Endangered Species Recovery Program
Taxonomy.-- Palmate-bracted birds-beak, a member of the snapdragon family (Scrophulariaceae), was first described as Adenostegia palmata (Ferris 1918). The type locality (i.e., the site from which the type specimen was collected) was "at Tule near College City, Colusa County" (Ferris 1918, p. 420). In a subsequent revision, Adenostegia was transferred to the genus Cordylanthus (Macbride 1919), resulting in the currently-accepted name Cordylanthus palmatus (Chuang and Heckard 1993). Plants from the southern portion of the range initially were considered by Pennell (1947) to be a different species, fleshy birds-beak (Cordylanthus carnulosus). The type specimen of fleshy birds-beak was collected 6 miles south of Kerman, in Fresno County (Chuang and Heckard 1973). Cordylanthus carnulosus later was reduced to a subspecies of C. palmatus (Munz 1958), and finally was merged completely with C. palmatus (Chuang and Heckard 1973).
Description.-- Palmate-bracted birds-beak (Figure 7) is a highly branched annual that can reach 30 centimeters (12 inches) in height. The glandular hairs are short (less than 1 millimeter; less than 0.04 inch) and excrete salt crystals, making mature plants appear grayish-green. In all Cordylanthus species, the corolla (the set of petals) is club-shaped and is divided lengthwise into two lips (groups of fused petals that differ in appearance). The upper lip is hooked like a birds beak and the lower lip is inflated like a pouch. The flowers are nearly hidden by bracts, which are leaf-like structures. In palmate-bracted birds-beak, the outer bracts are green; the inner bracts are lavender and deeply divided into finger-like segments (i.e., palmate). The corolla is hairy, whitish to lavender on the sides, and has fine purple stripes on the lower lip. The seeds have distinctive arching crests.
Identification.-- Palmate-bracted birds-beak differs from the closely-related hispid birds-beak (C. mollis ssp. hispidus) in that the latter has bristly hairs longer than 1 millimeter (0.04 inch), whitish to yellowish flowers, and lacks crests on the seeds (Ferris 1918, Chuang and Heckard 1993). Fleshy birds-beak is distinguished from palmate-bracted birds-beak by its branching pattern and hair characteristics (Chuang and Heckad 1973).
Figure 7. Illustration of palmate-bracted bird's-beak (from Abrams, Vol. 3, 1951, with permission).
Historical Distribution.-- Nine natural populations of palmate-bracted birds-beak were documented between 1916 and 1982, but only two were known to be extant as of 1985 (USFWS 1986). The historical occurrences were in the following vicinities: College City; Livermore (Alameda County); Alkali Sink Ecological Reserve, Kerman, and two near Mendota (Fresno County); between Firebaugh and Madera (Madera County); Stockton (San Joaquin County); and Woodland (Yolo County) (Chuang and Heckard 1973, CDFG 1995, Heckard 1977). Hoover (1937) indicated that palmate-bracted birds-beak grew near Bakersfield, but that locality has not been substantiated.
Current Distribution.-- As a result of intensive survey efforts and additional introductions, palmate-bracted birds-beak now is known to occur in seven metapopulations: four in the Sacramento Valley, one in the Livermore Valley, and two in the San Joaquin Valley (Figure 8). In approximate order from north to south, these metapopulations are (1) Sacramento National Wildlife Refuge in Glenn County, (2) Delevan National Wildlife Refuge in Colusa County, (3) Colusa National Wildlife Refuge in Colusa County, (4) the Woodland area, (5) Springtown Alkali Sink near Livermore, (6) western Madera County, and (7) the combined Alkali Sink Ecological Reserve and Mendota Wildlife Management Area. The total occupied surface area over the seven metapopulations is estimated at less than 300 hectares (741 acres). The Delevan National Wildlife Refuge and Colusa National Wildlife Refuge metapopulations account for approximately 80 percent of the total number of individuals, and the Springtown Alkali Sink metapopulation accounts for another 19 percent (Center for Conservation Biology 1994, CDFG 1995).
Cordylanthus species are hemiparasitic annuals, meaning that they manufacture their own food but obtain water and nutrients from the roots of other plants (i.e., host plants; Chuang and Heckard 1971). Saltgrass (Distichlis spicata) is the most likely host plant for palmate-bracted birds-beak. The combination of hemiparasitism, salt excretion, and a deep root system allows palmate-bracted birds-beak to grow during the hot, dry months after most other annuals have died (Coats et al. 1993).
Reproduction and Demography.--This species flowers from May until October (Skinner and Pavlik 1994). Bumblebees (Bombus californicus, B. occidentalis, and B. vosnesenskii) were the primary pollinators of palmate-bracted birds-beak at the Springtown Alkali Sink in 1993. The bees nested in uplands more than 100 meters (328 feet) distant from the population, and each bee visited only one group of palmate-bracted birds-beak plants (Center for Conservation Biology 1994). Both self- and cross-pollination can contribute to seed-set (Center for Conservation Biology 1993), and individual plants can produce up to 1,000 seeds in a single growing season (Center for Conservation Biology 1991). Despite the formation of a persistent seedbank, the number of plants in a population varies yearly in response to environmental conditions, particularly precipitation (Center for Conservation Biology 1994). Seasonal overland flooding may disperse seeds and promote seed germination by diluting the saline soils (Coats et al. 1993); in laboratory tests, seed germination rates were significantly higher in low-salinity than in high-salinity solutions, regardless of alkalinit (Center for Conservation Biology 1991). However, prolonged flooding would not be conducive to survival of palmate-bracted birds-beak (A. Howald pers. comm.).
Genetic studies of the Colusa, Delevan, Springtown, and Alkali Sink Ecological Reserve/Mendota National Wildlife Refuge populations indicated that the Springtown metapopulation incorporated almost all the genetic variability known in the species. The Alkali Sink Ecological Reserve population contributed some additional genetic variation, but the Colusa and Delevan National Wildlife Refuge metapopulations did not. Thus, protection of the Springtown and Alkali Sink Ecological Reserve metapopulations was considered to be crucial to recovery (Center for Conservation Biology 1994). Samples from Sacramento National Wildlife Refuge, Woodland, and Madera County were not evaluated.
Habitat and Community Associations.--This species is restricted to seasonally-flooded, saline-alkali soils in lowland plains and basins at elevations of less than 155 meters (500 feet). Within these areas, palmate-bracted birds-beak grows primarily along the edges of channels and drainages, with a few individuals scattered in seasonally-wet depressions, alkali scalds (barren areas with a surface crust of salts), and grassy areas. Palmate-bracted birds-beak occurs in the Valley Sink Scrub and Alkali Meadow natural communities in association with other halophytes such as iodine bush (Allenrolfea occidentalis), alkali heath (Frankenia salina), glasswort (Salicornia subterminalis), seepweed (Suaeda moquinii), and salt grass (Holland 1986, Coats et al. 1993, CDFG 1995, Bittman 1985, 1986a). At Springtown Alkali Sink, palmate-bracted birds-beak and hispid birds-beak occur together (Center for Conservation Biology 1994). Suitability of microhabitats for palmate-bracted birds-beak depends primarily on soil pH and to a lesser extent on soil layering, salinity, and moisture. This species occurs on neutral to alkaline soils (pH 7.2 to 9.5) under natural conditions but has been grown on acidic soils in greenhouse trials (Coats et al. 1993, Center for Conservation Biology 1993, 1994).
Reasons for Decline.--Agricultural conversion eliminated the formerly-known palmate-bracted birds-beak populations near College City, Kerman, and southeast of Mendota; reduced the size of the Woodland population; and destroyed extensive areas of potential habitat in the Sacramento and San Joaquin Valleys. Urban development was responsible for the destruction of the Stockton occurrence.
Threats to Survival.-- Urban expansion (including commercial uses, residential development, and construction of recreational facilities) poses imminent threats at the Springtown and Woodland sites. Numerous other factors threaten the remaining populations. Changes in the hydrologic regime (seasonal water cycles and movements) by drainage, diking, and channelization have interrupted the seasonal overland flows and altered water salinity at Springtown, Woodland, and on lands adjacent to the Alkali Sink Ecological Reserve and National Wildlife Refuges. Because of the lack of genetic variability within and among the Sacramento Valley populations and the limited number of individuals in the Alkali Sink Ecological Reserve, western Madera County, and Woodland populations, random or catastrophic events could result in elimination of the species at any of these sites. Road maintenance is a potential threat at the Alkali Sink Ecological Reserve. The Springtown metapopulation faces many additional threats, including unauthorized fill of wetlans, encroachment by exotic plant species, off-road vehicle use, and livestock wallowing in seasonal pools (Coats et al. 1993, Center for Conservation Biology 1994, CDFG 1995, A. Howald pers. comm.).
The state of California listed palmate-bracted birds-beak as an endangered species in 1984, and USFWS did likewise in 1986 (USFWS 1986). In 1988, CDFG funded a project to map suitable habitats from aerial photographs and soil survey data (A. Howald pers. comm.). Since then, CDFG has sponsored intensive research on the biology, ecology, and management of palmate-bracted birds-beak at the Springtown Alkali Sink. The first study focused on habitat characterization and resulted in development of a management plan for the area (Coats et al. 1993). The next series of investigations into the life history, reproductive biology, genetic composition, and site relationships were conducted by the Center for Conservation Biology and resulted in development of a long-term monitoring program for the Springtown Alkali Sink (Center for Conservation Biology 1994). Part of the Springtown Alkali Sink has been proposed as a mitigation banking area for surrounding development; under the proposed plan, restoration and management also would be undertaken (Coats et al. 1993). However, the mitigation bank would protect at most 25 percent of occupied habitat; it is a commercial enterprise that will continue only as long as it is profitable, and restoration may not begin for many years (A. Howald pers. comm.). A hydrologic study of the North Livermore Valley watershed is currently underway. Preliminary recommendations are contained in a report by Questa Engineering Corporation (1997), and include measures to reduce urban runoff and protect groundwater flows from the saline foothills north and northeast of the sink.
Personnel at the Sacramento National Wildlife Refuge complex have contributed to conservation of palmate-bracted birds-beak in several ways. In 1990, National Wildlife Refuge biologists established a new population at Sacramento National Wildlife Refuge by scattering seeds that had been collected from Delevan National Wildlife Refuge. The National Wildlife Refuge complex avoids inundating known occurrences of palmate-bracted birds-beak, and the hydrology and vegetation in occupied habitat are being restored to historical conditions. Refuge staff also monitor known populations on the Sacramento National Wildlife Refuge complex annually and consider the species when any management activities are proposed or planned in occupied habitat (G. Mensik pers. comm.). At least one group of plants has been fenced to restrict vehicle access and reduce the potential for trampling by waterfowl hunters (M.A. Showers pers. observ.).
Additional conservation efforts have included surveys and another reintroduction. The palmate-bracted birds-beak population on private land in western Madera County was discovered in 1993 during surveys by the Endangered Species Recovery Program. A small transplant colony was established at the Mendota Wildlife Management Area in 1973 using seed collected from a nearby population that was about to be eliminated (CDFG 1995, Heckard 1977). The Endangered Species Recovery Program currently is conducting demographic studies of palmate-bracted birds-beak at Alkali Sink Ecological Reserve. Seeds will be collected from this population in fall 1998 for banking at a Center for Plant Conservation facility.
The recovery goal for palmate-bracted birds-beak is to maintain self-sustaining populations in protected areas representative of the former geographic and topographic range of the species and in a variety of appropriate natural communities. Surveys will be necessary to determine whether natural populations remain in all target areas; if natural populations are not found, reintroduction will be necessary to achieve recovery. However, reintroduction is expensive and experimental, and thus the preferable course of action is to locate and protect the remaining occupied habitat wherever possible. Unoccupied habitat within metapopulations also should be protected to facilitate seed dispersal and pollinator movement. Thus, additional elements of the strategy are to protect land in blocks of at least 65 hectares (160 acres) and to avoid fragmenting any metapopulation into more than two blocks of contiguous, protected natural land. Buffer zones of 150 meters (500 feet) or more should be protected beyond the population margins to reduce external influences, provide pollinator habitat, and allow for population expansion. Finally, the natural hydrological regime, including appropriate height of the water table and periodic overland flows, must be maintained to ensure long-term survival of palmate-bracted birds-beak at protected sites.
To prevent the irreversible decline of palmate-bracted birds-beak in the near future, the Springtown Alkali Sink metapopulation must be protected from development and from incompatible uses. In addition, appropriate measures must be taken to protect and restore the hydrology after the Questa Engineering Corporation hydrologic study has been completed. Another high-priority task is to ascertain the genetic composition of the Woodland population. If it contains genes that differ from those in populations that are protected currently, the Woodland site should be considered for protection as a specialty reserve. If permitted development results in the loss of any natural populations, seeds should be salvaged for introduction into other suitable habitats. The occupied habitat on public land also is important to the survival of palmate-bracted birds-beak; management to promote the continued survival of this species must continue.
Additional actions that are necessary, but of somewhat lower priority, are to determine the genetic composition and extent of the population in western Madera County, conduct surveys, develop management plans for all sites, and model population viability. The occupied habitat in Madera County is not in imminent danger of destruction, but the area is important for recovery of a number of plant and animal taxa, and long-term protection should be assured through conservation easements or other mechanisms. If the genetic variability or population size of palmate-bracted birds-beak in the western Madera County site is low, techniques that can be used to increase population viability include augmentation (with seeds from other San Joaquin Valley populations) and habitat management. Management plans must be developed and implemented for each of the metapopulations. The plans should include monitoring to track population trends and evaluate management effectiveness. Seed samples should be collected from at least the Springtown, Woodland, and Alkali Sink/Mendota populations following established guidelines (Center for Plant Conservation 1991) to preserve the gene pool and provide sources for reintroduction or augmentation of populations, if determined to be necessary. Matrix projection models should be developed for the Springtown Alkali Sink and San Joaquin Valley populations, as well as for any others not currently known that are counted towards recovery. To do so, demographic studies must be instituted in these populations to identify critical stages in the life cycle. Additional research may e necessary to determine appropriate management to overcome limitations to population growth.