller populations introduced to a new environment.
12Under what conditions would an animal population most likely achieve its intrinsic rate of increase (rm)?
- When the death rate exceeds the birth rate due to habitat fragmentation.
- When resources are unlimited and environmental stressors like predation are absent.
- When the population has reached its carrying capacity.
- When high population density triggers intense intraspecific competition.
13Compare and contrast: Ecological Carrying Capacity and Economic Carrying Capacity.
The Ecological Carrying Capacity is the natural limit set by resources and environmental conditions.
The Economic Carrying Capacity is the population size that produces the maximum "offtake" or harvest.
They are related in that the economic carrying capacity, or maximum sustainable yield, occurs when net recruitment is maximized at intermediate population sizes - so well before the ecological carrying capacity is reached, when r is greatest.
14What is the formula used to estimate mark recaptures and what does each variable represent?
The Peterson-Lincoln model: Y=Mn/m
Y= unknown population we are solving for (number of animals) , M= number of animals captured and marked on night 1 , n= total number captured altogether on night 2 , m= number of marked recaptures on night 2
15What are the four basic field survey techniques and what animals are each of them best for?
The four basic field survey techniques are line transects, point counts, trapping grids, and camera traps.
-Line transects is used to gather counts along a line and is best used for bird and mammal surveys.
-Point count is used to gather data at specified points for specific amounts of time and is best used for bird and mammal surveys as well.
-Trapping grids are traps that are arranged in specific way and area. They are best used for small mammals such as rodents.
-Camera traps detect movement or heat of animals passing by. They are best used for animals that are more elusive such as medium to large sized mammals.
16Given the mean and the variance, how can you determine the different types of dispersion?
A random dispersal is when the mean and variance are more or less equal. Clumped dispersion is when the data variance is greater than the mean. Uniform dispersal is when the overall mean is greater than the data variance.
varaiance/mean ratio:
ratio > 1 = clumped
ratio < 1 = unifrom
ratio = 1 = random
17Compare and contrast the difference between “pre saturation dispersal” and “saturation” dispersal.
For pre saturation dispersal, juveniles leave when their population density is low. For saturation dispersal, juveniles leave when population density is high.
18When density dependence is weak, what happens to the range of k? What does k indicate?
When density dependence is weak, the range of k increases. K indicates the maximum capacity of a species that its environment can reliably handle.
19Is N t + 1
- Population size one time unit later (final population)
- Population size at a grow time (initial population)
- Finite rate of increase
- Exponential rate of increase
20when calculating simple estimates of line transects, when would you use the density formula containing SE as opposed to the density formula without SE?
use the formula containing SE when you need to quantify precisionncertainty around the estimate.