Analysis of Life History Typologies
September 2006 - March 2009
- Corps of Engineers
Most threatened and endangered species lie on a continuum ranging from species for which no data exists to species for which extensive demographic data exists over several locations and many years. Ideally, the level of demographic data available will dictate actions for species recovery. When adequate data exists, a formal PVA can be conducted. However, conducting a formal PVA is only possible for species where an abundance of data exists, typically mean and variance of demographic vital rates within (e.g. survival, reproduction) and amoung populations (i.e. dispersal). For the vast majority of threatened and endangered species - including those on military lands - these demographic data do not exist, and management decisions often need to be made before they can be collected. Thus, managers are left with very little scientifically based guidance regarding how best to restore populations of all but the best studied species. This occurs because the life history strategies and patterns of most endangered species are considered to be idiosyncratic. It is generally thought that there is no substitute for detailed, species specific information for guiding the mangement of imperiled species. Indeed, there are no "general rules" that an ecologist or manager can look to for guidance on how to best recover a particular species. This proposal is part of a larger multi-investigator effort to conduct demographic analyses to develop a general set of scientifically based rules, delineated by broad taxonomic groups, to aid in the management of species for which limited demographic data exist. We call these scientifically based rules Life History Typologies (LHTs), as they will be derived by synthesizing data from many well-studied species of a given taxonomic grouping and life history type. From these existing data sets the LHT will quantitatively characterize the influence of vital rates on population growth and recovery, the vulnerability of vital rates to disturbance, and management-induced changes to vital rates, thereby informing the management of similar species for which detailed data are lacking.