Savannah Sparrow (Passerculus sandwichensis)

Account prepared by:  Linda Moore, Humboldt State University

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Species: Savannah Sparrow (Passerculus sandwichensis)

Subspecies Status:
        P.s. alaudinus and P.s. beldingi are nonmigratory California residents;
        P.s. brooksi and P.s. nevadensis breed in California (and elsewhere) and migrate within California;
        P.s. rostratus and P.s. sandwichensis breed outside California and migrate to California;
        P.s. anulus, P.s. anthinus, P.s. atratus, P.s. guttatus, P.s. labradorius, P.s. magdalenae, P.s. oblitus, P.s. princeps,
        P.s. rufofuscus, P.s. sanctorum, and P.s. savanna are other AOU recognized subspecies

Management status: P. s. beldingi is endangered in California.

Range Maps: (BBS summer range map) (Sauer, et al. 1999)

I. Historical References: Historical documentation of the Savannah Sparrow in California is sometimes patchy and anecdotal. In 1923, Dawson described 11 total subspecies, of which 9 reportedly included California in their range. Grinnell and Miller (1944) accredited 8 subspecies to California.

Breeding range in California (from Grinnell and Miller 1944):

P.s. nevadensis: elevated Great Basin - Oregon border to Owens Lake, Inyo County; also an isolated population in upper Kern Basin, Kern County
P.s. brooksi: Coastal – Oregon border to Trinidad, Humboldt County
P.s. bryanti (now P.s. alaudinus): Coastal – Humboldt Bay to Morro Bay, San Luis Obispo County
P.s. beldingi: Coastal – Santa Barbara through San Diego County

Winter ranges for the 8 subspecies described by Grinnell and Miller (1944) collectively include the entire state below about 4000 feet, including the Great Valley, southeast desert, western Sierra Nevada lowlands, and coastal marshes north to Humboldt Bay.

II. Current Breeding Distribution:

P.s. alaudinus (formerly bryanti), P.s. beldingi, P.s. brooksi, and P.s. nevadensis same as above.

BBS data of abundance indices from 1966 to 1996 by region:
Pitt-Klamath Plateau
S. Pacific Rainforests
Columbia Plateau
Basin and Range
S. California Grasslands
Sierra Nevada 
Central Valley
Los Angeles Ranges
California Foothills


Savannah Sparrow populations tend to be classified as either salt marsh (coastal) or "typical" (upland); life histories and requirements of those populations vary accordingly.

I. Average Territory Size: 0.05 – 1.25 ha reported (Wheelwright and Rising 1993). Adult males and females tend to return to the same territory in successive years, with males returning 1 to 3 weeks earlier than females (Wheelwright and Rising 1993).

II. Time of Occurrence and Seasonal Movements

    A.  Arrival Date of Breeding Grounds: No information in California, arrival dates for other populations range from early March to early May (Wheelwright and Rising 1993).
    B.  Departure Date from Breeding Grounds: Little information in California is available, though Unitt (1984) documented departures of P.s. beldingi in late August. Other North American populations depart from mid-September to late November.
    C.  Spring migration period: No information
    D.  Fall migration period: No information
    E.  Extent of Wintering in CA: (According to AOU) P.s. alaudinus and P.s beldingi ranges are same as breeding ranges; P.s. brooski winters from northern breeding range down to Mexico border through western California; P.s. nevadensis may have a broad winter range, from northern central to southern coast and southern desert; P.s. rostratus winters at southern and central coasts; P.s. sandwichensis winters north coast south to Berkeley and central valley south to Merced county.

III. Migration Stop-over Needs / Characteristics:

    A.  Stop-over Period: No information
    B.  Habitat Use: During migration, birds are found in open fields, coastal marshes, ponds in open areas, and disturbed areas such as roadsides (Wheelwright and Rising 1993).
    C.  Routes: No information
IV. Nest Type: Nests on the ground, usually hidden by a canopy or having a tunnel entrance (Wheelwright and Rising 1993).

V. Foraging Strategy: Forages on the ground and around the bases of plants, also may take short leaping flights for flying insects (Wheelwright and Rising 1993). Sometimes employs "double scratch" method to dig beneath litter (Wheelwright and Rising 1993).

VI. Displays: Courtship displays limited to singing and flutter flights (Wheelwright and Rising 1993). Both sexes perform distraction displays (erect crest, quivering wing) to defend a nest from predators (Wheelwright and Rising 1993).

VII. Social Organization

    A.  Typical Breeding Densities: Densities reported of 8.7 pr/ha on Kent Island, New Brunswick (Dixon 1978), 5.4 pr/ha in Nova Scotia (Welsh 1975), and 3.7 pr/ha in Michigan (Potter 1972). For a study of P.s. beldingi, densities ranged from 4 to 28 pr/ha; densities were positively correlated with % Salicornia cover and negatively correlated with % Distichlis cover (Powell 1993).
    B.  Mating System: Monogamy and polygyny. System varies by population (Rising 1987), but southwestern coastal areas are probably monogamous (Wheelwright and Rising 1993).
    C.  Delayed Breeding: Though birds breed at age of 1 year, yearling females tend to arrive later to breeding grounds and are less successful (Wheelwright and Rising 1993).
    D.  Post fledging biology of offspring: Fledglings disperse from both nest and nestmates, receive parental care for about 15 days (Wheelwright and Rising 1993). Often the young of a first brood remain on natal territory until eggs of second brood have hatched (Wheelwright and Rising 1993). Juveniles flock in groups of 100 or more during the remaining summer (Wheelwright and Rising 1993).
    E.  Post Breeding Social Behavior: After breeding, individuals form loose, temporary groups. During nonbreeding season birds usually flock, in mixed-sex groups of up to 20 individuals, around food or shelter (Wheelwright and Rising 1993).
VIII. Clutch Size: For all subspecies, range is 2 – 6 eggs, though most commonly 4 (Wheelwright and Rising 1993). Clutch size is larger at higher latitudes: 4.7 in Manitoba (Weatherhead 1979) versus 3.2 for P.s.beldingi in southern California (Davis et al. 1984).

IX. Incubating Sex: Female (Wheelwright and Rising 1993).

X. Incubating Period: Ranges from 10 to about 13 days (Wheelwright and Rising 1993), with an average of 13.2 in southern California for P.s. beldingi (Davis et al. 1984).

XI. Nestling Period: Overall range is 7 to 11 days (Wheelwright and Rising 1993), range for P.s. beldingi is 7 to 9 days (Williams and Nagy 1985).

XII. Development at Hatching: Altricial

XIII. Number of Broods: Typically 1 to 2 - number of broods is restricted by weather at high latitudes (Wheelwright and Rising 1993) - though 4 clutches have been reported for P.s. princeps on Sable Island, Nova Scotia (Stobo and McLaren 1975). Coastal populations tend to have more clutches per season than inland subspecies (Wheelwright and Rising 1993).

XIV. Who Tends the Young: 85% of brooding is by females. Both parents bring food and defend nest, but paternal care is lower in polygynous populations (Wheelwright et al. 1992, Wheelwright and Rising 1993).

XV. Diet

    A.  Major food items (by season): In breeding season main food items include larval, pupal, and adult insects (especially beetles, flies, bugs, lepidopterans, hymenopterans, homopterans), small spiders, small millipedes, snails, and seeds (Wheelwright and Rising 1993). During migration and wintering, birds chiefly consume seeds, some fruits (strawberries, blueberries), and invertebrates, when available (Wheelwright and Rising 1993).
    B.  Drinking: Though salt marsh breeders reportedly can drink salt water (Wheelwright and Rising 1993), individuals in a population of P.s. beldingi were never observed doing so during a 5 year study (Williams and Nagy 1985). P.s. beldingi nestlings don’t drink free water (Williams and Nagy 1985).

XVI. Wintering Ground Needs and Distribution: See Extent of Wintering in CA. Habitat types include cultivated fields, pastures, roadsides, golf courses, and salt marshes (Wheelwright and Rising 1993). Salt marsh dwelling birds are frequently found in open, sparsely vegetated habitats (Wheelwright and Rising 1993).


I. Overview of Breeding Habitat: Salt marsh dwelling Savannah Sparrows breed in areas where Pickleweed, Allenrolfea, Suaeda, Atriplex, and saltgrass are dominant (Wheelwright and Rising 1993). High-success territories for P.s. beldingi are associated with tall, dense vegetation within large marsh fragments (Powell and Collier 1998). Upland Savannah Sparrows breed in open country such as grassy meadows, cultivated fields, pastures, roadsides, sedge bogs, and coastal grasslands, favoring areas of dense ground (especially grass) vegetation and moist substrates and avoiding areas of extensive tree cover (Wheelwright and Rising 1993).

II. Nest Site

    A.  Substrate (species): Nests are commonly built in depressions in grass clumps, within goldenrods, or at the base of woody shrubs (blueberry, raspberry, blackberry, wild rose, or bayberry, for example) (Wheelwright and Rising 1993). P.s. beldingi nest within middle intertidal areas of pickleweed, saltwort, saltgrass, and alkali heath (Powell 1993).
    B.  Height of Nest: On ground (salt marsh nests have been decribed as "close to the ground", as dictated by tidal heights).
    C.  Height of Plant: Salt marsh plants may range from 19 to 42 cm (Powell 1993). No information for upland habitats.
    D.  Nest concealment: Nests are well concealed. They often are covered with a canopy of dead grass or may have a tunnel of 5 cm or more. Also, nests are frequently placed at the base of woody shrubs (Wheelwright and Rising 1993).

III. Vegetation Surrounding the Nest:

    A.  Canopy Cover: No information
    B.  Dominant Plant Species in Canopy: No specific information aside from substrate plants; inland birds nest within grasses and under shrubs, salt marsh birds tend to favor plants found at mid-intertidal depths, usually pickleweed and saltgrass.
    C.  Average shrub cover: No information
    D.  Dominant shrub species: No information
    E.  Average forb cover: No information
    F.  Dominant forb species: No information
    G.  Ground cover: No information
    H.  Slope: No information
    I.  Aspect: No specific information, though typically with the entrance facing away from prevailing winds (Wheelwright and Rising 1993).
    J.  Tree DBH: No information
    K.  Snags: No information
    L.  Distance to Water: No specific information for upland populations, though Savannah Sparrows breeding in arid regions are restricted to irrigated areas and margins of ponds (Wheelwright and Rising 1993). P.s. beldingi nests within the middle intertidal zone, within 100 meters of a permanent water source (Powell 1993).

IV. Landscape Factors

    A.  Elevation: Grinnell and Miller (1944) report breeding P.s. alaudinus at up to 2800 feet at Kneeland Prairie in Humboldt County, P.s. beldingi at within 100 feet of sea level, P.s. brooski at within 300 feet of sea level, and P.s. nevadensis at up to 7000 feet at Whitmore Tub in Mono County.
    B.  Fragmentation: P.s. beldingi abundance increases with larger wetlands, though only 4 wetlands in southern California are greater than 100 ha; marshes less than 10 ha in size may not support any Savannahs (Powell and Collier 1998). The viability of wetland habitat for Savannahs is also influenced by the fact that some marshes are entirely surrounded by "hard" edges of urban development and roads, which may result in limited movement between marsh areas (Powell and Collier 1998). No information for upland Savannahs.
    D.  Patch Size: See Fragmentation
    E.  Disturbance: See Sensitivity to Human-Induced Disturbance
    F.  Adjacent Land Use: See Fragmentation

V. Other

Special Factors (factors influencing a species occurrence and viability)

      I.  Brood Parasitism: Brown-Headed Cowbirds parasitized between 0% and 1.9% of nests in studies conducted in Michigan and Canada (Wheelwright and Rising 1993). Egg-dumping by Grasshopper Sparrows has been observed (Wiens 1971).
      II.  Dietary: Differences in bill morphology by subspecies (especially P.s.rostratus, the Large-Billed Savannah Sparrow) suggest the ability by some to take larger prey items (Wheelwright and Rising 1993), but no evidence that occurrence or viability of any subspecies is limited by diet.
      III.  Sensitivity to human-induced disturbance: It has been speculated that human activity which creates open habitats (fields, hay fields, cropland) has benefited upland Savannah Sparrows by providing additional breeding and wintering habitat, but the productivity within those areas may be variable depending on specific land use (see Management Issues). Urbanization and reforestation of farmlands has removed viable habitat (Wheelwright and Rising 1993). For salt marsh Savannahs such as beldingi, development of high intertidal areas has had the net result of placing nesting sites closer to human activity and at potentially greater risk of predation; more research is needed.
      IV.  Pesticide Use: No information, research is needed.
      V.   Predators: Nest predators include snakes, red fox, skunk, domestic cats, weasel, Herring Gull, Common Raven; gulls and corvids prey upon nestlings; adults are taken by owls, snakes, hawks, Clapper Rail, and small falcons.
      VI.  Exotic Species Invasion / Encroachment: In southern Saskatchewan, Canada, the introduction of crested wheat grass as a grazed plant results in up to twice the bare ground as natural vegetation, and crowds Savannah Sparrows into remaining areas of the native mixed-grass prairie (Sutter and Brigham 1998).

POPULATION TREND: BBS trend data from 1966 to 1998 shows an overall non-significant increase for California (1.8, P=0.31). A non-significant increase occurs in the South Pacific Rainforest region (2.1, P=0.22), and non-significant declines occur in the Pitt-Klamath Plateau (-2.1, P=0.36), Columbia Plateau (-0.5, P=0.78), Basin and Range (-3.3, P=0.58), and Southern California Grasslands (-2.5, P=0.89). A significant decline occurs in the California Foothills (-19.5, P=0.05).


I. Age and Sex Ratio: In a study including several populations in the U.S., 55% of the wintering birds collected were male, with no geographic pattern in the sex ratio (Rising 1988). This trend is supported by accounts that 20-40% of territorial males may stay unmated, with a bias toward yearlings (Bedard and LaPointe 1984).

II. Productivity Measure: Modal lifetime production of fledglings is from 5 to 13, though most birds have few or no offspring that survive to breed (Stobo and McLaren 1975). Reproductive success tends to be higher on islands where there are no mammalian predators (Wheelwright and Rising 1993).

III. Survivorship: Annual adult mortality ranges from 31-73% throughout range, until age 5 or 6 when it reaches 90% (Wheelwright and Rising 1993).

IV. Dispersal: Wheelwright and Rising (1993) report that within a highly philopatric island population 7-14% of banded nestlings returned to the natal breeding site, and 17-25% of those nestlings that fledged returned. However, inland populations are not as site faithful as island ones; in two inland populations 0% and 0.01% of banded nestlings were resighted (Wheelwright and Rising 1993).

MANAGEMENT ISSUES: Although six subspecies of Savannah Sparrows are present in many varied regions of California, P.s. beldingi, the endangered Belding’s Savannah Sparrow, seems to be the only studied population. Since this salt marsh population has different life history requirements than upland Savannahs, research on these birds doesn’t help us understand the needs of birds throughout the state. P.s. beldingi requires more attention in order to better understand how to increase its abundance - can this be done with existing wetland areas?

The status of P.s. rostratus in California isn’t very clear, since it has been stated that "many" of these birds migrate to southern California marshes (Zink et al. 1991) but also that the migrating portion of that population is "reduced or extinct" (Wheelwright and Rising 1993).

Research about land use issues that likely affect upland Savannah Sparrows in California come from studies conducted in the Midwest and south-central to eastern Canada. In southern Saskatchewan, Savannah Sparrows nest in idle (unmowed) hay fields, but productivity drops by 80% after mowing (Dale et al. 1997). Since Savannahs are far less abundant in annually mowed hay fields, the authors suggest a regime of mowing most fields in alternate years (preferable after July 15) and leaving the rest idle for at least 3 years. Mowing is also an issue around east-central Illinois airports, where mowing of the surrounding grasslands is believed to cause most nest failures and to make airport grasslands into population sinks (Kershner 1996). Though mowing is a popular method of grassland management, Savannah Sparrows seem very sensitive to the timing at which it is done.

Agricultural fields in North Dakota and Iowa that were converted to perennial cover as part of the Conservation Reserve Program (CRP) supported higher densities of Savannah Sparrows than regular row-crop fields (Johnson and Igl 1995, Patterson and Best 1996). Though Savannahs do use crop fields, the dense cover provided by CRP fields may be more attractive to nesting birds and yield higher productivity. Similar land management in California may increase Savannah Sparrow abundance, though more research is needed.

The effects of introduced crested wheat grass for cattle grazing in southwest Saskatchewan include increased bare ground, less litter, and lower plant richness and diversity (Sutter and Brigham 1998). Savannahs are more abundant in areas of dense vegetation with abundant shelter, so grazed fields and other areas that utilize such nonnative plants may effectively reduce Savannah Sparrow populations, or crowd them into small remaining patches of native habitat.

ASSOCIATED SPECIES: Grasshopper Sparrow, Western Meadowlark, Red-winged Blackbird, Brown-headed Cowbird, Ring-necked Pheasant, Common Yellowthroat.


Research is needed for all 6 populations in California to determine their status: What are the nesting requirements (e.g. what plant species are used in different regions)? What aspects of the habitat are associated with breeding success? Is habitat loss an issue for any population besides beldingi? What is required to increase numbers of P.s. beldingi – if available habitat is the limiting factor, can a model suggest the amount of habitat necessary to increase population size so as to upgrade their status or delist them? Are the northern coastal populations (brooksi, alaudinus) similar to beldingi in habitat needs such as mid-intertidal nesting areas and patch size? Is there a minimum patch size required for any upland Savannah population? Are Savannahs affected by proximity to an urban or forest edge? Is the P.s. rostratus population vanishing from California – a study of color-banded birds, possibly also including research at their breeding site at the mouth of the Colorado River, may best address this question.

There are many unanswered questions regarding the effects of altered grasslands in California: What effects do nonnative plants used for grazing or agriculture (also unintentional plant invasions) have (e.g. vertical structure and degree of ground cover)? Other studies show that Savannah abundance is lower in crop fields, but is productivity affected? Does the use of pesticides in crop fields alter the abundance, productivity, or survivorship of Savannah Sparrows? Are overgrazing and nest trampling problems to Savannahs?


STATUS: P.s. beldingi is an endangered population in California. Elsewhere in the state Savannah Sparrows exist in moderate numbers and within their historical range, with the possible exception of P.s. rostratus, for which more information necessary. A significant decline in adundance in the California Foothill region (-19.5, P=0.05) is of concern.

HABITAT NEEDS: Upland Savannah Sparrows use a variety of open habitats; for breeding they favor areas of dense ground vegetation with little tree cover. P.s. beldingi uses tall, dense vegetation with the mid-intertidal zone of large marshes. Specific needs of other coastal populations are unknown.

CONCERNS: P.s. beldingi inhabits wetland areas that may be too few in number and too small in area to support the number of birds required to delist this subspecies. Upland Savannah Sparrows use manmade open areas (e.g. agricultural and grazed fields), but productivity in some areas may be so low that they serve as population sinks.

OBJECTIVES: Determine habitat needs for each of the six Savannah Sparrow populations that inhabit California, and study local issues (urbanization, agriculture, exotic plants, etc.) that may affect abundance, nesting success, distributions, and survival. Determine what is required to improve numbers of declining populations.

ACTION: Establish research and monitoring programs to address the research needs listed above; some studies can incorporate other species to determine the effects of certain land uses on whole communities. Habitat improvement (buffers or corridors) or restoration may be necessary for P.s. beldingi.


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