Fire and Coastal Marsh Birds

Although many areas of coastal salt marshes in the southeastern United States have declined in recent decades (reviewed in Noss et al. 1995), they continue to serve as critical habitat for many secretive marsh birds of special concern.  Breeding species of these birds include Clapper Rail (Rallus longirostris), perhaps Black Rail (Laterallus jamaicensis) and various subspecies of Seaside Sparrows (Ammodramus maritimus; Post and Greenlaw 1994).  Wintering species include Nelson’s Sharp-tailed Sparrow (Ammodramus caudacutus) , Yellow Rail (Coturnicops noveboracensis), Marsh Wren (Cistothorus palustris), and Sedge Wren (C. platensis). 

Preliminary observations for the Black Rail indicate individuals often survive fire but that adults attempt to seek shelter in moist areas rather than flee (Legare et al. 1998).  This behavior means that some individuals experience mortality in hot fires that leave few unburned patches of vegetation.  Legare et al. (1998) recommend prescribing marsh fires that create a habitat mosaic of burned and unburned patches.

The Cape Sable seaside sparrow, A. m. mirabilis, is endangered, and the dusky seaside sparrow, A. m. nigrescens, is extinct.  At times, both lightning- and human-ignited fires have been labeled as harmful for seaside sparrows (reviewed in Gabrey and Afton 2000), although the birds are obligate residents of ecosystems thought to have burned frequently prior to European settlement (Frost 1995).  In other instances, prescribed burns have been credited with producing vegetation structure that is beneficial to these same birds (reviewed in Gabrey and Afton 2000).  In earlier literature, fire was thought to have at least a short-term negative effect on two Florida subspecies, A. m. nigrescens and A. m. mirabilis (Gabrey and Afton 2000).  When a population of A.m. nigrescens experienced two burns in the same winter, singing males were reduced by half during the following breeding season (Gabrey and Afton 2000).  Taylor (1983) noted that A. m. mirabilis was generally absent in marshes that were burned the previous winter.  Two burns in one season is an extreme situation and may have been related, in part, to excess fuel build-up.  In addition, when observations were extended beyond a single year, seaside sparrow use increased in the second year following a burn (Taylor 1983; Post and Greenlaw 1994).  These positive multiple-year results are similar to those reported for A. m. fisheri in Louisiana (Gabrey and Afton 2000). 

Recent work, suggests that periodic fire may not only be tolerated by some marsh birds but may be necessary for effective management.  Gabrey and Afton (2004) considered three bird species [Seaside Sparrows (Ammodramus maritimus), Red-winged Blackbirds (Agelaius phoeniceus), and Boat-tailed Grackles (Quiscalus major)] that accounted for > 85% of birds observed on their study sites in a southern Louisiana marsh.  The first breeding season after winter burn, Blackbirds and Grackles increased and Seaside Sparrows decreased relative to previous year.  However, the patterns were reversed in second year after the burn and there was no difference in the third year.  The researchers suggest that bird abundances related to percent dead vegetation and Spartina patens (Gabrey and Afton 2004).  Tucker and Robertson (2003) reported comparable responses for Henslow’s and Bachman’s sparrows in longleaf savannas, and he demonstrated that growing-season fires enhance habitat for these savanna bird species.

Information on the effects of burning on most secretive marsh birds is generally lacking, although the recent work on seaside sparrows has clarified some issues.  However, confounding factors, such as season and time since burn, have not been considered for most species and these are areas of study that should be pursued in the future, 

Fire and Arthropod Prey

Few data document the effects of fire on arthropods in coastal marshes.  It has been suggested, but not documented, that invertebrates in coastal marshes recover rapidly following burns (reviewed in Nyman and Chabreck 1995).  Although there are no data on growing-season coastal fires, such burns in nearby inland pine forests result in decreased arthropods (abundance and perhaps diversity) in areas burned in the early summer compared to areas burned in the dormant season.  However by late summer (August), at a time when nestlings of many bird species are fledging, pine forest plots burned in the growing season supported more arthropods than did sites burned in the dormant season (Hermann et al. 1998).