However, providing survey bias is constant, the results can provide comparable estimates of abundance between localities and species, or within species over time. These indices are usually based on some measure of effort such as a unit of time or distance travelled. Indices that are highly variable require multiple counts to achieve precision when used for trend monitoring. Analysis of relative abundance is discussed in detail in Section 5.3. 2.1.3 Absolute abundance Absolute abundance refers to total numbers or density of a species.
Absolute abundance is usually more costly and difficult to measure than relative abundance.
Absolute density is also required for analysis of harvest strategies. Absolute abundance survey methods. Survey Method Advantages Disadvantages Total Counts not influenced by sampling errors if the assumption that all animals are counted is true. Radio-telemetry provides a further option which may serve as the basis for an inventory or to enhance traditional methods. Careful consideration of what question the inventory is supposed to address will provide guidance as to the appropriate level of intensity.