By Bob Allen, California Dept. of Fish and Game and Humboldt State University
Shortcut to Action Plan Summary
Section 1
Species: Western Meadowlark (Sturnella neglecta)
Subspecies Status: S. neglecta confluenta and S. neglecta
neglecta recognized by some authorities, but not by AOU
Management Status: No official status
Range Maps:
I. Historical References:
Grinnell and Miller (1944) state that the Western Meadowlark "occurs
throughout State (California), with exception of most arid and barren tracts
of deserts, roughest mountains and densest forests". Western Meadowlarks
have occurred in every county in California at one time or another, but
many of the more unusual records (i.e. the top of Halfdome in Yosemite
National Park) are not breeding records. Determining a specific breeding
range is difficult due to the abundance of the Western Meadowlark and the
tendency of historical and current authors alike to state the breeding
range in descriptive terms (e.g. Grinnell and Miller’s statement quoted
above).
II. Current Breeding distribution:
BBS relative abundance data (1966 to 1996) by region in California follows:
| Area |
|
| Columbia Plateau |
|
| Central Valley |
|
| Pitt-Klamath Plateau |
|
| Southern California Grasslands |
|
| California Foothills |
|
| Sonoran Deserts |
|
| Los Angeles Ranges |
|
| Southern Pacific Rainforests |
|
| Basin and Range |
|
| Mojave Desert |
|
| Great Basin Deserts |
|
| Sierra Nevada |
|
Ecology:
I. Average Territory Size: 1.2- 13.0 ha reported, but commonly between 3 to 7 ha (Lanyon 1994, Lanyon 1956, Kendeigh 1941, California Wildlife Habitat Relationships database 1983). Females reported to return to same territory rather than a particular male (Lanyon 1994). Many males have more than one female; in one study in Wisconsin, 53% of males were polygynous (Lanyon 1994).
II. Time of Occurrence and seasonal movements
A. Arrival date and departure date on breeding grounds: Most Western Meadowlarks are thought to have little seasonal movement in California. Exceptions include Western Meadowlarks breeding in higher elevation sites in the Sierras (they are thought to move downslope) and some upslope dispersal in late summer by juveniles. Males are probably defending territories in March in many parts of California. Most Western Meadowlark territories have broken up by late July and August.B. Extent of wintering in CA: Many Western Meadowlark migrate into California for the winter. According to Christmas Bird Count data, hotspots for wintering Western Meadowlarks (>100 birds/survey circle) are the Sacramento Valley and San Joaquin Valley.
III. Migration stop-over needs/ characteristics
A. Stop-over Period: No information.B. Habitat use: No information.
C. Routes: No information.
IV. Nest type: Ground nester. Often partially covered by a roof
or arch. Some have an entrance tunnel and runway (Lanyon 1994).
V. Foraging Strategy: Forages on ground surface and sometimes low-lying plants (DFG data 1983, Lanyon 1994). Also probes into soil and under soil clods and manure (Lanyon 1994). Feeds on grains in winter and early spring, insects in late spring and summer, and weed seeds in fall (Lanyon 1994).
VI. Displays: Wide array of courtship displays by male and female including aerial chases, jump-flights, and other posturing (Lanyon 1994)
VIII. Clutch size: Ranges from 3 to 7, generally around 5 (Lanyon 1994).
IX. Incubating Sex: Female (Lanyon 1994)
X. Incubation period: 13-14 days (Lanyon 1994)
XI. Nestling period: 10-12 days (Lanyon 1994)
XII. Development at hatching: Altricial
XIII. Number of broods: 2 (Lanyon 1994)
XIV. Who tends the young: Female (Lanyon 1994)
XV. Diet
A. Major food items (by season): "Marked seasonal differences in main staples: grain during winter and early spring, insects late spring and summer, weed seeds in fall" (Lanyon 1994).B. Drinking: No information..
XVI. Wintering ground needs and distribution: No specific information,
probably similar to needs on breeding grounds. Across North America, Western
Meadowlarks are only migratory in areas of extreme cold or snowfall (Lanyon
1994), so somewhat milder temperatures are probably a necessary factor.
Breeding Habitat and Nest site characteristics
I. Overview of breeding habitat
Western Meadowlarks breed in a variety of grassy areas ranging from sparse desert grassland to meadows in forests and woodlands where the density of trees is not too high (more research is needed on just what "too high of a percentage of trees" is to a Western Meadowlark). Examples of breeding habitat include: relatively undisturbed grasslands such as remaining native and naturalized grasslands, oak woodlands, edges of roads, orchards, and farms, in hay and alfalfa fields, and, finally, in grazed pastures. Most Western Meadowlark territories have several singing posts that average higher than the surrounding vegetation: common singing posts include shrubs, trees, electric lines and poles, fence lines, and, in the Central Valley, taller remnant vegetation such as native sunflower, poison hemlock, and black mustard (DFG unpublished data). However, males will sing from ground or from the tops of grass bunches if no taller structure is available.
II. Nest site
A. Substrate (species): Western Meadowlarks have been found nesting under a wide range of grasses and forbs. Vegetation structure seems more important than a particular species of plant.B. Height of nest: On ground.
C. Height of plant: No specific information
D. Nest concealment: Often placed at the base of a plant and is generally well-concealed. Some nests may be in a shallow depression in ground. Most nests have runways or tunnels leading to roofed nest, but open nests are also found (Lanyon 1994).
III. Vegetation surrounding the nest
A. Canopy cover: No information.B. Dominant plant species in canopy: Western Meadowlarks have been found nesting under a wide range of grasses and forbs. Vegetation structure seems more important than a particular species of plant.
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 information
J. Tree DBH: No information
K. Snags: No information
L. Distance to water: No information
IV. Landscape factors:
A. Elevation: Birds found breeding at –200 feet near the Salton Sea up to 8,000 feet on the eastern side of the Sierras (Grinnell and Miller, 1944).B. Fragmentation: Johnson and Temple (1990) found higher predation and parasitism rates for Western Meadowlarks nesting within 45m of a wooded edge.
C. Patch Size: See Fragmentation.
D. Disturbance (natural or managed): See management issues
E. Adjacent land use: See Fragmentation.
V. Other
Special factors (factors influencing a species occurrence and viability)
A. Brood parasitism: Brown-headed Cowbirds are known to uncommonly parasitize nests across range. For instance, Lanyon (1957) found that 22% of the 41 Western Meadowlark nests he found were parasitized. However, I could not find any published account of a parasitized nest in California.B. Dietary: None known.
C. Sensitivity to human-induced disturbance: None known.
D. Pesticide use: No information, study needed.
E. Predators: Avian and mammalian predation reported for young, raptors are said to "commonly prey" on adults (WHR database, 1983)
F. Exotic species invasion/encroachment: No information.
Population trend: BBS trend data indicates a non-significant
decline in California (-0.79, p=0.34). Non-significant increases in Western
Meadowlark numbers occur in the Central Valley (0.38, p=0.84) and the Southern
California Grasslands (2.19, p=0.33). A significant decrease in meadowlark
numbers has been found in the California Foothills region (-3.25, p=0.003).
Demographics:
I. Age and sex ratios: No information.
II. Productivity measure(s): No information.
III. Survivorship: Captive birds normally live 3-5 years (Lanyon 1994).
IV. Dispersal: Lanyon (1994) never resighted any of the 51 nestlings he banded on a 1.6 km site.
Management issues: Despite the Western Meadowlark being one of our most common and widely appreciated (it is the state bird of six different states) grassland songbirds, surprisingly little data exist on the California populations on which to base management decisions. BBS data indicate that there are four regions within California with the greatest meadowlark densities: the Columbia Plateau, the Central Valley, the Pitt-Klamath Plateau, and the Southern California Grasslands. Management for Western Meadowlarks that provides the most bang for the buck should be concentrated in these four areas. Once we determine some of the answers to several conservation questions (see Research needs below), we should have a much better feel on how to retain meadowlarks at relatively high numbers.
Some information exists that could impact management decisions in California, however it should be pointed out that much of this research comes from the Midwest. Whether Western Meadowlarks are consistent in most ecological aspects in California to other parts of the United States is open to debate.
For instance, research from the Midwest indicates that the Conservation Reserve Program (CRP) set-aside lands provide valuable habitat for many grassland birds, including Western Meadowlarks. A far smaller percentage of land exists in this fashion in California, however it would be interesting to know how grassland birds do respond to the California version of CRP or similar lands. If it turns out to have real or potential benefits for grassland birds, a statewide set-aside program could be extremely beneficial.
Johnson and Temple (1990) argue that Minnesota grassland areas should be burned frequently, so as to reduce parasitism and predation. Western Meadowlark response to grazing differs among several studies, but most studies found overgrazing to be a problem (Ryder 1980, Weins 1973, Owens and Myres 1973). Bartelt (1997) suggested that the use of fenced "refuges" (areas not actively grazed during the bird breeding season) within grazed areas could help increase grassland bird productivity. Trampling of nests by livestock known to occur (Bartelt 1997). Western Meadowlarks nesting in agricultural areas often incur heavy nest loss or mortality when crops are surface weeded or harvested (this is especially true when alfalfa is cut).
Associated species: Because the Western Meadowlark is a generalized grassland bird, preserving meadowlark habitat may or may not help conserve grassland birds with more specific habitat needs. Possible associated nesting species would be Grasshopper Sparrow, Northern Harrier, upland nesting waterfowl species (Mallard, Cinnamon Teal, and Gadwall), Ring-necked Pheasant, and Savannah Sparrow. Wintering species that could possibly benefit include Sandhill Crane, various raptors (Ferruginous Hawk, Northern Harrier, White-tailed Kite, American Kestrel, Prairie Falcon, Red-tailed Hawk, and possibly others), and many grassland wintering passerines such as sparrows and finches.
Monitoring methods and research needs: It seems to me that conservation-based research on the Western Meadowlark should center around four central issues:
1. Determine general and specific habitat needs for territory and nest site selection. For instance, is there a cut-off point in overall tree or shrub density where meadowlarks will no longer choose an area that otherwise has good grass cover? Is there any preference for bunch grasses versus annual grasses or grasses versus forbs? How do territories change in size and shape depending on the amount of high versus low quality (if we can determine what high and low quality are) habitat available? Do recent aggressive plant invasions (for instance, Perennial White-top Pepperweed and Yellow Star-thistle in the Central Valley) have any effect on meadowlark territory and nest site selection?
2. Determine what fragmentation and patch size effects, if any, there are on meadowlarks. Does distance to nearest urban settlement, riparian, wetland, agriculture, or road affect nesting success? Do neighboring alfalfa fields or wetlands constitute fragmentation through a meadowlark’s eyes?
3. Determine Western Meadowlark response to various grazing and agricultural practices and increasing urbanization. It is probably true that a large percentage of meadowlarks occur in areas that are already or soon will be dominated by human food production activities. Determining meadowlark response to various grazing strategies could clearly have extensive management implications. In addition, pasture lands in the Central Valley are being rapidly converted to crops, orchards, and urban settlements. The Central Valley represents that fastest growing region in terms of human population in California. What effects do these have on meadowlark numbers?
4. Determine what effect, if any, the various common herbicide and pesticides have on meadowlark nesting and survival.
The above mentioned research needs will most likely need to be met with spot-mapping and intensive nesting studies ideally including color-banded birds (Colin et al 1992, International Bird Census Committee 1970, Martin and Geupel 1990). Few, if any, mist-netting stations (MAPS or otherwise) in California effectively sample grassland birds. If this can be done in an efficient manner, it would be well worth our while to set up several stations throughout California.
Section 2. Action plan summary
Status: Western Meadowlarks remain plentiful and common throughout California. Significant declines (-3.25, p=0.003) in the California foothills is a concern.
Habitat Needs: Western Meadowlarks require grassy areas of at least 3 ha (the low end of the meadowlark territory size range). Extremely sparse deserts and dense forests are avoided.
Concerns: Concerns include the response by Western Meadowlarks to increasing agriculture, orchards, and urbanization in many grassland areas. Also effects of herbicides and pesticides on meadowlark survival and nesting success.
Objectives: Determine "meadowlark-friendly" managements for grazing, farming, and orchards and whether such strategies might be economically feasible. Determine specific variables that might describe high and low quality habitat for the Western Meadowlark. Determine if the grassland generalist qualities of the Western Meadowlark might serve as an "umbrella" species for other grassland birds.
Action: Initiate several studies to help answer the above conservation research questions. One such study is already being undertaken in the San Joaquin Valley involving DFG lands. Land purchases and habitat restoration targeted at other, more threatened, grassland birds will likely have benefits for Western Meadowlarks.
Colin, J.B., N.D. Burgess, D.A. Hill. 1992. Territory Mapping Methods in Bird Census Techniques. Academic Press Inc., San Diego.
International Bird Census Committee. 1970. An international standard for a mapping method in bird census work recommended by the International Bird Census Committee. Audubon Field Notes 24: 722-726
Johnson, R.G. and S.A. Temple. 1990. Nest predation and brood parasitism of tallgrass prairie birds. Journal of Wildlife Management. 54: 106-111.
Kendeigh, S.C. 1944. Measurement of bird populations. Ecological Monographs. 14: 67-106.
Martin T.E., and G.R. Geupel. 1993. Protocols for nest monitoring plots, locating nests, monitoring success, and measuring vegetation. Journal of Field Ornithology. 64: 507-519.
Patterson, M.P. and L.B. Best. 1995. Bird abundance and nesting success in Iowa CRP fields: the importance of vegetation structure and composition. American Midland Naturalist. 135: 153-167.
Renken, R.B. and J.J. Dinsmore. 1987. Nongame bird communities on managed grasslands in North Dakota. Canadian Field-Naturalist 101 (4): 551-557.
Rotenberry, J.T. and J.A. Wiens. 1980. Habitat structure, patchiness, and avian communities in North American steppe vegetation: a multivariate analysis. Ecology. 61 (5): 1228-1250.
Sauer, J. R., J. E. Hines, G. Gough, I. Thomas, and B. G. Peterjohn.
1997. The North American Breeding Bird Survey Results and Analysis. Version
96.3. Patuxent Wildlife Research Center, Laurel, MD