11 population density age fluctuations

Question 1

what is age distribution

Answer 1

The age distribution of a population is an important characteristic that influences its natality and mortality rates. it gives an indication of a population’s reproductive status

Question 2

three broad categorizations based on age distribution

Answer 2

Pre-reproductive:
➢ Yearlings or 1-year-olds
➢ 2-year-olds
➢ Sub-adults
Reproductive
➢Adults that are able to, and are actively
reproducing
Post-reproductive
adults which are no longer reproducing
(The length of these ages varies)

Question 3

what is age pyramid

Answer 3

shows the number of individuals in different age classes in a population, with the width of horizontal bars differing based
on the numbers in each age group

Question 4

three types of population in age pyramid

Answer 4

➢ A stable population(even distribution)
➢ An expanding population(more young)
➢ A declining population(more old)

Question 5

Methods for Age determination

Answer 5

*Birds: natal plumage/juvenile (or immature) plumage/adult plumage
➢ Hatch year or juvenile (HY)
➢ Second year or yearling (SY; clearly
identifiable in late summer and early
autumn)
➢ After second year or adult (ASY)
*tail fur of the of eastern gray squirrel
*Horns and antlers of older animals are usually larger than those of younger
*As mammals mature, there is a consistent pattern of
emergence and replacement of dentition
*For most species, analysis of cementum annuli is a reliable method for the estimate animal age
*Age can be estimated from adhesion lines or annual growth layers in bones

Question 5

Methods for Age determination

Answer 5

*Birds: natal plumage/juvenile (or immature) plumage/adult plumage
➢ Hatch year or juvenile (HY)
➢ Second year or yearling (SY; clearly
identifiable in late summer and early
autumn)
➢ After second year or adult (ASY)
*tail fur of the of eastern gray squirrel
*Horns and antlers of older animals are usually larger than those of younger
*As mammals mature, there is a consistent pattern of
emergence and replacement of dentition
*For most species, analysis of cementum annuli is a reliable method for the estimate animal age
*Age can be estimated from adhesion lines or annual growth layers in bones

Question 6

Methods for Sex determination

Answer 6

*Males of many bird species have breeding plumage that is distinct from that of females
*Males often have antlers whereas females do not

Question 7

what is Population Density

Answer 7

number of individuals per unit area

Question 8

Density-determination Methods

Answer 8

Quadrat sampling: is a widely used method
involving decisions on the size of the area to
be sampled and how many samples to take
The mark-recapture method : a sample of individuals are
caught, marked, released, and the proportion of marked individuals recaptured used to estimate the total population size in the area of study

Question 9

Controls on density

Answer 9

Density-dependent controls:competition for resources, predation
Density-independent controls: disturbances from
floods, hurricanes, drought, fire

Question 10

Population Fluctuation

Answer 10

Annual fluctuations: intra-annual changes in temperature and
precipitation
regular oscillations or cycles of peaks and depressions every few years with unclear reasons (e.x.snowshoe hare and the lynx
populations)