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Lower Colorado River Multi-Species Conservation Program Balancing Resource Use and Conservation

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Yuma Clapper Rail

      (Rallus longirostris yumanensis)

Yuma Clapper RailYuma Clapper Rail - USGS - Dr. Courtney ConwayYuma Clapper Rail

General Description

The Yuma clapper rail (Rallus longirostris yumanensis) is a large, gray brown to dull cinnamon rail, with a slightly down curved bill and long legs and toes relative to the body. It is one of the smaller subspecies of clapper rails. The total length for an adult clapper rail is 12.6-16.1 in (32-41 cm), with mass ranging from 5.6-14.1 oz (160-400 g). Males are typically 20% larger than females. The Yuma clapper rail is the largest rail found along the lower Colorado River.

Legal Status

The Yuma clapper rail was listed as endangered on March 11, 1967 pursuant to the Endangered Species Act of 1966. California originally listed the Yuma clapper rail as endangered in 1971; re-listed it as rare in 1978, and currently lists it as threatened. In 1978, Arizona classified the Yuma clapper rail as a species of special concern, similar to the Federal status of endangered. Nevada classifies the Yuma clapper rail as endangered. It is listed as threatened in Mexico.


Clapper rails (Rallus longirostris) are found from North America to South America and are classified into three groups: obsoletus, crepitans, and longirostris. The Yuma clapper rail (Rallus longirostris yumanensis) is one of four subspecies of the obsoletus group. The species was first described in 1923. It was initially designated as a separate species, Rallus yumanensis. The four species of clapper rails found along the west coast of North America (R. obsoletus, R. levipes, R. beldingi, and R. yumanensis) were later reclassified into subspecies.


The Yuma clapper rail is presumed to breed at 1 year of age. In Arizona, males begin advertising in February and then form pairs. Nests have been recorded in mid-March, but the average time frame is between April and May. Clutch size ranges from 6 to 8 eggs. Both sexes incubate nests, typically females in the day and males at night. The incubation period ranges between 23-28 days.

Yuma clapper rail nests can be found near shore, in shallow water, and in marsh interiors. Clapper rail young are precocial, meaning they are active and able to move freely after hatching and require little parental care. First-hatched chicks are led from the nest by one parent, while the remaining parent continues incubation of remaining eggs. Chicks are fed fragments of prey eaten by adults. Young rails learn foraging strategies from adults but may be fed, in part, by adults until the age of 6 weeks. Young are able to fly after 10 weeks and become indistinguishable from adults. There is no apparent association with brood mates or parents after fledging.


Clapper rails are sight feeders, gleaning the surface, making shallow and sometimes deep probes, gleaning below the water surface, moving at times erratically in search of prey, and at other times moving slowly and deliberately. Overall, clapper rails are selective, opportunistic, or limited in the variety of foods eaten depending upon habitat type.  They have been found to eat crayfish, weevils, water beetles, spiders, damselfly nymphs, dragonfly nymphs, shrimp, grasshoppers, insect eggs, ground beetles, plant seeds, fish (including mosquito fish, frogs (adults and tadpoles), leeches, crabs, an introduced freshwater clam, and a variety of plants.


Predation is the main mortality factor for adult Yuma clapper rails. Coyotes, raccoons, and raptors such as northern harrier, great horned owl, and Harris’ hawk, have been documented as predators of the Yuma clapper rail. Striped skunks are a potential predator of adult rails, and bullfrogs, black bass, soft shell turtle, and common king snakes are potential predators of young rails and eggs. Fire during the breeding season (mid-March to early September) can cause loss of eggs, young, and some adults. After breeding, adults go through a molt, lose their tail and flight feathers, and remain flightless for 3 to 4 weeks. This flightless period can occur through mid-September, and fires during this time could severely impact rails.

Degradation of habitat is thought to be a factor contributing to declines in rail populations. The lack of random flooding events that would shape and rejuvenate wetlands has allowed encroachment by woody vegetation and buildup of large amounts of decadent vegetation. Drying or drainage of wetlands can result in nest abandonment. Prolonged high water levels also can cause abandonment of territories. Rising water levels force rails to higher ground where they become predisposed to predation. Yuma clapper rails are threatened by river management activities that are detrimental to marsh formation, such as dredging, channelization, bank stabilization, and other flood control measures.

Selenium is also a concern, even though it occurs naturally within the lower Colorado River Basin. Although mortality or reproductive impairment have not been documented in Yuma clapper rail populations along the lower Colorado River, concentrations of selenium in the Yuma clapper rails food chain may be within the range that could cause adverse effects on reproduction.

More Information

Additional information on this species, as well as source documentation, can be found in the species accounts located at this link (PDF). Technical Reports on this species can be found here.

Updated December 28, 2015

The Yuma clapper rail was found along the lower Colorado River after construction of dams and the subsequent creation of marsh habitat.  On the lower Colorado River, this species is currently found in scattered marshes from the Colorado River Delta in Mexico, to Topock Marsh at Havasu National Wildlife Refuge (NWR), near Needles, California. Previously, the northern limit on the lower Colorado River was Laughlin Bay, Nevada. The species’ range now stretches north to the Virgin River and Beaver Dam Wash, near Littlefield, Arizona, and Mesquite, Nevada, the Muddy River near Overton, Nevada, and the Las Vegas Wash near Las Vegas, Nevada. The Yuma clapper rail is also found east of the Colorado River along portions of the Gila, Salt, and Bill Williams river drainages and several other locations in central and southwestern Arizona. Significant populations are also found in marshes at the south end of the Salton Sea. Surveys in the Colorado River Delta in Mexico determined that the majority of Yuma clapper rails are in the Ciénega de Santa Clara, the largest marsh wetland in the delta. Clapper rails present in mangrove marshes along the west coast of Mexico may also be the specific Yuma clapper rail subspecies. Significant populations of Yuma clapper rail are found within the LCR MSCP boundaries in reaches 3 through 6. An analysis of survey data from 1995 to 2005 showed that between 35% and 55% of Yuma clapper rails detected in the United States were within the LCR MSCP boundaries.

Click on the map below to see the distribution range of the Yuma clapper rail using the interactive GIS map.

Click here to see the distribution range of the yuma clapper rail


Yuma clapper rails are found in a variety of marsh types that are dominated by emergent plants, including southern cattail, bullwhip bulrush, three-square bulrush, and sedges. The presence of emergent cover, not the plant species or marsh size, is an important trait of habitat. In Arizona, habitat studies determined that sites with high coverage by surface water, low stem density, and moderate water depth were used for foraging during the nesting season, while sites with high stem density and shallower water near shorelines were used for nesting. Habitat used in early winter (November-December) has lower emergent stem density and ground coverage; less distance to water; greater overhead coverage by vegetation, distance to adjacent uplands, distance to vegetative edges, water depth and water coverage; and taller emergent plants than do randomly selected sites. Low stem densities and little residual vegetation are features of year-round rail habitat. The ideal habitat has also been described as being a mosaic of emergent plant stands of different ages, interspersed with shallow pools of open water.


LCR MSCP Conservation Measures

The Habitat Conservation Plan provides conservation measures specific to each species. Listed below are the species specific conservation measures for the Yuma clapper rail. Click on the arrows to expand the table.

CLRA1—Create 512 acres of Yuma clapper rail habitat

Create and manage 512 acres of marsh to provide Yuma clapper rail habitat (Figure 5-2 in the HCP). This created habitat will also provide habitat for the western least bittern and the California black rail (see conservation measures LEBI1 and BLRA1). Habitat will be created in patches as large as possible but will not be created in patches smaller than 5 acres. Smaller patches are likely to support isolated nesting pairs and be within the range of habitat patch sizes used by the species for foraging and dispersal. Larger patches would be expected to support multiple nesting pairs. Additional Yuma clapper rail habitat may be provided by marsh vegetation that becomes established along margins of the 360 acres of backwaters that will be created in Reaches 3–6. These small patches of habitat would provide cover for dispersing rails, thereby facilitating linkages between existing breeding populations and the colonization of created habitats.

Yuma clapper rail habitat will be created and maintained as described in Section in the HCP.  Marshes created to provide Yuma clapper rail habitat will be designed and managed to provide an integrated mosaic of wetland vegetation types, water depths, and open water areas. Within this mosaic of marsh conditions, Yuma clapper rail habitat will generally be provided by patches of bulrush and cattails interspersed with small patches of open water with water levels maintained at depths appropriate for this species (no more than12 inches).

CLRA2—Maintain existing important Yuma clapper rail habitat areas
The applicants, under agreements with cooperating land management agencies, will provide funding to those agencies to maintain a portion of existing Yuma clapper rail habitat within the LCR MSCP planning area (Section 5.4.2 in the HCP). Maintaining important existing habitat areas is necessary to ensure the continued existence of Yuma clapper rails in the LCR MSCP planning area, provide for the production of individuals that could disperse to and nest in LCR MSCP–created habitat, and support future recovery of the species. Habitat maintenance would likely be undertaken in conjunction with the maintenance of existing California black rail habitat.
MRM1—Conduct surveys and research to better identify covered and evaluation species habitat requirements
Conduct surveys and research, as appropriate, to collect information necessary to better define the species habitat requirements and to design and manage fully functioning created covered and evaluation species habitats. This conservation measure applies to those species for which comparable measures are not subsumed under species-specific conservation measures (Section 5.7 in the HCP). They are not applicable to species for which habitat would not be created under the LCR MSCP Conservation Plan, such as the desert tortoise, relict leopard frog, humpback chub, and threecorner milkvetch.
MRM2—Monitor and adaptively manage created covered and evaluation species habitats
Created species habitats will be managed to maintain their functions as species habitat over the term of the LCR MSCP. Created habitat will be monitored and adaptively managed over time to determine the types and frequency of management activities that may be required to maintain created cottonwood-willow, honey mesquite, marsh, and backwater land cover as habitat for covered species. This conservation measure applies to those species for which comparable measures are not subsumed under species-specific conservation measures (Section 5.7 in the HCP). They are not applicable to species for which habitat would not be created under the LCR MSCP Conservation Plan, such as the desert tortoise, relict leopard frog, humpback chub, and threecorner milkvetch.
MRM5—Monitor selenium levels in created backwater and marsh land cover types, and study the effect of selenium released as a result of dredging activities
Conduct monitoring of selenium levels in sediment, water, and/or biota present in LCR MSCP created backwater and marsh land cover types. If monitoring results indicate that management of the LCR MSCP conservation areas increases levels of selenium in created backwaters and marshes or in covered species that use them, the LCR MSCP will undertake research to develop feasible methods to manage the conservation areas in a manner that will eliminate or compensate for the effects of increased selenium levels. If feasible management methods are identified, they will be implemented. This conservation measure will include monitoring the effects of dredging and dredge spoil disposal associated with creating and maintaining backwaters and marshes. If monitoring results indicate that current or future dredging and dredge spoil disposal methods increase selenium levels, the LCR MSCP will only implement methods that will have the least effect on selenium levels. A study will also be conducted to look at the effects of potential releases of selenium from dredging in general.
CMM1—Reduce risk of loss of created habitat to wildfire
Management of LCR MSCP conservation areas will include contributing to and integrating with local, state, and Federal agency fire management plans. Conservation areas will be designed to contain wildfire and facilitate rapid response to suppress fires (e.g., fire management plans will be an element of each conservation area management plan).
CMM2—Replace created habitat affected by wildfire
In the event of created-habitat degradation or loss as a result of wildfire, land management and habitat creation measures to support the reestablishment of native vegetation will be identified and implemented.
AMM1—To the extent practicable, avoid and minimize impacts of implementing the LCR MSCP on existing covered species habitats
To the extent practicable, establishment and management of LCR MSCP–created habitats will avoid removal of existing cottonwood-willow stands, honey mesquite bosques, marsh, and backwaters to avoid and minimize impacts on habitat they provide for covered species. Temporary disturbance of covered species habitats, however, may be associated with habitat creation and subsequent maintenance activities (e.g., controlled burning in marshes and removal of trees to maintain succession objectives). LCR MSCP conservation measures that could result in such temporary disturbances will, to the extent practicable, be designed and implemented to avoid or minimize the potential for disturbance. In addition to implementing AMM3 and AMM4 below, these measures could include conducting preconstruction surveys to determine if covered species are present and, if present, implementing habitat establishment and management activities during periods when the species would be least sensitive to those activities; or redesigning the activities to avoid the need to disturb sensitive habitat use areas; staging construction activities away from sensitive habitat use areas; and implementing BMPs to control erosion when implementing ground disturbing activities.
AMM2—Avoid impacts of flow-related covered activities on covered species habitats at Topock Marsh

Impacts on groundwater levels that support covered species habitat at Topock Marsh will be avoided by maintaining water deliveries for maintenance of water levels and existing conditions. At times, flow-related activities could lower river elevations to levels that could disrupt diversion of water from the river to the marsh. Improvements to intake structures that allow water to continue to be diverted or other measures to maintain the water surface elevation will avoid effects on groundwater elevation. Avoidance of effects could be accomplished with the purchase, installation, and operation of two electric pumps sized to the current inflow at the Topock Marsh diversion inlet. The pumps would most likely need to be operated during summer to make up for the lower flow periods.

Implementation of this conservation measure would maintain existing habitat at Topock Marsh for the Yuma clapper rail, southwestern willow flycatcher, Colorado River cotton rat, western least bittern, California black rail, yellow-billed cuckoo, gilded flicker, vermilion flycatcher, Arizona Bell's vireo, and Sonoran yellow warbler. The extent of covered species habitat impacts that will be avoided by maintaining water deliveries to Topock Marsh are presented in Table 4-2 in the HCP. Maintaining water deliveries to Topock Marsh will also maintain razorback sucker and bonytail habitat associated with disconnected backwaters managed for these species.

AMM3—To the extent practicable, avoid and minimize disturbance of covered bird species during the breeding season
To the extent practicable, to avoid and minimize potential impacts on covered bird species, vegetation management activities (e.g., periodic removal of emergent vegetation to maintain canals and drains) associated with implementation of covered activities and the LCR MSCP that could result in disturbance to covered bird species will not be implemented during the breeding season to prevent injury or mortality of eggs and young birds unable to avoid these activities. Table 5-9 in the HCP describes the breeding period for each of the covered species during which, to the extent practicable, vegetation management activities in each species' habitat will be avoided.
AMM5—Avoid impacts of operation, maintenance, and replacement of hydroelectric generation and transmission facilities on covered species in the LCR MSCP planning area
To the extent practicable, before implementing activities associated with OM&R of hydroelectric generation and transmission facilities, measures will be identified and implemented that are necessary to avoid take of covered species where such activities could otherwise result in take. These measures could include conducting surveys to determine if covered species are present and, if so, deferring the implementation of activities to avoid disturbance during the breeding season; redesigning the activities to avoid the need to disturb covered species habitat use areas; staging of equipment outside of covered species habitats; delineating the limits of vegetation control activities to ensure that only the vegetation that needs to be removed to maintain infrastructure is removed; stockpiling and disposing of removed vegetation in a manner that minimizes the risk of fire; and implementing BMPs to control erosion when implementing ground disturbing activities.
AMM6—Avoid or minimize impacts on covered species habitats during dredging, bank stabilization activities and other river management activities
To the extent practicable, before initiating activities involved with river maintenance projects, measures will be identified and implemented that avoid or minimize take of covered species where such activities could otherwise result in take. Such measures could include alternative methods to achieve project goals, timing of activities, pre-activity surveys, and minimizing the area of effect, including offsite direct and indirect effects (e.g., avoiding or minimizing the need to place dredge spoil and discharge lines in covered species habitats; placing dredge spoils in a manner that will not affect covered species habitats).

Research and Monitoring Activities

LCR MSCP conducts a variety of research and monitoring activities along the LCR encompassing both MSCP and non-MSCP species. For a complete list of all activities, please see the Research and Monitoring Activities web page.


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