USING CARTOGRAPHY TO ILLUSTRATE WHERE SPECIES LIVE
By Michael Davenport, Marine Species & GIS Programs Manager
Conserve Wildlife Foundation of NJ (CWF) staff have been busy updating the CWF website’s on-line field guide with additional species’ profiles in order to add descriptions for New Jersey’s Species of Special Concern. One important component of the on-line field guide, like almost any other field guide, is the inclusion of a range map.
Our Online Field Guide
The CWF on-line field guide is specific to New Jersey, so the only portion of each species’ range illustrated is that portion within the boundary of the state. For a species’ full range, there are numerous additional sources of information. CWF, being focused on New Jersey wildlife, is uniquely able to provide more specific range information based upon the data available to our staff as well as our first-hand knowledge.
The range maps within the on-line field guide are created using Geographic Information Systems (GIS) software and multiple sources of data. First, we begin with the raw species observation data which is maintained within the NJ Endangered and Nongame Species Program’s (ENSP) Biotics database, a database which CWF staff maintains in partnership with ENSP. Then, like any range map, some generalization needs to be made to account for the fact that animals cannot be observed 24 hours a day, 365 days a year. In order to do so, data such as land cover types, hydrology, and/or topology is considered in order to fill-in the areas between observation points or omit other areas.
Because range maps may depict an entire state or larger geographic area, it is not necessary to display actual habitat utilized for a particular species. A range map is simply a guide which displays the extent where a species may be found – it is a tool, not a rule. The range map does not take into account those finer-scale features of the landscape which may be unable to be depicted in an easily read manner at the state level. For instance, freshwater mussel range maps have been created by depicting those watersheds where the species are known to occur, rather than the actual stream segments.
Depicting ranges for non-breeding species
Besides mapping the extent of a species range, range maps depict what that range represents for a particular species’ life cycle. Some species only occur in New Jersey during one season (breeding/summer, non-breeding/winter, migration) while others may be here year-round. This is especially important for mapping the ranges of bird species.
If you happen to notice any range maps which depict a species as not occurring at a location where you are sure that you’ve observed them, then you can assist the ENSP in possibly filling a data gap. Even for a state as small as New Jersey, wildlife biologists are unable to survey every corner of the state. Therefore, we rely on “citizen scientists” to assist by reporting their observations. Please visit our webpage for more information regarding this process and visit CWF’s on-line field guide to view the range maps.