Population density

Population density is one of the most complex measurement types in YouTHERIA (see screenshot, below).

Record the population density in the data value field and then complete all the following:

At present, the options for the unit of population density available in the drop-down (individual
or group density) are as follows:
• groups per 1000 nautical miles
• groups per ha
• groups per km (for transects)
• groups per km2
• individuals per 100 km2

• individuals per 1000 m2
• individuals per acre
• individuals per ha
• individuals per km (for transects)
• individuals per km2
• individuals per metre2
• individuals per square mile
• unspecified

Estimation Method
Choose one of:
• Unspecified
• Direct counts — sample or census of individuals directly observed, with no processing of raw count data apart from transformation (eg logarithmic) or multiplying/dividing by study area.
• Indirect counts — numbers of individuals inferred from indirect traces such as scats, tracks or hair-traps.
• Mathematical functions based on direct counts e.g. distance sampling or mark-recapture methods.
• Mathematical functions based on indirect counts.
• Home Range extrapolation — expressing population density as some function of mean home range size and size of study area.

Study Area Size
Record the size of the population density study area.

Study Area Units
These units will generally be the same as for the population density measure units. Specify the study area units as one of:
• acres
• hectares
• kilometres (for transects)
• kilometres2
• metres2
• square miles
• square nautical miles
• unspecified

Study Area Type
Choose one of:
• Unspecified
• Transect boundaries — the extent of the area directly sampled in obtaining counts of individuals (e.g. the area directly covered in a line and point transect).
• Human boundaries — political or administrative boundaries such as a national park.
• Ecological boundaries — natural boundaries such as a forest or other ecological unit.

The user must also specify the start date of the study. The start date should be recorded as precisely as possible but if only month or season are reported then record this information in the Study Start Date field. Total study duration and study effort should also be recorded. The miner should also record whether source contains data on prey density.

Generic value types: Data Value, Data Range, Measure, Sample Size, Captivity Status, Sex, Source Type, Ecological Study Type, Duration Value and Duration Units and Study Efforts Value and Units.