Porzana carolina


Table of Contents


INTRODUCTORY


Photo by Gary Houghton

AUTHORSHIP AND CITATION:
Meyer, Rachelle. 2006. Porzana carolina. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].

Revisions:
18 July 2013: DeGraaf, Richard M.; Rudis, Deborah D. 2001 citation corrected to DeGraaf, Richard M.; Yamasaki, Mariko. 2001.

FEIS ABBREVIATION:
POCA

SYNONYMS:
None

COMMON NAMES:
sora
sora rail

TAXONOMY:
Porzana carolina (Linnaeus) is the scientific name of the sora, a member of the Rallidae family [1].

ORDER:
Gruiformes

CLASS:
Bird

FEDERAL LEGAL STATUS:
No special status

OTHER STATUS:
Information on state-level protected status of animals in the United States is available at NatureServe, although recent changes in status may not be included.

WILDLIFE DISTRIBUTION AND OCCURRENCE

SPECIES: Porzana carolina


GENERAL DISTRIBUTION:
According to field guides, soras occur throughout most of North America [10,44]. Soras breed from Nova Scotia northeast to southern Yukon and Northwest Territories, south to California, Arizona, and New Mexico and northeast to Pennsylvania and New England. Sora wintering grounds include the northern portions of South America, including Ecuador, Columbia, and Venezuela, north through Central America and Mexico to southern California in the West and coastal regions of the Southeast. From southern Kansas south to northern and eastern Texas and east through the inland areas of the southeastern United States, soras are typically only observed during migration in the spring and fall. In a few areas of the western United States, including central California and areas of Arizona and New Mexico, soras may occur year round [10,44]. A general map of the sora's distribution can be found at Cornell's All About Birds website.

The following lists are speculative and are based on the habitat characteristics and species composition of communities soras are known to occupy during migration and on breeding and wintering grounds. There is not conclusive evidence that soras occur in all the habitat types listed, and some community types, especially those used rarely, may have been omitted.

ECOSYSTEMS [18]:
FRES37 Mountain meadows
FRES41 Wet grasslands

STATES/PROVINCES: (key to state/province abbreviations)
UNITED STATES

AL AZ AR CA CO CT DE FL GA HI
ID IL IN IA KS KY LA ME MD MA
MI MN MS MO MT NE NV NH NJ NM
NY NC ND OH OK OR PA RI SC SD
TN TX UT VT VA WA WV WI WY DC
PR VI


CANADA

AB BC MB NB NT NS ON PE PQ SK
YK


MEXICO

Ags. B.C.N. B.C.S. Camp. Chis. Chih. Coah. Col. Dgo. Edo. Mx.
Gto. Gro. Hgo. Jal. Mex. Mich. Mor. Nay. N.L. Oax.
Pue. Qro. Q.R. S.L.P. Sin. Son. Tab. Tamps. Tlax. Ver.
Yuc. Zac. D.F.

BLM PHYSIOGRAPHIC REGIONS [5]:
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

KUCHLER [29] PLANT ASSOCIATIONS:
K049 Tule marshes
K073 Northern cordgrass prairie
K078 Southern cordgrass prairie
K079 Palmetto prairie
K080 Marl everglades
K092 Everglades

SAF COVER TYPES [15]:
None

SRM (RANGELAND)COVER TYPES [56]:
216 Montane meadows
217 Wetlands
422 Riparian
726 Cordgrass
806 Gulf Coast salt marsh
807 Gulf Coast fresh marsh
818 Florida salt marsh
819 Freshwater marsh and ponds
822 Slough

PLANT COMMUNITIES:
Soras are commonly reported in plant communities dominated by the species listed below:

Cattails (Typha spp.) [8,24,28,34,36,38,51]
Sedges (Carex spp.) [24,27,36,38,51,54]
Bulrushes (Scirpus spp.) [8,24,27,38,40]
Smartweeds (Polygonum spp.) [36,40,54]
Rushes (Juncus spp.) [36,54]
Rice cutgrass (Leersia oryzoides) [40,50]
Barnyard grasses (Echinochloa spp.) [50,54]

Although soras use wetland and marsh habitats almost exclusively throughout the year, they may be found in other habitats.

Outside of wetlands, soras are most often reported in cultivated areas during migration or in the postbreeding period. For instance, a sora was observed 3 miles (5 km) from marshland in a cultivated field in Iowa in the middle of August [25]. A male sora was observed less than 1,000 feet (300 m) from a large wetland in a soybean (Glycine max) field in northwestern Iowa during the postbreeding period [26]. From early June to mid-July, soras were observed on farms in Saskatchewan sown mainly with wheat (Triticum aestivum) [57]. In addition, Ribic [51] cites 2 sources for the occurrence of soras in cranberry (Vaccinium macrocarpon) bogs.

Soras have also been reported in flooded wooded areas [19,34]. In western New York, soras occurred during the breeding season on a study site where 26% of the area was categorized as "flooded timber," and 5% was classed as "scrub/shrub marsh" [34]. In eastern and central Maine, an average of 2.1 soras was observed in wooded swamps per 100 hours of observation during the breeding season [19]. On a nonbreeding (August-April) site in southwestern Arizona, soras were found to use a "mixed shrub community" more than expected based on its availability [8]. Species composition of these areas was not described.

Soras were observed at low abundances on a site with Douglas-fir (Pseudotsuga menziesii), ponderosa pine (Pinus ponderosa), and trembling aspen (Populus tremuloides) in British Columbia. Details regarding the circumstances of these observations, such as distance to the nearest wetland or the degree of attachment to this site, were not included [41].

BIOLOGICAL DATA AND HABITAT REQUIREMENTS

SPECIES: Porzana carolina

 

Hays Cummins, Miami University

TIMING OF MAJOR LIFE HISTORY EVENTS:
Migration: Soras' northern migration occurs in spring, primarily in April and May. For instance, in east-central Kansas significantly (p<0.05) more soras were detected from 24 April to 7 May than the 2-week periods before or after [64]. In southeast Missouri, soras were observed from 25 March to 6 May [54]. Soras were 1st detected in April to early May in Colorado [24], Iowa, and Minnesota [28]. In a summary of the 1st detections of soras in Minnesota, Manitoba, and Saskatchewan, all occurred in April [46].

Soras depart their breeding grounds as early as July and as late as October. Soras were observed returning to wintering grounds in Arizona as early as late July [8]. Although local movements may obscure migration occurring in July, most migration occurred in August and September in Colorado [23]. In northern Ohio, sora abundance was increased in late August and September by migrating individuals [2]. In southeastern Missouri, soras were observed from 5 September to 27 October [54]. Soras have been observed in Manitoba and Saskatchewan as late as October [46].

Nesting: Although sora nesting activities have been observed from late April through early August, the peak nesting period typically occurs from May to early July. In New York, nesting was initiated in late April [34]. A nest search and literature review study of soras in Colorado reports a clutch initiated in early August. However, mean clutch initiation dates occurred in May and June in regions across the state [12]. Studies from northern Ohio [2], North Dakota [59], and Alberta [36] report nesting from May to July. In a review, sora nests with eggs were recorded from early May to early July in Indiana [42].

Sora females begin construction of saucer-shaped nests on the ground or on a platform over shallow water at the start of egg laying [12,34]. According to literature reviews, clutch sizes typically range from 8 to 13 eggs [12,42], although clutch sizes of up to 16 have been reported [12,28,36]. Both parents incubate the eggs. Incubation lasts approximately 19 days, although a wide range of incubation periods has been reported in the literature [36]. Eggs hatch over a span of 2 to 13 days [28]. Nestlings are precocial and are capable of walking and swimming short distances (<3 feet (1 m)) by the end of their 1st day. Young soras are independent by about 4 weeks of age [12,26]. According to a literature review, soras brood once per season [12]. Some late broods may be 2nd nesting attempts, but there is only 1 report in the literature of a 2nd brood attempt after a successful nest [36]. For information on breeding behavior of soras, see [28]. For information on conspecific nest parasitism and egg discrimination in soras see [58].

Sora nest success rates vary across locations and years. In summaries of the literature addressing sora apparent nest success, reported proportions of successful nests varied from 0.61 in Michigan to 0.833 in Minnesota [2,9]. In western New York, the nest success rate of 6 sora nests was 0.43, and the daily nest success rate was 0.97 [34]. Using data from the Cornell Laboratory of Ornithology's nest record program, nesting success rate of soras in North America was estimated as 0.529 over a 28-day period (n=108) [9]. On a site in Alberta, 80.6% of eggs successfully hatched, while the following year only 59.6% of eggs hatched. The authors conclude that diminished water level interacting with predators and trampling by cattle resulted in decreased hatching success [36].

During late summer, soras are flightless for a period during their post-nuptial molt [2].

Home Range: Sora home range size varies. Sora brood-rearing home ranges in northwestern Iowa averaged 0.5 acre (0.19 ha) [26]. In Arizona, sora home range size varied from 1.5 acres (0.59 ha) in the early breeding season to over 2 acres (0.91) ha in the postbreeding season. These seasonal differences in sora home range size were not significant (p>0.05) [8].

Survival: Few data are available on the survival of soras. Radio-marked soras in Arizona had a nonbreeding survival probability of 0.308. The authors suggest the low survival rate may be due to increased mortality of radio-marked birds [9]. Likely causes of mortality are predation (see Predators) and human-caused sources such as road kill [2].

PREFERRED HABITAT:
Water and emergent vegetation are important sora habitat characteristics.

Water: Soras use areas with a wide range of water depths. They are often observed in water less than 1 foot (30 cm) deep [24,38,50,54], although the average water depth of sora heavy-use areas in Arizona was 20 inches (52.2 cm) [8]. In northwestern Iowa, average water depth in sora territories was 15 inches (38.4 cm), which was significantly (p<0.025) more shallow than water depths at random locations in the marsh [27]. Sora nesting sites occurred in shallower water than random sites in western New York [34]. Average water depths reported at nest sites range from 4 inches (10.7 cm) for 4 sora nests in Colorado [23] to nearly 10 inches (24.2 cm) for sora nests in western New York [34]. In areas of deep water, soras typically wade on mats of floating vegetation [23,26].

Water level fluctuations may result in nest abandonment. For example, at a site in Colorado where water level increased more than 8 inches (20 cm), a sora nest with 7 eggs was abandoned [24]. In Alberta, soras nested in more vegetation types during a drought year, most likely due to substantially reduced water levels in the vegetation used the previous year [36].

Soras use areas with shallower water in fall than in spring [8,50,54]. It is likely that these seasonal differences reflect variation in availability of different habitats rather than habitat preference changing seasonally [54]. The mean water depths of sora locations in northeastern Missouri during spring and fall are shown in the table below [50].

Mean water depth in mm (range)
Spring (n=60) 181 (27-433)
Fall (n=68) 148 (54-301)

Soras typically avoid open water. There is a significant (p≤0.05) negative relationship between area of open water and sora use of wetlands in Maine [19] and sora relative abundance in Saskatchewan [57]. In western New York, sora nesting sites had a lower percentage of open water than random sites [34], and in Arizona soras used open water areas less than their availability [8].

Emergent vegetation: Sora nesting sites had larger percentage of emergent vegetation than random sites in marshes of western New York [34]. Sora numbers in wetlands of northeastern North Dakota were significantly (p<0.05) positively correlated (r=0.45) with hectares of live emergent vegetation [32]. In east and central Maine, wetlands used by soras had significantly (p=0.01) greater area of emergent vegetation than unused wetlands [19].

Density of emergent vegetation in sora habitat varies. Reported density of emergent vegetation ranges from an average of 121.9 stems/m in sora territories in northwestern Iowa [27] to 333 stems/m on sites in northeastern Missouri used during fall migration [50]. In western New York, cover was greater than 70% at 95% of sora nests. In addition, nesting sites had more horizontal cover at 20 inches (0.5 m) above water level than random sites [34]. However, average stem density on sora territories was not significantly (p>0.05) different from random sites in northwestern Iowa [27].

Height of emergent vegetation in sora habitat also varies. Height of vegetation reported in the literature ranged from 8 to 11 inches (20-30 cm) in the spring after a winter disturbance in northwestern Iowa [27] to 84 inches (213 cm) in areas heavily used by soras in Arizona [8]. In marshes of western New York, average vegetation height at sora nesting sites was shorter than at random locations [34]. However, the average height of emergent vegetation in sora territories in northeastern Iowa was not significantly (p>0.05) different from the height of vegetation in random plots [27].

In Arizona, both cover and height of vegetation used by soras varied with seasons. Conway suggested the differences likely reflected the varied diet of the sora [8]. The availability of habitat in different seasons is another possible source of seasonal differences in sora habitat [54].

Extent of woody vegetation surrounding South Dakota wetlands was not significantly (p=0.6) associated with sora occurrence [45]. However, in marshes of western New York, there was a significant (p=0.041) negative relationship between percent flooded timber on a site and sora relative abundance [34].

Soras may prefer some cover types. In Arizona, 65.3% of sora use was in southern cattail (Typha domingensis), although it comprised only 16.5% of the vegetation. Bulrushes and a mixed-shrub community were also used more than their availability, while saltcedar (Tamarix chinensis) and arrowweed (Pluchea sericea) were avoided [8]. A literature review notes sora avoidance of purple loosestrife (Lythrum salicaria)-dominated sites [6]. In east and central Maine, wetlands used by soras had significantly (p=0.05) more ericaceous vegetation, such as leatherleaves (Chamaedaphne spp.), sweetgales (Myrica spp.), and laurels (Kalmia spp.) [19]. In marshes of northwestern Iowa, broadleaf arrowhead (Sagittaria latifolia) occurred in sora territories significantly (p<0.01) more often than at random sites. Johnson and Dinsmore [27] imply that this likely results from both species preferring similar site conditions. In May and June in Wisconsin, soras were detected significantly (p<0.025) more often in cattail (Typha spp.) survey areas than in sedge areas [51]. However, in southeastern Wisconsin during the breeding season, there was no significant (p=0.943) difference in sora densities between habitats comprised predominantly of cattail, sedge, or bulrush [38]. In addition, soras' use of glaucous cattail (Typha glauca), broadfruit bur-reed (Sparganium eurycarpum), sedge, river bulrush (Schoenoplectus fluviatilis), and hardstem bulrush (S. acutus var. acutus) habitats in marshes of northwestern Iowa generally reflected availability of these habitats [27].

Seasonal differences in sora habitat use have been reported. In northeastern Missouri in spring, the likelihood of detecting sora in robust emergents, such as cattail (Typha spp.) and longroot smartweed (Polygonum amphibium var. emersum), was over 6 times that of detecting soras in these areas in fall. However, availability of habitats during various times of the year was not addressed [50]. In a study performed in southeastern Missouri, plant species used by sora during spring and fall migration differed significantly (p=0.005). However, the author qualifies this finding with his observation of major seasonal differences in vegetation availability [54].

Temperature: Temperature may also influence sora abundance. In Colorado, average April temperature was significantly (p<0.01) negatively correlated (r= -0.94) with sora abundance. On sites that had average April temperatures ≤42 F (5.6 C), soras were more abundant than closely related Virginia rails (Rallus limicola), while on warmer sites the sora to Virginia rail ratio declined [24].

Densities: Sora densities reported in literature reviews vary from to 12 soras/acre in Colorado [12] to 0.47 pair/ha in Indiana [42]. An average of 1.3 soras/ha responded to calls across sites in Colorado [24]. A similar density of soras was found in southeastern Wisconsin [38]. In Iowa, average density over 2 years and several marsh habitats was 1.3 pairs/ha [27].

Effects of spatial arrangement/area: Landscape factors, such as marsh area, habitat edges within marshes, and the number of marshes in a region may influence soras.

Although soras occur in marshes of all sizes, they may occur at higher densities in intermediate-sized marshes. Soras were significantly (p≤0.01) positively related with total wetland area and perimeter area of surface water in east and central Maine [19] and were significantly (p<0.05) positively related to area of wetlands in Saskatchewan [57]. In Maine, soras used 10% of 2.5-acre (1 ha) wetlands, 40% to 50% of wetlands from 2.5 to 50 acres (1-20 ha) in size, and 20% of wetlands larger than 50 acres (20 ha). [19]. In western New York, soras were significantly (p=0.007) more abundant in marshes from 100 to 250 acres (41-100 ha) in size than in smaller (<100 acres (41 ha)) or larger (250-380 acres (101-155 ha)) marshes. In addition, sora nests were detected more often in the 100- to 250-acre (41-100 ha) marshes [34].

Soras also seem to prefer edge habitats. Breeding sora density was significantly (p<0.001) correlated (r=0.62) with the perimeter:area ratio of northwestern Iowa marshes. The distance from the center of sora territories to a habitat edge was also significantly (p<0.005) less than from the center of Virginia rail territories [27]. In Arizona, habitat edges were closer to sora heavy use areas than random sites [8].

Wetland dynamics at a large scale can affect soras. Indices of sora population at 3 "levels of response" were significantly (p<0.01) correlated (r≥0.70) with the number of ponds present in the prairie pothole region of North Dakota in May [47].

FOOD HABITS:
Soras eat a wide range of foods. Animals that are commonly reported as sora food items include snails (Gastropoda), crustaceans (Crustacea), spiders (Araneae), and insects (Insecta), mainly beetles (Coleoptera), grasshoppers (Orthoptera), flies (Diptera), and dragonflies (Odonata) [25,39,40,53]. Soras often eat the seeds of plants, such as smartweeds, bulrushes, sedges, and barnyard grasses [2,25,39,40,53]. Seeds of annual wildrice (Zizania aquatica) and rice cutgrass are eaten by soras in the eastern United States [39,40]. A literature review lists crowngrass (Paspalum spp.) and rice (Oryza sativa) as relatively important food sources for soras in the Southeast. Plants comprising <5% of the sora's diet are also listed and include spikerushes (Eleocharis spp.), duckweeds (Lemnaceae), pondweeds (Potamogeton spp.), panicgrasses (Panicum spp.), cordgrasses (Spartina spp.), and saltgrass (Distichlis spicata) [39].

According to a literature review, soras eat more plant food in fall and winter (68%-69%) than in spring and summer (40%) [39]. Plant material such as hairy crabgrass (Digitaria sanguinalis), fall panicgrass (Panicum dichotomiflorum), and bristlegrass (Setaria spp.) occurred at substantially higher frequencies and in much larger volumes in sora esophagi collected in southeastern Missouri during fall migration than those collected in spring. In addition, animals comprised a larger volume of the spring diet than the fall diet. The volume of animal material in esophagi collected in spring was predominantly composed of adult beetles and snails from the Physidae family [53].

PREDATORS:
Sora eggs are eaten by several species including American minks (Mustela vison), skunks (Mephitidae), coyotes (Canis latrans), grackles (Quiscalus spp.), crows (Corvus spp.), and herons (Ardeidae) [2,14,36]. Predation of adult soras by American minks, coyotes and peregrine falcons (Falco peregrinus) has been reported [14,36,46].

MANAGEMENT CONSIDERATIONS:
Sora populations in the United States have been declining. Breeding bird survey data show a 3.3% annual decline in sora populations from 1966 to 1991. Although populations in Canada were stable from 1982 to 1991, sora populations in the United States declined significantly (p<0.01) during the same period, at an average rate of 8.5% annually. Population declines in central North America were the most severe [9]. Reviews also note sora declines [12,50].

Use of playback calls has been shown to increase detection of soras [20,34,51]. Use of playback calls in developing monitoring programs for soras has been investigated by [21,35,38].

Grazing is likely to negatively impact sora habitat. In southeastern Oregon, sora did not occur on a site where grazing was recently (0-2 years) excluded, but did occur on a nearby site where grazing had been excluded for 30 years. Soras occurred after 3 years of no grazing on the previous site [13]. Management recommendations based on expert opinion suggest that sora be considered when developing a grazing plan, as grazing consistently has a negative impact on wetland habitats [65].

FIRE EFFECTS AND USE

SPECIES: Porzana carolina
DIRECT FIRE EFFECTS ON ANIMALS:
Soras may be more vulnerable to direct fire impacts than many birds. In addition to their terrestrial habits, adult sora are flightless for a period after breeding while they molt [2]. However, 2 prescribed fires in the coastal prairie of Texas during February and March did not result in any rail (Rallidae) mortality. Rails, including soras, were thought to have survived by seeking shelter under damp vegetation. The authors suggest burning later in the spring or in the summer, when amounts of standing water are reduced, could lead to a larger direct impact [22]. See the Research Paper by Grace and others [22] for details of this study. In addition to season, the scale of burning can also influence rail survival. Patchy prescribed burns in Florida in August left many 0.1- to 2-acre (0.04-0.8 ha) unburned areas, where black rails (Laterallus jamaicensis) were observed immediately after burning. In contrast, widespread prescribed fires that burned 90% of 2,400 acres (970 ha) in January resulted in direct bird mortality, possibly due to burning of the areas birds used for shelter. The authors strongly encourage the incorporation of wildlife escape areas into burning plans [31].

Although there were no data directly investigating sora nest mortality due to fire as of 2006, literature reviews have used fire characteristics and life history of species to speculate on possible effects of fire on nesting success and bird populations [37,52]. Since soras nest on the ground, even low-severity fires could have negative impacts on eggs and nestlings. Young nestlings are less mobile than adults [28], which could limit their options when seeking shelter from fire. The possibility of sora renesting may reduce the direct effects of a fire on sora recruitment [37,52]. Nests impacted early enough in the breeding season could be compensated for by later nesting attempts. However, since soras typically rear only 1 brood per year (see Timing of Major Life History Events), fires in the mid- to late-breeding season may have a larger detrimental effect on sora recruitment. In addition to the timing and uniformity of the burn, other fire characteristics such as the fire severity and frequency are likely to influence the degree to which fire directly impacts sora reproduction [37].

Despite the lack of direct impact of fire on rails during prescribed fires in the coastal prairie of Texas, indirect mortality of Virginia rails and yellow rails (Coturnicops noveboracensis) due to fire-related predation was observed [22].

HABITAT-RELATED FIRE EFFECTS:
Very little information is available on the effects of fire on soras. The available information is limited in several respects including temporal and spatial scale. There is also a lack of information regarding the effects of various site and fire characteristics on soras' response to burning. In addition, as of 2006 there were no comparisons of sora demographic data from burned and unburned areas.

Soras may leave burned areas soon after fire. Within 4 days of a prescribed burn on the coastal prairie of Texas, a sora left the area, possibly due to unsuitable habitat [22]. Immediately after patchy prescribed burns in Florida, black rails were observed in unburned areas [31]. In addition, a review states that the lack of cover available after fire results in rails leaving burned areas [7].

Soras have been reported in recently burned areas. For instance, 2 soras were observed on the shoreline of a man-made pond in northern Florida within 5 months of a winter prescribed burn. Soras were not observed in the unburned portion of the shoreline [61]. On a Colorado site where 90% of the area had been burned under prescription in previous winters, a large number of rails, most likely Virginia rails and soras, was observed during spring migration in remaining and new (<12 inches (30 cm)) narrow-leaved cattail (Typha angustifolia) vegetation [23].

There is limited evidence that soras may not be greatly affected by fire. In a study on Matagorda Island, Texas, members of the Rallidae family did not exhibit significant (p>0.24) responses to winter or summer prescribed burns either 6 to 10 months or 18 to 22 months after fire [60]. In the Chenier Plain in southwestern Louisiana, winter prescribed burning in habitats of varying management history and salinity did not have substantial effects on soras. The following table shows the average number of soras detected per survey in each of the habitats in the 3 springs (April-June) following treatment [17]

Year

Burned

Unburned

Impounded Not impounded Impounded Not impounded
Brackish Intermediate Brackish Saline Brackish Intermediate Brackish Saline
1996 0.1 0.0 0.1 0.2 0.0 0.0 0.1 0.1
1997 0.0 0.1 0.1 0.0 0.0 0.1 0.1 0.0
1998 0.0 0.1 0.2 0.0 0.1 0.2 0.1 0.1

Since emergent vegetation provides cover and food for soras, the response this vegetation has to fire is likely to have a large influence on the effect a fire will have on soras. Wetlands typically recover quickly after fire. A review summarizes a report of vegetation in a Florida freshwater marsh nearing complete recovery 6 months after prescribed burning [62]. Vegetation structure on a site in southwestern Louisiana returned to prefire conditions within 1 year of a winter prescribed burn [17]. In Glacier National Park, Montana, sedge meadows were mostly revegetated the year following the 1988 Red Bench Wildfire [63]. In South Dakota, screening cover 1 growing season after spring prescribed burns was not significantly (p>0.05) different from cover before the treatment [55]. On a burned shoreline in Florida, frequency of maidencane (Panicum hemitomon) and swamp smartweed (Polygonum hydropiperoides) was similar on burned and unburned sites the May following a winter prescribed burn. In addition, burning resulted in higher productivity of the wet-prairie vegetation [61].

Somewhat longer recovery times have been reported. In cordgrass/crowngrass habitat on Matagorda Island, vegetation attributes recovered to prefire levels by 18 to 22 months after spring and fall prescribed burns [60]. After a wildfire in a Texas tidal flat, community structure did not recover for 16 months, vegetative cover did not met or exceed prefire cover for 19 months, and live and litter biomass had not reached prefire levels by postfire month 26 [33].

The response of marsh vegetation to fire is influenced by several factors including fire characteristics such as severity and season of burning, and site conditions such as salinity and hydrologic factors.

High-severity fires that burn into the organic layer are likely to result in long recovery times. Areas of sedge meadows of Glacier National Park where the peat had been completely consumed in the Red Bench Wildfire recovered more slowly than areas where rhizomes and roots had survived [63]. Rhizomatous plant species are likely to survive fires that do not burn deep into the organic ground layer, resulting in quick recovery of vegetation after fire [17,63]. A review summarizes the effect of fire severity on marshes, including references to severe fires consuming peat and resulting in long vegetation recovery times and the creation of open water [48].

Season of burn can affect the response of marsh vegetation to fire. There was no significant (p>0.05) difference in screening cover a growing season after spring prescribed burning in a narrow-leaved- and common cattail (Typha latifolia)-dominated wetland of South Dakota. However, sites that were burned in fall had significantly (p<0.05) less cover 1 growing season after fire than before the burn [55].

Site characteristics also influence vegetation response to fire. Results of a study on a marsh in Florida suggest that fire can have variable effects that are related to hydrology and nutrients [30]. Researchers investigating prescribed fires in southwest Louisiana note the probable influence of several site factors such as plant community composition before the burn, water depth, and salinity [17]. A review summarized the role of salinity and other preexisting site conditions on postfire succession in eastern marshes [62].

Fire ecology: According to a review, wetlands tend to burn during drought, and small wetlands and marshes can burn at frequencies similar to adjacent vegetation [11]. For information regarding presettlement fire regimes of marshes, peatlands, and swamps of the southeast see [16]. A review discusses succession in eastern marshes [62].

The following table provides fire return intervals for plant communities and ecosystems where sora is important. For further information, see the FEIS review of the dominant species listed below.

Community or ecosystem Dominant species Fire return interval range (years)
bluestem-Sacahuista prairie Andropogon littoralis-Spartina spartinae <10
northern cordgrass prairie Distichlis spicata-Spartina spp. 1-3 [49]
Everglades Mariscus jamaicensis <10 [43]
mountain grasslands Pseudoroegneria spicata 3-40 (x=10) [3,4]
tule marshes Scirpus and/or Typha spp. <35
southern cordgrass prairie Spartina alterniflora 1-3 [49]

FIRE USE:
There is a large amount of uncertainty regarding soras' response to fire, and much more data are need to make detailed recommendations. The data currently available suggest that low-severity fires, performed when soras are not present on a site and at frequencies that allow emergent vegetation to recover, will likely have the least negative impact on soras. Incorporation of escape areas into burning plans [31] will likely minimize direct impacts of fires on soras when they are present on a site. Patchy burns may have long-term benefits as well, given the possible preference of soras for edge habitats (see Effects of spatial arrangement/area). In addition to fire characteristics, site conditions that influence vegetation recovery, such as hydrology and species composition, may impact soras' response.

REFERENCES:


1. American Ornithologists' Union. 2011. The A.O.U. check-list of North American birds, 7th ed., [Online]. American Ornithologists' Union (Producer). Available: http://www.aou.org/checklist/north/index.php. [50863]
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