ML070720596
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| Site: | Susquehanna  |
| Issue date: | 03/07/2007 |
| From: | NatureServe |
| To: | Office of Nuclear Reactor Regulation |
| ALICIA MULLINS 301-415-1224 | |
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| Download: ML070720596 (5) | |
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Comprehensive Report Species - Cistothorus platensis
<< Previous l Next >> View Glossary Cistothorus platensis - (Latham, 1790)
Sedge Wren Search for Images on Spanish Common Names: Chivir*Sabanero, Cherc*de las Vegas Google French Common Names: Troglodyte *ec court Other Common Names: Curru*-do-Campo Unique Identifier: ELEMENT_GLOBAL.2.105322 Element Code: ABPBG10010 Informal Taxonomy: Animals, Vertebrates - Birds - Perching Birds Kingdom Phylum Class Order Family Genus Animalia Craniata Aves Passeriformes Troglodytidae Cistothorus Genus Size: B - Very small genus (2-5 species)
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Concept Reference http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cistothorus+platensis (1 of 5)3/7/2007 11:24:09 AM
Comprehensive Report Species - Cistothorus platensis Conservation Status Distribution Ecology & Life History Basic
Description:
A small bird (wren).
General
Description:
ADULT: plumage is warm and pale brown overall, giving the birds a "dull, plain-faced" appearance (Vickery 1983). The deep brown wing coverts and short tail are barred, the flanks are buff-orange, the chin, throat and center belly are dull white, and the undertail coverts are plain buff. The crown is "finely, somewhat obscurely, streaked with tan and dark brown" (Vickery 1983), and the tail is typically cocked over the back. Sexes have similar plumages, and males are about a gram heavier than females (Taylor et al. 1983).
JUVENILE: similar to adults except that the streaking on the head and neck is less conspicuous, and the juvenal plumage is darker above and more buffy on the throat and abdomen (Forbush 1929, Walkinshaw 1935).
NEST: well-hidden, rounded balls made of woven, fine grasses and culms of sedges, and are often built near the ground (< 0.5 m) and attached to live stems of grasses and sedges (Walkinshaw 1935, Tordoff and Young 1951, Harrison 1978). Typically have a single side-entrance.
EGGS: ovate or pointed-ovate, white and unmarked, and smooth and moderately glossy (Harrison 1978). Measurements of 50 eggs averaged 16 x 12 mm (Bent 1948).
VOCALIZATIONS: The song of males is a dry, staccato chattering: "chap chap chap chapper-rrrrr" (Peterson 1980). Among individuals, the song's introduction is stereotyped, whereas the trill is highly variable (Kroodsma and Verner 1978). The call note is "churr churr," "chap churr," or "chap" (Bent 1948, Peterson 1980). Frequently sing at night (Vickery 1983).
Diagnostic Characteristics: In contrast to marsh wrens (CISTOTHORUS PALUSTRIS), the only other wren occurring in eastern wetlands, sedge wrens lack a distinct white stripe over the eye, are lighter-colored, and have a shorter bill (Vickery 1983).
Reproduction Comments: CHRONOLOGY: Nesting phenology may be related to site latitude and often occurs in two "waves" during a given season. Arrive at nesting areas as early as mid-April (Bent 1948) in some regions or as late as July in others (Lingle and Bedell 1989), and have been observed nesting as late as the end of September (Schwilling 1982). Nesting in many northeastern states is not initiated until July. In more northerly latitudes, nesting may be initiated from May to June, e.g., in North Dakota, Wisconsin, Minnesota, and Michigan, and again in late July through August, whereas in more southerly areas, e.g., Kansas and Arkansas, nesting may not be initiated until the latter period (Lingle and Bedell 1989). Late nesting at certain sites could represent renesting attempts by birds arriving from elsewhere or could be an adaptive response of local birds to delayed availability of moist, but unflooded, grassland habitats. Peak nesting populations in mixed-grass prairie in North Dakota occurred after unusually wet springs, but nesting activity showed little response to spring temperature (Cody 1985). Occupancy of a given site varies among years, and sites used one year may be abandoned the next (Palmer 1949, Burns 1982).
COURTSHIP AND BREEDING BEHAVIOR: Upon arrival at nesting areas, males establish territories that are used for courtship, nesting, and foraging (Burns 1982). Territory boundaries are fluid throughout the nesting season, and males may shift their activity and defend new areas as the season progresses. Males defend territories and attract mates by singing vigorously throughout the breeding season, as much as 22 h/day and at rates of up to 12-15 songs/min (Walkinshaw 1935, Kroodsma and Verner 1978). This combination of song components may permit mixing of highly dispersive populations (Kroodsma and Verner 1978) and may represent an evolutionary compromise between species identification and sexual selection among individuals. Because local dialects would be swamped in such highly mobile populations, neighboring males do not share song-type repertoires nor do they counter-sing by matching song-types (cf. marsh wren).
NESTING: Male CISTOTHORUS wrens build multiple, domed nests that figure prominently in courtship, and may also serve as dormitories and decoys for predators (Verner 1965, Picman and Picman 1980, Burns 1982). In Minnesota, males built an average of 7.4 complete nests and 0.8 incomplete nests on each territory (Burns 1982). Nests used for incubating eggs are built closer to the ground than dummy nests (Walkinshaw 1935) and have a substantial inner lining of grass, sedge, and feathers added by the female (Burns 1982).
Females begin laying one egg daily about the third day of nest lining (Burns 1982), and initiate incubation before the clutch is complete. Usually 7 eggs are laid per clutch (range is 2 to 8), although clutches laid later in the season may be smaller than earlier clutches (Bent 1948, Harrison 1978, Burns 1982). Clutch size 4 in Costa Rica (Stiles and Skutch 1989). Incubation is by the female only and lasts about 14 days (Burns 1982).
http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cistothorus+platensis (2 of 5)3/7/2007 11:24:09 AM
Comprehensive Report Species - Cistothorus platensis Females in some populations are double-brooded (Walkinshaw 1935, Burns 1982), but are single-brooded in others (Crawford 1977). Males may be serially or simultaneously polygynous and females may be serially polyandrous (Crawford 1977, Burns 1982).
Mates of monogamous males had higher reproductive success than both primary and secondary females mated with polygynous males, whereas polygynous males had higher reproductive success than monogamous males (Burns 1982).
Nest success (nests with at least one egg hatching) was reported at 68% (n = 31 nests, Crawford 1977) and 69% (n = 18 nests, Burns 1982). Sources of nest loss include predation, infertile clutches, heavy rains, trampling by grazing cattle, and nest destruction by other sedge wrens (Walkinshaw 1935, Crawford 1977, Picman and Picman 1980, Burns 1982). The nestling period lasts 13-14 days (Walkinshaw 1935, Crawford 1977). Fledging success (number of young fledged per number of eggs laid) has been reported at 0.67 in Minnesota (Burns 1982). Virtually all parental care of nestlings is provided by the female, although males occasionally feed nestlings (Walkinshaw 1935, Burns 1982). Nest-building and continual defense by males of territories with abundant food may compensate females for a lack of male parental care of offspring. Fledglings move about in small groups until migration occurs (Gibbs and Melvin 1992).
Ecology Comments Nesting territory size averages about 0.2 ha (Byrd and Johnston 1991). Forty weekly estimates of territory size for five males in Minnesota averaged 1,280 meters squared (Burns 1982). Densities (males per ten ha) of nesting birds have been reported as four in grazed areas and 12 in ungrazed areas in Nebraska (Lingle and Bedell 1989), 86 in Michigan (Walkinshaw 1935), 18 in Wisconsin (Manci and Rusch 1988), 12 in Illinois (Birkenholz 1984), 15 in North Dakota (Higgins et al. 1984), 19 in Minnesota (Hanowski and Niemi 1986), three in Kansas (Cink and Sepahi 1983), seven in Iowa (Wilson 1983), and three in Maryland (Stewart and Robbins 1958). May destroy the eggs of other sedge wrens or other small birds.
Habitats are characterized by vegetation types and soil moisture regimes that are highly susceptible to drying or flooding caused by annual and seasonal variation in rainfall. Vegetative succession and disturbance by grazing, haying, and planting also impart a highly transitory character to nesting habitats. This habitat instability may lead to the high mobility and low site tenacity of sedge wrens (Kroodsma and Verner 1978). The complete regional absence in some years, however, suggests that some factor in addition to habitat instability is involved in population fluctuations, perhaps regional patterns of rainfall (Cody 1985) or weather conditions during migration. The nature of the communication system as a unique adaptation to high population mobility (Kroodsma and Verner 1978) suggests that opportunistic breeding and low site tenacity has occurred for a long time, rather than being of recent origin, such as in response to agriculture and habitat loss (Burns 1982). These birds are "curiously local" and occur sporadically within the Andean Zone of South America, and there is no reason to believe that anthropogenic factors influence the species' distribution there (Fjeldsa 1988).
Non-Migrant: N Locally Migrant: Y Long Distance Migrant: Y Mobility and Migration Comments: Migration occurs in September or October, depending on the region (Bent 1915, Walkinshaw 1935). Incidental kills at transmitting television towers in Florida suggest that most fall migration occurs in October, well after the migration of most warblers, vireos, and other, similarly sized passerines is underway (Taylor et al. 1983). Clustering of multiple wren species at tower kills indicates that sedge wrens migrate in flocks with other wrens (Taylor et al. 1983). In southern South America, migrates north for the austral winter.
Estuarine Habitat(s): Herbaceous wetland Palustrine Habitat(s): Bog/fen, HERBACEOUS WETLAND, Riparian Terrestrial Habitat(s): Cropland/hedgerow, Grassland/herbaceous, Savanna Habitat Comments: BREEDING: Grasslands and savanna, especially where wet or boggy; sedge marshes; moist meadows with scattered low bushes; upland margins of ponds and marshes; coastal brackish marshes of cordgrass, herbs, and low shrubs; locally in dry cultivated grainfields (AOU 1983). Avoids cattail marshes. Sings from exposed perch, otherwise creeps and hops on or near ground in tall sedgy grass or wet tangles at the bases of shrubs (Colombia, Hilty and Brown 1986). Nests low in tall dense growths of sedges or grasses, or similar herbage, very near ground, or over shallow water (Harrison 1978).
Nesting areas may change opportunistically from year to year as conditions change. Several nests are built within a single breeding territory each season. Nesting takes place among dense, tall growths of sedges and grasses in wet meadows, hayfields, retired croplands, and upland margins of ponds and marshes. It also occurs in coastal, brackish marshes. Scattered shrubs and an http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cistothorus+platensis (3 of 5)3/7/2007 11:24:09 AM
Comprehensive Report Species - Cistothorus platensis absence of standing water are also typical features of nesting habitats. Highly sensitive to habitat conditions, and abandon sites rendered too dry by drainage or drought or too wet by flooding. Will also abandon sites if shrubs become too prevalent.
Opportunistic breeders and may renest at different locations during the same breeding season. Usually do not occupy the same site for more than one to three years.
In South Dakota, preferred sites within landscapes dominated by grassland; size of individual breeding habitat patch was not as important as was its landscape context (Bakker et al. 2002).
In New England, Bagg and Eliot (1937) suggested that sedge wrens colonized wet meadows early in the nesting season but, due to summer drying, used permanently wet, tussocky marshland in July for renesting. Nesting has been reported in Maine from a variety of habitat types, including wet fields, bush-covered pastures, sedgy and grassy meadows, marshes, bogs, and thick, grassy areas on barren lands (Palmer 1949). Preferred habitats in tidewater areas in Maryland consisted of switchgrass (PANICUM VIRGATUM) meadows along the inner margins of tidal marshes (Stewart and Robbins 1958). In the Allegheny Mountains of Maryland, sedge meadows in boreal bogs were usually occupied, whereas orchard grass pastures and hayfields were used at upland sites elsewhere in the state (Stewart and Robbins 1958).
At moist soil impoundments in Missouri, associated with unflooded areas with rank or dense vegetative cover, and avoided short, sparse, or open vegetative cover, openings, and flooded areas (Fredrickson and Red 1986). In a large, marsh complex in Wisconsin, Manci and Rusch (1988) observed them primarily in habitats dominated by sedges (CAREX spp.), and secondarily in upland grasslands. Avoided areas of deepwater cattail (TYPHA spp.), shallow-water cattail, dry cattail, and river bulrush (SCIRPUS FLUVIATILIS).
In Minnesota, preferred dense sedge growth intermixed with patchy, one to two m high shrubs (Niemi and Hanowski 1984).
Average vegetative characteristics territories in Minnesota were 303 sedge stems/meter squared, 16 forb stems/meter squared, 50 shrub stems/meter squared, and a predominant vegetation height of 1.1 m (Niemi 1985). Higher densities occurred in areas with medium shrub densities (11-32 stems/0.0025 ha) than in areas with more or less shrub growth (Niemi and Hanowski 1984). At another Minnesota site, major vegetation types in territories were stands of great bulrush (SCIRPUS ACUTUS), tussock sedge (CAREX STRICTA), and water sedge (C. AQUATILIS) and monotypic stands of C. AQUATILIS (Burns 1982).
At Delta Marsh, Manitoba, occurred in wet, white-top (SCOLOCHLOA FESTUCACEA) and sedge (CAREX ATHERODES) meadows (Picman and Picman 1980). Crawford (1977) studied them in a glacial marsh complex in Iowa, and found nests in drier sites around marshes in areas dominated by reed canary grass (PHALARIS ARUNDINACEA) (17 nests) and river bulrush (14 nests) stands. Reproductive success was higher, however, for males with territories consisting primarily of bulrush (SCIRPUS FLUVIATILIS). Similarly, Walkinshaw (1935) considered the portion of a marsh intermediate between deepwater sections and the bordering meadow to be preferred habitats in Michigan. Birds used areas where sedges and grasses predominated, with clumps of shrubs and herbaceous growth, and with no standing water.
In a Nebraska study, wrens avoided high ground and occurred most commonly along moist, ungrazed margins of relict channels (sloughs) where water sedge, common ragweed (AMBROSIA ARTEMISIFOLIA), and river bulrush predominated (Lingle and Bedell 1989). A southward-sloping hillside dominated by a mixture of rank grasses and weeds about one m high, interspersed with clumps of smooth sumac (RHUS GLABRA), supported a nesting population during a particularly wet year in Kansas (Tordoff and Young 1951).
NON-BREEDING: Little information is available on wintering habitats. Presumed similar to breeding habitat, but in migration and winter also in brushy grasslands (AOU 1983). Brackish and freshwater sedge meadows and marshes are used, as are old fields and prairies with dense, matted grass or weeds (Howell 1932). Drier portions of salt marshes may be used during migration (Forbush 1929, Palmer 1949).
Adult Food Habits: Invertivore Immature Food Habits: Invertivore Food Comments: Eats insects and spiders (Terres 1980); picks items from the ground or from foliage. Information on diet is limited. Howell (1932) examined 34 stomachs of sedge wrens overwintering in Florida and concluded that the diet consisted wholly of spiders and insects, including ants, bugs, weevils, ladybird beetles, moths, caterpillars, locusts, crickets, and grasshoppers.
Seven stomachs of sedge wrens from Pennsylvania contained beetles and spiders (Warren 1890). Walkinshaw (1935) observed the birds feeding their young moths, spiders, mosquitos, flies, grasshoppers, and bugs.
The "mouse-like," inconspicuous foraging behavior (Howell 1932, Walkinshaw 1935) suggests that these birds forage mainly at ground level, probably for insects hiding in moist soil and among bases of sedges and grasses. Particular adaptations of sedge wrens to foraging in shrubby grasslands include their small size, relatively long bills, and longer pelves and legs in comparison to congeners using forested habitats (Niemi 1985). The abundance of insect food in frequented upland habitats is probably a function of rainfall, soil moisture, and productivity of adjacent marshlands. Aquatic insects characteristically move from wetlands following http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cistothorus+platensis (4 of 5)3/7/2007 11:24:09 AM
Comprehensive Report Species - Cistothorus platensis metamorphosis and seek refuge on nearby uplands (Orians 1980), where they may serve as an important food source.
Adult Phenology: Diurnal Immature Phenology: Diurnal Length: 11 centimeters Weight: 9 grams Economic Attributes Management Summary Population/Occurrence Delineation Not yet Population/Occurrence Viability assessed U.S. Invasive Species Impact Rank (I-Rank)
Not yet Authors/Contributors assessed Not yet assessed References Use Guidelines & Citation Version 6.1 (9 November, 2006)
Ecological systems data last updated:
February 10, 2007 NatureServe All other data last updated: October 6, 2006 http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cistothorus+platensis (5 of 5)3/7/2007 11:24:09 AM