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Effects of Management Practices on Wetland Birds:

Marsh Wren

This resource is based on the following source:

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Organization and Features of this Species Account

Information on the habitat requirements and effects of habitat management on wetland birds were summarized from information in more than 500 published and unpublished papers. A range map is provided to indicate the relative densities of the species in North America, based on Breeding Bird Survey (BBS) data. Although the BBS may not capture the presence of elusive waterbird species, the BBS is a standardized survey and the range maps, in many cases, represent the most consistent information available on species' distributions. Although birds frequently are observed outside the breeding range indicated, the maps are intended to show areas where managers might concentrate their attention. It may be ineffectual to manage habitat at a site for a species that rarely occurs in an area. The species account begins with a brief capsule statement, which provides the fundamental components or keys to management for the species. A section on breeding range outlines the current breeding distribution of the species in North America, including areas that could not be mapped using BBS data. The suitable habitat section describes the breeding habitat and occasionally microhabitat characteristics of the species, especially those habitats that occur in the Great Plains. Details on habitat and microhabitat requirements often provide clues to how a species will respond to a particular management practice. A table near the end of the account complements the section on suitable habitat, and lists the specific habitat characteristics for the species by individual studies. The area requirements section provides details on territory and home range sizes, minimum area requirements, and the effects of patch size, edges, and other landscape and habitat features on abundance and productivity. It may be futile to manage a small block of suitable habitat for a species that has minimum area requirements that are larger than the area being managed. The section on brood parasitism summarizes information on intra- and interspecific parasitism, host responses to parasitism, and factors that influence parasitism, such as nest concealment and host density. The impact of management depends, in part, upon a species' nesting phenology and biology. The section on breeding-season phenology and site fidelity includes details on spring arrival and fall departure for migratory populations in the Great Plains, peak breeding periods, the tendency to renest after nest failure or success, and the propensity to return to a previous breeding site. The duration and timing of breeding varies among regions and years. Species' response to management summarizes the current knowledge and major findings in the literature on the effects of different management practices on the species. The section on management recommendations complements the previous section and summarizes recommendations for habitat management provided in the literature. The literature cited contains references to published and unpublished literature on the management effects and habitat requirements of the species. This section is not meant to be a complete bibliography; a searchable, annotated bibliography of published and unpublished papers dealing with habitat needs of wetland birds and their responses to habitat management is posted on the main page under the section Searchable Bibliography.

Figure.  Breeding distribution of the Marsh Wren in the United States and southern Canada, based on Breeding Bird Survey data, 1985-1991. Scale represents average number of individuals detected per route per year. Map from Price, J., S. Droege, and A. Price. 1995. The summer atlas of North American birds. Academic Press, London, England. 364 pages.

Key to management is maintaining wetlands that have dense stands of emergent vegetation.

Breeding Range:

Suitable habitat:

In seasonal wetlands in eastern South Dakota, the presence of Marsh Wrens was significantly and positively related to the percent of wetland area that was vegetated, dominance of thick-stemmed emergent plants, and presence of untilled land surrounding the wetland (Naugle 1997). In semipermanent wetlands, the presence of Marsh Wrens was positively related to the percent of wetland area that was vegetated and to dominance of thick-stemmed plants. Preliminary data from D. H. Johnson (unpublished data) indicated that in North Dakota and South Dakota, number of breeding pairs of Marsh Wrens was highest in temporary, seasonal, and semipermanent wetlands and was lowest in alkali and permanent wetlands. Number of pairs was higher in restored wetlands than in natural wetlands, and on public land than on private land. Number of breeding pairs increased with increasing amounts of emergent vegetation to a point at which breeding pairs leveled off. Marsh Wrens were more common in wetlands that had semipermanent wetlands within 0.4 km than in wetlands without semipermanent wetlands nearby.

In Iowa, Marsh Wrens were more likely to be present in natural wetlands than in restored wetlands (Fairbairn and Dinsmore 2001a). The occurrence of Marsh Wrens was positively related to habitat diversity, which was a measure of the evenness of distribution of vegetation zones within a wetland. Density was positively related to the percent of wetland area within a wetland complex that was composed of wet-meadow vegetation, and to the area of emergent vegetation within a complex (Fairbairn and Dinsmore 2001b). Complexes were defined as tracts of land containing from 4 to 15 wetlands ranging from 44 to 144 ha. Occurrence was negatively related to the percent area of a wetland composed of mud flat and percent area composed of open water (Fairbairn and Dinsmore 2001a). Density was negatively related to the ratio of total wetland perimeter to total area of wetlands within a complex (Fairbairn and Dinsmore 2001b). In Wisconsin, density of Marsh Wrens varied according to habitat type (Manci and Rusch (1988). Densities were higher in stands of shallow- and deep-water cattails than in stands of river bulrush and dry cattails. Water depth in shallow-water cattail stands averaged 5 cm in early June, deep-water cattail stands averaged 29 cm in early June, dry cattail stands contained no standing water by late June, and river bulrush contained standing water until mid-August. In Alberta, Marsh Wrens were present in wetlands surrounded by newly planted dense nesting cover, but were absent from wetlands surrounded by cropland (Prescott et al. 1993). In Manitoba, densities and nest success were higher in a more heterogeneous wetland that supported mixed stands of cattail, common reed, and hardstem bulrush than in a wetland that supported homogeneous stands of cattail (Leonard 1986, Leonard and Picman 1987b). The heterogeneous wetland had taller (29 cm versus 12 cm), denser (measurements not given) vegetation and deeper (132 cm versus 92 cm) water than the homogeneous wetland.

Marsh Wrens nest over water or damp ground in domed structures anchored to emergent vegetation (Burt 1970, Salt and Salt 1976, Burger 1985, Picman 1986, Peck and James 1987, Kroodsma 1997). In Iowa, 96% of 227 nests were located in hairy sedge (Burt 1970). Nest locations indicated that Marsh Wrens were not selecting nest sites based on distance to open water or distance to a different vegetative cover type (vegetative cover types included cattail, hairy sedge, bluejoint, bur-reed, sweetflag [Acorus americanus], river bulrush, or prairie cordgrass [Spartina pectinata]). The height above water of 93 nests averaged 32 cm and ranged from 28 to 112 cm. In North Dakota, 88% of 25 nests were located in cattail, alkali bulrush, or mixtures of hardstem bulrush and sprangletop (Scolochloa festucacea) (Stewart 1975). Additional nests were located in river bulrush, hardstem bulrush/alkali bulrush, and cattail/sprangletop. The height of 23 nests above water averaged 41 cm and ranged from 18 to 63.5 cm. The water depth at 19 nests in North Dakota averaged 30 cm and ranged from 0 to 48 cm (Stewart 1975). In another North Dakota study, the height above water of eight nests averaged 12 cm (Krapu and Duebbert 1974). In Minnesota, Marsh Wren nests were found in stands of reed canary grass and timothy (Phleum pratense) (Svedarsky 1992). Nests in a restored wetland in Minnesota were found in stands of cattail, bulrush, and common reed (Svedarsky 1992). In Ontario, Marsh Wrens most commonly nested in stands of cattail; elevated nests were most often found in cattail (38% of 476 nest records) and less often in bulrush, grass, sedge, horsetail (Equisetum sp.), bur-reed, loosestrife (Lythrum), spiraea (Spiraea) or willow (Salix) (Peck and James 1987). The height of 234 nests ranged from 0.2 to 1.5 m above water. The vegetation supporting nests was usually dead, sometimes living, or a combination of both. Locations of 14 nests ranged from being adjacent to open water to 91 m from it, and water depths at 31 nests ranged from 5 to 91 cm. In Washington, Marsh Wrens preferred building nests in broad-leaved cattail (Typha latifolia) as long as standing water was present (Verner and Engelsen 1970). As cattail stands dried out, birds abandoned cattail stands to nest in stands of softstem bulrush (Schoenoplectus tabernaemontani) located in standing water. Presence of water could serve as protection against predation or to increase available food sources. Nest height of 81 nests used for breeding (as opposed to unoccupied nests) ranged from 76 to 93 cm (Verner 1965). Nest height of 548 unoccupied nests ranged from 80 to 95 cm.

In Manitoba, successful nests were surrounded by a significantly greater number of inactive multiple nests than were depredated nests. In Washington, pairing success (defined as the number of mates a male acquired) was positively correlated with total nest sites in a territory (Verner and Engelsen 1970). Male Marsh Wrens build multiple nests within individual territories, but only one is chosen by the female as a nest site; less commonly, new nests are built by females (Provost 1947, Burt 1970, Leonard 1986, Leonard and Picman 1987a, Metz 1991, Kroodsma 1997). Verner (1965) found that males build from 11 to 32 nests. Multiple nests may serve to increase nest success by decreasing the probability that a searching predator will find an active nest (Verner and Engelsen 1970, Leonard and Picman 1987a). Multiple nests also may indicate to females the presence of an ample food supply in that males have more time to build multiple nests because of less time needed to forage (Verner and Engelsen 1970). A table near the end of the account lists the specific habitat characteristics for Marsh Wrens by study.

Area requirements:

Brood parasitism:
Brood parasitism by Brown-headed Cowbirds (Molothrus ater) is rare due to the Marsh Wren's characteristic dome-shaped nest and small entrance hole (Picman 1986, Kroodsma 1997). In British Columbia, Picman (1986) found that only one of 1200 nests was parasitized. The nest contained one cold, undamaged cowbird egg and two broken Marsh Wren eggs.

Breeding-season phenology and site fidelity:

Species' response to management:

Wetlands that have been modified for waterfowl production are commonly used by Marsh Wrens (Brady 1983). In eastern South Dakota, Marsh Wrens were found in dug-brood complexes (system of channels, ponds, and human-created islands constructed on wetlands to provide deep, open water and upland nesting areas for waterfowl) (Brady 1983). Marsh Wrens nested in stands of cattail and bulrush along the shorelines of islands in the dug-brood complexes. Although they were common in both habitats, Marsh Wren densities were higher in unmodified wetlands than in the dug-brood complexes.

Marsh Wrens readily colonize restored wetlands (Hemesath 1991, Svedarsky 1992, Hemesath and Dinsmore 1993, Hartman 1994, Kroodsma 1997). In Iowa, Marsh Wrens have been found to nest in restored wetlands, although densities were higher in natural wetlands (Delphey 1991, Delphey and Dinsmore 1993, Schreiber 1994, Schuster 1998). In other Iowa studies, Marsh Wrens nested in restored wetlands 1-5 yr following restoration; studies did not examine restored wetlands older than 5 yr (Hemesath and Dinsmore 1993, VanRees-Siewert 1993, Schreiber 1994, VanRees-Siewert and Dinsmore 1996). In Indiana, Marsh Wrens occurred in restored wetlands, but not natural wetlands, although the number of natural wetlands sampled was small (Hartman 1994). Restored wetlands often lack wet-meadow zones (VanRees-Siewert 1993, VanRees-Siewert and Dinsmore 1996, Schuster 1998). In Iowa, the absence of wet-meadow zones in restored wetlands may have restricted the use of these wetlands by Marsh Wrens (VanRees-Siewert 1993, VanRees-Siewert and Dinsmore 1996). Hemesath and Dinsmore (1993) found that emergent cover was greater in restored wetlands drained ≤30 yr ago than restored wetlands drained >30 yr ago. Emergent cover is an important habitat requirement for Marsh Wrens and the age of a drained wetland may need to be considered when selecting suitable sites for restoration.

Conversion of wetlands to cranberry (Vaccinium macrocarpon) beds may negatively affect Marsh Wrens because commercial cranberry production requires scraping away native vegetation and soils, ditching, diking, and depositing sand (to provide drainage for the cranberry beds) (Jorgensen and Nauman 1993). Extensive road systems also are built to provide access for maintaining the cranberry beds. In Wisconsin, Marsh Wrens occupied natural habitat within 100 m of the cranberry beds, but they avoided the cranberry beds themselves. Edges created between the cranberry beds and the surrounding native vegetation resulted in higher numbers of Brown-headed Cowbirds in the cranberry beds than in areas near water impoundments.

In North Dakota, glyphosate (N-[phosphonomethyl] glycine) herbicide was aerially applied at a rate of 5.8 L/ha to reduce cattail in 23 wetlands (Linz et al. 1996). Wetland area was treated at 50%, 70%, or 90% spray coverage. Marsh Wren densities were monitored once immediately prior to treatment and for 2 yr following treatment. Based on seven control wetlands and 16 treated wetlands, densities were significantly higher in control wetlands than in wetlands in all treatment levels combined (2.21 birds/ha versus 0.66 birds/ha, respectively). Based on two wetlands within each treatment, densities were greater in wetlands with 50% spray coverage than wetlands with 90% spray coverage (1.04 birds/ha versus 0.26 birds/ha, respectively). Following treatment, densities of Marsh Wrens were positively related to percent cover of live vegetation, negatively related to percent cover of dead vegetation, and not affected by percent open water. In Wisconsin, open water areas were created by eliminating cattails using Amitrol* (1H-1,2,4-triazole-3-ylamine), Radapon or Dowpon (both 2,2-dichloropropionic acid) (Beule 1979). Amitrol and Radapon were applied at rates ranging from 3.85 to 34 kg/ha. Application rates for Dowpon ranged from 5.6 to10 kg/ha. Marsh Wrens preferred to nest in living, green cattail stands than in dead, residual cattail stands.

Marsh Wren mortalities due to collisions with television towers have been reported in Iowa and North Dakota (Avery and Clement 1972, Dinsmore et al. 1987). Casualties occurred during nights with overcast skies. Both adults and juveniles were susceptible (Dinsmore et al. 1987).

* References to chemical trade names does not imply endorsement of commercial products by the Federal Government.

Management Recommendations:

With the exception of VanRees-Siewert (1993) and VanRees-Siewert and Dinsmore (1996), no species-specific management recommendations were found for Marsh Wrens. The management recommendations that follow are based on habitat requirements or apply to the community of wetland bird species as a whole.

Marsh Wrens require dense, robust, vegetatively heterogeneous stands of emergent vegetation (Leonard 1986, Kroodsma 1997). The long-term protection of wetlands can be achieved through conservation easements and purchases of wetland basins (VanRees-Siewert 1993, VanRees-Siewert and Dinsmore 1996). Protecting wetlands >10 ha in size will maintain area-dependent species, decrease the proportion of habitat edge, and decrease brood parasitism by Brown-headed Cowbirds (Daub 1993). Protection and restoration of a diversity of wetland types and sizes, and wetlands with a diversity of vegetation zones, is of primary management importance to provide habitat regardless of water conditions in a given year (Fairbairn and Dinsmore 2001b). When selecting wetlands for protection or restoration, the number of other wetlands in the surrounding landscape and the number of wetlands that support emergent vegetation should be considered as a way to increase density of Marsh Wrens and increase species richness of other waterbird species.

Restoration projects should focus on creating a complex of various-aged wetlands to provide a variety of vegetational stages (Hemesath 1991, Schuster 1998). Restoration of recently (<30 yr ago) drained wetlands may promote quick regeneration of wetland vegetation (Hemesath 1991, Hemesath and Dinsmore 1993). In Iowa, emergent cover was greater in restored wetlands that were drained ≤30 yr ago than in wetlands drained >30 yr ago. Restore wetlands that have not been effectively drained, such as those typically used for pasture or hayfields where there is less incentive to completely drain the area. Given that restored wetlands often lack a wet-meadow zone, wet-meadow species may need to be planted in long-since drained wetlands (VanRees-Siewert 1993, VanRees-Siewert and Dinsmore 1996). The absence of wet-meadow zones in restored wetlands may reduce the use of these wetlands by Marsh Wrens.

Grazing of wetlands may be detrimental if the vegetated wetland perimeter that protects nesting habitat and deters nest predators is eliminated (Naugle 1997). In South Dakota, presence of Marsh Wrens increased with percent of wetland area that was vegetated and with amount of untilled land adjacent to wetlands (Naugle 1997). In Alberta, Marsh Wrens appeared to prefer wetlands surrounded by dense nesting cover over wetlands surrounded by cropland (Prescott et al. 1993).

Marsh Wrens have been reported in wetlands of water depths varying from 0 to 132 cm (Stewart 1975, Leonard and Picman 1987b). Little is known about the effect of fluctuating water levels on Marsh Wrens. Experimental manipulation of a semipermanent wetland involving drawdown and reflooding resulted in Marsh Wrens inhabiting the wetland 1-4 yr after reflooding, and numbers of Marsh Wrens decreasing 5-6 yr after reflooding as water began to inundate vegetation (Weller and Fredrickson 1973). Reduction of cattail coverage may reduce populations of breeding Marsh Wrens (Linz et al. 1996). If cattail control must be conducted, treatments should be staggered in order to maintain various stages of cattail regeneration and growth (Linz et al. 1996). Beule (1979) provided general management recommendations for manipulating cattail growth.

Table.  Marsh Wren habitat characteristics.

* In an effort to standardize terminology among studies, various descriptors were used to denote the management or type of habitat. "Idle" used as a modifier (e.g., idle tallgrass) denotes undisturbed or unmanaged (e.g., not burned, mowed, or grazed) areas. "Idle" by itself denotes unmanaged areas in which the plant species were not mentioned. Examples of "idle" habitats include weedy or fallow areas (e.g., oldfields), fencerows, grassed waterways, terraces, ditches, and road rights-of-way. "Tame" denotes introduced plant species (e.g., smooth brome [Bromus inermis]) that are not native to North American prairies. "Hayland" refers to any habitat that was mowed, regardless of whether the resulting cut vegetation was removed. "Burned" includes habitats that were burned intentionally or accidentally or those burned by natural forces (e.g., lightning). In situations where there are two or more descriptors (e.g., idle tame hayland),the first descriptor modifies the following descriptors. For example, idle tame hayland is habitat that is usually mowed annually but happened to be undisturbed during the year of the study.

Literature Cited