Effects of Prescribed Fire on Seaside Sparrows
By Gregory Gough
Despite their difficult accessibility, marsh habitats throughout the United States have undergone intense human alteration. The effects of these impacts on associated marsh fauna and flora are rarely quantified.
Prescribed fire is a prime example a disturbance frequently practiced by wildlife managers on coastal marshes along the Atlantic and Gulf coasts of the United States.
Unfortunately, little is known about the effects of prescribed fire on non-game species such as the coastal plain swamp sparrow, the saltmarsh sparrow, the seaside sparrow, the black rail, and other secretive marsh birds that use tidal marshes as foraging and breeding areas.
To date research has focused on measuring the impacts of fire on species composition and abundance. Few studies however examining the effects of fire on animal communities have censused animal populations at appropriate frequencies or for long enough periods of time to be able to estimate true patterns of population change. And no studies have examined the effects of fire on population parameters such as age/size structure, or reproduction.
Research was conducted to evaluate the impact of prescribed burning on the breeding ecology of the migratory seaside sparrow. The research took place in the Blackwater National Wildlife Refuge and Fishing Bay Wildlife Management Area, areas located within the Chesapeake Bay estuarine system.
In the first year of the study nests were depredated during incubation 35.3% of the time on areas that had been burned in the winter but only 13.3% of the time in unburned areas (see chart below). During the nestling stage depredation rates were similar between the 2 areas.
However, during the second year of study there was no apparent difference in depredation rates between burned and unburned sites. This might have been due to more precipitation in the second year.
This article summarizes the information in this publication:
Almario, Barbara S., Marra, Peter P., Gates, J. Edward and Mitchell, Laura 2009. Effects of Prescribed Fire on Depredation Rates of Natural and Artificial Seaside Sparrow Nests. The Wilson Journal of Ornithology, 121(4): 770-777.
We compared depredation rates of natural and artificial nests of Seaside Sparrows (Ammodramus maritimus) within winter burned and unburned marsh breeding habitats. Natural nests on burned sites in 2002 were depredated at a higher rate (35.3%) during the incubation stage, compared to unburned sites (13.3%). Depredation rates of natural nests were similar between burn treatments during the nestling stage. Artificial nests exhibited significantly higher depredation rates during the incubation stage on burned compared to unburned sites in 2002. No artificial nest studies were conducted in 2003, but we examined natural nest depredation rates. Depredation rates on natural nests in 2003 were similar between burned and unburned sites during both incubation and nestling stages. Differences in nest depredation rates between 2002 and 2003 may be due to increased rainfall in 2003 leading to higher biological productivity, reduced burn effectiveness and coverage, as well as a change in nest placement by Seaside Sparrows on burned sites. Shrub-nesting species may not be as vulnerable to higher rates of nest depredation induced by prescribed burning because fire appears to only minimally impact woody shrubs, while greatly reducing biomass of herbaceous vegetation.
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