The use of the Collector for ArcGIS app offers a powerful tool for field data collection. The app, available for smartphones and tablets, allows setup of field data sheets for collecting GPS-tagged data and photos. Data sheets can incorporate existing plant inventories or use custom-designed plant lists, can be tailored to constrain choices to a required vocabulary, or allow for free text fields of species names, sizes, or notes. Data for each point can then be tracked for subsequent data collection while data can be analyzed and displayed using standard GIS analytical tools. However, the advance setup required can be challenging (it can be difficult to predict all contingencies), and retrieving and matching data for analysis requires a well defined workflow. We will present an example of the benefits and challenges of mobile GIS as used for collecting data on deer impacts on vegetation in Ann Arbor.