Rarely is it the case that creating a map of a species’ range is the goal of a monitoring program. Usually maps are side products generated by the collection of systematically taken data in. However, it is worth discussing and thinking about the mapping of your monitoring data as maps are perhaps the most understandable and attractive summaries of your data. This can be particularly important during the first or first few years of your project. While for biological and statistical reasons population trends are not worth calculating until after the first 5-15 years, maps can be produced after the first year. Also maps are the first products you can produce (thus providing some tangible result to your funders, volunteers, and supervisors).

A good example of using maps to summarize both abundance and population trends of species can be found using Breeding Bird Survey data.

Just as with calculating population changes from the data generated by monitoring programs, species maps are equally affected by the sampling frame and the technique that you choose. Biased coverage and biased techniques will yield biased data and biased maps that don’t really represent the true distribution and abundance of a species. Mapping your data should be one of the quality control checks you apply. Discrepancies and bias in your sampling program are often easy to spot (both for you and your reviewers) when mapped, particularly compared to simple tabulations or raw data in a spreadsheet.

To map your data you need:

• Geo-referenced data. That is, your sampling points, plots, or transects must have accurate coordinates in latitude/longitude or UTM coordinates.
• Mapping Software. While it is possible to produce simple range or dot maps by hand, more complicated maps that show isoclines of abundance require fancy mathematical routines to calculate. Two of the most common Windows-based programs used to calculate such maps are ARC-GIS, and Surfer.
• Appropriate data. As mentioned above your maps are only as good as your data and your date is only as good as your sampling frame and collection techniques.

Mapping is important, but to create good maps one should sample as many sites in as many different habitats as possible. In a monitoring program one should return to the same sites each year to measure change over time efficiently. Mapping is often part of an extensive inventory phase to find out what species are present and where.