Texas Natural Diversity Database (TXNDD): Methodology

The Texas Natural Diversity Database (TXNDD) was established in 1983, and along with the Wildlife Diversity Program, the TXNDD is a member program in the NatureServe network. The NatureServe network consists of state, provincial, and national member programs dedicated to collecting, managing, and disseminating biological information using a standardized methodology. For more information on the NatureServe network click on the links below:

• NatureServe Homepage
• NatureServe Explorer
• NatureServe Methodology

The TXNDD maintains information on over 700 natural resource Elements. An Element can be a species, a native plant community, or an animal aggregation, such as a colonial waterbird rookery or a bat roost.

The TXNDD record for any Element is known as an Element Occurrence (EO). An EO is an area of land or water where an Element is or was present and has practical conservation value. Each EO is based on at least one observation, and potentially hundreds of observations, of an Element in a specified location. The EO can be thought of as a representation of the known population of an Element in a particular area. The TXNDD currently has over 8,500 EO records.

The observations that comprise each EO are submitted to the TXNDD from a variety of different sources, including TPWD personnel, conservation organizations, and consulting firms. In addition, TXNDD and Wildlife Diversity Program staff search published articles, project reports, museums, and herbaria for additional information. Each source of information is documented in a TXNDD Reference record and then archived. Each EO record includes a reference list documenting what information was used to create the record.

Each EO consists of two parts: the geographic location of the observation and the data that goes along with the observation. The basic data needed to create an EO includes who observed the element, when was the element observed, where was the element observed, and how many of the element was observed. In addition to the basic data, a TXNDD EO record may contain information about the surrounding habitat, the condition of the habitat, the condition of the element, any possible threats to the long term survival of the element in that location, and much more.

Click here to request data by species or by geographic area.