a group of organisms of the same species populating a given area
mark and recapture technique
Involves capturing samples of animals from a population, marking them, releasing them, and allowing them to redistribute among unmarked individuals. A sample of animals are recaptured and the proportion of marked to unmarked is determined. Can be used to provide information on birth, death, and movement rates, as well as absolute abundance.
Short falls of mark and recapture techniques
Require considerable time and effort to get enough data and each technique has a set of strict assumptions that should be met in order for the estimate to be reliable.
Petersen mark and recapture Method
When the population is closed and a single marking is used. Used when the sample is closed.
An extension of the Petersen method where a series of samples are colllected. You treat multiple samples as a series of Petersen samples and calculate a weighted average of Petersen estimates. Easier to determine violations of marks and recapture assumptions
a release and recapture method used when the population is open. A series of samples are taken and individuals are marked at each sampling time. This enables researchers to know when and where individuals were last captured and what were their movement patterns like.
6 assumptions of petersen method
The marking method must not affect the animal. The mark must last for the entire sample period. Marked animals disperse completely in the population b/t time of release and time of next sample. The likelihood of an animal being captured must not change with its age. Th population is closed. No births or deaths during the study.
A range of values that is expected to include the true population size a given percentage of the time.
the exactness of a measurement