Lab 12: Population Ecology

1. Lab 12: Population Ecology

2. What is Population Ecology? • Ecology: • study of interactions between organisms and their environment • Population: • group of conspecifics living in the same area • Population ecology: • how the environment influences a population and vice versa

3. What is Population Ecology? • Population Ecology Topics: • population growth • endangered species (conservation) • effects of habitat fragmentation on the population

4. Population Growth & Demography • Demography: • Study of populations • How many? • What’s the age structure? • Growth rate determined by: • Birth rate • Death rate • Immigration and emigration

5. Population Growth & Demography • Demography: • Study of populations • How many? • What’s the age structure? • Growth rate determined by: • Birth rate • Death rate • Immigration and emigration

6. What can affect Population Size? • Stochasticity • random events such as drought, severe winter, fire, etc. • Demographics – age distribution of population • How many are of reproductive age? • Pre-reproductive age? • Post reproductive age? How can we tell if a population is growing or shrinking?

7. Life Tables • Used to estimate age-specific fecundity and survival rates • Fecundity = reproduction • Look at Table 12.5 on page 202 • You’ll be filling this out in lab today • Made for females – too difficult for males • Cohort life table • Follow individuals born at the same time for their whole lives • Static life table • Random sample of individuals, marked at the same time

8. Life Tables – what’s in them? • x = age class • sx= survival in age class • lx= survival to age class x • bx= age-specific fecundity • R0= net reproductive rate • 0-1 years, 1-4 years, etc. • proportion in age class that are alive • all the sx up to that age class multiplied • # of female offspring produced by female in that age class • # of female offspring produced by a female during its lifetime You’ll have to do these calculations – look at pg 187!

9. How do we estimate population size?

10. Mark-Recapture Method(you’ll be doing this today) • Animals are trapped, marked for ID, and then released • In birds, we mark them by putting colored bands on their leg • Later, a second set of animals is trapped (or observed) from the same population • Some of these animals will be from the first, marked group • The total number of animals within the population can then be estimated (pg. 188)

11. Total that were banded in the 1st round Total in population Total observed this time # observed this time that were banded

12. Radio Telemetry • Place transmitter on animal – use receiver to pick up signal • Uses • Find animals to observe • Track activities • Determine home range size • Look at dispersal • Look at migration • Etc. • Mortality

13. Triangulation(you’ll be doing this today) • Used to find animal from far away • Use receiver to get directional readings at 2 locations • Use map and compass to draw lines • Where lines cross is location of transmitter

14. Plan for today • Take a look at lab report BEFORE starting lab • There are some things you will need to do before leaving • Go out and find owls • Work on computers • Lab report

15. Hints and tips • For table 12.7 – only change one parameter per age class – don’t change it too much • Find 40-50 living owls (won’t take too long) • For the discussion in the lab report – read page 195 carefully • Will need to discuss biology and conservation concerns • Think about which age class is having trouble – is there something we can do to help that age class? • Think about old growth vs new growth forests