Information from natural history collections is becoming increasingly available via online databases and their use has been encouraged for investigating a variety of ecological topics. However, the data they contain are not without limitations—collector bias, inconsistent survey frequencies, and lack of absence data, to name a few. One limitation that has not yet been adequately addressed is the age at which historic non-native invasive species (NNIS) records cease to be useful in predicting current distributions. We recently used one such database in selecting sites for a revisitation study in southern Illinois to address this issue. Results from that study will be used to infer the temporal consistency (shelf life) of historic NNIS occurrences.  The database used is the product of a 2006 inventory of non-native species records from the 11 southernmost counties of Illinois.  As of 2010, it contained 10448 records. We initially selected targets to include a variety of plant forms and gave preference to more aggressive invasive species. This list was then reduced to only include records with enough information to estimate their collection locations to within 2 km. Final selections were made from the remaining subset based on the quantity and temporal distribution of records.

Results/Conclusions

The resulting dataset contained 1139 records (11% of the original database) and includes 10 of 33 species originally selected. Only 192 of these records pre-dated 2000. Moreover, we will have to combine data from multiple species for statistical analyses. The limited number of usable records in our final dataset is predominantly due to three factors: (1) only 28% of the records in the entire database contained sufficient details to estimate their locations to within 2km;  (2) some NNIS only had records dating back 10 years and  we were hoping  for a minimum of  60;  and (3) few species were collected consistently from decade to decade, leaving gaps in our timeline of records. The potential for use of such databases in areas of temporal and spatial inquiries is great, but has yet to be fully realized. More natural history collection information needs to be made available in online databases and those making new additions to natural history collections should make every effort to record GPS coordinates from collection sites. Additional research is also needed to address the issue of imperfect detection for studies such as ours.