Shifting baselines, reconstructed baselines, and moving targets for management of rare and endangered species in South Florida

by Dr. Steven Whitfield

Abstract: Mitigating global biodiversity loss is a grand challenge for scientists - and for humanity. Major threats to wildlife (i.e., habitat loss, overharvesting, emerging infectious diseases, climate change) are accelerating on a global scale. Management of species requires some understanding of wildlife population densities and distributions from before human impacts (a historical baseline). However, inadequate data on historical baselines can lead to "shifting baseline syndrome" - a phenomenon where over generations, scientists and managers fail to identify a correct historical baseline for threatened species, and set a management target on a shifted (and generally reduced) baseline. In this seminar, I will provide two case studies that illustrate shifting baselines for rare and endangered species in South Florida: Gopher Tortoises (Gopherus polyphemus) and American Flamingos (Phoenicopterus ruber). I will overview our research to reconstruct lost baseline with archival data from a range of sources, and illustrate how reconstructed baselines drive wildlife management decisions and policy. Gopher Tortoises are ecosystem engineers that create deep burrows used by hundreds of other animal species, and are important seed dispersers with impacts on plant community structure. In south Florida, rapid urbanization limits available habitat for Gopher Tortoises and leads to high rates of illegal displacement of tortoises by humans. Absence of realistic baselines for Gopher Tortoises in Miami's pine rocklands ecosystem has resulted in management deficit for a keystone species in a critically endangered ecosystem, and reconstruction of baselines has led to active measures to protect and restore tortoise populations in urban pine rockland preserves. American Flamingos are a cultural icon of Florida, but disappeared from the state in the late 1800s under heavy hunting pressure. For more than a century, it has been unclear if rare flamingos observed within Florida are the last individuals of a formerly large population - or are escaped individuals from captive populations in zoos or private collections. Reconstruction of historical baselines for American Flamingo populations in Florida from narrative accounts from the 19th century and natural history specimens has led to formal recognition of flamingos as a native species, and urged management efforts within the United States. These two examples of shifting baselines illustrate a profound deficiency of biodiversity information from South Florida, and are within a broader context of rare and endangered species management in a region with high terrestrial biodiversity and insufficient research or management attention.