Although recent research has greatly expanded our knowledge of the Swainson's Warbler, there is much to learn about the biology of this species.
Renesting after failure and double-brooding appear to be common, but we lack information on rates and factors that influence the probability of these events. Similarly, more research is needed on singing behavior, parental care, extra-pair paternity, female survival, conspecific attraction as a habitat-selection mechanism, and fledgling survival and movements. Given the reliance of this species on early-successional forests, work on dispersal following habitat change, including succession, flooding, fire, and timber harvest, would be valuable. The effects of natural disturbances (including hurricanes, storms, tornadoes, and floods) on occupancy and population dynamics, as well as the recovery of affected habitat, also demand further research. The use of permanent research plots to document these changes would be useful. The post-breeding biology of this species is almost entirely unknown; in particular, studies are needed on timing and patterns of molt, and migration departure.
Outside of the breeding period, little is known about Swainson's Warbler. More research on migration routes, important stopover areas, and migratory connectivity would be helpful. The overwintering range remains poorly known; additional work with audio playbacks would help in this regard. Quantitative information on habitat use, habitat quality, and survival during the overwintering period is also needed.
Although forest management is known to improve habitat quality for the Swainson's Warbler, little is known about which practices produce optimal habitat. The frequency at which forests should be managed needs to be assessed, considering unique characteristics of forests and geographical areas. Reconstructing the management history of forests inhabited by the Swainson's Warbler may provide insights about the species' response. Because much of the remaining Swainson's Warbler habitat is on private lands, an understanding of silvicultural practices that allow for viable populations while providing for economic sustainability also need to be examined. Additionally, the range-wide distribution of suitable Swainson's Warbler habitat on both public and private lands should be determined.
Information on population status and viability of this species throughout its breeding range would be valuable. Existing monitoring programs like the Breeding Bird Survey do not adequately sample Swainson's Warbler populations throughout their range, and better estimates of population trends and population size are needed for both small and large scales.