The core breeding range of Swainson's warbler (Limnothlypis swainsonii) overlaps a zone of exceptionally high tornado frequency in southeastern North America. The importance of tornadoes in creating breeding habitat for this globally rare warbler and other disturbance-dependent species has been largely overlooked. This paper estimates tornado frequency (1950–2021) and forest disturbance in the 240 counties and parishes in which breeding was documented from 1988 to 2014. The frequency of destructive tornadoes (EF1-EF5) varied 6-fold across the breeding range with a peak in the Gulf Coast states. Counties from east Texas to Alabama experienced the lowest median return interval of 5.4 years per 1000 km², resulting in approximately 2477 ha of forest damage per 1000 km² per century, based on current forestland cover. Tornadoes were significantly less frequent north and east of the core breeding range, with return intervals increasing to 9.1 years per 1000 km² for breeding counties on the Atlantic coastal plain, 10.2 years per 1000 km² in the Ozark Mountains, and 32.3 years per 1000 km² in the Appalachian Mountains. Breeding counties within 150 km of the coastline from east Texas to North Carolina are also subjected to the highest frequency of hurricanes in the Western Hemisphere. Hurricanes often cause massive forest damage but archived meteorological and forestry data are insufficient to estimate the aggregate extent of forest disturbance in breeding counties. Nevertheless, the combined impact of tornadoes and hurricanes in the pre-Anthropogenic era was likely sufficient to produce a dynamic mosaic of early-successional forest crucial for the breeding ecology of Swainson's warbler. To ensure the long-term survival of this rare warbler, it is advisable to develop habitat management plans that incorporate remote sensing data on early-successional forest generated by catastrophic storms as well as anthropogenic activities.

This dataset comprises a catalog of 1717 song recordings of male Swainson's warblers (Limnothlypis swainsonii) on breeding territories in the southeastern United States.  Songs were recorded from 1988 to 2014.  The spreadsheet includes song recording field number (GRG), state, county or parish, date, latitude, and longitude. Breeding territories were located in 240 counties and parishes, which served as the geographic template for storm data analysis.  Geographic coordinates were plotted in Fig 1 of "Catastrophic storms, forest disturbance, and the natural history of Swainson's warbler" (doi.org/10.1002/ece3.11099). Questions or inquiries regarding the dataset can be directed to the author.  

Geolocation of territorial Swainson's warblers. From 1988 to 2014, I surveyed breeding populations in 15 states as part of a comprehensive study of the warbler’s natural history. These surveys targeted Swainson’s warbler and were not incidental components of broader community censuses. Territorial males were documented in 240 counties and parishes documented by song recordings. Surveys were conducted during the breeding period, which began on 22 April in the Gulf Coast states and ended on 30 June in the Appalachian Mountains. I surveyed a wide spectrum of forestland and shrubland habitats, broadly classified as “forest land” by the USDA on public and private land and along waterways. Most breeding territories of this monogamous species were located using playback of songs, utilizing a protocol that was field-tested and fine-tuned in the late 1980s on the breeding and wintering ranges. Territorial males respond to playback by approaching the song source and delivering agitated “chip” notes, but usually refrain from singing until the playback source retreats or playback ends. Response to playback, mate-guarding, persistence during “playback-and-follow” trials, and counter-singing with other males were regarded as evidence of territoriality. Mist-netting or other handling was not required to document territoriality. The geographic coordinates of territories were recorded on site with Garmin™ GPS receivers (post-1998) or with Google Earth Pro from field notes and maps. All fieldwork was performed by the author.