Great Basin Naturalist
Volume 57 Number 2 Article 2
5-7-1997
Boggy meadows, livestock grazing, and interspecific interactions: influences on the insular distribution of montane Lincoln's Sparrows (Melospiza lincolnii alticola)
Carla Cicero University of California, Berkeley
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Recommended Citation Cicero, Carla (1997) "Boggy meadows, livestock grazing, and interspecific interactions: influences on the insular distribution of montane Lincoln's Sparrows (Melospiza lincolnii alticola)," Great Basin Naturalist: Vol. 57 : No. 2 , Article 2. Available at: https://scholarsarchive.byu.edu/gbn/vol57/iss2/2
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BOGGY MEADOWS, LIVESTOCK GRAZING, AND INTERSPECIFIC INTERACTIONS: INFLUENCES ON THE INSULAR DISTRIBUTION OF MONTANE LINCOLN'S SPARROWS (MEWSPlZA LINCOLNII ALTICOLA)
Carla Cicerol
ABSTRACT.-I surveyed 34 meadows in California and Oregon to count Lincoln's Sparrows (Nelospb,a lincolnli alt/oola) uod to identify habitat features that might influence their local, insular occurrence. Lincoln's Sparrows were found at 72% of the sites surveyed. Counts of singing males were low and uncorrelated with meadow size. Lincoln's SpatTOWS were most t:ommon in wet meadows with little damago by gra:.r.ing. Singing males were ooncentrated in flooded or boggy areas near meadow edges, where pines (PUlUS .~p.) provided c1evated pcrdles fOr .~inging and vigilance. Patche..~ ofwillows (Salix sp.) wen; often present nearby. Numbers of male Lincoln's Sparrows were strongly and negatively correlated with ahun dance ofsympatric Song Sparrows (M melodroff$lwreUa). Lincoln's Sparrows breeding in montane meadows are poten tially vulnemble to local extirpation because of their im:ular distribution, low population density, and fluctuating habitat conditions. Heavy damage from liv~10cJc grazing drastically increase" the probability oflocal extirpation.
Key words: Melospiza lincolnii, Lincoln's Sparrou>, montane meadow, insular populatwns, habitat ussocf.atKm., live stock grazing, conservation biology, MclospWi. melodia, Scn~ Sparrow.
Mcadows form ecological islands through fragments (e.g., Forman et al. 1976). However, out montane forests of the western United detailed studies ofspecifIC taxa occupying nat States. Although these systems generally sup ural insular habitats such as meadows are port a rich avifauna, they are highly variahle in scarce. terms of physiographic, hydrologic, edaphic, The montane form of Lincoln's Sparrow vegetative, and floristic characteristics (e,g., (Melospi:w lincolnii alticolo.; Miller and McCahe see Kuramoto and Bliss 1970, Benedict and 1935, American Ornithologists' Union 1957) is Major 1982, Ratliff 1982, 1985, Allen 1987). well suited to such a study. This taxon breeds Grazing and fire history also shape meadow insularly in particular kinds of meadows from environments (Kuramoto and Bliss 1970, Oregon to California and from Idaho to New DeBenedetti aod Parsons 1979, 1984, Parsons Mexico. Such sites are separated from other 1981, Ratliff 1985). Changes in grazing and suitable islands nf habitat by unoccupied coni fire management practices, combined with cli· ferous forest Two other subspecies (M. I. lin mate, further influence the ecology and stability colnii and M. I. gracili8) occur more broadly of meadows by promoting invasion of lodge in broshy bogs from central Alaska through pole pine and other conifers (Franklin et al. Canada to the northern contiguous United 1971, Dunwiddie 1977, Vale 1981a, 1981b, States. Despite the widespread distribution of Ratliff 1985). Lincoln's Sparrows, the species has been poorly Because of their mobility, birds respond studied compared with either ofits congeners, quickly to habitat change aod thus are model the Song Sparrow (M. melodia) or Swamp orgaoisms for illustrating the effect of habitat Sparrow (M. georgiana). Information on the dis on the distribution and abundance of insular tribution and natural history ofM. I. alticola is as well as cootioental populations (Cody 1981, especially lacking. In this study I provide hase Wiens 1989). Numerous researchers have exam line data on occurrence, abundance, habitat ined total avifaunal distribution and abundance association, and other factors potentially related on montane islands (e.g., Johnson 1975, Kratter to their local. distribution in western montane 1992, Lentz 1993), in natural habitat patches meadows. Secondarily, I evaluate the potential (e.g., aspen; Flack 1976), or in disrnrbed forest impact livestock grazing has on this taxon.
IMuseum ,,(~dlf1lle lDoIO!D', U,.M:nity ufCaliforn.iil, Berkeley, C.... lt4721I.
104 1997] LINCOLN'S SI'ARROWS IN MEADOWS 105
Range ecologists have shown unequivocally dance may reveal degradation of meadows by that grazing occurs unevenly across montane livestock. vegetation types and that meadows and other riparian areas receive disproportionately heavy STUDY AREAS AND METHODS use relative to their total acreage (Cook 1966, Roath and Krueger 1982a, 1982b, Gillen et aI. I surveyed meadows for Lincoln's Sparrows 1984, Platts and Nelson 1985). Numerous stud from mid-May to early July 1987-1989. A total ies have assessed the impact of such use on of 34 meadows belonging to 29 systems were riparian habitats and associated wildlife (e.g., visited, including 1 in northern Oregon and 28 Leege et aI. 1981, Kauffman et a1. 1983, Kauff in California from the southern Cascade Moun man and Krueger 1984, Ihylor 1986, Ohmart tains (Lassen County) through the Sierra Nevada 1994). Montane Lincobis Sparrows are paten· to the San Bernardino Mountains (Fig. 1). Ele tially vulnerable to disturbance by heavy graz vations ranged from 1365 to 2470 m, with ing because oftheir tendency to nest on or near lodgepole pine (Pinus contorta) forest dominat swampy ground in wet meadows (Grinnell ing the surrounding vegetation. Size, land own and Miller 1944, Austin 1968). Consequently, ership, and type and intensity oflivestock graz changes in their local occurrence or abun- ing varied among meadows. Although several
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J:i'ig. L Breeding distribution of Lincoln's Sparrows in Califomia. The general locations of 28 meadow systems sur veyed in California are indicated; an additional me-d.dow in Oregon is not shown. Closed circles denote meadows where Lincoln's Sparrows were present; open circles, meadows where Lincoln's Sparrows were absent. Closed. squares show other known breeding localities based on specimens depo!>iled in the Museum ofVertebrate Zoology, Berkeley, Califor nia.; published records (Grinnell and Miller 1944, Lentz 1993); records obtained during ~l survey ofmeadows for Willow Flycatchers (Empidonm: traillU., M. A. Flett and J. Harris unpublished data). 106 GREAT BASIN NATURAUST [Volume 57 groups of meadows were clustered geographi grazing. Surveys took longer in large meadows cally, differences in habitat characteristics, ele or at sites 'vith high numbers of Lincoln's vatioIl, and/or grazing regime occurred between Sparrows. Because the amount of time spent even the most proximal sites. Consequently, at each site varied, count values were stan each meadow was treated as an independent dardized by dividing the number of singing sample point. nventy-five sites consisted ofsin males observed per visit by the length of the gle meadows without any connection to other survey. As with all count methods, some silent sites. Another meadow (Beasore Meadow [site males may bave been overlooked. Thus, these 22]) was divided by a fence into 2 parts with counts represent minimal estimates of total strikingly different grazing regimes; because abundance. the 2 sides also contrasted dramatically in The geographic scope of tbis study pre abundance of Lincoln's Sparrows, they were cluded surveying all meadows simultaneously. separated for purposes of analysis and discus To verify the reliability of counts conducted at sion. Three meadow systems (Lacey [8], Hay different times, I surveyed 17 meadows (50%) press Creek [9], and Sagehen Creek [12]) con twice or more during the same or subsequent tained multiple meadows witbin 1 drainage or seasons. Counts of singing males in the same basin that were separated from each other by meadow at different stages of the breeding a distance of at least 0.8 km. Because these cycle were identical. Because annual climatic were visited only during the breeding season, differences might also influence counts taken when males were singing and thus territorial, in different years, I obtained data on mean presumably there was no movement ofLincoln's temperature and precipitation during May and Sparrows between meadows. This was con June 1987-1989 (National Oceanic and Atmos firmed by multiple visits to the same meadow pheric Administration 1987, 1988, 1989) from system (e.g., Haypress Creek) during a single weather stations located near 3 main clusters breeding season, when individual singing males ofmeadows: (1) northern Sierra Nevada-Sage could be identified repeatedly by their loca hen Creek, Nevada County, California, 1932 m; tion in each meadow. (2) central southern Sierra Nevada-Hunting To ensure breeding status, counts were lim· ton Lake, Fresno County, California, 2140 m; ited to singing males. Lincoln's Sparrows sing (3) San Bernardino Mountains-Big Bear Lake, vigorously from elevated perches during the San Bernardino County, California, 2070 m. I breediog season, particularly near watercourses analyzed tbese data by analysis-of-variance or along the meadow edge, and thus are easily using Slalview for the Macintosh (Abacus Con detectable. Numbers of singing males were cepts 1988). With the exception of mean June counted by traversing each meadow and record temperature, which was slightly different among ing their presence and location. Because my years (P = 0.0387), there was no annual effect goal was to survey a broad range of sites in on temperature or precipitation (P > 0.05). I order to evaluate the kinds ofmeadows inhab counted similar numbers of Lincoln's Spar ited by montane Lincoln's Sparrows, lengthy rows at the same meadow in different years. and repealed visits to individual meadows In a daily field journal, I recorded numbers were not possible. However, the size and dis of other singing birds at each meadow and crete, linear configuration of most meadows provided detailed descriptions and sketches of enabled complete surveys of all singing males the meadows. I also took notes on the charac during lor, at most 2, consecutive mornings teristics ofmeadows with and without Lincoln's (2-5 hJmorning). Thus, standard census tech Sparrows, and on tl,e location of singing males niques appropriate for expansive areas of non relative to the meadow edge and to habitat insular habitat were unnecessary. features sucb as extent offlooding, presence or Complete counts of singing males were ob absence of willows (Salix sp.), presence or ab tained at 26 (76%) of the 34 meadows. Partial sence of corn lily (Vera/mm sp.), and presence sUlVeys were conducted at the remaining 8 sites or absence of pines (Pinus sp.). The first 3 because of their large size and/or because habitat variables (flooding, willows, corn Wy) fencing restricted access. Nonetheless, these are presumably important for breeding (Grin estimates still provide valuable information re nell and Miller 1944, Austin 1968, Speirs and garding the occurrence of Lincoln's Sparrows. Speirs 1968). Although published accounts do Six of the 8 sites were visibly impacted by not provide information on the use of edges 1997] LINCOLN'S SPARROWS TN MEADOWS 107
TAlILli: 1. Rating scheme used for characterizing meadows based on wetness and extent ofgra;-;ing damage. Score Characterization
WETNESS 1 Meadow very dry: no standing water or boggy ground; single, well-defined stream channel 2 Less than 25% of meadow wet: few areas ofstanding water or boggy ground 3 25-50% of meadow wet: some flooded or boggy areas, other areas dry 4 50-75% of meadow wet: many areas of:o;tanding water or boggy ground; some rivulets ofrunning water 5 75-100% of meadow wet: most or all ofmeadow covered with standing water and/or rivulets of running water GHAZ1NG 1 Mcadow essentially pristine: no bare ground exposed; gra:'!sy, undercut streamhanks; no evidence of gullying and/or hank erosion; few to no signs oflivestock 2 Slight grazing damage: <25% ofmeadow with bare ground exposed; slight gullying and/or streambank erosion; low density oflivestock droppings and trails 3 Moderate grazing damage: 25-50% ofmeadow with hare ground exposed; gullying and/or streambank erosion clearly evident; low to moderate density oflivcstock droppings and trails 4 Heavy grazing damage: 50-75% of meadow with bare ground exposed; pronounced gullying and/or streambank erosion; moderate to high density ofJivestock droppings ,md trails 5 Meadow severely damaged: > 75% ofmeadow with bare ground exposed; extreme ).,'Ullying and/or streambank erosion; very high density oflivestock droppings and trails
and/or pines, observations ofsinging males sug meadows caused by livestock grazing (see Fig. gest that these features might be equally im 2) was assessed subjectively and also rated on portant. Because of the broad geographic sam a scale of1 to 5, taking into account the amount pling and concomitant variability in meadow ofbare ground exposed. extent of gullying and/ type, data on the herbaceous composition of or streambank erosion, presence ofold or recent each meadow were beyond the scope of this livestock droppings, and network of livestock study. Differences in habitat features associated trails (Table 1). As with wetness. scores were with individual males (n = 75) were tested sta assigned based on overall damage observed tistically using a nonparametric binomial test, during the period of study. Although gradient with the normal approximation for N > 35 (see and/or soil type also may contribute to difler Siegel and Castellan 1988:38-44). ences in erosion seen between meadows, im A complex classification system has been pacts from grazing clearly had a major effect. developed for meadows in the Sierra Nevada, Evaluation of the effects of grazing on plant incorporating similarities in physiographic, species composition and diversity was beyond hydrologic, edaphic. vegetative. and floristic the scope ofthis study. Both wetness and graz characteristics (Ratliff 1985). However. only "in ing damage may vary with changes in grazing a few situations have enough sites been studied practices. to adeqnately define the [classification] series" Areas of meadows were estimated from (Ratliff 1985:9). Because of the close associa USGS 7.5-minnte topographical maps using a tion between breeding Lincoln's Sparrows and point-grid system modified for a seale of boggy or flooded ground. I used a simpler 1:24.000; these data were supplemented by approach to rate meadows on a scale of 1 to 5 U.S. Forest Service data where available. For according to wetness (Table 1). Scores assigned large meadows where counts are incomplete, to meadows reflect the wetness characteristics both the total area and the area surveyed were observed during the period of study. Higher estimated. or lower ratings may be more appropriate at other times depending on seasonal and annual RESULTS variability in hydrologic regimes. Quantitative information on livestock use in Distribution and Abundance each meadow was difficult to obtain because of ofLincoln's Sparrows variability in land-ownership patterns and be I found Lincoln's Sparrows in 26 (76.5%) of cause stocking rates, determined for entire tl,e 34 sites surveyed (Table 2). Absolute nnm grazing allotments, do not accurately reflect the bers of breeding males varied from 1 to 16. concentration of livestock on meadows and which translates to standardized counts of o.~ other riparian areas. Consequently, damage to males/h. Counts were low in most meadows: 108 GREAT BASIN NATURALIST [Volume 57
TABLE 2. Characteristics of meadows sUlVeyed for M. L olticola in California (1-28) and Oregon (29). See Figure 1 for locations in California. Number of Th'.! Area Time per Number of singing males Grazing ..... surveyed Number of sUlvey singing per survey Wetn"" damage Type of M=I_ ~rn) (ha) sUlve)'sl> (h) m.Ie. hou' """e< ,.",..0 gt'llZingd I. Battle Creek Meadows. 1460 m (P) 511 447 1 10 0 0.0 3 4 CatOe 2. Grtl$l; Lake, 1980 01 (NF) 5 5 1 2 3 1.5 5 1 NQtgrazed 3. Church Mendows, 2040m (P) 6 6 2 5 U 2.2 3 2 Sheep 4. French Meadows, 2035 1TI (P) 16 16 1 3 6 2.0 2 3 Cattle 5. Lincoln Valley, 2220m (P) 26 26 3 4 16 4.0 4 1 Cattle?<: 6. Ortlonwooo Creek, 177001 (NF) 52 52 2 4 0 0.0 4 2 Sbeep 7. Perano Meado~. 2OLO m (P) 369 59 1 5 0 0.0 3 4 Cattle 8A. Lacey 1; <2 males/h were recorded in 16 (61.5%) ofthe species was absent from all meadows with 26 meadows, 2--3 males/h in 8 meadows, and heavy grazing pressure (score > 4). The pres 3--4 males/h in only 2 meadows. Numbers of ence of Lincoln's Sparrows at these 2 sites is singing males were highest at Church Mead accounted for by the method of analysis, in ows (3) and Lincoln Valley (5) in the northern which scores were assigned based on overall Sierra Nevada, Bluff Lake (27) and Metcalf appearance of the meadow. Thus, all 3 males Creek (28) in the San Bernardino Mountains, at Little Lacey Valley were concentrated in the and Hood River Meadows (29) in northern lower, wetter portion of the meadow, where Oregon. Counts were not correlated with impacts from grazing were 5light; none was meadow size (r = 0.240, P > 0.05). observed in the more heavily damaged, upper Distribution and abundance were clearly reaches. Likewise, the single male in Upper associated with scores for wetness and/or extent Beasore Meadow occurred at the lower edge ofgrazing damage (Fig. 3). Lincoln's Sparrows of the site, which was in good condition rela were most common in moderately wet to very tive to the meadow as a whole. As expected. wet, i.e., flooded, meadows with low levels of Lincoln's Sparrows were absent from the single grazing damage. Except for Little Lacey Valley site that lacked standing water and showed (8B) and Upper Beasore Meadow (22A). tbe signs ofheavy grazing (Pleasant Valley [15]). 1997J LINCOLN'S SFARJlOWS IN MEADOWS 109 TABLE 2. Continued. Num'berof T,ta1 Area Tune per Number of singing males Grazing ,wveyed Numherof ''''''''Y singing per survey Wetness damage Typenf MoadowO "'"(h.) (ha) (h) m.I", hour =re< =re< grazing Despite this general tendency, the distribu Habitat Features Associated with tion of Lincoln's Sparrows showed a more com Individual Male Lincoln's Sparrows plex pattern. For example, I failed to find the Singing males were strongly associated with species in several meadows with fairly high particular habitat features (Fig. 4). The most scores for wetness and low scores for grazing damage (Cottonwood Creek [6], Swauger Can important attribute was the presence of nearby yon [16], White Wolf [17]). Although abun surface water. Only 3% of the males were ob dance was highest in the wettest, most pristine served in areas ofdry ground, while 93% were meadows (e.g., Lincoln Valley [5J, Metcalf Creek seen in either boggy (54.2%) or flooded (38.9%) [28], Hood River Meadows [29]), other equally sites (a difference significant at P < 0.001). wet sites had notably fewer males (e.g., Upper Numerous locations had networks of small, Haypress Creek [9A], west ofCoppins Meadow narrow channels with runing water that coursed [11], Lower Sagehen Creek [12B], Hogdon through tussocks of sedges, grasses, or other Meadow [19], Markwood Meadow [24], Dinkey herbaceous plants. The presence of willows, Meadow [25]). Meadows with lower wetness com lily, and pines (especially P. contorta) also scares also supported relatively high numbers appeared to be important attributes of Lincoln's of Lincoln's Span-ows as long as grazing dam· Sparrow habitat. Approximately 84% of all males age was fairly low (e.g., Church Meadows [3J, occun-ed near clumps of willows (P < 0.001), Coppins Meadow [lOJ, Bluff Lake [27]). and 59% were in areas with at least scattered 110 GREAT BASIN ATURALIST [Volume 57 F1~ 2. Views of the lower (lOp) and upper (bottom) portions of Bensore Meadow, Madera County, Califomia (sHe 22). Photos illustrate 2 cxtr~mes in the condition of ml:Jadows surveY(;Jd in this study. Lower Beasore Meadow, which was not grazed, had an uncfmk:d creekbank, swampy ground, rich herbaceolls covel; and scattered patches of willow (Salix sp.). Upper Bt;::llsore Meadow showerl severe soil erosion, compaction, tlnct dessication due to cattle grazing, with 3-7 III gully ing. Lincoln's Sparrows were fairly common in Lower Rpa';ol'e Mcadow hill essentially ahsent from Upper Beasore Mcadow. Song Sparrows were abundant in the willows in Upper Beasore Meadow. 1997] LTNCOLN'S SPARROWS IN MEADOWS 111 FioodedIBo9gy 5 2 o 25 50 75 100 1 1 2/ % of Singing Males Associated with 2 Different Habitat Characteristics GraZing D 4 4 ~0....~flj~0 Fig. 4. Proportion of singing male Lincoln's Sparrows Scor;rnage 5 / srP associated with different habitat attributes. Ecotonal males were those singing along the edge between the meadow and adjacent coniferous forest. All pairwise com Fig. 3. Three-dimensional graph illustrating the relative parisons, except for the presence/absence of corn lily, abundance (vertical axis; counts per hour) of singing male were significant at P < 0.01. Lincoln's Sparrows in 29 meadows systems scored accord ing to wetness and grazing damage (see Table 1). Mead ows me numbered as in Table 2. Circles indicate sites with Lincoln's Sparrows; squares, sites where 13noolo's tufts of grass aud/or other plants. Approxi Sparrows were absent. mately 35% of the nests in the WFVZ records were situated under a patch ofwillows. Negative Association Between patches of lily (although this proportion was Distribution and Abundance of Lincoln's nonsignificant, P = 0,0823). However, unlike Sparrows and Song Sparrows Song Sparrows, which were observed only in arcas with willow, Lincoln's Sparrows were not Counts of singing male Lincoln's Sparrows limited to willow patches. The concentration of and Song Sparrows showed a strong negative male Lincoln's Sparrows was greatest near the correlation (r = 0.701, P < 0.01; Fig. 5). edges of meadows (67% of males, P < 0.01), Although some meadows had approximately where they were often seen perched or singing equal numbers ofthe 2 congeuers (e.g., Dinkey in pines (68% of males, P < 0.01). Although Meadow, Little Lacey Valley, Lower Beasore most Lincoln's Sparrows were observed within Mcadow), most sites appeared to he dominated meadows, singing males or pairs were occa by one or the other species. Song Sparrows sionally seen in small, nearby openings in sur were common at several meadows where Lin rounding forest as long as suitable habitat was coIn's Sparrows were either absent (Battle present. Creek Meadows, Cottonwood Creek, Perazzo Data from egg sets at the Western Founda Meadows, Pleasant Valley, Swauger Canyon, tion ofVertebrate Zoology (WFVZ) also revealed aud Ackerson Meadow) or rare (Lacey Valley, the importance of wet ground and clumps of Sagehen Creek, Upper Bcasore Meadow). These herbaceous vegetation or shrubs for breeding. sites included dry, heavily grazed meadows as Of 65 records from California, 56 contained well as wet, fairly pristine arcas that othelWise information on moisture characteristics at the looked suitable. Likewise, Song Sparrows were nest site, and 54 (96%) ofthese indicated damp absent or rare from several meadows with rel to very wet conditions. Over 90% of the nests atively large numbers of Lincoln's Sparrows were placed on the ground or slightly above (e.g., Lincoln Valley, Coppins Meadow, Metcalf ground, where they were well concealed hy Creek, Hood River Meadows), as well as from 112 GREAT BASIN NATURALIST [Volume 57 20 of singing males, combined with descriptions r= 0.701 of nest sites from WFVZ egg data slips, indi cate that combinations of the following attrib 15 • utes are important for breeding: boggy or flooded ground; thick groundcover of herba • ceous vegetation, often with raised tussocks of 10 • • live or dead grasses or sedges; patches of corn • lily; willow thickets or other low shrubs; and some conifers. Raised clumps of herbaceous vegetation are probably critical for breeding under such wet conditions, as suggested by the nest site descriptions. Likewise, dense herbaceous plant material, in conjunction with willows and corn lily, may provide important concealment. The association between male Lincoln's Sparrows and pines undoubtedly Number of Male reflects the importance ofelevated perches for Song Sparrows singing and vigilance. Although Lincoln's Sparrows were present Fig. 5. Negative correlation between number of singing in the majority of wet meadows studied, their male Lincoln's Sparrows and Song Sparrows. absence at certain sites that othenvise looked suitable deserves discussion. One example is other sites where Lincoln's Sparrows were less White Wolf (17) in Yosemite National Park, common (west of Coppins Meadow, Austin where Beedy and Granholm (1985:190) reported Meadow, Leek Spring Valley). the species in summer but did not present any The negative association between these 2 dates of nesting. Although Grinnell and Storer species was also evident when comparing (1924:471) noted that Lincoln's Sparrows arrive counts between meadows within a single sys in the Yosemite region by mid-May, this date tem. For example, whereas Lincoln's Sparrows may apply to lower elevation meadows in outnumbered Song Sparrows at Upper Hay Yosemite Valley. White Wolfis one ofthe high press Creek (4 versus 2 males, respectively), est (2380 m) meadows surveyed in this study, Song Sparrows were slightly more numerous and it is possible that the timing of my visit in than Lincoln's Sparrows at Middle Haypress early June preceded the arrival of this species Creek (6 versus 3 males), and noticeably more for breeding. However, examination ofmuseum abundant at Lower Haypress Creek (8 versus records (MVZ, WFVZ) showed that Lincoln's 2 males). Similar patterns were observed within Sparrows already have nests with eggs by early single sites. Although approximately equal num to mid-June at sites of similar or higher eleva bers (3 males) of the 2 species were observed tion, both in the central Sierra Nevada and at Little Lacey Valley, for example, Lincoln's elsewhere. Furthermore, I observed Lincoln's Sparrows occurred in the \vettest portion of Sparrows singing in mid-May at otber high the meadow while Song Sparrows were found elevation meadows such as Bluff Lake and only in the drier, more heavily grazed areas. Metcalf Creek, when temperatures were cold Similarly, although both Lincoln's Sparrows and snow was still present on the ground. and Song Sparrows were fairly common in Although these 2 meadows were visited in a Lower Beasore Meadow (5 and 3 males, re different year than White Wolf, the lack of a spectively), the former species dropped out in significant annual difference in climate during Upper Beasore Meadow, while Song Sparrows the period of study suggests that timing alone increased significantly in abundance to 14 males. cannot account for the disparity. Additional surveys are needed to determine the popula DISCUSSION AND CONCLUSIONS tion status of Lincoln's Sparrows breeding at White Wolf Of the 34 meadows surveyed, Lincoln's Another wet meadow where I failed to find Sparrows occurred only in sites with certain Lincoln's Sparrows was Swauger Canyon (16), habitat features. Data on the specific locations northeast of Yosemite Nalional Park in the 1997] LINCOLN'S SPARROWS IN MEADOWS 113 Sweetwater Mountains. According to Johnson and, in all cases, Song Sparrows instigated the (1975), the species has never been found to chase, displacing male Lincoln's Sparrows sing nest in that range despite extensive fieldwork ing from elevated posts. Although there is no there by parties from the Museum of Verte evidence that Lincoln's Sparrows and Song brate Zoology. More puzzling was the absence Sparrows are interspecifically territorial, addi of Lincoln's Sparrows along Cottonwood Creek tional behavioral and ecological studies are (6) and Lower Sagehen Creek (12B) in the north needed to understand the underlying factor(s} ern Sierra Nevada, especially since the species responsible for the negative association observed breeds regularly at other comparable meadows between these 2 congeners on both a local and in the same region. (Subsequent visits to these regional scale. Removal experiments, in which 2 sites have confirmed the results of earlier Song Sparrows are excluded from boggy mead counts.) Both meadows had large areas that ows within the range of Lincoln's Sparrows, were flooded by beaver (Castor canadensis) would especially shed light on the role ofinter activity during the period ofstudy. Unlike Lower specific competition, ifany, in controlling Lin Sagehen Creek, however, the meadow along coin's Sparrow distribution and/or abundance. Cottonwood Creek is grazed by sheep during Spatial or temporal fluctuations in the dis the summer, with the season of use occurring tribution and abundance ofcertain bird species from mid-June through September (S. F Bishop may indicate short-term or long-term trends in personal communication). Although damage climate, resource availability, and habitat qual caused by sheep (e.g., trampling ofherbaceous ity. Such effects are probably most pronounced vegetation, browsing of willows) may be suffi in populations occupying ecological islands, cieut to disrupt breeding ofLincoln's Sparrows which may be in nonequilibrium dynamics along Cottonwood Creek, it does not explain (Johnson 1975, 1995). Species with narrow their rarity along Lower Sagehen Creek. habitat requirements are especially useful as In contrast to Lincoln's Sparrows, Song Spar indicators of trends because of their greater rows were among the most common birds seen vulnerability to nalural or human-induced at both of these meadows, with abundance changes. Of the 4 species of sparrows occupy higher than at most other sites surveyed. Dif ing meadows in the Sierra Nevada-Cascade ferences in habitat choice and tolerance for mountains (Savannah Sparrow [Passereulus disturbance may account, at least partially, for sandwiehensis], Song Sparrow, Lincoln's Spar the unexpected negative association between row, and White-crowned Sparrow [Zonot·richia the 2 species at these and other meadows sur leueophrysD, Lincoln's Sparrows may be most veyed. For example, Song Sparrows were abun susceptible to local extirpation because oftheir dant at several dry, severely grazed sites that generally low population size and their restric were wlsuitable for Lincoln's Sparrows. Like tion to wet or flooded areas. Although different wise, heavily flooded areas such as Hood River lines ofevidence suggest that mountain mead Meadows may be shunned by Song Sparrows ows may be as temporally stable as the sur (only 1 singing male was observed). Of greater rounding environment (Benedict 1982), mois interest than these extremes, however, are the ture characteristics ofmeadows are highly vari patterns observed at intermediate sites, which able depending on annual precipitation. Short were often dominated by one or the other spe term fluctuations in precipitation may affect cies. In fact. Lincoln's Sparrows were common habitat quality directly through snowmelt and at a number of wet meadows that appeared groundwater recharge (Wood 1975) and/or similar in habitat to both Cottonwood Creek indirectly through availability of food (e.g., and Lower Sagehen Creek and where Song insect) resources (Cody 1981, Johnson 1995). Spalmws were surprisingly scarce. One hypoth In addition, beaver activity can profoundly in esis is interspecific competition, acting in con fluence the extent offlooding in meadows. cert with differences in habitat use and/or Livestock grazing can alter natural hydro tolerance for disturbance caused by grazing. logic regimes by increasing runoff and exacer Speirs and Speirs (1968:1440) noted that Song bating erosion and gullying, thereby lowering Sparrows often utilized the same perches and the groundwater table (e.g., Upper Beasore were able to "compete strongly and very suc Meadow, Fig. 2B; also see Rauzi and Hanson cessfully" against Lincoln's Sparrows. I observed 1966, Lusby 1970, Platts 1981, Kauffman et a!. interspecific interactions on at least 5 occasions 1983, Ratliff 1985). Consequently, grazing may 114 Gl\EAT BASIN NATUIlALIST [Volume 57 eliminate potential nesting habitat for Lincoln's and an anonymous reviewer for reading: drafts Sparrows. In addition, hydrologic and vegeta of this manuscript and offeling many useful tive changes associated with grazing can alter suggestions. Fieldwork was supported partially the distribution and abundance of more toler by 2 Frank M. Chapman grants from the Amer ant species such as Song Sparrows, which may ican Museum of Natural HistOly. compete with Lincoln's Sparrows for territories and other resources. These indirect effect.s of LITERATUKE CITED livestock grazing, combined with direct impacts such as reduction of cover and trampling of AIJACAUS CONCEPTS, INC. L988. Slalview. version 1.03. Berkeley, CA. nests, undouhtedly have resulted in the extir Al.LEN, H. Ii. 1987. Forest and meadow ecosystems in Cali pation of Lincoln's Sparrows from some mead fornia. Rangelands 9: 125-128. ows. Because populations of this species arc AMERICAN ORNITIIOJ.OCISTS' UNION. 1957. Check-list of already vulnerable to natural fluctuations io NortJl American birds. 2nd edition. Lord Baltimore Press, Baltimore, MD. moisture, any further changes caused by graz AUSflN, O. )•. , JR. 1968. Mewspiza lincolnii ulticcla (Miller ing may exacerbate their probability of local and McCabe)-Monl"ane Lincoln's Sparrow. Pages extirpation. 1467-1472 in O. L. Austin, Jr., editor, Life histories of Careful range management practices can North American cardinals, grosbeaks, buntings, tow significantly reduce the impacts of grazing on hees, finches, sparrows, and allies. U.S. National Museum BulJetin 237, p.... rt 3, Washington, DC. plant and animal communities in riparian or BJo:EDY, E. C., AND S. L. GRANHOLM, 1985. Dis<..'Ovcring meadow ecosystems (Leege et a!' 1981, Gillen Sierra birds: wesl~m slope. Yosemite Natural History et a!' 1985, 'Iuylor 1986, Schulz and Leininger Association and Sequoia Natural IIistory Associa 1990, I'opolizio et al. 1994, Bich et a!' 1995). tion. Although mnge conditioo will vary with land BENEOH...,., N. B. 1982. Mountain meadows: stability and change. Madroiio 29; 148-153, ownership pattenlS (Loriog and Workman 1987), BENElJIC'I~ N. 8., AND I. MAJOR. 1982. A physiographic strict control ofgrazing intensity and season of cla.~sifieation of subalpine meadows of the Sierra use will result in higher abundances of breed Nevada, California. Madroiio 29: 1-12. ing birds, primarily through iocreased shrub BICH, B. S,,]. L. BUTLER, AND C. A. SCHMIlJ1: ]995. E:lIects volume and height (Taylor 1986). Long-term ex of difTerentiallivestock use on key plant species and rodt:mt populations within selected O"'yzop8is hyrnen clusion oflivestock on meadows, combined with oides/Hilaria jamesii communities of Clen Canyon erusion·control measw'es, will especially bene National Recreation Area. Southwestern NahJmIi"t fit lincoln's Sparrows and other similar species 40, 281-287. bec-ause of the combined ve!\etative and hydro (',(JDY, M. L. 1981. Habitat selection in birds: the roles of vegetation stnlcture, competitors, and productivity. logic effects. Baseline data on abundance and Bioscience 31: 107-113. distribution, such as those provided in this CooK. C. W 1966. Factors a(fociing utilization of moUll study, are essential for monitoring population lain slopes by cattle. Journal of Range Man~ement trends resulting from disturbance or restoration 19,200-204. ofsensitive, ephenleral meadow systems. DERENEDlITTI, S, H., ANn D. J. ,PAHSONS. 1979. Natural fire in subolpine meadows: a ease description from the Sierra Nevada. Journal ofl'brcstry 77: 477-479. ACKNOWLEDGMENTS ___. 1984. Postfire succession in a Sierran subalpine meadow. American Midland Naturalist 111: 118--125. Numerous people from the U.S. Forest Ser DUNWIDDI&. P. W 1971. Recent tree invasion of subolpine vice and National Park Service assisted with meadows in the Wi.nd River Mountains. Wyoming. Arctic AlpiDe Research 9; 393-399. general information on meadows within their loucK. J. A. D. 1976. Bird populations of aspen forests in jurisdiction. Marianne Flett and John Han·is weslem North America. Ornithological Monographs kindly provided unpublished data on avian 19, 1-97- species composition of meadows surveyed in FORMAN. R. T. T., A. E. CALLI, AND C, E LECK. 1976. For· est size and avian diversity in New Jers~y woodlots 1986 for Willow Flycatchers (EmpilWna-T tmil with some land use implications. Occologia 26: 1--8. iii), including presence or absence of Lincoln's FRANKLIN, J. E, W. II. Mom, G. W. DOUGLAS, AND Sparrows. Lloyd Kiff supplied photocopies of C. WIBERG. 1971. Invasion ofsubalpine meadows by data slips for eM sets housed at the Western trees ill the Cascade Range, Washington and Ore Foundation of Vertebrate Zoology. Karen Klitz gon. Arctic Alpine Research 3: 215-224. GlUEN, R. L.• W C. KnUECl£.l1. ANn R. F. MlLLI::K. 1984, sketched the Lincoln's Sparrow in Figure 1. Cattle distribution on mountain rangeland to north I am grateful to Ned K. Johllson, Ross Lein, c;:\.Stcm Oregon. Ioumal of Range Management 37: Martin Morton, Robert Ohmart, James Rising, 549-S5J. 1997] LINCOLN'S SPARROWS IN MEADOWS 115 __'"'. 1985. Cattle use ofriparian meadows in the Blue PARSONS, D. J. 1981.1'1re in a subalpine mcadow. }+'remon Mountains ofnortheastelll Oregon. Journal of Range tia 9: 16--18. Management 38: 205-209. Pl.ATI'S, W. S. 1981. Effects ofsheep gnlZLng on a ripMian GR[NNELL, J., AND A. II. MILLliJl. 1944. The distrihution stream environment. U.S. Forest Scrvi~ Re.~earch of the birds of Californin. Pncific Coast Avifauna 27: Note INT·307. 1-617. Purrs, W. S., AND H. L. NF.I_~ON. 1985. Streamside and GRINNELL, J.• AND T. I. STomm. 1924. Animal life. ill the upland vegetation use by cattle. Rangelands 7: 5-10. Yoscmit~. University ofCalifornia Press, Berkeley. POPOLlZlO. C. A., II. GOP:T7., AND P. L. CHAPMAN. 1.994. JOIINSON, N. K. 1975. Controls of llumbel' ofbird species ShorHenn rru;ponse of riparian ve~etation ~o 4 graz on montane islands in the Grell Basin. Evolution 29: ing treatments. Journal of Range Managemell~ 47: 545-567. 48-.,3. --ceo 1995. Seven avifaunal censuses spanning one-half RATLIFF. R D. 1982. A meadow site clasSification for the century un an island of white firs (Abies concolor) in Sieml evada, California. U.S. Forest Servicc Gen the Mojave Desert. Southwestern Nahlr.ollist 40: eral 'technical Report PSW-60. 76-85. ___.' 1985. Meadows in the Sierm Nevada of Califor KAUFFMAN, J. 8., AND W. C. KRUEGER. 19&1. Livestock nia: state of knowledge. u.s. Forest Scrvi~ Ceneral im(l