Josh Ackerman completed his PhD in Ecology at UC Davis in 2002, with a dissertation entitled "From individuals to populations: The direct and indirect effects of predation on waterfowl nest success." [Also available online - restricted to UC campuses]
He stayed on through 2003 as a post-doctoral fellow. He is now a Research Wildlife Biologist and Principal Investigator with the US Geological Survey, and an Associate in the Department of Wildlife, Fish, and Conservation Biology at UC Davis.
Josh's dissertation research focused on the direct effects of predation, and the indirect effects of alternate prey, on waterfowl nest success, particularly the population dynamics of mallards and other dabbling ducks resulting from individual behavior and community structure. At the individual level, he studied the parental investment decisions of nesting mallards to determine the population consequences of partial clutch depredations. At the community level, he examined the role of shared predation in structuring prey communities, and specifically how alternate prey (rodents) abundance influences waterfowl nest success. He evaluated these dynamics using both observational and experimental techniques within the Grizzly Island Wildlife Area in Suisun Marsh, California, in conjunction with the California Waterfowl Association.
Nest depredation is recognized as the most important factor influencing avian nest success, particularly in waterfowl. Consequently, waterfowl management practices currently seek to reduce nest depredation by focusing on the direct effects of predators on waterfowl nests in a variety of ways. These include predator removal and the enhancement of nest site vegetation features that reduce a predator’s ability to find nests. However, these practices have variable success and often require intense management. Recently there has been a general shift in management philosophy from single species management towards ecosystem/community management. In order to apply this shift in management philosophy to waterfowl, managers need to develop strategies that enhance upland habitats near wetlands to the benefit of multiple species.
An alternative approach to managing for the direct effects of predators on waterfowl nests is to focus management on community structure and take into account the indirect effects of alternate prey on waterfowl nest success. By increasing the diversity and abundance of alternate prey species (e.g., rodents), predation pressure on waterfowl nests may be relieved via the behavioral responses (e.g., prey switching) of shared predators to their preferred prey. Josh examined whether this management approach can increase waterfowl nest success while considering multi-species conservation issues.
Read more about Josh's contribution to the study of factors limiting the breeding production of mallards in California.